The Philosophy of the Young Kant: The Precritical Project

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T H E P H I L O S O P H Y O F T H E YO U N G K A N T

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The Philosophy of the Young Kant

-0 The Precritical Project

Martin Scho¨nfeld

1 2000

3 Oxford New York Athens Auckland Bangkok Bogota´ Buenos Aires Calcutta Cape Town Chennai Dar es Salaam Delhi Florence Hong Kong Istanbul Karachi Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi Paris Sa˜o Paulo Singapore Taipei Tokyo Toronto Warsaw and associated companies in Berlin Ibadan

Copyright 䉷 2000 by Martin Scho¨nfeld Published by Oxford University Press, Inc. 198 Madison Avenue, New York, New York 10016 Oxford is a registered trademark of Oxford University Press All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of Oxford University Press. Library of Congress Cataloging-in-Publication Data Scho¨nfeld, Martin, Ph.D. The philosophy of the young Kant : the precritical project / Martin Scho¨nfeld. p. cm. Includes bibliographical references. ISBN 0-19-513218-1 1. Kant, Immanuel, 1724–1804. I. Title. B2798.S315 2000 193—dc21 99-30602

1 3 5 7 9 8 6 4 2 Printed in the United States of America on acid-free paper

Preface

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THIS BOOK IS about the young Kant. It is an investigation of the ﬁrst two decades of his philosophical life, from the Thoughts on the True Estimation of Living Forces (1746/7) to the Dreams of a Spirit-Seer (1766). I examine the rise and fall of the ‘‘precritical’’ theories and place them in their historical and topical context—exploring how Kant resolved problems his predecessors and contemporaries were wrestling with, how his proposals for settling the issues compared to theirs, and in particular, how his inquiries cohered in what could be called the ‘‘precritical project.’’ This project was the expression of Kant’s desire to create a systematic philosophy of nature. He wanted to harmonize scientiﬁc and metaphysical perspectives such that the paradigm of explaining nature, Newtonian physics, could be reconciled with the deepest metaphysical convictions. These convictions were the presence of purpose, the possibility of moral freedom, and the existence of a divine being. The quest for such a reconciliation was the driving force behind the early Kant. Part I (the 1740s) concerns the very beginnings of Kant’s philosophy. Kant wrote his ﬁrst book, the Living Forces, in response to a question. The question concerned the nature of force and involved a complicated dispute over its metaphysical character and mathematical measurement (chapter 1). The Living Forces contained an attempt at the problem’s resolution (chapter 2). Soon after, Kant realized that his response had not been adequate. His

vi Preface

realization of its particular ﬂaws prepared the way for the precritical project (chapter 3). Part II (the 1750s) is about the emergence of the precritical project. Kant signaled his conversion to Newtonian physics with the Spin Cycle essay, a conversion that gave the incipient precritical project its direction (chapter 4). Now he began to build a grand system of nature. He tried to reconcile physical processes with purpose in the Universal Natural History (chapter 5), endeavored to deduce the compatibility of mechanical determinism with freedom in the New Elucidation (chapter 6), and attempted to link physics, teleology, and ontology through a theory of active matter outlined in the Physical Monadology (chapter 7). Part III (the 1760s) is the story of the completion and collapse of Kant’s project. He extended the precritical project to God and advanced a physical and a metaphysical argument for a divine being in the Only Possible Argument (chapter 8). Next he concerned himself with the question of method. In the Prize Essay, he assessed the viability of metaphysical research and suggested a way of unifying the strategies of metaphysics and science (chapter 9). But Kant was forced to realize that his earlier efforts did not meet the demands of the new methodology and that his philosophical ediﬁce had been built on unstable ground. This realization led to an intellectual and emotional crisis. The Dreams of a Spirit-Seer reveals the depth of Kant’s torments and represents the difﬁcult recognition of the precritical project’s failure (ch. 10). The objects of science and the entities of metaphysics do not reside in the same world, and accordingly Kant divorced them in the Inaugural Dissertation. A number of Kant’s shorter and marginal texts are treated only in passing. I ﬁnd little of signiﬁcance in On Fire (1755), Motion and Rest (1758), False Subtlety (1762), and Negative Quantities (1763). Therefore, their salient points are discussed rather quickly. For the same reason, I omit detailed expositions of the Aging Earth essay (1754), the earthquake articles (1756), the papers on the theory of winds (1756–1757), the eulogy on Funk (1760), and the Silberschlag review (1764). The famous Observations on the Feeling of the Beautiful and the Sublime (1764) and the curious essay on mental illnesses (1764) have little to do with Kant’s precritical project of a uniﬁed philosophy of nature. Because I wish to tell here the story of this precritical project from its earliest beginnings to its bitter end in 1766, the precritical texts that Kant composed after the collapse of the project—such as the Directions in Space essay (1768), the Inaugural Dissertation (1770), the Moscati review (1771), the essay on human races (1775), and the Philanthropin essays (1776/7)—are outside the scope of this study. The relative scarcity of precritical scholarship is partially compensated for by the fact that studies of Kant’s early work or its background are often very good. In preparing this book, I am indebted to the excellent research of Erich Adickes, Karl Ameriks, Lewis White Beck, Frederick C. Beiser, Ernst Cassirer, Jean E´cole, Michael Friedman, Gottlieb Florschu¨tz, Fred Gebler, Paul Guyer, Heinz Heimsoeth, Dieter Henrich, Alison Laywine, Franc¸ois Marty,

Preface vii

Irving I. Polonoff, John A. Reuscher, William R. Shea, Giorgio Tonelli, Jules Vuillemin, David Walford, Eric Watkins, Richard S. Westfall, and many others. These scholars and philosophers provided the Grundlegung, the ‘‘groundwork.’’ Without their efforts at clarifying the ideas of the early Kant and of Kant’s relevant predecessors and contemporaries, this inquiry would have been all but impossible. I conceived the idea for this book while writing my dissertation in Bloomington on a theme in Kant’s precritical philosophy. I received enormous assistance along the way. None of this would have been possible without the support of my two advisors, Frederick C. Beiser and Michael Friedman, whose comments and complaints were invaluable. I also owe gratitude to the late Richard S. Westfall for our discussions on Newton, to Bruce Silver for our chats on Leibniz, and to Jay Conway for thoughtful and invariably useful stylistic suggestions. For their ﬁnancial support of my explorations of Kant, philosophy, and nature, I thank the Studienstiftung des Deutschen Volkes, the John D. and Catherine T. MacArthur Foundation, the Indiana University Graduate School, and the Division of Sponsored Research at the University of South Florida. For their advice and encouragement, I thank my colleagues in the philosophy department of the University of South Florida, Kristin Shrader-Frechette at the University of Notre Dame, and Sidney Axinn at Temple University. For their helpful suggestions and constructive criticisms, I thank the anonymous referees at Oxford University Press. For their patience with my questions and ﬂexibility with my requests, I thank the librarians at Indiana University, at the University of South Florida, the Staatsbibliothek Mu¨nchen, the Universita¨t Heidelberg, and at the Universita¨t Regensburg. For their friendship, I thank Hartmut Beinroth, Nick Haschke, and Ivan Marquez. This book is for Diane Nai-Yu Liu. M. S. Tampa, 1999

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Contents

-0 Note on Sources, Citations, and Abbreviations Introduction 3 I

xi

The 1740s: Kant’s Starting Point 1 The Vis Viva Debate: Kant’s Starting Point 17 2 The True Estimation of Living Forces: Kant’s Theory of Dynamics 36 3 On the Way toward the Precritical Project 56

II

The 1750s: The Precritical Project 4 The Conversion to Newton 73 5 The Universal Natural History: The Purposiveness of Nature 96 6 The New Elucidation: The Struggle for Freedom 128 7 The Physical Monadology and the Elements of Nature

III

161

The 1760s: Climax and Crisis 8

The Only Possible Argument: The Culmination of the Precritical Project 183 9 The Newtonian Program of the Prize Essay and Kant’s Crisis 209 10 The Reductio and Collapse of the Precritical Project

Conclusion 245 Notes 247 Bibliography 309 Index 333

229

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Note on Sources, Citations, and Abbreviations

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THE LIST BELOW contains the short titles that I use for Kant’s publications up to the Critique of Pure Reason. The short titles are on the left. The full English titles, on the right, follow the Cambridge edition. The original German titles are underneath. The dates of the composition of the works are listed in parentheses, followed by the location of the works in the Academy edition (roman numerals indicate the volume, and arabic numbers indicate the page). Living Forces Thoughts on the True Estimation of Living Forces Gedanken von der wahren Scha¨tzung der lebendigen Kra¨fte und Beurteilung der Beweise derer sich Herr von Leibniz und andere Mechaniker in dieser Streitsache bedienet haben, nebst einigen vorhergehenden Betrachtungen welche die Kraft der Ko¨rper u¨berhaupt betreffen (1747; I 1–182) Spin Cycle Investigation of the Question whether the Earth in Its Rotation on Its Axis . . . Has Undergone Any Alteration since the Earliest Times of its Origin Untersuchung der Frage, ob die Erde in ihrer Umdrehung um die Achse, wodurch sie die Abwechselung des Tages und der Nacht hervorbringt, xi

xii Note on Sources, Citations, and Abbreviations

einige Vera¨nderungen seit den ersten Zeiten ihres Ursprungs erlitten habe und woraus man sich ihrer versichern ko¨nne. . . . (1754; I 183–192) Aging Earth The Question whether the Earth Is Aging Considered from a Physicalistic Point of View Die Frage, ob die Erde veralte, physikalisch erwogen (1754; I 193–213) Universal Natural History Universal Natural History and Theory of the Heavens, or Essay on the Constitution and Mechanical Origin of the Entire Universe, Treated in Accordance with Newtonian Principles Allgemeine Naturgeschichte und Theorie des Himmels, oder Versuch von der Verfassung und dem mechanischen Ursprunge des ganzen Weltgeba¨udes nach Newtonischen Grundsa¨tzen abgehandelt (1755; I 215–368) On Fire Concise Outline of Some Reﬂections on Fire Meditationum quarundam de igne succincta delineatio (1755; I 369–84) New Elucidation New Elucidation of the First Principles of Metaphysical Cognition Principium primorum cognitionis metaphysicae nova dilucidatio (1755; I 385–415) Physical Monadology The Employment in Natural Philosophy of Metaphysics Combined with Geometry, of which Sample I Contains the Physical Monadology Metaphysicae cum geometria iunctae usus in philosophia naturali, cuius specimen I. continet monadologiam physicam (1756; I 473–87) Earthquake Papers (1) Concerning the Causes of the Terrestrial Convulsions on the Occasion of the Disaster which Afﬂicted the Western Countries of Europe towards the End of Last Year Von den Ursachen der Erderschu¨tterungen bei Gelegenheit des Unglu¨cks, welches die westlichen La¨nder von Europa gegen Ende des vorigen Jahres betroffen hat (1756; I 417–27) (2) History and Natural Description of the Most Remarkable Occurrences Associated with the Earthquakes Geschichte und Naturbeschreibung der merkwu¨rdigsten Vorfa¨lle des Erdbebens, welches an dem Ende des 1755sten Jahres einen großen Theil der Erde erschu¨ttert hat (1756; I 429–61) (3) Further Observation on the Terrestrial Convulsions which Have Been for Some Time Observed Fortgesetzte Betrachtung der seit einiger Zeit wahrgenommenen Erderschu¨tterungen (1756; I 463–72) Theory of Winds New Remarks towards an Elucidation of the Theory of Winds

Note on Sources, Citations, and Abbreviations xiii

Neue Anmerkungen zur Erla¨uterung der Theorie der Winde (1756; I 489– 503) West Winds Outline and Announcement of a Course of Lectures on Physical Geography, Together with an Appendix . . . whether the West Winds in Our Regions are Humid because They Have Traversed a Great Sea Entwurf und Anku¨ndigung eines Collegii der physischen Geographie nebst dem Anhange einer kurzen Betrachtung u¨ber die Frage: Ob die Westwinde in unsern Gegenden darum feucht seien, weil sie u¨ber ein großes Meer streichen (1757; II 1–12) Motion and Rest New Theory of Motion and Rest. . . . Neuer Lehrbegriff der Bewegung und Ruhe, und der damit verknu¨pften Folgerungen in den ersten Gru¨nden der Naturwissenschaft, wodurch zugleich seine Vorlesungen in diesem halben Jahre angeku¨ndigt werden (1758; II 13–25) Optimism Attempt at Some Reﬂections on Optimism Versuch einiger Betrachtungen u¨ber den Optimismus (1759; II 27–36) Funk Essay Thoughts on the Premature Demise of . . . Herr Johann Friedrich Funk. . . . Gedanken bei dem fru¨hzeitigen Ableben des . . . Herrn Johann Friedrich Funk. . . . (1760; II 37–44) False Subtlety The False Subtlety of the Four Syllogistic Figures Die falsche Spitzﬁndigkeit der vier syllogistischen Figuren erwiesen (1762; II 45–63) Only Possible Argument The Only Possible Argument in Support of a Demonstration of the Existence of God Der einzig mo¨gliche Beweisgrund zu einer Demonstration des Daseins Gottes (1763; II 63–103) Negative Quantities Attempt to Introduce the Concept of Negative Quantities into Philosophy Versuch den Begriff der negativen Gro¨ssen in die Weltweisheit einzufu¨hren (1763; II 165–204) Observations Observations on the Feeling of the Beautiful and the Sublime Beobachtungen u¨ber das Gefu¨hl des Scho¨nen und Erhabenen (1764; II 205–56)

xiv Note on Sources, Citations, and Abbreviations

Maladies of the Mind Essay on the Maladies of the Mind Versuch u¨ber die Krankheiten des Kopfes (1764; II 205–56) Prize Essay Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morals Untersuchung u¨ber die Deutlichkeit der Grundsa¨tze der natu¨rlichen Theologie und Moral (1764; II 273–301) Lecture Advertisement Announcement of the Organization of his Lectures in the Winter Semester 1765–66 Nachricht von der Einrichtung seiner Vorlesungen in dem Winterhalbenjahre, von 1765–66 (1765; II 303–13) Dreams Dreams of a Spirit-Seer Elucidated by Dreams of Metaphysics Tra¨ume eines Geistersehers, erla¨utert durch Tra¨ume der Metaphysik (1766; II 315–73) Directions in Space Concerning the Ultimate Foundation of the Distinction of Directions in Space Von dem ersten Grunde des Unterschiedes der Gegenden im Raume (1768; II 375–83) Inaugural Dissertation Concerning the Form and Principles of the Sensible and Intelligible World De mundi sensibilis atque intelligibilis forma et principiis (1770; II 389– 419) Moscati Review Review of Moscati’s Book: ‘Concerning the Essential Physical Differences between the Structure of Animals and Human Beings’ Recension von Moscatis Schrift: Von dem ko¨rperlichen wesentlichen Unterschiede zwischen der Structur der Thiere und der Menschen (1771; II 421–5) Races of Mankind On the Different Races of Humankind Von den verschiedenen Racen der Menschen (1775; II 427–43) Philanthropin Essays Essays Concerning the Philanthropin Academy Aufsa¨tze, das Philanthropin betreffend (1776/7; II 445–52) References to Kant’s works are from the Academy Edition: Immanuel Kant, Gesammelte Schriften, edited by the Akademie der Wissenschaften (Berlin: Reimer; later DeGruyter: 1910ff.). Roman numerals indicate the volume; arabic numerals indicate the page number.

Note on Sources, Citations, and Abbreviations xv

A Gottfried Wilhelm Leibniz, Sa¨mtliche Schriften und Briefe, ed. by the Deutsche Akademie der Wissenschaften (Berlin: Akademieverlag, 1923ff.) AG Gottfried Wilhelm Leibniz, Philosophical Essays, ed. by R. Ariew and D. Garber (Indianapolis/Cambridge, England: Hackett, 1989) AT Rene´ Descartes, Oeuvres, 12 vols., ed. by C. Adam and P. Tannery (Paris: Le´opold Cerf, 1897–1913) C Christian August Crusius, Die philosophischen Hauptwerke, 4 vols., ed. by G. Tonelli, S. Carboncini, and R. Finster (Hildesheim: Georg Olms, 1969ff.) Cott Rene´ Descartes, The Philosophical Writings, 3 vols., translated by J. Cottingham, R. Stoothoff, and D. Murdoch (Cambridge/New York: Cambridge University Press, 1984) G Gottfried Wilhelm Leibniz, Die philosophischen Schriften, 7 vols., ed. by C. I. Gerhard (Berlin, 1875–1900. Reprint Hildesheim: Georg Olms, 1978) GM Gottfried Wilhelm Leibniz, Die mathematischen Schriften, 7 vols., ed. by C. I. Gerhardt (Berlin, 1849–55) K Isaac Newton, Philosophiae Naturalis Principia Mathematica. The Third Edition with Variant Readings (1726), 2 vols., ed. by A. Koyre´ and I. B. Cohen (Cambridge, Mass.: Harvard University Press, 1972) M Isaac Newton, Mathematical Principles of Natural Philosophy and His System of the World, 2 vols., transl. by A. Motte (1729), ed. by F. Cajori (Berkeley/Los Angeles: University of California Press, 1962) W Christian Wolff, Gesammelte Werke, ed. by J. E´cole et al. (Hildesheim: Olms, 1960ff.) WM Immanuel KANT, Theoretical Philosophy, 1755–1770, edited and translated by David Walford and Ralf Meerbote (Cambridge, England: Cambridge University Press, 1992)

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T H E P H I L O S O P H Y O F T H E YO U N G K A N T

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Introduction

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SURVEYS OF KANT’S thought often begin with a discussion of the Critique of Pure Reason. This work, though, was not the starting point for Kant’s philosophical career. By the time he completed the manuscript of the Critique of Pure Reason in the spring of 1781, Kant was a relatively old man, a ﬁfty-sixyear-old full professor who, had he lived today, would not have been that far away from retirement. He had written his philosophical debut, the Thoughts on the True Estimation of Living Forces, as a twenty-two year old university student. In the thirty-ﬁve years before the eventual publication of the ﬁrst Critique, Kant would become a proliﬁc philosopher authoring a number of books, treatises, and essays. These works make up Kant’s precritical philosophy. The focus of The Philosophy of the Young Kant is Kant’s philosophical development from 1746 to 1766, the ﬁrst two decades of his career. I shall argue that the central theme in this period was Kant’s struggle for a coherent philosophy of nature from 1754 to 1766. This was Kant’s precritical project, and it turned out to be the most ambitious venture of his life. He attempted to integrate Newtonian physics in a comprehensive and speculative framework that explained the macroscopic features of the universe as well as its microstructure, that accounted for its past as well as for its present, that permitted the copresence of rational freedom and deterministic lawfulness, and that illuminated the relation of God to the world. 3

4 The Philosophy of the Young Kant

The precritical project of a uniﬁed philosophy of nature emerged in 1754, eight years after the completion of the major portions of the Living Forces. (Kant wrote the Thoughts on the True Estimation of Living Forces in 1746, added a dedication and a preface in 1747, and had it published in 1749). The precritical project fell apart in 1766. Although the project spanned only twelve years, it involved Kant’s most intense and inspired productivity before the 1780s. The precritical period lasted from 1746 to 1780, but most of the precritical texts were written between 1754 and 1766. Of the thirty precritical texts, twenty-three belong to the phase of the precritical project. Kant published two books during this phase, the Universal Natural History and Theory of the Heavens (1755) and The Only Possible Argument in Support of a Demonstration of the Existence of God (1763). In addition to numerous papers, he also composed six major treatises, the New Elucidation (1755), the Physical Monadology (1756), the Negative Quantities (1763), the Observations (1764), the Prize Essay (1764), and the Dreams of a Spirit-Seer (1766). After this phase, Kant would write the essay on the Directions in Space (1768) and the important Inaugural Dissertation (1770). In the ten years that followed, only a book review and three marginal essays appeared. During this so-called silent decade, Kant wrestled with what would become the ﬁrst Critique. With few exceptions, the works from 1754 to 1766 were stepping stones toward Kant’s envisioned reconciliation of metaphysics and natural science. In eighteenth-century German philosophy, metaphysics was an energetic philosophical discipline. Its archetype was Christian Wolff ’s Vernu¨nfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen u¨berhaupt (1719; ‘‘Rational Thoughts on God, the World, the Human Soul, and All Things in General’’). This book, commonly referred to as the German Metaphysics, was an exercise in conjectural exuberance as well as in dogmatic scholasticism. The branches of metaphysics were rational theology, rational psychology, rational cosmology, and ontology. Rational theology involved arguments of God’s existence and analyses of God’s character; rational psychology was concerned with the constitution of the soul and its interaction with the body; rational cosmology contained imaginative and sweeping vistas of corporeal nature; and ontology consisted largely of variations on the well-trodden themes of contradiction and sufﬁcient reason. For the young Kant, metaphysics was about speculative arguments that address the grand questions of philosophy, such as the existence of a divine being, the immortality and freedom of the soul, and the structure and purpose of the universe. He had not yet identiﬁed the synthetic a priori as the hallmark of metaphysical propositions. The actual metaphysical arguments of the day, including Kant’s own, comprised empirical generalizations as well as conceptual constructions. ‘‘Natural science’’ meant physics for the young Kant. Isaac Newton’s Principia (1686) became his authoritative model of a text in natural science. Kant was not alone with this assessment; in the course of the eighteenth century, Newtonian celestial mechanics emerged as the uncontested paradigm of physics. Natural science, in the sense of a Newtonian physics, amounted to

Introduction 5

the use of observation and experimentation to articulate quantiﬁable laws, describing a regular, predictable, and deterministic system of nature. In the ﬁrst half of the eighteenth century, natural science and metaphysics had not yet been divorced. Both were part of what was known as philosophy of nature. As the title of Newton’s work already revealed—Philosophiae Naturalis Principia Mathematica (‘‘Mathematical Principles of Natural Philosophy’’)—Newton offered his ﬁndings as the mathematical principles of philosophy of nature. In general, philosophy of nature was about the organization and composition of physical reality. It involved two modes, the quantitative-empirical procedure that was characteristic of Newton’s perspective and which would later evolve to natural science, and the qualitativespeculative approach of metaphysics. In the generation before Kant’s birth, tensions between these two modes began to fracture their common ground. One ﬁssure appeared during the priority dispute (the controversy over the invention of the calculus). Newton concluded his rebuke of Leibniz, in the Account of the ‘‘Commercium Epistolicum’’ (1715), with a condemnation of the metaphysical leanings of the latter. Another crack emerged during the Pietismusstreit, the Pietists’ quarrel with Wolff. In his Caussa Dei et religionis naturalis adversus atheismum (1723; ‘‘The Case of God and of Natural Religion against Atheism’’), the metaphysician and theologian Joachim Lange denounced Wolff ’s sympathy for a mechanist explanation of nature as blasphemy and materialism. A further fault-line opened in the wake of the success of the third edition of the Principia (1729) on the continent. The third edition of Newton’s great work caused the effective demolition of the Cartesian theory of the vortices in the 1740s. The theory of universal gravitation was becoming the dominant explanation of the universe. Whereas Cartesian mechanics involved a comfortable mixture of speculative, quantitative, and empirical elements, Newtonian physics projected itself as a more rigorous enterprise. Following the dictum of their master, ‘‘I feign no hypotheses,’’ many Newtonians, in particular in France and Great Britain, tended to be less tolerant of speculative approaches than their Cartesian predecessors. By mid-century, the tensions between the scientiﬁc and the metaphysical approaches to nature had become so visible that the status of physics was anything but clear. Physics still had something to do with philosophy, but it had reached a level of autonomy that distinguished it from straightforward philosophical disciplines such as logic or ontology. Christian August Crusius’s Physics, that is, the Anleitung u¨ber natu¨rliche Begebenheiten ordentlich und vorsichtig nachzudencken (1749; ‘‘Guide to an Orderly and Careful Reﬂection on Natural Events’’), begins with a discussion of the meaning of physics. Crusius claims that physics, in the wide sense, is a branch of philosophy that deals with the contingent things in the world and, in the narrow sense, is a science that investigates the composition and effects of natural bodies. In the Living Forces, Kant had been quite fond of the approach of the Leibnizian-Wolfﬁan School Philosophy. After this student piece, he grasped the fundamental signiﬁcance of Newton’s work. At the same time, he con-

6 The Philosophy of the Young Kant

tinued to sympathize with certain aspects of the systems of the School Philosophers. The scientiﬁc perspective, exempliﬁed by Newtonian physics, and the metaphysical viewpoint, embodied in the tomes of the School Philosophers, had now acquired equal relevance for Kant. The uneasy relationship of the two approaches to the investigation of nature deﬁned his task, and it gave the precritical project its direction: a new philosophy of nature needed to be created that would once again succeed as a common ground and that could avert the threatening rift between quantitative-empirical inquiries and qualitative-speculative demonstrations. The precritical theories have often been dismissed as unworthy of attention—there is the ‘‘important’’ Kant, the author of the three Critiques, vital for every student of philosophy, and there is the ‘‘immature’’ Kant, the author of the works preceding the Critiques, relevant for antiquarians at best. Kant himself was in no small part responsible for this view. Arguing that his early investigations were metaphysical and thus untenable, he publicly rejected his early writings, discouraged his students from reading them, and urged his ﬁrst editor to exclude them from a collection of his works. When Kant reviewed the Ideen zur Philosophie der Geschichte der Menschheit (1784; ‘‘Ideas to a Philosophy of the History of Mankind’’) by his former student Johann Gottfried Herder and realized that it had been inspired by his own early views, he reacted with dismissive irony. The aging Kant balanced the frank repudiation of his early writings with a hearty approval of his later works. The discovery of the subjectivity of space and time as a priori forms of intuition implied an ontological dualism between the sensible and the intelligible, which ruled out the notion of the uniﬁed nature that the precritical project had presupposed. This discovery struck him as a ‘‘great light.’’ The Critique of Pure Reason (1781) was for Kant a ‘‘philosophical revolution’’ that overthrew the precritical efforts for good.1 The neo-Kantians of the nineteenth century implicitly endorsed Kant’s self-assessment and merely promoted the critical philosophy. Leading Kant scholars of the twentieth century left as their legacy a negative appraisal of the precritical philosophy. Four points of their critique were particularly conspicuous: that the early philosophy lacked originality because the early views were just eclectic blends of Leibnizian-Wolfﬁan and Newtonian ideas; that it lacked continuity because of a clean break between the precritical and the critical periods; that it lacked relevance to the subsequent development of philosophy because it dealt with obsolete issues; and worst of all, that it lacked coherence because Kant underwent an erratic development characterized by sudden reversals of opinion. As Lewis White Beck put it, Kant prior to the critical philosophy ‘‘would deserve a quarter of a page in U¨berweg.’’2 Most people, it seems, agree: of the 500-odd articles on Kant that appeared in the Kant-Studien in the last sixty years, less than two dozen are about the precritical philosophy.3 I think that such a dismissal of the precritical period is implausible, not the least because it suggests an overly black and white picture of Kant’s intellectual life: a mediocre thinker until his mid-forties who, all of a sudden,

Introduction 7

became transformed into the philosophical giant we are familiar with. There was originality in his early philosophy, in part, because Kant’s attempt at bridging the growing rift between science and metaphysics went against the tide of the times. In addition, he criticized the Leibnizian-Wolfﬁan School Philosophy and creatively revised Newtonianism instead of simply combining the two. There was also more continuity between Kant’s early and late philosophies than appears at ﬁrst sight. For one thing, the crisis of the precritical project was the catalyst that triggered the development of the critical system. Furthermore, the inception of the critical philosophy was not an abrupt conceptual breakthrough as Kant portrayed it in B xvi and B xxii of the ﬁrst Critique, but rather a series of incremental steps that had begun with his growing disenchantment with the precritical project in the 1760s. Finally, the critical Kant preserved the same metaphysical assumptions he had advocated earlier (the existence of God, the possibility of moral freedom, the presence of purpose), only now, more tenuously as postulates. In addition, and perhaps most important, the early texts are not devoid of relevance to the subsequent course of natural science and philosophy, for as often as the early Kant was dead wrong in his scientiﬁc conjectures and metaphysical constructions, he was right on the mark. It is true that the precritical texts concerned numerous themes which we would now regard as obsolete—such as the living forces, the ether-theory of ﬁre, the cosmic teleology, the physical monadology, or the demonstrability of God’s existence. Nonetheless, the young Kant came up with numerous insights of farreaching consequence. On the side of metaphysics, he made contributions that would survive him. He replaced miracle-based teleologies with functionalist explanations that were intended to be compatible with scientiﬁc descriptions. He expanded the hypothesis of physical inﬂux into a full-ﬂedged theory of causality, thereby presenting a third option to the not altogether satisfactory alternative of occasionalism and preestablished harmony. He proposed a compatibilist resolution of the conﬂict between freedom and deterministic processes for the sake of permitting the possibility of moral action in this world. He recognized (already in the precritical period) that existence is not a property and that the traditional ontological arguments of God’s existence were in need of revision. And he argued that linguistic analysis ought to be the foundation for aprioristic constructions. On the side of natural science, Kant’s conjectures foreshadowed a number of eventual discoveries, anticipating some of them by as much as two centuries. He found out that the friction caused by the oceanic tides (determined primarily by lunar gravitation) would eventually decelerate the rotation of the Earth until the terrestrial day would last as long as a lunar revolution. He suggested that the solar system accreted from a gaseous cloud that started spinning through the interplay of its own forces. He proposed that the Milky Way is a disk-shaped, dynamic system of suns that rotates around its center of gravity. He stipulated that the so-called foggy stars observable with the telescopes of the time were galaxies similar to our own. And he discovered that the rotation of the Earth affects the patterns of the monsoon

8 The Philosophy of the Young Kant

winds. Even the very essence of Kant’s precritical project, the uniﬁcation of natural science and metaphysics into a philosophical model of nature, remained a theme of post-Kantian thought, as the systems of Schelling, Hegel, and Schopenhauer so colorfully illustrated. Thus, despite what Kant later had to say about it, the precritical project pushed philosophy forward. But was there such a thing as the precritical project? After all, the biggest interpretive challenge raised by Kant’s early philosophy consists of its apparent incoherence. When reading through the precritical texts, it often seems as if their author jumped from topic to topic and adopted whatever perspective suited the occasion. In his inﬂuential study of Kant’s life and works (1918; transl. 1981), Ernst Cassirer gave a trenchant description of this precritical oddity: Looked at closely, [Kant’s] life did not progress at all ‘‘in perfect regularity,’’ but moved in a very irregular way toward its goals. . . . Everywhere one comes upon places at which his thought, after it is just on the point of arriving at a deﬁnite solution, suddenly steps backwards. A problem is taken up, thought through, and its solution reached—but suddenly it is shown that the conditions under which it was ﬁrst worked out were not appropriate and complete enough, and hence not one step of the solution is valid, but instead the whole way in which the question is put has to be framed anew. Reticent as they normally are about questions of his inner development, Kant’s letters tell us again and again of reversals of this kind. A conceptual whole is not constructed bit by bit in a steady, unbroken progression, but new threads seem continually to be spun, only to be immediately severed. (Cassirer, 1981; 92–3)

Cassirer’s description has become the standard assessment of the young Kant: a second-rate thinker who moved from problem to problem, adopted different points of view, overturned them, and utterly failed to develop a coherent philosophical perspective. This interpretation naturally reinforced the dualistic picture of Kant: ﬁrst an inept writer who zigzagged off into all kinds of wrong directions, only to backtrack later on—and then, a genius, who serenely built the architectonic ediﬁce of the critical system. The great pioneers of Kant’s precritical philosophy did not challenge Cassirer’s reading. As Henrich remarked in a review of Schmucker’s study of Kant’s precritical ethics (Schmucker, 1961), Wilhelm Wundt, Giorgio Tonelli, and Heinz Heimsoeth were the ﬁrst explorers of Kant’s intellectual development (Henrich, 1965, p. 254). Wundt’s book on Kant’s metaphysics (1924), Tonelli’s monograph on the methodology and metaphysics of the precritical philosophy (1959b), and Heimsoeth’s studies of various aspects of Kant’s early thought (especially 1956; 2nd ed. 1971) have indeed made fundamental contributions to our understanding of the young Kant.4 To a greater or lesser extent, all of these scholars were wrestling with the phenomenon of Kant’s precritical capriciousness. Whereas the critical period of Kant’s thought exhibits a sustained perspective that would only dissolve in the Opus Postumum, such a sustained perspective seems absent from the

Introduction 9

precritical period. Instead, these erratic transitions pose a problem for the interpreter of the philosophy of the young Kant. Two recent readings may serve to illustrate this difﬁculty. In his book on Kant’s philosophy of mind (Ameriks, 1982), which contains an informative analysis of the paralogisms, as well as valuable discussions of the precritical views, Ameriks distinguishes four precritical phases. According to Ameriks, Kant began as an empiricist, turned toward rationalism in 1756, shifted to a scepticist position in 1766, and ﬁnally adopted a quasi-critical point of view after 1768 (ibid., 12–16). Beiser, in his study of Kant’s intellectual development (Beiser, 1992), identiﬁes four phases as well, but they are remarkably different from Ameriks’s proposal. According to Beiser, Kant was initially infatuated with metaphysics, then became disillusioned in 1760, partially reconciled himself with metaphysics in 1766, and ﬁnally divorced himself from metaphysical concerns in 1772 (ibid., 26). Other commentators, such as Friedman (1992b), Laywine (1991; 1993), Watkins (1995a; 1995b), or Shell (1996), have followed a different course. They respond to the problem of Kant’s seemingly erratic transitions by insisting on the existence of signiﬁcant continuities. Friedman characterizes the young Kant as a committed and sophisticated Newtonian, who attempted to construct the philosophical underpinnings of the Principia. Laywine and Watkins identify Kant’s concern with physical inﬂux as the dominant theme of the early works. Shell suggests a sustained interest in the mind-body problem and in the notion of community were the unifying motifs. I do not think that any of these mentioned investigations from the 1920s to the present have been fundamentally misguided. What interests me, is that one can tell the story of the precritical philosophy with far greater systematicity than has been attempted before. Although the precritical philosophy of nature was not a system, it did consist of preliminary investigations aimed at bringing about a system. Kant’s early thought was guided by a vision of combining a modern mechanical model of physical nature with the metaphysical assumptions of a uniform structure of nature, of a purpose to the world, and of the possibility of freedom. There was coherence in Kant’s early philosophy because the sustained effort of reconciling the perspectives of science and metaphysics characterized almost all of the major precritical writings up to the mid-1760s. Of course, such a reconciliation is an extraordinarily ambitious goal. The very height of Kant’s ambition explains the erratic transitions noted by Cassirer. Some of these reversals of opinion occurred because Kant wrestled with his goal: sometimes he failed and had to start anew. Others, however, were not reversals of opinion at all; they were transitions, but not erratic—they were shifts of interest dictated by the sequence of issues he encountered while advancing the precritical project. The sequence of the issues Kant investigated also sheds light on the proposals of breaking the early philosophy into distinct phases. In the 1740s, before the precritical project was underway, Kant investigated a problem in mechanics. In the 1750s, when the precritical project took off, he tried to

10 The Philosophy of the Young Kant

reconcile the perspectives of science and metaphysics over celestial mechanics and cosmology. These early interests, ﬁrst in classical mechanics, then in astrophysics, led to an empiricist style of investigation that Ameriks identiﬁes as the fundamental feature of the ﬁrst period. Kant’s subsequent tasks were the reconciliation of the two perspectives over the physical microstructure (by means of a monadology) and over God (by means of a rational theology). This shift in interest suggested a more rationalistic type of investigation to Kant, which Ameriks takes as the characteristic trait of the second period. As unresolved difﬁculties continued to accumulate, Kant’s conﬁdence in the project waned during the time that Ameriks views as the third or ‘‘sceptical period.’’ Finally, when Kant, after the collapse of his project, began to investigate what had gone wrong, his second-order research about the failure of his previous efforts paved the way toward the ﬁrst Critique. This is the fourth and quasi-critical period that Ameriks suggests. Although I have some reservations about Beiser’s speciﬁc organization of the precritical phases, the rise and fall of the precritical period does indeed reﬂect Kant’s changing attitude toward metaphysics: an initial infatuation followed by a laborious and increasingly strained relationship ending in divorce. As Friedman successfully demonstrated, Kant’s attitude toward Newtonian science, by comparison, remained constant throughout most of the precritical period. However, it was not the case that Kant was a straightforward Newtonian. Instead, Kant evolved from initial scepticism to the acceptance of Newton’s physics to the construction of a cosmology. His cosmology was more inspired by than actually based on the Principia. It involved the expansion of the applicability of Newtonian physics beyond Newton’s intentions and the replacement of Newton’s metaphysical underpinnings with Kant’s own. These metaphysical assumptions (of nature’s purpose, God’s existence, and man’s freedom) are quite general in content. They are not the exclusive feature of a speciﬁc school of thought. Kant’s arguments draw from the conceptual groundwork prepared by the Leibnizian-Wolfﬁans and by the Pietists, but they were essentially Kant’s creations. Instead of being variations of themes familiar to the School Philosophers and their religious rivals, the precritical articulation of the metaphysical underpinnings shows an independent and creative thinker at work. This broad endeavor, of fusing Newtonian science with Kantian metaphysics, was the essence of the precritical project. It is the most compelling argument for the continuity and coherence of the philosophy of the young Kant. Although the theme of the physical inﬂux plays a signiﬁcant role in the early works, as Laywine and Watkins observe, it is, in comparison to the enormity of the precritical project, a marginal issue. Thus, the theme running through Kant’s early philosophy was not merely the gossamer strand of physical inﬂux. Nor was it the question of community and the mind-body problem, as Shell tried to suggest. Moreover, it was not a bundle of related but ultimately loose strands, as Polonoff (1971) contends.5 The theme running through Kant’s early philosophy was the thick cable of his precritical project, the reconciliation of natural science and metaphysics.

Introduction 11

How could the young Kant intend a reconciliation of natural science and metaphysics if their actual separation was a later development? The separation came about in the last third of the eighteenth century; that is, years after the end of the precritical period. Ironically, the old Kant contributed to it. In the preface of the second edition of the Critique of Pure Reason (1787), he distinguished the treatment of cognitions following the ‘‘secure path of a science’’ from ill-fated attempts that are ‘‘a mere groping about’’ (B vii).6 Natural science is a success story. Its revolutionary strategy of testing hypotheses through deliberate experimentation has put natural science on the ‘‘secure path of a science.’’ In natural science, reason approaches nature ‘‘in the capacity of an appointed judge who compels the witnesses to answer the questions that he puts to them’’ (B xiii). But metaphysics has been an all-out failure. It is, as Kant remarked, ‘‘a combat arena . . . in which not one ﬁghter has ever been able to gain even the smallest territory and to base upon his victory a lasting possession’’ (B xv). In contrast to the procedure of natural science, the ‘‘procedure of metaphysics has thus far been a mere groping about, and—worst of all—a groping about among mere concepts’’ (B xv). The divorce of natural science and metaphysics was the ﬁnal outcome of a problematic association that had been steadily deteriorating throughout the eighteenth century. Kant had striven for their reconciliation in the decades before the Critique. The precritical project had emerged in the phase of estrangement of the two approaches to nature, and it had been a lastditch effort of saving the difﬁcult marriage of natural science and metaphysics before it was too late. That the precritical project was an attempt to save the worsening relationship of natural science and metaphysics is also what makes Kant’s early philosophy of nature unique. Kant recognized the rift between the scientiﬁc and metaphysical perspectives, and he wanted to do something about it. In his view, a reconciliation was needed because both perspectives are indispensable. Natural science supplies us with knowledge of the physical world; metaphysics provides us with answers to our questions about the intelligible framework of the physical world. This was Kant’s precritical position. But most philosophers in eighteenth-century Germany and elsewhere reacted differently to the impending split between the two approaches. The School Philosophers, for instance, did not take the threat seriously. Their systems evaded the conﬂict by compartmentalizing the two perspectives. The differences between the two perspectives mattered little to Wolff and his disciples because, in their view, the two approaches concerned distinct components of reality. Natural science was supposed to be about the empirically accessible and quantiﬁable surface layer of nature, and metaphysics concerned the rationally securable and nonquantiﬁable essence of the world. Those, on the other hand, who did take the threat seriously did not care for a reconciliation, because they tended to be partisan to one of the perspectives, hoping that it would triumph over the other. The Pietists fought against the emerging new science by challenging its legitimacy on metaphysical and theological grounds, whereas the French philosophes, the British empiricists,

12 The Philosophy of the Young Kant

and the Newtonians intended to discredit the established metaphysical systems with the weapons of Ockham’s razor, methodological rigor, and common sense. Johann Christoph Gottsched’s Erste Gru¨nde der Gesamten Weltweisheit, darinn alle Philosophische Wissenschaften in ihrer natu¨rlichen Verknu¨pfung abgehandelt werden (1733/4; ‘‘The First Grounds of Complete Philosophy, in Which All Philosophical Sciences Are Treated in Their Natural Connection’’) is characteristic of the complacency of the School Philosophers. In the ﬁrst volume of his work, on theoretical philosophy, Gottsched repeatedly refers to Newton’s work. He paraphrases the laws of motion, mentions the determination of the speed of light, describes the use of the prism for the spectral analysis of sunlight, and explains the celestial mechanics of the solar system. Over many chapters, Gottsched supplies the reader with a nicely organized account of the scientiﬁc knowledge of the day. In the same volume, he also expounds the basic principles of ontology, describes the nature of substances, discusses the cosmological structure and the physicotheological perfection of the world, explains the mind-body interaction, proves God’s existence, and identiﬁes God’s properties. Gottsched’s ‘‘Complete Philosophy’’ is an idyllic garden of Eden where the lion of science lays down next to the lamb of metaphysics. Newtonian physics and rational speculation live in a peaceful and mutually proﬁtable coalition. Physics, which Gottsched deﬁnes as the science of the material bodies (#602), generates knowledge about the properties of bodies by empirical means (#666). But as the senses have access only to the exterior of things, the work of the physicist is supplemented by the work of the metaphysican who illuminates their interior with conceptual devices (#398; ##664–666). Among those who acknowledged the presence of tensions and took sides, the defenders of metaphysics were typically German. Moses Mendelssohn championed the superiority of metaphysical cognition in his Abhandlung u¨ber die Evidenz in Metaphysischen Wissenschaften (1764; ‘‘Treatise on the Evidence in the Metaphysical Sciences’’). Crusius argued in his Physics that the use of mathematics in philosophical investigations of nature is misguided. Because he believed to have demonstrated that mathematical terms have nothing to do with real entities, he supposed that the quantitative approach used by Newton and his ilk was a dead end. On the other side of the fence was a growing alliance of European thinkers who recognized the merits of Newton and the faults of the metaphysicians. In the Lettres a` une Princesse d’Allemagne sur quelques sujets de Physique et de Philosophie (3 vols., 1768–72; translated as ‘‘Letters on Different Subjects in Natural Philosophy,’’ 1833), Leonard Euler took a swipe at the School Philosophers and ended his ‘‘Letter on the Systems of the Monads of Wolff ’’ (1760) with the withering remark that ‘‘these gentlemen have no knowledge of the real nature of bodies.’’ Voltaire played the same tune. He published an introduction to Newtonian physics, the E´le´ments de la philosophie de Newton (1738; ‘‘Elements of Newton’s Philosophy’’) while ridiculing the pretenses of the metaphysicians in Microme´gas (1752), Candide ou l’Optimisme (1759), and other works. David

Introduction 13

Hume, the sober Scot, concluded his Enquiry Concerning Human Understanding (1748) with the famous polemics, If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the ﬂames: for it can contain nothing but sophistry and illusion.

Thus, the young Kant was pretty much alone in his venture. The thinker who exerted the greatest inﬂuence on him was his teacher Martin Knutzen. Only ten years older than Kant, he taught philosophy, physics, and astronomy at Ko¨nigsberg, where he had been promoted to the post of an associate professor (ausserordentlicher Professor) at the tender age of twenty-one. In his well-received Philosophischer Beweis von der Wahrheit der christlichen Religion (1740; ‘‘Philosophical Demonstration of the Truth of the Christian Religion’’), Knutzen couched Pietist tenets in a school-philosophical framework in order to argue against the heresy of the ‘‘freethinkers,’’ the English Deists. He wrote a logic textbook, the Elementa philosophiae rationalis seu logicae cum generalis tum specialioris mathematica methodo demonstrata (1747; ‘‘A Mathematical Exposition of the Elements of Basic and Advanced Rational Philosophy or Logic’’), as well as a sophisticated treatise on the mind-body problem, the Commentatio philosophica de commercio mentis et corporis per inﬂuxum physicum explicando (1735; ‘‘Philosophical Commentary on the Interaction of Mind and Body, Explained by the Physical Inﬂux’’), which exerted a considerable inﬂuence on Kant. He also published some papers on mathematical problems and penned a larger, ill-fated work in astronomy, the Vernu¨nftige Gedancken von den Cometen (1744; ‘‘Rational Thoughts on Comets’’). Knutzen taught Kant metaphysics and natural science. He introduced Kant to Newton’s works, and he embodied an unlikely synthesis of Wolfﬁan and Pietist ideas. Like Kant, he acknowledged the equal relevance of metaphysical and scientiﬁc ideas. But Knutzen’s inﬂuence on the precritical project was limited. He never addressed the question of the tension between the scientiﬁc and the metaphysical perspectives. He did not concern himself with the issue of their synthesis, and when Kant began to grapple with it in earnest, Knutzen had already passed away. Kant’s mentor died in 1751, three years before the precritical project unfolded. But Kant still had the chance of meeting a kindred spirit. This was the great philosopher and mathematician Johann Heinrich Lambert. Here, ﬁnally, was a thinker who appreciated both the scientiﬁc and metaphysical perspectives, who worried about their tensions, and who was searching for a truce. In his Cosmologische Briefe u¨ber die Einrichtung des Weltbaues (1761; ‘‘Cosmological Letters on the Establishment of the Universe’’), Lambert worked on the same topic as Kant had in his earlier Universal Natural History. The tasks and results of both works resemble each other. Both were proposals of integrating Newtonian physics into a larger cosmological frame-

14 The Philosophy of the Young Kant

work, and both contained a theory of the dynamic constitution of the universe. Moreover, in contemplating the possibility of mediating between natural science and metaphysics, Kant and Lambert realized that the biggest obstacle was the absence of a coherent methodology that would do justice to either approach. Kant struggled with this challenge in the Prize Essay (1764); Lambert wrote two essays on the subject at the same time, which he subsequently incorporated into his Neues Organon (1764; ‘‘New Organon’’). Both thinkers recognized that they were—almost—soul mates. Lambert wrote to Kant about ‘‘the similarity of our ways of thinking,’’ and Kant replied that he had already noticed the ‘‘fortunate agreement of our methods.’’7 But Kant’s encounter with Lambert occurred too late. He learned about Lambert’s plans when he was on the verge of giving up. The Prize Essay was not only Kant’s last attempt at coming to terms with the difﬁculties that the precritical project posed, but it also remained his only effort of discussing the methodological differences of the two perspectives. Kant and Lambert agreed that a methodology capable of unifying science and metaphysics would require a conceptual overhaul of the latter perspective—an overhaul consisting of a systematic clariﬁcation of all basic philosophical notions and their implications. Lambert became engrossed in this task. In the two volumes of the Neues Organon, he endeavored to isolate the simple concepts, to derive a set of logically true statements from them, and to show that some of these propositions entailed metaphysical truths about the properties of existing things. Kant, however, lost heart and admitted defeat in the Dreams of a Spirit-Seer (1766). When Lambert invited him to join him in his venture, Kant had already been paralyzed by doubts. The last major precritical work, the Inaugural Dissertation (1770), was the starting point for a new philosophical path. Having jettisoned the idea of combining metaphysics and natural science on the same level, Kant sliced his model of reality into two halves, an intelligible dimension relevant for metaphysics and a sensible dimension accessible to science. Kant’s philosophical development is a story full of high hopes and great drama. In the precritical period, he revealed little of the conservative, circumspect caution so typical of his later work. Sometimes crudely, but always in bright colors, he painted with bold strokes a picture of reality that is enchanting in its beauty and tantalizing in its promise. Ultimately, the promise remained unfulﬁlled, and Kant’s fall from hope was hard indeed. But throughout the meanderings of Kant’s early journey, one notices an extraordinarily creative mind at work, a mind with an uncanny knack for combining ideas. Already in the precritical period philosophy was pushed to levels never attained before.

I

THE

1740S

-0 K A N T ’ S S TA RT I N G P O I N T

Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one ﬁrst learns to comprehend the language and read the letters in which it is composed. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric ﬁgures without which it is humanly impossible to understand a single word of it; without these, one wanders about in a dark labyrinth. Galileo Il Saggiatore (1623) I cannot promise to achieve something decisive and irrefutable in a merely metaphysical examination. Like many other sciences, our metaphysics stands indeed only at the threshold of certain knowledge; God knows when we will see metaphysics crossing it. Kant Living Forces #19 (1747)

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O N E

The Vis Viva Debate Kant’s Starting Point

-0

1.1 The Problem of Living Forces Kant’s philosophy is divided into the precritical period from the 1740s to 1770 and the critical period from the 1780s to the late 1790s.1 The gap between the two periods, from 1771 to 1780, is known as the so-called silent decade, in which Kant published little.2 The unifying moment of Kant’s early philosophizing was the precritical project. It involved, on one level, the reconciliation of the perspectives of natural science and metaphysics, and, on another level, the construction of a uniﬁed, nondualistic model of nature. With the precritical project, Kant hoped to establish a model of nature capable of harmonizing Newtonian physics with the main assumptions of metaphysics—the presence of purpose, the possibility of freedom, and the existence of God. Although the construction of this model of nature took Kant only a few years in the mid-1750s, the precritical period as a whole stood under its shadow. The years before 1755 prepared the ground for the envisioned philosophy of nature. They did so in a negative sense through the failure of his ﬁrst work, and in a positive sense through his later Newtonian conversion. The years after 1756 saw the completion of the project and Kant’s subsequent doubts. In the early 1760s, he established a bridge from nature to God and formulated the methodology of his scientiﬁcmetaphysical model of nature. But in the mid-1760s, the struggle with the 17

18 The 1740s: Kant’s Starting Point

second-order question of method had increasingly destructive aftereffects, shaking the ediﬁce until it collapsed. This failure left a void in which Kant would eventually erect his critical system. The fate of the young Kant is the story of an ambitious philosopher driven by the hope of solving the big questions of metaphysics with big answers, but who was forced to realize that his answers had failed and that the big questions loomed larger than ever. The precritical philosophy begins with the Thoughts on the True Estimation of Living Forces (wr. 1746–7, p. 1749), but this is not the starting point for the precritical project. Kant pursued the precritical project after the Living Forces. When writing his ﬁrst book, Kant had not yet experienced the Newtonian conversion that would dominate his thoughts on nature for the rest of his life, and he had not yet given thought to the grand issues of metaphysics that would govern the precritical project. In this regard, the Living Forces occupied a position all on its own. However, the precritical project of the 1750’s did not just emerge after Kant’s ﬁrst book; it was that book’s indirect consequence. The strategy of the Living Forces foreshadowed the strategy of the later and grander endeavor. In the Living Forces, Kant intended to remove the confusions surrounding the phenomenon of force by arguing that one needs to give both quantitative-physical and qualitativemetaphysical accounts their due place. He would eventually expand this idea into his overall position; the resolution of any general phenomenon of nature, he came to believe, required such a two-prong approach. It was Kant’s ﬁrm conviction that both the quantitative investigations of physics and the qualitative explorations of metaphysics have their relevance. To the extent they are at odds with each other, they deﬁne the task of the natural philosopher as the determination of the manner of their consistent copresence. Kant wrote the Thoughts on the True Estimation of Living Forces as a student at the Herzog Albrecht University (the ‘‘Albertina’’) of Ko¨nigsberg before ﬁnancial problems following the death of his father forced him to drop out of school and earn his living as a tutor. The book was an exercise in natural philosophy designed to identify the metaphysical nature and mathematical formula of physical force. Some commentators (de Vleeschauwer, 1939; Beiser, 1992) regard the Living Forces as Kant’s dissertation, but in fact Kant did not earn any degree with the book (it would take him ten more years to complete a master’s thesis and doctoral dissertation).3 Kant composed most of the manuscript in 1746 and submitted it to the censor. The dean approved it, and a wealthy relative helped Kant to ﬁnance the printing. The publisher Hartung slated its publication for 1747 but delayed the actual press until 1749. Kant’s philosophical debut was a false start. He later considered the True Estimation of Living Forces a thorough embarrassment, which, for all practical purposes, it was. Not only was Kant incapable of resolving the problem of force, but also unbeknownst to him, Jean Le Rond d’Alembert had already published a theory that effectively settled the debate three years before Kant turned his mind to it. In the Traite´ de Dynamique (1743), d’Alembert argued for a scientiﬁcally promising conception of force and an assessment of the relevant formulas that implied the correct mathematical

The Vis Viva Debate

19

resolution of the controversy. In 1758, d’Alembert added a ‘‘Discours Pre´liminaire’’ to the second edition of the Traite´, explicating the philosophical aspects of his resolution. But what always distinguished Kant was his extraordinary intellectual honesty. He admitted to himself the extent of his initial failure and carefully learned the painful lesson it entailed. When he realized that the Cartesian mechanics was an insufﬁcient physical account of force, he abandoned it and opted for Newton’s physics. When he recognized that the LeibnizianWolfﬁan metaphysics was ailing from problems, he broke with the School Philosophy and constructed his metaphysical demonstrations on a more sophisticated and independent basis. The Living Forces cast a long shadow over Kant’s subsequent endeavors. The deﬁciencies of the philosophy of mathematics that both inspired and impeded the theory of force led to Kant’s attempt, in the Universal Natural History (1755), to come to terms with the relation of quantitative and qualitative approaches to physical phenomena. The confused reﬂections over the relations of substance, interaction, and world, in the ﬁrst part of the Living Forces (#4–14), prompted Kant, in the New Elucidation (1755), to systematically clarify these notions and formulate a general ontology of nature. The vague assumption that matter involves an entelechy, which stands at the beginning of the Living Forces (#1, I 17), required an explanation, and Kant eventually unpacked it in terms of a general dynamic theory of matter in the Physical Monadology (1756). The precritical project grew out of the systematic reappraisal of the suppositions of the Living Forces and constituted the philosophical lesson learnt from the errors of the initial theory. In a similar manner, Kant would later learn an epistemological lesson from the metaphysical shortcomings of the precritical project, drawing, with the critical turn, second-order conclusions from the project’s ﬁrst-order difﬁculties. The Living Forces was a contribution to a protracted controversy that concerned two questions. First, is there such a thing in nature as a ‘‘living force,’’ a self-generating, essential vis viva, distinct from sheer mechanical pushes and pulls? Second, can the proposed measurement of the living force (as the product of mass and the square of velocity) be justiﬁed in the face of the measurement of sheer mechanical or ‘‘dead’’ force, the vis mortua (as the product of mass and velocity)? The controversy over the conception of force had started in 1686 between Leibniz and the Cartesians and had engaged many of the leading philosophers of nature of the last two generations. Since the debate had gone on for almost sixty years before Kant joined the fray, there was a plethora of literature on the subject, and the continuous exchange of proposals and counterproposals had given a highly technical character to the issue. Kant, who intended to settle the controversy once and for all, wrote the Living Forces as a technical response to both of the adversarial views—the Leibnizian position in favor of vis viva, and the Cartesian (and, to a lesser extent, the Newtonian) position repudiating it. Accordingly, an unsuspecting reader of the Living Forces, who thinks that the B-Deduction in the Critique of Pure Reason is the most difﬁcult text in Kant’s oeuvre, will be in for a surprise. Studying Kant’s ﬁrst book is an

20 The 1740s: Kant’s Starting Point

extraordinarily strenuous and frustrating undertaking. Since the treatise is about a topic that is now in the dustbin of history, the reader will encounter theoretical constructs that have nothing to do with our understanding of force, as well as deceptively familiar notions that sound like our modern concepts while actually involving the metaphysical underpinnings of the vis viva debate. The Living Forces was not written for a general audience, but was addressed to the participants of this debate. Its language mirrors the terminology of the natural philosophers in the seventeenth and eighteenth century and bears little resemblance to our modern scientiﬁc vocabulary. Reading Kant’s contribution to the vis viva controversy is a disorienting experience. It is similar to the dizziness felt when entering a room full of specialists discussing an unfamiliar issue in an unfamiliar jargon. The difﬁculties of reading the Living Forces are compounded by the fact that its twenty-two-year-old author was an inexperienced writer. Sentences are always verbose and complicated, frequently clumsy and ambiguous, and sometimes grammatically incorrect; positions are seemingly defended only to be repudiated later on; the solution to the problem of force is different in the beginning and at the end of the treatise; the structure is rambling and consists for the most part of an excruciating enumeration of ﬂawed objections to ﬂawed arguments. It is not exaggerated to say that the Living Forces is the worst text Kant ever wrote. But since his ﬁrst book is the key to things that would come later, the effort of penetrating its forbidding terrain has its rewards. We cannot ignore the Living Forces if we want to understand Kant’s philosophical development. The apparent difﬁculties of the treatise will dissolve if we begin our account with a look at the debate which the Living Forces was intended to settle. We need to recapitulate what happened in the smoky room full of quarreling specialists before we, and Kant, appeared on the scene. The problem of living force arose in the context of seventeenth-century mechanics. The debates over force involved a whole range of issues about the nature, manifestations, measure, kinds, and conservation of force. In particular, the controversy over living force concerned two main questions. How is force measured? Is force only a quantity? Measuring force requires the identiﬁcation of the right formula and thus involves a quantitative approach, while examining force as a quality is on a different level, requiring a philosophical clariﬁcation of the fundamental nature of force. That these two issues were not clearly distinguished in the controversy led to terminological confusions and misunderstandings among the participants, making the problem of living force almost impossible to solve. Even if a certain formula applied to some experimental contexts and measured something, it was not clear what it was that had been measured. The debate over the two questions occurred between two groups, the one siding with Descartes, the other following Leibniz. Descartes had argued that force is a quantity and nothing more. Force should be measured as the product of velocity and the quantity of matter. Because force, in Descartes’s measurement, is thus directly proportional to velocity, it is directly propor-

The Vis Viva Debate

21

tional to motion. The Cartesians conceived of force accordingly as the quantity of motion. Leibniz rejected this description. He thought that force was neither the particular quantity of motion nor reducible to a quantity in general. Leibniz considered force a quantity as well, but in contrast to Descartes, he was not persuaded that it was only a quantity. He viewed force as an essential and qualitative component of matter. According to Leibniz, this dynamic essence of matter or the substantial force has kinematic effects that we can measure. So force, in this view, is a quality that involves a quantitative aspect. Leibniz claimed that this quantitative aspect should be measured as the product of the square of velocities and the quantity of matter. Leibniz’s label for this conception of force was ‘‘living force’’ (vis viva). Depending on the context, ‘‘living force’’ referred to the essential quality as such, or to the formula describing its quantitative manifestation. In the jargon of the time, ‘‘living force’’ denotes the Leibnizian force and its measurement as the product of the quantity of matter and the square of velocities, whereas ‘‘dead force’’ or ‘‘dead pressure’’ (vis mortua) denotes the Cartesian force measured as the product of the quantity of matter and velocity. The term ‘‘quantity of matter,’’ which occurs in both conceptions of force, has disappeared from the vocabulary of modern physics. In his discussion of moving bodies in Le Monde (1633; see AT 11:51), Descartes identiﬁed ‘‘quantity of matter’’ as size. In a subsequent letter, to Christiaan Huygens on 5 October 1637, he identiﬁed ‘‘quantity of matter’’ with weight (cf. AT 1: 435–9). The context of this latter identiﬁcation is the mechanics of simple machines. In the Specimen Dynamicum I (1695), Leibniz referred to the ‘‘quantity of matter’’ as ‘‘magnitudo corporis’’ (magnitude of a body), which has been variously rendered as magnitude (Loemker, 1956, 2:725), simple mass (Loemker, 1956, 2:726), and size (Ariew and Garber, 1989, 128). In fact, the degree of a body’s resistance to changes in place and motion depends on the body’s mass—a concept that nobody understood before Isaac Newton’s deﬁnitions of mass and inertia became public knowledge.4 We can trace the origin of the concept of mass to the drafts of De motu corporum in gyrum (1684), a short treatise that Newton wrote and sent to Edmond Halley in response to the latter’s questions about celestial mechanics. Hypothesis 2 of De motu states, ‘‘Every body by its innate force alone proceeds uniformly to inﬁnity in a straight line, unless it be impeded by something extrinsic’’ (Add. 3965.7; fol. 55r; see De Gandt, 1995, 18–19). This was the germ of the ﬁrst law of motion. In the Principia, Newton generalized the hypothesis to include rest, and he dropped the stipulated relation of inertial motion and innate force. The thus revised law of inertia of the Principia states, ‘‘Every body continues in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed upon it’’ (M 1:13). As Newton explains, ‘‘body,’’ ‘‘mass,’’ and ‘‘quantity of matter’’ mean the same thing in his terminology; they each refer to the measure of matter that arises from its density and bulk conjointly (deﬁnition 1, see M 1:1). Hence, in Newtonian physics, mass or quantity of matter is the measure of the amount of matter in a body which determines

22 The 1740s: Kant’s Starting Point

the body’s resistance to acceleration by an applied force. Newton considered mass to be constant. (We know through Einstein that mass varies with the velocity of a body and that it represents a stockpile of energy.) Although Newton had published his ﬁndings in the late seventeenth century—the ﬁrst edition of the Principia appeared in 1687—it would still take decades before Newton’s deﬁnition of the quantity of matter in terms of mass was generally accepted. If we (anachronistically) substitute ‘‘mass’’ for the ambiguous ‘‘quantity of matter,’’ then both Descartes’s quantity of motion (mv) and Leibniz’s living force (mv2 point to actual physical quantities. The Cartesian product of the quantity of matter and speed anticipated the product of a body’s mass and its linear velocity that we now call momentum. The Leibnizian product of the quantity of matter and the square of velocities is the precursor to work. The quantity that we now label force derives from Newton’s second law of motion (the law of acceleration) and Euler’s quantitative formulation of this law. Thus, force is actually the product of mass and acceleration. Neither Descartes nor Leibniz succeeded at identifying force, but both Cartesian momentum and Leibnizian work are related to it. Momentum (in modern notation, p mv) is an aspect of force in that force (F ma) denotes the rate of change of momentum. Work or kinetic energy (k 1⁄2mv2) is the transfer of energy to a body by an application of force. In the context of simple machines, work signiﬁes the product of an applied force and the resulting displacement. Both Descartes and Leibniz were inﬂuenced to some extent by Galileo, the founder of modern mechanics. In the old Aristotelian metaphysics, which Galileo overcame, force had been an entelechy and motion had been a process. For Aristotle, there was no such thing as free motion; if the cause of motion stopped acting on the object in motion, the motion of the object would cease. Galileo was the ﬁrst to realize that motion is not a process requiring a continuous cause, since it persists until something external acts on it. The insight that motion is not a process made modern mechanics possible. It implied that motion must be a state and is thus just like rest. Although Descartes and Leibniz had different views on Galilean mechanics (which contributed to the prolongation of their dispute), Galileo’s idea of considering motion to be a state served as the common ground of their rivaling theories of force. Galileo’s mechanics was an intermediate point between the old and the new. Two deﬁciencies prevented Galileo from constructing a full account of inertia. His mechanics lacked a concept of mass, operating with weight instead, which precluded the determination of the acceleration by a force on a horizontally moving body. It also involved a strange concept of curvilinear inertia according to which not only uniform linear but also uniform circular motions are natural states that maintain themselves without the active exertion of a force. (The idea is that a body is at rest on a horizontal plane that is actually a segment of the spherical surface of the Earth; hence, bodies are at rest on a plane whose points are equidistant from the Earth’s center.)

The Vis Viva Debate

23

Nevertheless, Galileo’s conceptual revolution, his contention that motion and state are equivalent states, was a ﬁrst step toward the notion of inertia expressed in Newton’s ﬁrst law of motion.5 In addition to his new conception of motion, Galileo’s call for a new methodology shaped the vis viva debate and particularly impressed Descartes’s followers.6 Nature stands continually open to our gaze, Galileo declared in Il Saggiatore (1623), hence, nothing in nature is intrinsically occult. Since the book of nature is written in the language of mathematics, Galileo continued, we must investigate phenomena in quantitative rather than in qualitative terms.7 Moreover, as Galileo remarked in the earlier Macchie solari (1613), we should investigate the phenomena and their properties instead of trying to penetrate the essences of natural substances.8 Predictably, an occult, qualitative Aristotelian entelechy that is neither empirically accessible nor suited to mathematical description cannot be part of the book of nature. In some regards, Descartes’s mechanical philosophy looks like an expansion of Galileo’s methodological proposal. Three cornerstones of the Cartesian philosophy mutually reinforce the conception of force as a quantity of motion. First, since mathematics can describe physical nature, force can be described by mathematics as well, hence, force is quantiﬁable.9 Second, because matter consists only of extension, matter is wholly inert, lacks any inherent tendency to move, and does not possess any resistance to being set in motion.10 Accordingly, an active force cannot be an internal component of passive matter. Force is not only quantiﬁable, it is a quantity as such— there is no qualitative dynamic residue pertaining to the internal constitution of matter. Third, God is the sole causal agency of nature, and hence, essential forces cannot exist, for if they did, they would be causal agencies in their own right. Generally, then, force is merely a quantity, and since the only true dynamic source of nature is God, force is reduced to an humble kinematic quantity. It is simply the quantity of motion. Occult and unobservable forces such as sympathies and antipathies, congruences and incongruences, or attractions and repulsions had no place in the Cartesian world of inert bodies. Descartes freed mechanics from the quagmire of qualitative medieval conceptions, but perhaps he streamlined mechanics too much. For him, forces were relevant only in terms of external actions that are observable and measurable. Descartes equated ‘‘force’’ with an ‘‘action’’ exempliﬁed in motions.11 In this way of looking at nature, a mechanics of force could only take a kinematic form—any kind of dynamics would smack of an illicit metaphysics. The Cartesian equation of mechanics with kinematics has interesting philosophical consequences. In a section of the Principia Philosophiae (1644), Descartes argued that God not only created nature and initiated its motions, but also preserves the original amount of motion in the universe. Motion is a modiﬁcation of matter. Although the motion of individual parts of matter is not ﬁxed, and local motions can increase or decrease, a ﬁxed, unchanging quantity of motion remains in the universe. If one particle moves with twice the velocity as another particle and this second particle is twice as big as

24 The 1740s: Kant’s Starting Point

the ﬁrst, there is as much (quantity of) motion in the smaller as in the bigger, and whenever the motion of one particle decreases, the motion of another particle increases proportionally. Despite the changes we see in the world, Descartes concluded in this passage, God conserves an equal quantity of motion in matter.12 This particular chapter in Descartes’s Principia Philosophiae—section 36 in part 2 of the work—was the spark that ignited the ﬁght over living forces. What remained constant for Descartes, the sum-total of mechanical energy or force in the world, is the quantity of motion. Force is measurable such that a unit of force corresponds to a unit of motion. If two particles of unequal size move at different speeds, their quantities of motion are identical if the products of their size and speed are the same.13 Descartes’s argument in the Principia Philosophiae illustrates that the subsequent vis viva debate involved, from the very beginning, a mixture of distinct issues. The principle of conservation was such a question, mixed into the general cluster of problems about the nature and measurement of force. Both sides agreed that there is something that is conserved in physical nature; the question was, what is it? Descartes thought that God preserves the quantity of motion; the principle of conservation accordingly concerns that quantity which is expressible in the formula mv. Leibniz, on the other hand, thought that God preserves vis viva; for him, the principle of conservation is about the quantity of force describable by the formula mv2. It seemed to Descartes that experimental data supported his measurement of what he called force. The same formula applies to the mechanics of simple machines such as levers, pulleys, and balances. For Descartes, force is always the product of two simple factors. He wrote Huygens (in the aforementioned letter from 5 October 1637; AT 1:435–6) that all simple machines are based on the principle that the same force can raise a body weighing 100 pounds 2 feet, another body of 200 pounds 1 foot, and a body of 400 pounds 12⁄ foot. In each case, an equal force is involved, which means that force must be calculated as the weight of a body multiplied by its vertical displacement. To use the Cartesian mv formula as a universal measurement of force in all kinematic situations presupposes that v can stand for velocity in the case of bodies in real motion, as well as for displacement in the case of the virtual motion involved in simple machines.14 Leibniz agreed with Descartes that we can express force mathematically, but he did not believe this would capture the nature of force. Descartes viewed the extension of matter, which is inert, as the ﬁnal component of physical reality. By assumption, the structure of material reality is inert; by deﬁnition, force is not inert. It follows, Descartes concluded, that force cannot be part of the structure of material reality. Instead, force is reducible. The Cartesian force can be reduced to a number, and what appears as a dynamis is in fact the kinematic quantity of motion. In the Cartesian picture, motion was more real than force.15 In the Leibnizian picture, motion and force trade their ontological places. In Leibniz’s philosophy, force becomes a genuine entity, and motion is just a relation among phenomena. As the famous deﬁnition of substance as un eˆtre capable d’action testiﬁes, there is an irreducible dynamic component to

The Vis Viva Debate

25

reality.16 This irreducibility does not preclude the mathematical expression of force, but it precludes the mathematical reduction of force. Force can be quantiﬁed as a mechanical magnitude, but force is not a quantity as such. As Leibniz argues, ‘‘everything happens mechanically in nature, but . . . the principles of mechanism are metaphysical.’’17 Force is such a metaphysical principle of mechanism; it subsists as an ultimate quality and is the dynamic essence of matter. The vis viva controversy got under way with Leibniz’s paper Brevis demonstratio erroribus memorabilis Cartesii et Aliorum (1686). The ‘‘memorable errors of Descartes and others’’ consisted of the assumption that the quantity of motion is conserved and of the identiﬁcation of force with the quantity of motion—what Leibniz regarded as ‘‘the most famous proposition of the Cartesians.’’18 According to Leibniz, this identiﬁcation is erroneous because it involved two speciﬁc mistakes. First, Descartes considered v, velocity, as a positive quantity, not as a vector quantity. (Several years earlier, John Wallis, Christopher Wren, and Christian Huygens had shown that the quantity conserved in one-dimensional collision was not mv with v as a positive quantity, but mv with v as a vector quantity whose direction is variable and must be taken into consideration.)19 Next, Leibniz accused Descartes of confusing the force of motion with the quantity used in statics for the case of simple machines.20 In general, Leibniz’s ‘‘brief demonstration’’ employed Galilean mechanics as a weapon against Descartes. A simple analysis of rising and falling bodies by means of the times-squared law (Galileo’s formula of free fall) reveals a difference between the quantity of motion and the force of motion. Obviously, if there is a difference, then force cannot be measured as the quantity of motion.21 In the ensuing debate, this argument became one of the crucial weapons of the Leibnizians against the Cartesian camp, and Leibniz repeated and restated it numerous times. Of course, the argument raises a question: If we cannot measure force as a quantity of motion, then how should we measure it? Leibniz proposed his solution in another version of the argument.22 A body A weighing 4 units moves in a horizontal plane with a velocity of 1 unit. The force that propels A could, in theory, raise A to a height of 1 unit. (According to Galileo’s times-squared law, the resulting height is calculated as the square of the velocity; 12 1.) Now, imagine that A collides with a body B, weighing 1 unit and resting in the same plane. Suppose A could transfer the full amount of its force to B. B would then acquire A’s force, and if Descartes’s mv-formula for force were true, B would now move with a velocity of 4 units (FA 4 • 1 4; FB 4 1 • vB; hence vB 4). According to Descartes, the force that moves A of weight 4 with velocity 1 would move B of weight 1 with velocity 4. Is this true? No. Because, as Galileo found out, the height of a rising body equals the square of the body’s velocity. Descartes’s formula entails that A’s force, now acquired by B, could raise B to the dizzying height of 16 units (42 16). Leibniz recognized that the Cartesian calculation could not be true, for the height to which a body is raised is inversely proportional to the body’s weight (in our terms: mass). So, a force F that raises a body A of weight 4

26 The 1740s: Kant’s Starting Point

to unit height would actually raise a body B of unit weight to a height of 4, but never to a height of 16. Descartes’s formula conﬂicts with established principles of mechanics; it must be wrong because it implies an effect four times larger than expected, an effect more powerful than its cause. Descartes’s measurement implies, in effect, the absurd possibility of a perpetuum mobile. A different formula is needed. Now, if one employs mv2 instead of mv, Leibniz argued, such a conﬂict with the principles of mechanics does not arise. For then, a body A of a weight of 4 units and unit velocity will possess 4 units of force (F 4 • 12 4); transferred fully to B of unit weight, FA will impart a velocity of 2 units to B (v2 F/m 4/1 4; so v 2). By means of the Leibnizian formula, FA will raise B to the predicted height of 4 units (since h v2 22 4).23 Leibniz did not yet speak of vis viva in the Brevis demonstratio (1686); he coined the term, in its French equivalent force vive, in the unpublished Essai de Dynamique(1691) and in a 1692 version of the same text. Leibniz mentioned vis viva publicly for the ﬁrst time in the Specimen dynamicum (1695).24 In the 1686 essay, Leibniz implicitly defended the mv2 measure of force in terms of the square root of the distance of the fall of the bodies. Although Leibniz fought for the new measure of force, he did not discover it. Christiaan Huygens realized that Descartes’s conservation of motion is valid in some but not in all frames of reference. Since mv is not conserved in every frame, Descartes’s principle of the quantity of motion is not correct. Huygens, who tutored Leibniz in mathematics during the latter’s Paris years (1672–76), discovered that the quantity mv2 is conserved in each frame of reference; ‘‘the sum of the products of the size of each hard body multiplied by the square of its velocity is always the same before and after impact.’’25

1.2 The Controversies from 1686 to 1741 Descartes had died in 1650, before the vis viva debate, and upon the publication of Leibniz’s incendiary article in 1686, Descartes’s followers took up the cause of the quantity of motion. The strange thing about the debate is that not much happened. The same arguments were repeated ad nauseam.26 No group could convince the other. Predictably, the Germans sided with Leibniz, the French with Descartes, the British with Newton; the battle over vis viva acquired national overtones, which certainly did not help settle the issue. The ﬁrst stage of the battle was waged between Leibniz and the Abbe´ de Catelan, who was joined in 1689 by Denis Papin. De Catelan replied to Leibniz’s piece in the Acta Eruditorum with a paper in the Nouvelles de la Re´publique des Lettres. Leibniz replied to the ‘‘sc¸avant Cartesien de Paris’’ with several articles and letters. Unfazed, the abbot replied to the reply of the reply, which precipitated another shower of Leibniz’s writings. The LeibnizCatelan exchange remained essentially fruitless.27 The subsequent controversy with Papin was more valuable. Papin conceded to Leibniz one element of his objection, that a perpetuum mobile is absurd. If it could be shown that the quantity of motion really implied perpetual motion, then it would follow

The Vis Viva Debate

27

that the quantity of motion could not measure force. But this does not follow, Papin insisted, because Leibniz’s objection erroneously presupposes that the complete quantity of A’s force can actually be transferred to B.28 Papin was right about this, and Leibniz’s further attempts to demonstrate a full dynamic transference did not work out. Ultimately, however, no opponent could defeat the other, and by the close of the seventeenth century, both sides were exhausted. More than a decade later, between November 1715 and November 1716, the controversy ﬂared up again. Princess Caroline of Wales, a good friend and student of Leibniz, had met a visiting English minister, Samuel Clarke, at the Prussian court, with whom she had argued over Newton’s theological views and Leibniz’s recently published Essais de The´odice´e (1710). Caroline related the incident to Leibniz. Leibniz wrote her in November 1715, criticizing Newton’s claims that space is God’s organ for sensing the things in the world and that the world is a machine at risk of running down unless God winds it up like a watch.29 Caroline forwarded this letter to Clarke. Clarke, ‘‘Newton’s bulldog,’’ reacted by sending an aggressively worded missive directly to Leibniz. Instead of simply defending Newton’s views, Clarke launched an all-out counterattack against Leibniz. Stung, Leibniz fought back, and the correspondence (with Clarke writing in English, and Leibniz in French) was under way. The Leibniz-Clarke correspondence bloomed into a general philosophical debate that repeatedly touched upon Leibniz’s claim of the conservation of vis viva (G 7:352, 370, 376, 387, 413–4). However, when Leibniz’s death in 1716 cut short the exchange, matters remained undecided. Leibniz had simply reiterated his earlier views on living force, to which Clarke responded with general philosophical objections. The second stage of the controversy occurred after Leibniz’s death.30 In the 1720s, Leibniz’s philosophical allies took up the cause of the living forces. The leading exponents of the Leibnizian camp were Jacob Hermann, Christian Wolff, Georg Bernhard Bilﬁnger (also known as ‘‘Bu¨lﬁnger’’ or ‘‘Bu¨lfﬁnger’’), Marchese G. Poleni, W. J. s’Gravesande, Peter van Musschenbroek, and Jean and Daniel Bernoulli. A brief digression on the Bernoullis is in order here, because it is easy to confuse the various members of this extraordinary family.31 The family lived in the German part of Switzerland; their ancestors had been Belgian Protestants of Dutch extraction. Not only are there six Bernoullis of historical importance, but three of them carry the same ﬁrst name, and two others are known by three name variations each. The head of the family was Nicholas Bernoulli (1623–1708), a government leader in Basel. He had three sons, Jacques (Jakob, James), Nicholas, and Jean (Johann, John). The third son Jean fathered Daniel, and the second son Nicholas fathered yet another Nicholas (‘‘the younger’’). Jacques Bernoulli (1655–1705), the ﬁrst born, was a professor of mathematics at Basel university and is the author of the Ars coniectandi (1713), one of the ﬁrst works on probability theory. He formulated the Bernoulli Theorem for predicting probable frequencies of occurrence of repetitive events. Jacques was the most important of the Bernoullis with

28 The 1740s: Kant’s Starting Point

regard to the development of probability theory. Nicholas, the second of the three sons, did little scholarly work, but his son Nicholas (1687–1759) applied probability theory to legal problems and prepared the posthumous edition of his uncle Jacques’s Ars coniectandi. Jean Bernoulli (1667–1748), the youngest of the three sons of the elder Nicholas and an uncle to the younger Nicholas, was a professor of mathematics in Groningen and Basel. He collaborated extensively with his older brother Jacques. Jean wrote treatises on differential equations and on geometry, worked on the application of mathematics to mechanics, and expressed d’Alembert’s principle of virtual velocities in analytic form. Jean’s son Daniel (1700–1782) was perhaps the most remarkable of all the Bernoullis. He was a physician by training and worked as a professor in Basel and St. Petersburg. His contributions to mathematics involved the discussion of the so-called Petersburg Problem (a riddle in probability theory), the articulation of the Law of Errors, and the development of methods for applying calculus to probability theory. His contributions to physics culminated in the work Hydrodynamica sive de viribus et motibus ﬂuidorum commentarii (1738), which laid the foundation for ﬂuid dynamics. Daniel Bernoulli formulated what has become known as the Bernoulli Principle in ﬂuid dynamics, which in turn expresses the Bernoulli Constant, a ﬁxed quantity of the relation of pressure, velocity, and density of a current. Two of the Bernoullis, Jean and his son Daniel, defended the vis viva measure. The list of the leading exponents of the Leibnizian camp continued with the Abbe´ Camus, who was not a Leibnizian but an ally of the Bernoullis, and with Leonhard Euler, who once defended vis viva before changing his mind. In 1726, Peter the Great founded the Russian Academy of Sciences at St. Petersburg which became the new home for the Leibnizian camp after the dissolution of the ﬁrst Berlin Academy. The ﬁrst volume of the Commentarii Petropolitanae (1728) immediately revealed the academy’s journal as the major platform for Leibnizian publications on the vis viva question.32 At the same time, Isaac Newton’s inﬂuence grew in natural philosophy, but it did little to clarify this particular debate. Although Clarke had employed Newton’s views as weapons against Leibniz, the public appraisal of Newtonian physics did not correspond to the frontlines of the dispute. In the 1720s, two leading Leibnizians, s’Gravesande and Musschenbroek, embraced Newton’s physics while championing living forces. Other Newtonians, on the other hand, followed Clarke’s lead, agreeing with the Cartesians on the rejection of living forces. Until 1732 (when Pierre-Louis M. de Maupertuis began to defend Newton as the ﬁrst of the French philosophers), the lines in the vis viva dispute remained drawn along the already-mentioned national boundaries. Swiss, German, Dutch, and Italian voices defended Leibniz; British members of the Royal Society in London defended Newton; French natural philosophers of the Acade´mie Royale des Sciences in Paris defended Descartes. Among the British opponents to living forces, Henry Pemberton, G. Eames, Colin Maclaurin, Samuel Clarke, and James Jurin participated in the controversy.33 Among the French, the most noteworthy of

The Vis Viva Debate

29

the Cartesians after the Abbe´ de Catelan was J. T. Desaguilliers (‘‘Desaugliers’’) and J. J. d’Ortous de Mairan, whose position Kant would later discuss at length in the Living Forces.34 The dramatis personae is really all that was important in this second stage of the dispute. An amazing number of mathematicians and philosophers of nature were sucked into the quarrel, but to no avail. Once again, the new surge of publications failed to settle the debate. By the early 1730s, the appeal of the issue waned. Although the problem had stubbornly resisted all attempts at solving it, the attention of natural philosophers turned to other matters. The vis viva debate seemed to have ended in a draw. Around 1740, the issue that was originally a puzzle for mathematicians and mechanical philosophers became a topic among literati and intellectuals. The vis viva question became party talk in French salons, in particular in Mme la Marquise de Chaˆtelet’s circle at Cirey, frequented by the likes of Maupertuis and Voltaire. The Marquise de Chaˆtelet (‘‘Chastelet,’’ ‘‘Chastellet’’) was a correspondent of Frederick the Great (who, at the time of the correspondence, was still a prince and not yet ‘‘the Great’’) and would later prepare the ﬁrst French translation of Newton’s Principia (1756). She took up the Leibnizian cause and entered into a widely heard but inconclusive argument with the Cartesian Mairan.35 Why was it so difﬁcult to settle the issue of living forces? One reason has to do with the historical origin of dynamics. Dynamics had taken its cue from statics, and mechanical laws had been derived from the forces involved in the so-called simple machines such as the lever. Because of irreducible differences between statics and dynamics, the construction of a general mechanics on the basis of the lever led to inescapable confusions. In the context of the virtual motions of the lever, velocity and displacement are interchangeable, but in the context of real motions of freely falling bodies, they are not. Some ‘‘force’’ can be measured in the lever in terms of the quantity indicated by velocity or displacement, suggesting the mv formula. But in cases of free fall, displacement corresponds to the square of velocity instead (as Galileo’s formula of free fall shows), suggesting the mv2 formula. Since static and dynamic situations were not sufﬁciently distinguished, two different formulas with overlapping applicability were ﬂoating around in mechanics. Moreover, the Cartesian mv formula, involving v as a positive rather than a vector quantity, was inadequate. Leibniz’s criticism in this regard was right on the mark. Although the level of the vis viva debate deteriorated after Leibniz’s death, at least its ﬁrst stage was more than a worthless ﬁght of momentum versus work. In addition, the ambiguities of the lever resulted in ambiguous conceptions of force that burdened mechanics and the vis viva debate in particular. Robert Hooke, whose work was by no means atypical of the terminological despair of his time, employed ‘‘strength,’’ ‘‘quantity of strength,’’ ‘‘force,’’ ‘‘force of a moving body,’’ ‘‘pressure,’’ ‘‘power’’ all synonymously, and on one occasion, referred to force as ‘‘pressure, endeavour, impetus, strength, gravity, power, motion, or whatever else you will call it.’’36 As the mechanical

30 The 1740s: Kant’s Starting Point

measurement of force was bogged down by the ambiguities of the lever, the philosophical conception of force was bogged down by terminological confusions. The controversial status of Galilean mechanics augmented the difﬁculties of the vis viva issue. Galileo’s assessment of motion as a state, in theory the common ground of Cartesian mechanics and Leibnizian dynamics, was in practice too limited to allow a reconciliation. Descartes’s and Leibniz’s particular interpretations of motion-states radically differed—Descartes claimed that motion and rest are nonarbitrary opposites; Leibniz, by contrast, argued for a relativistic notion of motion that was interchangeable with rest. With respect to the issue of living force, Galilean mechanics was not much help either because Galileo’s times-squared law that Leibniz used in support of living force was unambiguously endorsed only by other Leibnizians. Descartes had rejected Galileo’s kinematics of free fall because the continuous acceleration of freely falling bodies was at odds with the kinematics of Cartesian vortices. The times-squared law continued to remain controversial among Cartesians; those who accepted it were unsure of its sense. Furthermore, those who acknowledged the validity of Galileo’s principle were not logically committed to buy into Leibniz’s employment of the times-squared law on behalf of vis viva. In this regard, Leibniz’s mechanical arguments suffered from a crucial ﬂaw: the fall of heavy bodies, on which Leibniz’s reasoning turns, involved contingent features of our world having nothing to do with the basic laws of physics.37 Since it was just this fundamental nature of mv2 that Leibniz hoped to establish—as the measure of the dynamic substratum of the world and as the dynamic quantity that is conserved in the world—these mechanical arguments were bound to fail. One could even say that it was impossible to say which party was right because, in a sense, both parties were right considering the compound meanings of ‘‘force’’ and the multiple levels of the debate. Both formulas (F mv and F mv2) could be justiﬁed in some mechanical contexts, and both formulas obviously measured something—even though it was not yet clear what. Both camps could produce some evidence for ‘‘their’’ measurement. Already at the earliest stage of the dispute, in the exchange between Leibniz and Catelan, both parties acknowledged the veracity of the competing empirical evidence and thus the soundness of the rival formula. Catelan conceded to Leibniz that in some cases (involving unequal times) the mv2 calculation is correct. But Catelan insisted that the mv calculation applies in the ‘‘general’’ and ‘‘more regular’’ cases of two bodies falling in equal times.38 Leibniz, on the other hand, granted the existence of a vis mortua or dead pressure measurable by mv, which he saw exempliﬁed in centrifugal and gravitational forces.39 This ‘‘dead force’’ is not really force yet, Leibniz believed, because it concerns only the beginning (nisus) of motion, not motion itself. Leibniz argued that the very ﬁrst, inﬁnitely small instant of a body’s fall or motion is measurable by the mv formula, whereas the mv2 formula more accurately represents force after the initial moment and for the whole duration of a body’s motion or fall (Spec. Dyn., 14–16).

The Vis Viva Debate

31

1.3. The Traite´ de Dynamique (1743) and D’Alembert’s Preface of 1758 Trying to unravel the bundle of confusions concerning the measure and nature of force was hopeless, and the only promising approach involved cutting through the Gordian knot of the issue. This is what Jean Le Rond d’Alembert did, the historical winner of the vis viva debate. According to a frequently repeated story (de Vleeschauwer, 1962; Schultz, 1965; Ho¨ffe, 1994), d’Alembert rejected both the mv and the mv2 measurements, and proposed F 12⁄ mv2 as the deﬁnitive formula for force; everybody believed d’Alembert, and the controversy was over.40 Another story (Iltis, 1970; Shell, 1996) has it that d’Alembert merely completed what others had prepared, and that he should have split the prize with Roger Boscovich or Leonhard Euler.41 The real course of events was different from either account. D’Alembert was not an independent outsider who terminated the quarrel by rejecting either position, nor was it the case that others before him had resolved the issue of forces as clearly as he did. The mechanics of d’Alembert’s Traite´ de Dynamique (1743) was inﬂuenced by Newton; its methodological approach was indebted to Descartes (despite d’Alembert’s harsh words about the Cartesians). D’Alembert did not so much propose a new conception of force in his Traite´ but rather tried, like Huygens before him, to reduce dynamics to kinematics, to a mere geometry of motion. In this sense, one could argue that the Traite´ sidestepped the problem of force rather than solving it. Nonetheless, d’Alembert’s kinematic proposal amounted to a solution. As we know, the Cartesian formula anticipated momentum, and the Leibnizian formula anticipated work. Because ‘‘momentum’’ and ‘‘work’’ denote real and distinct aspects of physical interaction, Descartes and Leibniz were both right in their own way. This was d’Alembert’s insight in the Traite´ de Dynamique. It is not true that d’Alembert rejected both formulas, as one story has it; instead, he pointed out that both the Cartesian and the Leibnizian measure were of equal validity. D’Alembert’s resolution of the vis viva dispute in the ﬁrst edition of the Traite´ was technical and largely inaccessible to readers not well versed in the mathematical treatment of kinematics. Had Kant read it before writing the Living Forces (he did not), he might not have understood it very well. In 1758, a second, revised, and expanded edition of the Traite´ de Dynamique appeared; d’Alembert had added an introductory essay, the ‘‘Discours Pre´liminaire,’’ containing a forceful rejection of vis viva in a metaphysical sense and a clear statement of the new quantitative conception of force. Ultimately, it was this ‘‘Discours Pre´liminaire’’ that ended the debate. The Traite´ de Dynamique did not answer the question of force, which kept on playing a signiﬁcant role in nineteenth-century physics (for instance, in energetics), but it succeeded in answering the question of living force in physical contexts. Since the vis viva debate was a multifaceted dispute, the ﬁrst step of its resolution consisted in isolating the individual facets and

32 The 1740s: Kant’s Starting Point

dealing with them separately. D’Alembert transformed an issue that had been a motley mixture of metaphysical and mechanical elements into a purely mechanical question. During the same time, and perhaps sped along by the publication of d’Alembert’s work, Newtonian physics celebrated a belated triumph on the continent, ﬁrst in France in the 1730s and ’40s, and soon thereafter (in the 1740s and ’50’s) in Germany.42 Because Newton had emphatically rejected any inquiry into underlying causes, causal questions about the origin of force or the source of motion quickly fell out of fashion, and this, in turn, helped d’Alembert to have the ﬁnal word in the controversy. The ‘‘Discours Pre´liminaire’’ in the 1758 edition of the Traite´ begins with a proposal for a methodology in mechanics that has Cartesian overtones.43 The more abstract and fundamental a ﬁeld is, the more certainty it is capable of. Since d’Alembert’s objective was to overhaul mechanics and transform it into an inquiry allowing of rigor and certitude, one must apply geometry, a more basic and certain science, to mechanics, a more advanced and specialized ﬁeld (Traite´, iii, iv). By generalizing mechanics in this way, its principles will aquire maximum clarity (v). This clarity, however, requires that the principles of mechanics be reduced to their smallest possible number; rigor and parsimony go hand in hand—‘‘en un mot, d’e´tendre les Principes en les re´duisant’’ is the key to progress in mechanics (v). D’Alembert recognized that a ﬂood of principles, approaches, and concepts had turned the vis viva debate into a morass; accordingly, any progress about these things requires draining the irrelevant from mechanics. The ‘‘ﬁrst and foremost’’ object of mechanics is motion (v), hence, dynamic questions should be approached kinematically. Mechanics should be oriented to mathematics, hence, mechanics should be a consistently quantitative investigation. Metaphysical principles are woefully lacking in clarity, and d’Alembert did not endeavor to refute them (iv)—metaphysics belongs to the irrelevant, and it does not have a place in this treatment of the issue. Because mechanics is primarily about motion, force is relevant only in terms of the motion it produces (xvi). D’Alembert wanted to reduce talk about forces to a minimum. He refers to them only if constrained by the established terminology (for instance, by calling inertia with Newton the ‘‘force d’inertie’’). Like Newton, d’Alembert could not care less about the causes of forces, or the ‘‘causes motrices.’’ Forces are relevant only in terms of their effects. As inherent forces, they are simply ‘‘eˆtres obscurs & me´taphysiques,’’ whose consideration would only obfuscate matters (xvi). For all practical purposes, such metaphysical, inherent forces do not exist, and if they did, they would not make a difference. D’Alembert declared that only external causes can alter the uniform movement of a body (I.1, 22). He stripped the question of living force of its metaphysical aspect, reducing it entirely to a question of measurement. Whereas Leibniz’s qualitative living force was measurable only in its phenomenal counterpart, d’Alembert transformed it into a pure quantity, equating the force vive, as he called it, with the measurement itself. That d’Alembert excised the qualitative aspect of

The Vis Viva Debate

33

force from the investigation was both good and bad. On the one hand, it left one dimension of the issue of force unresolved (which eventually led to the resurrection of the Leibnizian notion of kinetic energy in nineteenth-century physics). On the other hand, the quantitative focus on force gave subsequent physicists unambiguous concepts to work with. In d’Alembert’s account, one cannot measure force by the space traversed, or by the time taken, or by an analysis of mass and velocity. Force is measurable only through the obstacles encountered and the resistance that it gives these obstacles (xviii). Force is now relevant as a quantity determined by the resistance of its obstacles. The mass-velocity formulas of Leibniz and Descartes do not capture force as such, only some of its speciﬁc aspects. If the resistance of an obstacle destroys the motion of a colliding body instantly, it will give rise to an equilibrium. The resistance of the obstacle and the impetus of the colliding body cancel each other out in an equilibrium. Both obstacle and body possess the same product of mass and virtual motion (vitesses virtuelles). In this case, force is measured as the sum of resistances and can be represented by the Cartesian quantite´ de Mouvement (xx). On the other hand, if the resistance of an obstacle does not destroy the motion of a colliding body instantly, but destroys it gradually (as a spring does for instance), then one deals with a case of retarded motion. But in that case, the number of obstacles overcome is like the square of the velocity of the moving body; force is then measured by the absolute quantity of resistances, and the Leibnizian force vive applies (xx). D’Alembert concluded that all the difﬁculties of the vis viva issue boil down to the decision of whether the kinematic situation to be examined falls in the category of equilibrium or in the category of retarded motion (xxi). Now, this conclusion is partially false. As the classiﬁcation of obstacles and the curious connection of obstacle-type to force-type show, d’Alembert was still confused about work and momentum. But what is fundamentally right about this conclusion is its underlying thought: although neither the Cartesian nor the Leibnizian formula succeed in capturing force as such, both capture speciﬁc and distinct aspects of force. D’Alembert apparently sensed that his overt and erroneous conclusion, linking force-type to obstacle-type, was wrong. He added, almost as an afterthought, that one could also apply the mv formula to cases of retarded motion—if one wants to estimate, in such cases, force qua the sum of the resistances of the obstacles. So, it all depends on what one wants to measure. D’Alembert had realized that both formulas are of general validity in expressing different quantiﬁable aspects of mechanical phenomena. Finally, the rivalry between the two formulas was exposed as an illusion. If we want to make sense of this convoluted controversy from our contemporary vantage point, then we shall see that the vis viva debate resulted in a scientiﬁcally appropriate employment of the Leibnizian and Cartesian formulas. In our terms, the formula of Leibniz’s vis viva, or F mv2, anticipated the modern concept of work. Work is the product of a force and a distance and depends on the angle between force and displacement. It is a

34 The 1740s: Kant’s Starting Point

scalar quantity, a quantity involving magnitude only, like kinetic energy, to which work is closely related. Work could also be deﬁned as the transference of energy that equals the product of the distance through which the point of application moves, and the component of force acting in the direction of the force’s moving point of application. By comparison, the formula of Descartes’s quantity of motion anticipated the momentum of a moving particle, usually expressed as p mv. Momentum is related to the impulse of a moving particle. Unlike work or kinetic energy, momentum and impulse are vector quantities, quantities involving both magnitude and direction. The impulse of a force refers to the product of the force acting on a particle and the time during which it acts. This product can also be expressed as the product of mass and velocity of the particle at two different times, and this product is called ‘‘linear momentum.’’ The irony of the debate was that both adversaries hoped to deﬁne force, but both deﬁned something else. After all, neither mv2 (work) nor mv (momentum) are the same as force. The modern concept of force derives from Newton’s second law of motion and is equal to the product of the mass of a moving particle and the particle’s acceleration. Our measure of force is the legacy of Euler, who put Newton’s second law into the formula F ma.44 Although Leibniz and Descartes failed to identify force as such, unintentionally arriving at work (kinetic energy) and momentum, they were still in the ballpark. Loosely speaking, Leibniz’s formula correctly expresses a spatial aspect of Newtonian force, and Descartes’s formula correctly expresses a temporal aspect of Newtonian force. In short, kinetic energy is the Newtonian force F acting through space; momentum is F acting over time.45 The loser of the debate was vis viva, understood in its qualitative sense as a dynamic property of matter. But this exile from scientiﬁc discourse was only temporary. D’Alembert’s solution rested on a deliberate choice: he wanted to investigate what could be investigated quantitatively and simply ignored the rest. This choice settled the debate, but it did not refute the possibility of a dynamic property of matter. Many followers of Newton latched on to precisely this option. According to Newton, matter was a basic building block of nature, and force was imposed on this essentially passive matter. But what was force by itself? Was it an active constituent of nature? Or was it rather a mere phenomenon reducible to motion? Already in the early Letters to Serena (1704), the deist John Toland reinterpreted Newton’s ambiguous concept of force as an immanent property of matter. Toland argued that motion is inherent in matter—that this essential motion or ‘‘autokinesy’’ is tantamout to the gravitational force, and that therefore matter is active.46 Toland’s conception of an active matter turned out to be a success, and later Newtonians viewed force along similar lines, such as Robert Greene in The Principles of the Philosophy of Expansive and Contractive Forces (1727), or Joseph Priestley in his Disquisitions relating to Matter and Spirit (1777).47 Kant, after the Living Forces, was no exception, arguing for forces immanent to an active matter in the Universal Natural History (1755) and

The Vis Viva Debate

35

the Physical Monadology (1756), although he would now carefully avoid the terms ‘‘living force’’ and ‘‘vis viva.’’48 At the end of the eighteenth century, living force and vis viva returned from their exile. The vitalists resurrected these terms but disconnected them from their origin in mechanics. The physician Herrmann Boerhaave rehabilitated vis viva for chemistry; the biologist Albrecht von Haller (whose poems Kant would quote in the Universal Natural History) advanced a theory of irritability that suggested a living force for physiology on the basis of the contraction of muscle tissues. Later, Johann Gottfried Herder would reintroduce these terms into teleology with his treatise Vom Erkennen und Empﬁnden der menschlichen Seele (1778). What all of these thinkers, from the Newtonians to the vitalists, suspected, was that there were some kinds of dynamic properties in matter that still awaited clariﬁcation. They were, of course, right. Through Faraday’s work on electricity and Maxwell’s on electromagnetism, the dynamis of matter returned in the nineteenth century to physics in the guise of energy, ﬁnally acquiring a form that permitted its systematic investigation.

T W O

The True Estimation of Living Forces Kant’s Theory of Dynamics

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2.1. The Circumstances of Kant’s Proposal The Thoughts on the True Estimation of Living Forces appeared too late to have any impact on the vis viva controversy, and the whole debate unfolded, progressed, and ended without Kant. At the date of its publication the issue had already been settled for mechanics, and the topic of living forces was dead. What was worse, the proposal failed to solve the problem; even if the book had appeared earlier, it would not have made any difference. Historically, it was too late; philosophically, it was misguided. Kant (never known to be a stellar writer and never reputed to be an entertaining thinker) demanded a lot from the readers of his ﬁrst treatise. The treatise was not written for the educated public; its author addressed the specialists in the ﬁeld. Kant examined the issue of force in an excruciatingly pedestrian fashion. The bulk of the treatise is a report of the numerous arguments that had emerged on either side of the controversy, and each and every one of the arguments is appraised in detail and at length. Overall, the book was an embarrassment. Kant declared that he wanted to settle the debate once and for all, and he intended to formulate in this tract the universal principles of dynamics (cf. #106, I 117). His concluding remarks glow with self-complacency. He expected to lay claim to ‘‘incontrovertible certainty’’; it was ‘‘not difﬁcult’’ to resolve the mathematical aspect 36

The True Estimation of Living Forces 37

of the puzzle and ‘‘almost impossible to miss’’ the solution to the ontological aspect of the problem. A ‘‘brief absence of partisan spirit’’ and a ‘‘quick equilibrium of the inclinations’’ sufﬁced to settle the dispute ‘‘immediately’’ (#163, I 181). But the laugh is always on the loser, and Lessing ridiculed the young author with the jingle, Kant shoots for an ambitious aim To provide us with a course On estimating living force But his mental force is just too lame.1 In short, Kant’s philosophical debut was a debacle. The 256-page book was ignored, and Kant, soon rejecting the treatise himself, later did his best to keep things that way. He kept mum about his juvenile publication and never mentioned it. Already in his next two publications, the Spin Cycle essay (1754) and the Universal Natural History and Theory of the Heavens (1755), he proceeded from quite different premises. This embarrassment was not entirely Kant’s fault. The Prussian book trade concentrated on Leipzig. Ko¨nigsberg, a sleepy, faraway town at the eastern edge of the kingdom of Prussia, did not always receive the current works and journals from Paris, London, and St. Petersburg. It is quite likely that the provincial whereabouts of Ko¨nigsberg prevented Kant from realizing the impact that d’Alembert’s Traite´ de Dynamique had on the vis viva controversy.2 Another fact, and one that is frequently overlooked, is that d’Alembert’s clariﬁcation of the confusions surrounding vis viva, his ‘‘Discours Pre´liminaire,’’ did not appear prior to the Living Forces but rather twelve years later. When Kant wrote his treatise, the resolution of the debate existed in only a technical and rigorous document, the ﬁrst edition of the Traite´. The only other text prior to 1746 that contained the germ of the right solution was Roger Boscovich’s De viribus vivis (1745), but it lacked sufﬁcient clarity to make much of an impact. The Leibnizian arguments against the Cartesian measure typically involved the objection that an analysis of certain experimental contexts by means of mv entailed an illicit increase of force, evoking a perpetuum mobile. According to Boscovich, the Cartesian mv measure does not imply this absurdity because the increase of force is imaginary. Boscovich emphatically declared that living forces do not exist. His acceptance of Huygens’s theorem for the collision of perfectly elastic solids, involving F mv2, appeared in his writing more as an exception conﬁrming the Cartesian rule than as an acknowledgment of the general copresence of both formulas. Technically, Boscovich’s proposal suggests the correct solution, the equal validity of mv and mv2. But it was all too easy to read De viribus vivis as just another anti-Leibnizian mechanics, in particular since Huygens, the discoverer of mv2, had rejected its Leibnizian interpretation as a metaphysical force, vis viva, and Boscovich merely followed him in that.3 In any case, neither the Traite´ nor De viribus vivis was in all likelihood accessible to Kant in Ko¨nigsberg.

38 The 1740s: Kant’s Starting Point

This may explain the embarrassment of the Living Forces but does not justify it. Kant could have written a better book than he did. His grasp on mechanics was weak, and he frequently misunderstood issues that beared on the vis viva debate. For example, Leibniz’s famous ﬁrst argument of the vis viva debate involved the reductio of the Cartesian measurement by appealing to Galileo’s times-squared law. Kant’s presentation of the argument, however, confounded the ‘‘square of velocity’’ that appears in both Galileo’s and Leibniz’s formula, as if the times-squared law and mv2 were one and the same thing. Another misunderstanding was Kant’s claim that the mv2 formula had no mechanical relevance, something he could only assert if he was ignorant of Huygens’s demonstration of the conservation of mv2 in every frame of reference. Huygens, who had no axe to grind in the whole controversy, showed the physical applicability of the mv2 formula. Finally, Kant failed to appreciate Newton’s signiﬁcance for mechanics. Kant backed the wrong horse and believed in the promise of Cartesian mechanics for determining the quantitative aspects of the vis viva issue. That his laws of dynamics were at odds with Newton’s laws of motion merely illustrated the shortcomings of Newtonian mechanics for him. It is hard to escape the impresssion that at the time of writing the Living Forces, Kant’s knowledge of mechanics was superﬁcial at best.4 Nonetheless, the Living Forces is fascinating. It reveals how the mind of the budding philosopher worked. Echoes of thoughts that had been formulated here ﬁrst reverberate through the whole precritical period, despite Kant’s quick rejection of the treatise. Attitudes emerged here that were later transformed into the dominant motives of his philosophizing. Assumptions that Kant boldly introduced in the Living Forces later returned as problems requiring solution or claims needing explication, and as a result, many themes of the Living Forces—the beauty and perfection of nature, the tension between physical inﬂux and preestablished harmony, the concepts of substance and world, the idea that force generates space—blossomed into the topics of the major precritical treatises in the next decade, the Universal Natural History (1755), the New Elucidation (1755), and the Physical Monadology (1756).

2.2 The Metaphysical Prelude and the Leibnizian Essence of Force The Living Forces consists of a preface and three sections containing 163 paragraphs. The ﬁrst section of the book carries the title, ‘‘On the Force of Bodies in General.’’ Kant characterizes it as the ‘‘metaphysical groundwork’’ of the investigation (I 28). The metaphysical groundwork involves reﬂections on various subjects that have something to do with the phenomenon of force: motion and force in general (#1–4); the interaction of material and immaterial substances, such as between the mind and the body (#5–6); the totality of interacting substances, or the unity of reality as compared to a

The True Estimation of Living Forces 39

plurality of worlds (#7–11); the view that force is a striving toward motion (#12–14); and the distinction between living and dead forces (#15–19). Kant’s aim in the Living Forces was to settle the vis viva debate. His strategy consisted of giving both camps their due. He wanted to show that the controversy persisted for such a long time because both sides had been partially right. The truth must accordingly lie in the middle, and the only possible resolution of the issue will be a compromise. Instead of declaring one side to be the winner, Kant constructed a synthesis of the Cartesian and Leibnizian views. Such a mediating stance precluded allegiance to either view, and he went to great lengths to emphasize his impartiality. Already the preface begins with a declaration of independence. Kant announced that he no longer wanted to respect the authority of someone like Newton or Leibniz; one no longer had to cower in fear of the sway of great men (i, I 7). The argumentative structure of the book itself shows how its author avoids being pinned down to one of the standard views in the debate. Kant praised whom he criticized, and he criticized whom he praised. The ﬁrst section is essentially a defense of Leibniz against Descartes; the second section is a defense of Descartes against Leibniz; and the third and concluding section is an attempt at transforming the two antagonistic views into complementary components of a comprehensive dynamics. An impartial arbiter who does not have a stake in the conﬂict that he adjucates—this is how Kant hoped to present himself in the Living Forces. But the advertisement did not entirely match the product. Kant did have a stake in the conﬂict for he wanted to rescue the Leibnizian position from its critics. The Thoughts on the True Estimation of Living Forces is and remains a defense of living force—that is, a defense of the very hypothesis that the followers of Descartes repudiated. ‘‘My main intention,’’ Kant writes, ‘‘is to improve the Leibnizian measure of force’’ (#15, I 15). When describing how the force of freely moving bodies can only be measured according to the Leibnizian square of velocities, he adds, because I actually want to counter Leibniz’s opinion with certain objections in this tract, it seems that I contradict myself, since I present in this paragraph a proof that conﬁrms his opinion. But I will show in the ﬁnal chapter that Leibniz’s view genuinely applies as long as it is qualiﬁed in a certain fashion. (footnote to #17, I 29)

Perhaps in an effort to pretend greater originality, Kant emphatically rejected aspects of the standard Leibnizian position—only to argue for a view that is almost indistinguishable from the one just rejected. For instance, Christian Wolff ’s conception of a vis motrix does not clarify the issue of force in the least, Kant says, and it involves a grave metaphysical mistake (#2, I 18). Yet, Kant’s distinction between the types of motion and force mirrors Wolff ’s own (#15–18, I 28–30). Kant’s argument is original, but his conclusion is not. It involves common fare in the philosophy of nature of the time.

40 The 1740s: Kant’s Starting Point

In the Leibnizian camp, the distinction was already drawn by Leibniz, Wolff, and Jean Bernoulli.5 There is a genuine departure from Leibniz, however, and this involves Kant’s appraisal of the preestablished harmony early in section I. The doctrine of preestablished harmony is the causal theory, suggested by Leibniz, that substances fail to affect each other, that an intersubstantial causation does not exist, and that substances can only act on themselves. Kant did not accept these claims. Instead, he thought that substances are capable of affecting changes on each other. He reveals his allegiance to the rival doctrine of physical inﬂux (the causal theory, originally coined by Sua´rez, that afﬁrms an intersubstantial causation), and asserts that physical inﬂux has ‘‘triumphed’’ over preestablished harmony (#6, I 20).6 Perhaps one could take his sympathy for the inﬂuxus physicus to be an early indication of his later anti-Leibnizian stance in the 1750s and ’60s—that underlying metaphysical structures should agree with the physical phenomena.7 Georg Bernhard Bilﬁnger, a disciple of Wolff, had defended the preestablished harmony in the treatise De harmonia praestabilita (1723) and in his main work Dilucidationes philosophicae (1725).8 Martin Knutzen had argued in his Systema causarum efﬁcientium (1735) against Bilﬁnger’s view (and perhaps also against Wolff, who, despite his reluctance to commit himself to a speciﬁc position in the Psychologia rationalis, had launched a volley of objections against the physical inﬂux). Knutzen advocated the physical inﬂux both as a general theory of causation and as a speciﬁc account of mind-body interaction. He had characterized the physical inﬂux as an ‘‘impression of motion’’ (motus impressionem) that sparks perceptions in the monad (in other words, in the mind).9 Although Kant subscribed to Knutzen’s inﬂuxionist resolution of the mind-body problem, he recognized that the identiﬁcation of the physical inﬂux with a communication of motions only exchanges one problem for another. The interaction between mind and body would occur in a mechanistic fashion if the essential power involved in their causal connection would be a mere motion. And if mind and body mutually set each other in motion, this would mean, because motions always occur in space, that the mind occupies a spatial location just like the body. But the mind is not a spatial substance. Does Knutzen’s conundrum imply that mind and body do not affect each other, and that the appearance of their interaction is actually a preestablished harmony? No, Kant argued, because the interaction between mind and body need not necessarily take a kinematic form. The inﬂuxionist explanation of the mind-body interaction remains plausible, he insisted, because one has to allow that the substantial force has a variety of other, nonkinematic effects that ‘‘must not be determined more precisely’’ (#6, I 20). Although this argument shows us that Kant had gained a certain degree of independence from Knutzen, it also reveals his philosophical innocence—after all, it is hard to believe that we can solve the mind-body problem by claiming nonmechanical force-effects whose further explanation is forbidden.

The True Estimation of Living Forces 41

Kant begins the book with the claim that an essential force, an entelechy, is at the heart of each body or substance. The appeal to Aristotle in this context (I 17) does not indicate a deviation from the Leibnizian course, because Leibniz had already described primitive active force as an Aristotelian entelechy on various occasions.10 Toeing the rationalist line, Kant maintains that it is a mistake to interpret this force as an empirical factor (#1), and that motion is merely an external phenomenon of force (#3). In addition, force involves manifestations other than just motion, and considering this, Hamberger’s narrow conception of force in terms of a striving toward motion will not do (#12–14).11 The essential force constitutes bodily changes, alterations in the soul (#6), the locations of and relations among substances (#7), extension, space, and the three-dimensionality of space (#9–10). Aside from the mentioned rejection of the preestablished harmony, Kant’s notion of force as a universal and essential dynamis that determines the constitution of phenomena mirrors the Leibnizian stance. To what extent was the earliest Kant a loyal disciple of Leibniz? Were the inﬂuxionist leanings the only anti-Leibnizian elements of the Living Forces? Referring to the arguments in #8–11, Shell (1996) claims that Kant rejected the doctrine of the best of all possible worlds. According to this Leibnizian doctrine, God made a choice before creation; from the inﬁnite series of possible worlds, He chose the best of them as the cosmos to be created. Hence, there exists only a single universe. Shell argues that Kant afﬁrmed a plurality of universes instead.12 I think that this reading is not quite right. For, although Kant concedes that ‘‘it is metaphysically true that more than one world could exist’’ (#8, I 22), he adds in #11 that such a plurality of worlds would be possible only if these copresent but distinct worlds were spatially incommensurate (I 25): For if only a single type of space that has three dimensions is possible, then the other worlds, which I posited outside of the one in which we exist, would be connected with ours through space—for they are spaces of the same kind. Hence the question would arise why God separated one world from the other, if He could have imparted a greater perfection to his work through their connection—for the more connection there is, the more harmony and conformity will be in the world, whereas gaps and separations violate the laws of order and perfection. It is therefore not likely that many worlds exist (albeit it is possible as such), unless various species of space, as mentioned above, are possible. (#11, I 25)

Leibniz’s doctrine of the best of all possible worlds presupposes that only one universe (the best of the possible ones) is actual, and that a plurality of existing universes does not come into existence. Kant thinks that a plurality of universes is conceivable under the condition of ontologically discrete spatial continua that differ in their number of dimensions. Although multiple spaces of varying dimensions cannot be ruled out as a theoretical possibility,

42 The 1740s: Kant’s Starting Point

such a splintered array of isolated universes would be at odds with a harmonious creation. Since an omnipotent and benevolent God would rather have created a harmonious and thus spatially uniﬁed creation, Kant reasons that the actual existence of a plurality of worlds is unlikely. In this fashion, he remains committed to the Leibnizian doctrine of the best of all possible worlds. Shell (1996) also asserts that #9–11 anticipate the later critical treatment of space and time as forms of intuition.13 Once again, it seems that this claim ascribes greater originality to the young Kant than the text supports. Section I of the Living Forces involves neither a critique of Leibniz’s theodicy nor an anticipation of the forms of intuition. (Time is not even mentioned in the text.) Instead, the discussion of space reveals the depth of Kant’s allegiance to Leibniz. For Leibniz as well as for Kant, space is the sum-total of substantial relations. Possibly inspired by Newton’s inverse square law of universal gravitation, Kant speculates that the degree of the substantial forces weakens in inverse proportion to the square of the distance (#10, I 24). He argues that the radiating effects of this essential force generate a three-dimensional whole. Perhaps he imported universal gravitation into the monadology, as Friedman (1992b) suggests.14 Evidently, Kant thought that the essential force, which supposedly governs the motion of objects as well as the changes in the soul, can also function as a gravitational power that generates a spatial structure. But whatever this force may be, it dwells in substances; and despite a possible Newtonian inspiration, the resulting conception of space is not Newtonian at all. Kant’s space is not Newton’s fundamental receptacle that persists regardless of the matter and force within it. Nor is it the case, as Tonelli (1966) proposes, that Kant endeavored to construct a metaphysical foundation for Newton’s force of gravity here.15 After all, the explanandum of the reﬂections in #9–11 is space, not gravity; Kant offers a dynamic explanation of space, not a spatial explanation of force. If anything, he hoped to illuminate the Leibnizian, relational conception of space with the appeal to an inverse square law. In sum, Kant’s space is the structural result of the force-effects of substances, a standard Leibnizian space, but with the unique feature that its dynamic generation can be quantiﬁed in a speciﬁc way. Toward the end of section I, Kant discusses empty space (#17, I 29), noting that motion would persist forever in a void. Yet, the real space of the world is not empty, but ‘‘inﬁnitely subtle,’’ as Kant puts it (ibid.); that is, space itself exhibits a slight impediment to motion. One can measure the force of a body traversing the inﬁnitely subtle space through the sum of its effects. He notes that a body moving through space requires a force to plow its path through the resisting moleculae of space. Because space has a resistance of its own, and because the degree of its resistance increases with the speed of the body traversing it, it takes more force for a faster body than for a slower body of equal size to move through the same continuum. On another occasion (#104, I 114–5), Kant elaborates on this idea. The spatial resistance shows why velocity is a dynamic factor: one cannot conclude from

The True Estimation of Living Forces 43

two equal bodies traversing an equal distance that they are endowed with equal force because their velocities must be taken into account as well. It is interesting that Kant refers in #17 to the resistance of the small particles of space (not the resistance of small particles of air). Both in #17 and in #104, Kant characterizes space as being ‘‘inﬁnitely subtle,’’ and claims that the mass (Masse) and resistance of space are ‘‘inﬁnitely small.’’ If ‘‘inﬁnitely small’’ in these descriptions referred to a vanishing quantity, then the spatial resistance would be nil. But this cannot be, because Kant’s claim that force can be measured by its ability to overcome the resistance of space, would then appear puzzling, as would his reason for the dynamic relevance of velocity. The particular measurement of force and the relevance of velocity are intelligible only if Kant’s physical space is ﬁlled with an etherlike substance whose mass and resistance might be very, very small, yet big enough to be dynamically relevant. It is evident here that Kant’s earliest conception of space did not involve a void and thus differed from the conception of space scholars usually attribute to Newton. The characteristic feature of Newton’s gravitational attraction is that it is a ‘‘stringless pull’’; gravity can act over a distance. The Sun holds Earth in its grip and thus continually diverts the rectilinear tangential motion of Earth.16 The Sun’s force of gravity is an external action on Earth producing a change in its motion, even though these two masses are not in direct contact. Nor is there an indirect contact between Sun and Earth through a spatial medium (which would propagate the gravitational forces like waves on a lake surface and thus bridge the distance from Sun and Earth). The unifying theme of book II of the Principia is to show that a dynamics allowing forces is preferable to a kinematics requiring an ethereal medium. But bald forces in an empty void, without the help of an ether to transmit their effects, then appear to act at a distance. In the Principia, Newton did not accept a cosmic ether that was dynamically or kinematically relevant. He did not support the view that the cause of gravity might be an ethereal whirlpool along the lines of Descartes’s vortex theory—as regards such possible causes, he decided he had nothing to say about them (cf. ‘‘Scholium Generale’’; K 2:764, M 2:546–7). Newton found nothing unreasonable about the possibility that matter in space is rareﬁed to the point of being a void (cf. book III, proposition 6, corollary 3, K 2:575, M 2: 414). In contradistinction to the Newtonian void, the Leibnizian and the Cartesian conceptions of space involve two (albeit rather different) versions of a plenum.17 Kant’s ‘‘inﬁnitely small spatial resistance’’ emphasized the great rarefaction of an ether that remained dynamically relevant. He considered a Newtonian void as a theoretical possibility with certain kinematic implications in #17, but he did not (and could not) utilize it on behalf of living force. The purpose of the Living Forces was to reconcile Leibnizian dynamics and Cartesian kinematics, both of which presuppose a plenum. Considering this context, Kant’s decision of conceiving space as a dynamically relevant medium, although wrong, made strategic sense.18

44 The 1740s: Kant’s Starting Point

Kant concluded the metaphysical, ﬁrst section by distinguishing between two types of motion and their corresponding types of force (#15–18). These ﬁnal pages of section I contain the argument on which Kant’s later solution of the vis viva problem rests. When one gently pushes a ball across a tabletop, the persisting motion of the body depends on a continuous, external, impelling force (#15). The motion starts when the force is applied; the motion ‘‘partly destroys itself ’’ and comes to a sudden halt when the force disappears (#16, I 28). The cause of the motion is a vis mortua, an externally applied dead pressure. Because of the direct proportionality between force and motion, the force of the moving body can be measured in terms of the body’s velocity, and the quantity of force is the product of mass and velocity, mv. On the other hand, a gunshot reveals a different type of motion (#15–17). The externally impelling force disappears the very instant the bullet leaves the barrel. Yet, the motion of the projectile continues after the initial dead pressure. It follows that the force of the moving body is able to overcome the incremental pressures of the resisting spatial masses. The force involved here, responsible for the continued motion, is different from an external dead pressure. After all, the motion persists even after the initial dead pressure is over, and it perseveres in the face of the subtly resisting ether of space. Therefore, there must be ‘‘an interior source of an eternal force’’ within the body (#16, I 28). Kant believes that the inner force of the freely moving projectile is selfpreserving (#15) and inﬁnite (#16). How can we measure this new type of force? A force is measurable by its effect, he says, and the quantity of this force must be in proportion to the resistance of the spatial particles that the freely moving projectile encounters on its path (#16). The faster a bullet moves through ‘‘empty’’ space, the more violently it will collide with the spatial particles, and the more force will be required to keep it going. Thus, the quantity of a body’s inner force is proportional to the velocity of the body. But a faster body will also encounter more space-particles in a given time than a slower body; to plow through the greater number of obstacles will require a greater force, too. Hence, in addition, Kant argues, the quantity of a body’s inner force must also be proportional to the number of particles. The total effect of a body’s inner force is thus proportional to the product of the body’s velocity and the amount of particles encountered. This amount of particles encountered is proportional to the velocity of the body, too. Hence, the total effect of the force involved in the fast moving projectile is measured by the square of velocity, mv2. Of course, Kant’s inferences are wildly wrong. They violate the laws of mechanics that were already known at the time, and they ﬂy in the face of common sense. Why not simply assume that the projectile ﬂies with constant speed as long as it meets no resistance? And, as soon as the projectile meets resistance, say in the guise of the spatial ether, why not conclude that such impeding forces gradually bleed the projectile’s motion away until it is drained of its original impetus and comes to a stop? The reason for Kant’s strange attribution of a boundless internal power supply to a fast moving

The True Estimation of Living Forces 45

body lies in his allegiance to Leibnizian dynamics. As Leibniz asserts and Kant repeats, there are essential entelechies, wellsprings of force that inﬂuence the overt kinematic behavior of bodies in certain circumstances. It is only a small step from this assumption to the conclusion that rapid bodily motions can persevere in the face of resistance and express a dynamic quantity measured by the square of velocities. The assumption of an internal power supply has the unappealing sideeffect of propelling Kant’s mechanics back to pre-Galilean times. The notion of inertia implicit in the Living Forces resembles a genuine vis inertia; an active force instead of a passive property. Both types of motion described by Kant are continually caused processes rather than states—a continuous external cause (dead pressure) generates the kind of motion involved in the pushed ball; a continuous internal cause (living force) generates the kind of motion involved in the shot bullet. Kant’s neglect of basic methodological guidelines compound these confusions. As the methodology of Galileo’s experiments ﬁrst illustrated, the analysis of kinematic situations always requires the abstraction of relevant from irrelevant factors. In most situations involving moving bodies, friction tends to be such an irrelevant factor. Yet, for Kant, friction is relevant in one case and irrelevant in the other. According to his argument, the quantity of friction makes a qualitative difference in force. In other words, a difference in degree (a lot of friction in the case of the ball versus a little friction in the case of the bullet) entails, for Kant, a difference in kind (dead pressure as mv versus living force as mv2). Kant reasons that the motion of the bullet does not depend on an external, transient factor but stems from an internal, eternal, self-preserving source, the vis viva. Because the body’s motion is a kinematic effect of an inner dynamic source, there are two factors at play here, the motion and its essential source. This contrasts with the merely external motion of the previously considered dead pressure. Proceeding from this consideration, he offers a second and more metaphysical proof for the mv2 measurement: But the living force is a different case. The state of a substance in free motion with a certain speed is completely caused by the substance’s own inner determinations. Hence, the substance wants to preserve itself in this state. An external resistance must possess a special force, in addition to some force that counteracts the velocity of this body, in order to break the striving that the inner force of the body has for keeping itself in the state of free motion. Thus, a resistance capable of stopping the freely moving body must have a total force that is a composite consisting of quantities proportional to the body’s velocity and to the body’s force which the body employs to preserve itself in this state of striving. That is, the force needed by the resistance must be like the square of the velocity of the colliding bodies because both quantities are equal to another. (#18, I 30)

Predictably, this argument is not better than the previous one. It fails as a demonstration because it presupposes the very claims that it sets out to

46 The 1740s: Kant’s Starting Point

defend: the existence of an essential living force fueling the motion of the substance, and the continuation of this motion despite constant resistance. The shortcomings of the ﬁrst, metaphysical section of the Living Forces must have dawned on Kant not long after the completion of the manuscript. As it turned out, section I of the Living Forces became a ‘‘list of things to do.’’ Kant had introduced a series of assumptions which, upon reﬂection, turned out to be problematic. Those that he hesitated to dismiss required further elucidation and proof. The measure of living force would disappear; Kant recognized its defense as what it was: a lost cause. The quality of living force would transform into the teleological concept of active matter, elaborated in the Universal Natural History (1755). In the treatise On Fire (1754), Kant would ﬂesh out the hypothesis of the ether, but once more failed to demonstrate anything conclusive about it. In the Physical Monadology (1756), he would decide to get rid of it, explaining what appears to be an ether as a dynamic effect of the forces of matter. The thoughts on substance, world, and substantial interaction, which set the tone of section I of the Living Forces, would become a focus of investigation in the New Elucidation (1755). There, in the third section of that treatise on ontology, Kant would construct a richly detailed and systematic theory on substance and causation in order to eliminate the ambiguities of the Living Forces.

2.3. The Mathematical Counterpoint and the Cartesian Mechanics of Force Section I concludes with a confession that sheds light on the overall structure of the Living Forces. Kant writes, I cannot hope to achieve anything decisive and deﬁnitive in a merely metaphysical investigation. Hence I turn to the following chapter, which will perhaps be capable to be more persuasive through the application of mathematics. (#19, I 30)

The metaphysical reﬂections in section I, in other words, cannot resolve the issue. They need to be supplemented by ‘‘the application of mathematics’’; that is, by the mathematical inquiry that constitutes section II of the book. There, Kant examines the quantitative conception of force held by the Cartesians, showing that it is valid and that the Leibnizian alternative fails on mathematical grounds. But mathematics does not have the last word; rather, the combination of mathematics and metaphysics does. He begins section III, the ﬁnal part of the Living Forces, with a reminder of the difference between mathematics and nature. According to Kant, laws that are mathematically invalid could still express genuine patterns in nature (#114, I 139), and bodies that are described by mathematics are ‘‘completely distinct’’ from the bodies in nature (ibid., I 140). Section II is longer than sections I and III combined. This longest part of the Living Forces, entitled ‘‘Examination of the Tenets of the Leibnizian Party

The True Estimation of Living Forces 47

on Living Forces,’’ consists of ninety-four paragraphs and a four-part appendix. This critical examination is the Cartesian-mathematical counterpoint to the initial Leibnizian-metaphysical theme. Upon a closer look, the focus of the section blurs into a hodge-podge of various motifs and ideas. Kant begins with a declaration of his method (#20–21), delves into a general critique of Leibniz (#22–30), and then expands this critique into a fastidious analysis that extends over the main stretches of the section (#31–87, #92– 113a). The critique en detail consists of considerations that concern falling bodies (#31–37), collisions of elastic bodies (#38–57), collisions of inelastic bodies (#58–70), composite motions and the parallelogram of forces (#71– 87), and Leibniz’s original argument against Descartes and Catelan (#92– 101). Finally, the critique peters out in a series of afterthoughts about various arguments and counterarguments by Wolff, Musschenbroek, Jurin, Chaˆtelet, and Richter (#102–13). As if these afterthoughts were not enough, Kant tacks on an appendix—but instead of addressing anything new, the appendix contains additional elucidations of previous paragraphs and an appraisal of the exchange between Chaˆtelet and Mairan. In the midst of the whole rambling sequence is a short essay on method (#88–91). With section II of the Living Forces, Kant reached the stylistic and philosophical nadir of his career. It shows Kant, the writer, at his absolute worst. The reader is forced to wade through a swamp of vague, repetitive demonstrations, mostly false, that pivot around ambiguous and insufﬁciently deﬁned terms. The organization of Kant’s critique, from the general to the particular, from the particular to the additional, and from the additional to the supplementary, creates a tedium of suffocating proportions.19 At any event, the crucial thesis advanced in section II, which Kant hopes to support through the long series of critical remarks, is that mathematics cannot prove mv2, and that mv2 does not correspond to a real existing physical quantity. The announcement of this thesis comes comparatively early in the section, after some preliminary objections to the Leibnizian measurement: We want to draw two inferences of importance from this consideration. The ﬁrst is: that mathematics can never provide . . . proofs in support of the living forces, and that a force estimated in this manner, even if it actually occurred, would remain, at the very least, outside of the realm of mathematical consideration. . . . The second inference, which I draw from the aforegoing considerations, is this: that the reasons of mathematics, instead of being favorable to the living forces, will always conﬁrm Descartes’s law instead. (#28, I 40–41)

Implicit in this passage is that Kant approves of Catelan’s objections regarding isochronous and asynchronous motions to Leibniz’s critique in the Brevis demonstratio, and that he remains unconvinced by Leibniz’s original argument itself (see also #30, I 43). He decides to defend Descartes’s quantiﬁcation to the hilt, unaware that he is digging his own grave in doing so. Confusing the Galilean times-squared law with Leibniz’s mv2, Kant believes

48 The 1740s: Kant’s Starting Point

that Leibniz misinterpreted Descartes’s remarks on the lever and was thus led into the error of the inverse proportion between a body’s height and its weight (#29–30, I 42–3).20 While discussing Leibniz’s core argument for the quantity of vis viva, he sums up the Cartesian result of the case: F gives body B a velocity of 4 units and raises B to a height of 16 units, after having previously raised A to the height of 1 unit (#92, I 101). If now both A and B are placed on a lever (inclinirte Schnellwage), B will raise A by means of F to a height of 4 units (I 102; see also ﬁg. 14, I 519). Remember that this is the same F which previously managed to raise A to a mere height of 1 unit. Undaunted, Kant sticks to his guns and thinks that the Cartesian measurement is right anyway. If the same force can suddenly increase fourfold, then so be it! Yes, Leibniz objected to this (#92, I 102), but he should not have said that the greater force is merely an effect of the previously transferred force (#93, I 103). It is certainly true that an effect can never be greater than its cause, but since the later force is greater than the earlier force, the greater force contained now in the machine must be a different force not derived from the smaller, original force. What about the inexplicable increase in force? Does this suggest a perpetuum mobile, as Leibniz charged? Evidently unaware of earlier Cartesian surrenders to this objection, like Denis Papin’s, Kant bites the bullet and declares, ‘‘eternal movement as such is not an absurdity in this case.’’21 Why does Kant make such curious claims in section II? Aside from their questionable scientiﬁc content, these claims are at variance with the results of section I. There, he had offered two arguments purporting to demonstrate the existence of vis viva. Both of these arguments aim not only to prove the existence of the metaphysical quality that is living force, but they also defend the accuracy of the mathematical quantity that is proportional to the square of velocities.22 Having argued for the metaphysical concept and its measurement in section I, he turns around in section II and demolishes one Leibnizian argument after another. Furthermore, he defends a Cartesian reading of the data in each and every case he considers.23 Of course, the central thesis of section II is patently false. Mv2 is indeed a quantity that describes a physical phenomenon (kinetic energy or work). But apart from this error, and despite the confusing appearances, the conﬂicting claims resolve into one—more or less—coherent perspective on the vis viva issue. Although Kant intends to preserve both vis viva and the quantity of motion (which had already been Leibniz’s intention), he does so by sacriﬁcing the mathematical aspect of living force (which was not an orthodox Leibnizian position). He employs a dialectical strategy to get where he wants. The Leibnizian thesis of vis viva is presented in section I, the explicitly metaphysical chapter of the treatise. But metaphysics, for Kant, is about quality and essence, and vis viva is going to be relevant in precisely this form—as a quality, not as a quantity. The Cartesian antithesis of the quantity of motion is presented in section II, the explicitly mathematical chapter. Mathematics is about quantity and measurement, and the quantity of motion matters to Kant in just this respect—as a quantity and not as a quality.

The True Estimation of Living Forces 49

Both the initial metaphysical theme and the subsequent mathematical counterpoint prepare the way for Kant’s synthesis in section III which reconciles the qualitative Leibnizian vis viva with the Cartesian quantity of motion. In the course of his Cartesian critique on Leibniz, he explains that this critique does not entail the renunciation of living forces: If the Leibnizians consider it necessary to the preservation of the world machine that the force of bodies is subject to the estimation according to the square, then we can grant them this minor demand. Everything that I have hitherto demonstrated and intend to demonstrate until the end of this section serves merely to convince them of the following: neither in an abstract assessment, nor in nature does there exist an estimation of the force of bodies according to the square and in the mathematical manner of the Leibnizians. But I do not completely renounce living forces on these grounds. I am going to show in section III of this tract that such forces, whose measure is the square of velocities, are indeed to be found in nature—only with the restriction that one can never discover them according to the traditional procedures; that they will always remain concealed from this type of examination (namely, the mathematical approach); and that nothing but a metaphysical investigation or a special kind of experience is capable of acquainting us with them. Therefore, we contest the mode of cognition [den modum cognoscendi], but not the issue as such. Accordingly, we agree with the Leibnizians on the main point, and perhaps we shall manage to achieve a consensus regarding the inferences drawn from it as well. (#50, I 59–60)

Although Kant’s gauche presentation gives the appearance that he switches sides from section to section, he pushes for the same agenda throughout. His overall goal in the Living Forces was neither to show that Leibniz was mistaken, as Watkins suggests (1995a), nor to show that Descartes was essentially right, as Adickes surmises (1924a). Instead, Kant intended to construct a better account of Leibniz’s living force—an account capable of digesting the long-standing Cartesian objections.24 This account, suggested already in the above quoted passage from the central section of the book, seems to involve a curious distinction between Cartesian mechanics and Leibnizian metaphysics in terms of quantity and quality. There are two approaches to nature, Kant implies; the one is mathematical in kind, the other is metaphysical in character. Metaphysics can, but mathematics cannot, conﬁrm the hypothesis of living force. Cartesian mechanics, which Kant equates with the mathematical approach, successfully identiﬁes the kinematic quantity of motion, but fails in its rejection of the quality of vis viva. Similarly, Leibnizian dynamics, which is taken as a metaphysical approach, succeeds in identifying the quality of vis viva, but fails in its proposed quantiﬁcation. Vis viva, in other words, is metaphysically and physically real, but it is not mathematically veriﬁable in the way that the Leibnizians hoped it would be. Kant’s distinction between Cartesian mathematical mechanics and Leibnizian metaphysical dynamics in terms of quantity and quality is curious.

50 The 1740s: Kant’s Starting Point

Kant lines up metaphysics with quality and mathematical natural philosophy with quantity. These claimed equivalences gloss over a number of actual differences—not only did Leibnizian dynamics concern itself with quantities and involved mathematical and mechanical aspects, but Cartesian mechanics dealt with qualities (such as shape and elasticity) as well and certainly had its share of metaphysical assumptions. Kant ’s actual assessment of the two investigative endeavors was more differentiated than his distinction suggests. He obviously knew about the quantitative side of Leibnizian dynamics and the qualitative side of Cartesian mechanics, because the overall argumentation in section II concerns both. Nonetheless, he presents the simplistic contrast between a mechanical, mathematical approach to nature that is lined up with quantity, and a metaphysical approach to nature that is lined up with quality. Why this historically problematic simpliﬁcation? Part of the answer is that Kant regarded this contrast as a useful means of categorizing investigative approaches in terms of their characteristic ‘‘modes of cognition’’ (#50, I 60); that is, in terms of their dominant cognitive tendencies and investigative foci. The Cartesian approach typically concerns mathematics and quantity (but is not reducible to these concerns). The Leibnizian approach evinces a characteristic interest in metaphysics and quality (although it is not restricted to it). Finally, mathematics involves quantities, whereas metaphysics is about qualities. This ﬁnal distinction, implicit throughout the Living Forces, is explicated in the student notes to Kant’s metaphysics course called Metaphysik L1: With regard to the cognitive principle, sciences are either (1) rational in that we attain cognitions through the autonomous activity of the understanding, or (2) empirical, when we encounter cognitions in that we are passive and are affected by external things. . . . With regard to the object, sciences are divided into (a) rational disciplines, whose subject-matter consists of pure objects. These sciences are philosophy/metaphysics and mathematics. The former deals with the qualities of the things; the latter concerns the quantities of the same. Or, [sciences are divided into] (b) empirical disciplines, whose subject-matter consists of the concepts of experience. (XXVIII.1 172–3; my emphasis)

To some extent, Kant’s agenda in the Living Forces foreshadows the strategy of the later precritical project. His agenda in the 1740s is that the ‘‘qualitative’’ approach of metaphysics and the ‘‘quantitative’’ approach of a mechanical philosophy are jointly needed for an exhaustive elucidation of the phenomenon of force. In the coming decades, the 1750s and ’60s, his strategy would be to harmonize qualitative and quantitative approaches and to combine them into a comprehensive philosophy of nature. A genuine understanding of any phenomenon of nature, not just of force, demands both a qualitative and a quantitative investigation. In the precritical project, both metaphysics and natural science had their due. A further element of Kant’s later strategy is that in head-on conﬂicts, natural science has the right of way and metaphysics must yield. Metaphysics must not be antiscientiﬁc; it

The True Estimation of Living Forces 51

must not set itself in direct opposition to scientiﬁcally proven claims; and to the extent that metaphysics states something that directly contradicts science, metaphysics is wrong and in need of revision. This further element would eventually sharpen into the methodology of the Prize Essay (1764), which subjugates metaphysics to the yoke of natural science. The germ of this attitude is contained in section II of the Living Forces. In the direct conﬂict between Leibnizian dynamics and Cartesian mechanics over the quantity of force, Leibniz is wrong and Descartes is right.

2.4. Kant’s Synthesis of Metaphysical and Mechanical Force Up to this point, Kant’s attempt at settling the dispute consisted of rescuing vis viva (the result of section I) while rejecting it as a quantity (the result of section II). The long middle section of Kant’s treatise, as turgid as it is, is essential to the development of this synthesis. There, Kant wants to make it emphatically clear that mv2 is not a physically relevant quantity, and that one should understand the earlier characterization of vis viva as a force proportional to the square of velocity merely as a mathematical convention and not as a physical description. Afﬁrming vis viva and rejecting mv2 seems to be Kant’s crucial move for settling the dispute. According to Kant, the Leibnizians captured what force is really about but failed in its quantiﬁcation; the Cartesians succeeded in quantifying force but erred in its metaphysical conception. Such a synthesis, however, needs a defense; in particular, since it apparently involves wildly implausible claims such as the suggestion of perpetual motion in section II. In the third and ﬁnal section of the book, Kant tries to explain what he means. Section III bears the title ‘‘On the True Estimation of Living Forces’’ and consists of 49 paragraphs. The organization of this section is tighter than the preceding inquiries. It begins with a discussion of mathematical and natural bodies (#114–6) which leads to an explanation of Kant’s concepts of intension (#117–21) and viviﬁcation (#122–3). The full account of living force follows (#124–5) supported by an experiment performed by Kant himself (#130). Next, Kant expounds his own ‘‘laws of viviﬁcation’’ (#131–46) and concludes the book with a survey of some empirical proofs for vis viva. Some, he thinks, are acceptable, some are not (#147–63). How can it be that both Descartes and Leibniz are right—that the Cartesian formula is the only correct formula, whereas the Leibnizian force is the only true force? The reason, Kant believes, lies in a fundamental distinction between mathematics and nature. He explains the gist of his synthesis in #115 (I 140). A quantiﬁcation of physical phenomena works only to a limited extent, and it cannot fully capture what physical phenomena are about. As the principles of mechanics illustrate, mathematics does not permit bodies to possess a force unless the force is fully generated by an external cause of the body’s motion. According to the mathematical conception of bodies,

52 The 1740s: Kant’s Starting Point

there is no internal force of the body, and the quantity of force must be proportional to the external cause of motion. This means that one can mathematically measure force as the quantity of motion, mv. In nature, however, things are different. A body in nature has an internal force which springs from the body’s inner potential (Vermo¨gen) and is triggered rather than fully caused by an external factor. The external cause of a body’s motion only ‘‘awakens’’ the slumbering living force of the substance, and the living force, once awake, multiplies the power the body receives from the external substance. As a result, the substance can possess a quantity of force bigger than the external quantity of motion would allow; the living force is not proportional to the quantity of motion but instead multiplies this external quantity giving rise to free motion. This means that living force is represented by mv2. The strange violations of mechanical and philosophical principles—the possibility of perpetual motion, the exception to the equality of cause and effect, the seeming creation of something out of nothing—will disappear, Kant thinks, if one takes a closer look at the inner potential of living force resting within substances. On the outside, it appears as if the force of a body can generate a kinematic effect that is larger than its external causal factor. But because the body possesses an immanent force all along, the kinematic effect that seems disproportionately large on the outside remains in fact causally proportional to the immanent dynamic cause. After all, motion is merely the empirical manifestation of an inner force. Considering that only external effects are measurable, Kant’s stipulated proportionality of internal dynamic causes and their kinematic effects still begs the question! In any event, the inner potential, or intension, is supposed to be the condition of force and the ultimate basis of dynamic activity (#117, I 141–2). Although there is vis viva only in nature and not in mathematical mechanics, there is vis mortua both in nature and in mathematics. The demarcation between mathematics and nature is not an insurmountable division between two incompatible spheres. Rather, mathematics underdetermines nature—mathematics captures some aspects of the dynamics in nature, such as dead pressure, but it does not capture all of them. Therefore, a mathematical dynamics is impossible given Kant’s premises, for mathematics can only describe part of the dynamic processes of nature. Metaphysics, the qualitative consideration of force and substance, must remain an essential part of dynamics. For Kant, the fact that dead pressure is the causal trigger for the kinematic effects of living force in free motions is indicative of a connection between the two types of force. Since physical processes occur in time, there must be a time interval after the external trigger and before the full presence of living force. This time interval embodies the transformation of a substance’s intension to its force; it is the viviﬁcation of the living force (#123, I 146–8). During the viviﬁcation, the body’s force remains measurable as mv; the measure mv2 applies only after the viviﬁcation has been completed (I 147). In this process, the dead pressure applied on a substance causes internal dy-

The True Estimation of Living Forces 53

namic echoes, repeated in ever-increasing magnitude by the intension, until the living force roars into existence (#122, I 146).25 In contrast to other Leibnizians, such as Wolff, Kant thinks he can furnish empirical proof of the viviﬁcation.26 He states in section III (#130, I 153) that he has performed a gunshot experiment which conﬁrms the successive awakening of living force. A bullet ﬁred at a piece of wood only inches away from the muzzle does not penetrate as deeply into the wood as a bullet ﬁred at a piece of wood several feet away from the muzzle. Kant reasons that the greater force of the bullet ﬁred at a greater distance is due to the internal multiplication of power from dead pressure into living force. The problem with this experiment, of course, lies in the interpretation of the result. It is true that the kinetic energy of a bullet ﬁred depends on the length of its travel, and that a bullet hitting a very close target has less terminal velocity than a bullet that hits a target farther away. But what actually happens is that the combustion of the gunpowder produces rapidly expanding gases that propel and accelerate the bullet. The expansion of the gas and the corresponding acceleration of the bullet do not stop inside the barrel of the gun but continue for a short distance beyond the muzzle. This explains the phenomenon that Kant mistook as the empirical evidence of a viviﬁcation. With the viviﬁcation of dead pressure into living force, Kant constructs a bridge spanning Cartesian mechanics and Leibnizian metaphysics. Vis viva, stripped of its quantitative meaning and trimmed to its metaphysical bones, is the dynamic essence of the monad. Seen in this way, there is nothing wrong with the self-generation of vis viva. The causal responsibility of the disproportionally small external factor for the larger ensuing kinematic effect is in some sense only apparent but not real. What seems like an absurd acceptance of a perpetuum mobile emerges as a qualiﬁed endorsement of an eternal intrasubstantial causation reminiscent of the preestablished harmony. On the other hand, the Cartesian dead pressure, capable of causal inﬂuence on the substance by triggering its internal development, reveals Kant’s sympathies to the mechanical philosophy and its corresponding causal theory of a physical inﬂux. At this point of Kant’s career, the two clashing accounts of causation remain in tense and uneasy juxtaposition. Instead of elucidating the connection, the viviﬁcation only furnishes a label for it. The problems of the Living Forces are obvious. Kant’s nonquantitative conception of living force is mistaken because mv2is in fact a physical quantity. His kinematic characterization of ‘‘dead pressure’’ and ‘‘living force’’ have little to do with their modern equivalents of momentum and work. The theory of viviﬁcation is sheer fantasy. The proudly declared experimental veriﬁcation of living force is a dud. Kant’s new dynamic law, that free motion, the kinematic effect of a viviﬁcation into living force, cannot occur in all grades of velocity (#132, I 154) is in ﬂagrant violation of Newton’s ﬁrst law of motion. Apart from these factual errors, this proposal for rescuing vis viva reels with internal contradictions as regards the proposed dynamics

54 The 1740s: Kant’s Starting Point

and its underlying philosophical assumptions. Having argued earlier that freely falling bodies rule out living force (section II, #31–7), he now declares that they do not rule it out after all (section III, #139); and having ﬁrst declared the triumph of physical inﬂux in section I (#6), the concept of viviﬁcation in section III opens once more the door to the preestablished harmony (#123–4). However, the most serious interpretive difﬁculty of the Living Forces involves the absence of a uniﬁed point of view. Considering Kant’s remarks in the earlier sections of the book, it seemed clear where he was heading: a synthesis of Cartesian and Leibnizian ideas was to be obtained by means of a dialectical maneuver. This involved a metaphysical argument in section I which played out the Leibnizian vis viva against Cartesian doubt, and a mechanical argument in section II, which played out the Cartesian measurement against the Leibnizian formula. The intended result of this antithetical maneuver, announced by Kant at numerous occasions, was supposed to be that living force is a metaphysical quality of physical signiﬁcance but is incapable of mathematical description. But in section III Kant changes his course. Now he remarks that one can measure living force anyway—vis viva turns out to be a quantity, and now, all of a sudden, the mathematical description embodied in mv2 accurately captures certain kinematic situations. Thus, at several points in section III, the hoped-for and promised synthesis collapses into its Leibnizian thesis. Having excised living force from the mathematical consideration of dynamics in section II and in the beginning of section III, Kant announces now the demonstration of mv2 from experience ‘‘with mathematical precision’’ (I 150). In sum, Kant’s own inconsistencies undermine our attempt to understand his approach as striving for a synthesis between the two conceptions of force. This theme, dominant in the bulk of the treatise, unravels at last, and Kant, who began with the announcement that one no longer had to cower in fear of the sway of great men, in the end meekly returns as a loyal soldier to the Leibnizian camp. The mocking verses by Lessing quoted in the beginning are not friendly, but they are justiﬁed. An unusually ambitious and intensely focused mind was at work in this treatise, but this mind was hamstrung by inferior writing skills and by gaps in academic knowledge. Even a charitable reading cannot rescue Kant’s ﬁrst philosophical treatise from the fact that it was an illinformed, disorganized, and self-contradictory student paper. Kant would later agree with this negative assessment. The Living Forces involved topics of supreme importance in the philosophy of nature, but their treatment fell short of a successful elucidation. Because the assumptions of the Living Forces were in need of further clariﬁcation, the book became for Kant a list of things to do. Sections I and III generated the items on this list. The conﬂict between mathematics and metaphysics—in particular, the limits of the applicability of quantitative investigations—became a topic that would resurface in the Universal Natural History (1755). Only there would he be able to suggest a satisfactory compromise. The hypothesis of viviﬁcation in-

The True Estimation of Living Forces 55

volved a union of two clashing accounts of causation. This union was forced because no arguments supported it. A more careful examination of physical inﬂux and preestablished harmony was necessary. In this regard, the New Elucidation of the First Principles of Metaphysical Cognition (1755) would become the philosophical legacy of these early stipulations.

T H R E E

On the Way toward the Precritical Project

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3.1 ‘‘Bilﬁnger’s Rule’’—The Method of the Middle Way Already when the Thoughts on the True Estimation of Living Forces appeared in print, Kant had second thoughts about this work. In August 1749, he wrote to Albrecht von Haller that he was busy with a sequel.1 If Kant thought that the treatise had truly succeeded, as he boasted in the conclusion of the tract, why would he want to continue working on the subject? Apparently, more needed to be said. The cocky conclusion of the Living Forces had been premature. But nothing ever came of the sequel; no drafts have survived, and we do not know when Kant dropped the idea. The next time he appeared to the public, with an essay on the question of whether the spin cycle or the speed of the axial rotation of the Earth will ever change, he employed an entirely different set of presuppositions. Neither Leibniz nor Descartes play a role in the Spin Cycle essay (1754); for the ﬁrst time, Kant proceeded exclusively from Newtonian considerations. It seems that the Living Forces had become in retrospect a false start. But despite the apparent discontinuity between Kant’s thoughts in the 1740s and the ’50s, the Living Forces is the key for understanding his works of the next decade. The Living Forces was a sustained attempt to harmonize two distinct perspectives on nature, although that attempt ailed from the contradictory meanderings of Kant’s argumentation. What he tried to rec56

On the Way toward the Precritical Project 57

oncile were not only two rivaling opinions on the estimation of force but also, more fundamentally, two views about the thrust of investigations in the philosophy of nature. Whereas the Cartesians stressed the quantiﬁable and empirical features of nature, selecting them as the objects of their inquiries, the Leibnizians emphasized the qualitative and metaphysical aspects of nature. As the quarrels over the right formula of force and over the correct explication of the principle of conservation revealed, Leibniz acknowledged a mechanical level of nature. His disagreement with the Cartesians was not over the possibility of a quantitative-empirical approach, but over its significance. Leibniz’s own changes of mind toward this issue illuminate Kant’s position in the Living Forces. In the Hypothesis physica nova (1671), probably the earliest of Leibniz’s writings on natural philosophy, the young Leibniz declared his ‘‘complete agreement’’ with Descartes and Gassendi.2 In the following years, Leibniz moved away from this position and adopted in the 1680s the adversarial position that would characterize his mature philosophy. But the disagreements over the principle of conservation, the laws of motion and collision, and the measurement of force only partially explain the conﬂict between the mature Leibniz and the Cartesians. Even after his rejection of the Cartesian premises, Leibniz considered a mechanical philosophy that would explain everything in terms of motion, size, shape, and extension as a laudable and useful enterprise. Mechanical philosophy as such is not the problem. It becomes a problem only if physics is reduced to it. Leibniz rejected such a reduction because the mechanical philosophy merely scratched the surface of phenomena. Motion, size, shape, and extension derive from and depend on a more basic dynamic constitution of nature, and a proper investigation of physical nature must take into account this ultimately nonmechanical structure. He wrote in the Discours de la Me´taphysique (1686), the ﬁrst presentation of his mature philosophy of nature, although all the particular phenomena of nature can be explained mathematically or mechanically by those who understand them, nevertheless the general principles of corporeal nature and of mechanics itself are more metaphysical than geometrical, and belong to some indivisible forms or natures as the causes of appearances, rather than to corporeal mass or extension. (#18, AG 51–52)3

If Kant was inﬂuenced by this distinction between a quantiﬁable surface level and a qualitative constitution of nature, he would have known it from remarks in Leibniz’s later Specimen Dynamicum I (1695).4 The famous Discours de la Me´taphysique, which contains the passage quoted above, and which came into existence a decade earlier, remained unpublished. It did not appear in print until 1765, when it was included in the ﬁrst edition of Leibniz’s works.5 In fact, surprisingly few of Leibniz’s texts were accessible when Kant worked on the Living Forces. During his lifetime, Leibniz had appeared to the public merely with one book, the The´odice´e (1710), and several articles in the Acta Eruditorum (such as the Specimen Dynamicum I) and

58 The 1740s: Kant’s Starting Point

in the Journal des Savants. The Monadologie was printed posthumously in 1721. The Protogaea and the Principes de la Nature et de la Grace, the only other texts that had become available after Leibniz’s death before the edition of his works, were published in 1749—that is, after the completion of the Living Forces. In Kant’s opinion, the quantitative-empirical perspective of Cartesian mechanics and Leibniz’s metaphysical perspective on the ‘‘general principles of corporeal nature and of mechanics itself ’’ address different levels of nature. They do not contradict each other, but rather complement each other. Kant’s hope in the Living Forces was that their successful combination would generate a universal dynamics that would be the ﬁrst step toward a comprehensive philosophy of nature. In the 1750s, Kant realized the two main errors of the Living Forces: he had put too much stock in Cartesianism, underestimating Newtonian physics, and he had misconstrued the relation of mathematics and nature. Newtonian mechanics became his new paradigm for a quantitative-empirical perspective on nature. But the switch to a new paradigm, to a new instantiation of the quantitative-empirical perspective, did not compel him to alter the original thrust of his philosophical explorations. The switch that occurred after the Living Forces replaced the instantiation not the perspective. During the two decades following the Living Forces, Kant kept on trying to unify the quantitative-empirical and the qualitative-metaphysical vantage points into a comprehensive model of nature. In that fundamental sense, the reconciliation of a quantitative kinematics with a qualitative dynamics in the Living Forces set the tone for the things to come. Kant had asserted in the Living Forces that the conﬂict over force would disappear as soon as one acknowledged that both sides were partially right— Descartes’s conception of force is the correct mathematical representation of force, and Leibniz’s conception of force is the correct metaphysical representation of force. Kant’s methodological remarks illuminate what he had in mind. He believed that his synthesis was entirely new and original, and he intended to reject any statement that struck him as being false, regardless of the fame of its author (I 9). To possess a ‘‘certain and noble’’ conﬁdence in one’s powers is not useless, because the search for truth may beneﬁt from leaving the mainstream of venerable doctrines (I 10). This ‘‘declaration of independence’’ had been the preamble of the Living Forces; it went further than similar declarations by other thinkers of the day. Christian August Crusius, Kant’s contemporary and the leading German philosopher at midcentury, maintained a certain amount of philosophical independence from theology. But the young Kant wanted to be independent from theology and from the philosophical tradition. Authorities are not always right he thought. The search for truth requires a critical scrutiny of any received idea. If this leads to the rejection of established views, then so be it. Neither Crusius’s nor Kant’s remarks were meant as outright rejections of the old. Crusius suffered, like Christian Thomasius, from the ideological rigidity of his pietist peers and wished to emancipate himself from their

On the Way toward the Precritical Project 59

theological constraints.6 Pietists such as Franz Budde (‘‘Buddeus’’), the most inﬂuential author of philosophical textbooks in Germany before Wolff, contended that the Bible is the only source of genuine knowledge. For example, in his popular Elementa philosophiae theoreticae (1703), Budde acknowledged the scientiﬁc superiority of the Copernican system but nonetheless opted for the Tychonian system because, as he reasoned, Tycho Brahe’s model harmonizes better with the words of the Scripture.7 Crusius resisted such dogmatic pressures and maintained his intellectual freedom, but in contrast to Thomasius never broke with the pietist cause.8 Similarly, Kant did not intend to repudiate the philosophical tradition and ignore the ‘‘venerable doctrines’’ altogether. But he did reserve the right to select from the philosophical tradition whatever might serve his aims, leaving the rest behind.9 Kant believed that independence was the stepping stone to the envisioned philosophical synthesis, but he also realized that no synthesis is possible without openness to established views. Independence as well as openness must be elements of any synthesis, but how can they be harmonized? Kant found a promising strategy in an insight by Georg Bernhard Bilﬁnger (‘‘Bu¨lﬁnger’’), a Wolfﬁan member of the St. Petersburg Academy. He begins section II of the Living Forces with the words: In the treatise, which Bu¨lﬁnger submitted to the Petersburg Academy, I ﬁnd an insight that I have always used as a rule for the examination of truths. If men of good sense, who either do not deserve the suspicion of ulterior motives at all, or who deserve it equally, maintain diametrically opposed opinions, then it accords with the logic of probability to focus one’s attention especially on a certain intermediate claim that agrees to an extent with both parties. (#20, I 32)

Bilﬁnger defended vis viva in contributions to the 1728 volume of the Commentarii Petropolitanae. His main work was the Dilucidationes philosophicae de Deo, anima humana, mundo, et generalibus rerum affectionibus (1725), a commentary to Wolff ’s German Metaphysics. In contrast to Wolff, whose views on causation and mind-body interaction began to waver under the continuous onslaught of his pietist critics, Bilﬁnger was known as a hard-headed defender of Leibniz’s preestablished harmony—in particular through his treatise Commentatio hypothetica de harmonia animi et corporis humani maxime praestabilita (1721). He belonged to the ‘‘textbook authors’’ who defeated the pietists and turned Wolfﬁanism into the reigning metaphysics of eighteenthcentury philosophy. The other members of this author group were Ludwig Philipp Thu¨mmig, Johann Christoph Gottsched, Johann Peter Reusch, Friedrich Christian Baumeister, Alexander Gottlieb Baumgarten, Gottlob Canz, Johann Friedrich Stiebritz, Andreas Bo¨hm, Georg Friedrich Meier, Heinrich Samuel Formey, and Johanna Charlotte Unzer (the only known female German philosopher of the age).10 Bilﬁnger’s promotion of the ‘‘certain intermediate position,’’ as Kant calls it, originally stems from his reconciliation of the Cartesian and the Wolfﬁan

60 The 1740s: Kant’s Starting Point

views on the metaphysical determination of being. This arcane controversy concerned the question of whether the notion of being needs to be analyzed through the notion of essence, as the Cartesians argued, or, whether the notion of being is better understood as the logico-ontological complement to the notion of possibility, as Wolff contended.11 In contrast to the vis viva debate, this ontological disagreement was resolved relatively painlessly. Bilﬁnger, in his Dilucidationes, suggested that both parties had been on the right track. The Cartesians had correctly identiﬁed the presence of a relation between being and essence, and Wolff had understood that this relation is a complementary one. Thus, Bilﬁnger suggested that the metaphysical determination of being must involve an essential analysis that reveals being as the complement of essence.12 Although Wolff did not change his mind upon the publication of Bilﬁnger’s Dilucidationes (1725) and continued to defend the unrevised deﬁnition of being as the complementum possibilitas in the Philosophia prima sive Ontologia (1729), Bilﬁnger’s intermediate position was a success with other textbook authors.13 In particular, Alexander Baumgarten, probably the most famous of the group, decided to follow Bilﬁnger rather than Wolff. In the inﬂuential Metaphysica (1739), Baumgarten deﬁned being as the complement of essentia, containing all the determinations needed for the internal possibility of being.14 Kant, who was well acquainted with the Dilucidationes, as well as with the Metaphysica (he would later adopt Baumgarten’s work for classroom use), found the desired methodological criterion of combining independence and openness in the strategy that Bilﬁnger had employed with such success in the resolution of the debate between the Cartesians and the Wolfﬁans over being. Bilﬁnger’s ‘‘rule,’’ as Kant calls it in the Living Forces, consists of the identiﬁcation of an intermediate position that agrees to an extent with both diametrically opposed opinions. Such a middle way, Kant observes, is the ‘‘safest route’’ for determining the truth in philosophical controversies (#21, I 32). For Bilﬁnger, the rule of the middle way was a strategy of constructing fair compromises between opposing views. For Kant, however, Bilﬁnger’s rule was more than that. The construction of a compromise is the end, but the means for achieving it consists of a dialectical comparison of the rivaling views. Kant remarks that many mistakes could be avoided if one put equal effort to ﬁnding proofs not only for the opinion one favors but for the opposite opinion as well (#58, I 68). We should not scorn anything that seems to support the contrary view; in fact, we should try our best to defend the contrary opinion. An ‘‘equilibrium of the understanding’’ will result from such an antithetical stance, and from this rational equilibrium, the truth will emerge (#59, I 68). In this modiﬁed and richer sense, Bilﬁnger’s rule is the methodological strategy that governs the organization of the Living Forces.15 It is not far-fetched to assume that Kant’s pietist background prompted his decision to adopt Bilﬁnger’s rule and modify it accordingly. As Hinske

On the Way toward the Precritical Project 61

(1972) observes, Kant attended Franz Albert Schultz’s lectures on dogmatics during his student years.16 Schultz, a pietist theologian at Ko¨nigsberg, favored a heuristic strategy in his lectures that involved the examination of opposing views. The concept of antithesis was central in postreformatory lutheran theology, and Schultz, who employed the ‘‘antithetic method’’ (as Hinske calls it) in his classes, was an important ﬁgure in Kant’s life. Schultz was not only the minister of the local congregation and a professor of theology, but he also served as the spiritual counselor of Kant’s mother, Anna Regina Kant (b. Reuter). As a close friend of the family, Schultz had been decisive in guiding the young Immanuel to an academic education;17 he had convinced the parents to send their son to the Collegium Fridericanum, a high school emphasizing classical languages and theology. Anna (the mother) admired Schultz, and both mother and pastor tried to persuade Kant to pursue a career as a lutheran minister.18 But Kant’s feelings toward pietism became ambivalent when he grew up. He continued to regard pietism highly in its theoretical and normative aspects, but he soon rejected it in its practical consequences. The pietist upbringing failed to make a believer of Kant. His experience at the Fridericanum had been mostly negative. He stopped going to the Sunday services, and after a few initial university classes in theology, he decided to study philosophy, mathematics, and science.19 Nevertheless, his later attitude toward pietism remained one of a respectful, appreciative distance and never soured to an outright rejection. He could not help being inﬂuenced by pietist concepts. Schultz was the ﬁrst to expose Kant to the style of reasoning that involved the dialectic scrutiny of opposing viewpoints in the search of the truth. The Living Forces was supposed to be a compromise solution to the vis viva dispute of the Leibnizians and the Cartesians. Evidently, this context precluded the mention of pietist pastors and their methods. On the other hand, Georg Bernhard Bilﬁnger’s credentials were impeccable. He was a Leibnizian philosopher, he had successfully settled an earlier philosophical argument with the Cartesians, and he had published on the vis viva question. Bilﬁnger was the perfect facade for Kant’s pietist method. Bilﬁnger’s rule was the philosophical guise of Schultz’s theological strategy, and this may have been why Kant so greatly emphasized it in his ﬁrst book. Without going into the speciﬁc roots and causes of this rule, other commentators, such as Gerhardt and Kaulbach (1979) argue that ‘‘dialogic-dialectic procedures’’ are characteristic of Kant’s development as a whole. These procedures, far from being limited to the Living Forces, were visible ﬁrst in the mediation between Leibniz and Newton, then in the mediation between Leibniz and Hume, and ﬁnally in the antinomy-chapter of the ﬁrst Critique.20 There is certainly some merit to this perception, and it is interesting to consider that the middle way, sparked by lutheran theology, articulated by a revisionist Wolfﬁan, and implemented as a method of mediating compromises, may have been Kant’s prototype of such procedures. On the one hand, Bilﬁnger’s rule makes practical sense for a newcomer who joins an ongoing controversy. Keeping an actively open mind, scruti-

62 The 1740s: Kant’s Starting Point

nizing both sides, and aiming for an intermediate position is the best way to learn what the controversy is about. The rule has an evident didactic and heuristic value for acquainting oneself with rivaling positions. Furthermore, the rule is worthwhile in political and diplomatic contexts; in situations, in other words, where compromises are the preferred solutions to conﬂicts between equally powerful parties. On the other hand, Bilﬁnger’s rule is worthless for settling philosophical disputes. Here, truth is at stake. The identiﬁcation of a middle way for the sake of ascertaining the truth is not the ‘‘safest route,’’ as Kant thinks, but a dead end. He surmises that both sides are somehow right because there are competent and reasonable men on either side and because their views are equally plausible (#20–21, I 32). His proposed ‘‘equilibrium of the understanding’’ begs the question by presupposing that there is merit to either side. It is a fallacy to assume that the truth will emerge in a ‘‘rational equilibrium’’—if there are two conﬂicting theories about a phenomenon, there is no logical reason to suppose that an intermediate position will be the correct one. This is the problem with Bilﬁnger’s rule: the very fact that it governs the organization of the Living Forces is the reason why the treatise failed. Kant’s self-imposed precept that the correct account had to be, in one form or another, a mean between two extremes was a methodological prejudice. It made an unbiased examination of the evidence all but impossible, and it prevented Kant from exploring the route taken by d’Alembert. In the Traite´ de Dynamique, d’Alembert settled the issue by deliberately avoiding a middle way. Because the qualitative perspective of force remained too vague, d’Alembert integrated both measures of force into his own dynamics while restricting himself to a quantitative, antimetaphysical perspective. The later revival of living force did not challenge d’Alembert’s deliberate onesidedness. The vis viva of the vitalists was short-lived and failed to evolve to a scientiﬁc concept, and the dynamic aspect of matter embodied in energy returned to science only when it had acquired a quantiﬁable form. The implementation of Bilﬁnger’s rule doomed Kant’s proposal in the Living Forces. But in a wider sense, the middle way of the Living Forces deﬁned Kant’s challenge for the next two decades: Kant’s quest for a grand synthesis of Newtonian science with his own metaphysical assumptions in the 1750s and ’60s found its ﬁrst explicit methodological expression in Bilﬁnger’s rule.

3.2 The Ontology of Mathematics and Crusius’s Mistake Kant was forced to deal with the ontological status of mathematics because mathematics played different roles in the perspectives of Leibniz and Descartes. According to the Leibnizians, mathematics can illuminate physical phenomena, in part, but for the Cartesians, mathematics can describe them in their entirety. In the spirit of Bilﬁnger’s rule, Kant’s early views on mathematics were a precarious balancing act between two incompatible positions. Kant agreed with the Cartesians that mathematical assessments are relevant for philosophy; since the investigation of force has to take quantitative con-

On the Way toward the Precritical Project 63

siderations into account, philosophy ought to be assisted by a quantitative approach. Therefore, mathematics needs to supplement metaphysics (#19, I 30).21 But he also sympathized with the Wolfﬁan assessment of mathematics: mathematical objects are in some sense artiﬁcial; they do not precisely map onto the objects of nature. That certain putative features of force ﬂy in the face of mathematical principles exempliﬁes this asymmetry between mathematics and nature. Mathematical entities and natural bodies differ in fundamental ways (#114–6). For Kant, this shows it is perfectly possible for metaphysical laws to stand at variance with mathematical laws (I 139–40). Crusius proposed a similar middle way between metaphysics and mathematics. Because Crusius was more outspoken than Kant, the problems that lingered as unresolved tensions in Kant’s assessment of mathematics were out in broad daylight in Crusius’s theory of mathematics. Like Kant, Crusius argued in the preface to his Physics, the Natu¨rliche Begebenheiten (1749), that mathematics needs to supplement metaphysics (C 4.1:454).22 Metaphysics alone cannot fully account for physical phenomena; such accounts also require mathematical and empirical inquiries. Thus, the philosophical investigation of nature cannot do without mathematics (C 4.1:454, pref.; 508, #5).23 On the other hand, Crusius noted, mathematical concepts differ from real objects; mathematical forces are not identical with the basic physical forces of efﬁcient causes, and mathematical hypotheses do not capture the real causes of things (C 4.1:481–2; pref.). Crusius’s ontology of mathematics, probably indebted to Andreas Ru¨diger, expressed a pietist consensus, but it remained untenable.24 Why should mathematics be part of an investigation of nature, if mathematics, given its abstract character, could not contribute anything essential to the disclosure of the structure and forces underlying nature? Crusius observed that mathematics is useful for natural philosophy because it provides us with precise concepts of bodies, their relations, and their manner of producing effects (C 4.1:517–8; #9). But if mathematical concepts are fundamentally distinct from physical objects and are thus of little use in describing them, as Crusius emphasized, why should the philosophy of nature need precise mathematical concepts for bodies in the ﬁrst place? Once again: What is the point of mathematics supplementing philosophy if the one is abstract, the other concrete? Perhaps Crusius could reply that mathematics clariﬁes the relations between the things, even though it does so only on the basis of data already given. In that case, mathematics would indeed be useful for physics. Such a reply would ﬁt into the traditional pietist perception of the auxiliary role of mathematics. But Crusius was paralyzed by a problem. His own conception of physics precluded him from putting the perceived worth of mathematics into philosophical practice. In the Natu¨rliche Begebenheiten, Crusius identiﬁed two functions of the ‘‘applicierten Mathematik’’ which at ﬁrst sight seem important for physical investigations: applied mathematics investigates magnitudes (C 4.1:507; #5), and it describes the extension of space (C 4.1:602; #59). If one compares these functions with what Crusius had to say about physics, then it becomes clear that he painted himself into a corner. The

64 The 1740s: Kant’s Starting Point

investigation of magnitudes and space is worthwhile but cannot have any bearing on physics, because physics, for Crusius, is not about magnitudes but about qualities (C 4.1:508; #5). In contrast to mathematics, physics investigates the essences of things: the properties and effects of natural bodies, and their efﬁcient and ﬁnal causes (ibid., 507). Physics, so to speak, is applied metaphysics. Since the investigation of magnitudes and space is the task of applied mathematics but does not concern physics, the mathematical elucidation of space turns out to be irrelevant as well. Space is an abstraction, an abstract quality derived from bodily existence, and not a genuine part of nature (C 4.1:636; #73). As a consequence, there is no such thing as empty space in Crusian physics, and space as such, the object of mathematics, is not an object of physics. In the end, Crusius was left with an unfortunate inconsistency. He wished mathematics to play a supplementary role, but he could not fulﬁll this wish. Whereas Newtonian physics involved mathematical investigations of magnitudes and relations, and assumed space as an objective framework in which bodies move, Crusian physics was hamstrung by its qualitative orientation and its ontological reduction of space. The young Kant anticipated the view of the Natu¨rliche Begebenheiten, but he hoped to keep the gap between mathematical entities and physical objects somewhat narrower. For Kant, such a gap existed only because bodies are different in mathematics and physics (cf. #114–5, I 139–40). Because Kant asserted that mathematical calculations can still map out some of nature’s real structures, the gap between mathematics and physics seemed to be bridgeable. Unfortunately, the result is more confusing than it is liberating, as Kant’s appraisal of the Cartesian measurement illustrates: The Cartesian analysis goes against the grain of nature. Thus it is not the true measurement of force in nature, but this does not prevent it from being the true and rightful measurement of force in mathematics. For there is a great difference between the mathematical concepts of the properties of bodies and their forces, and the concepts encountered in nature. It is sufﬁcient that we see that the Cartesian estimation does not contradict the latter. Now, we must connect the metaphysical laws with the rules of mathematics in order to determine the true measurement of force in nature. This will ﬁll the gap and will make better sense of the intentions of God’s wisdom. (#98, I 107)

Kant’s conundrum was that the Leibnizian conception of an inner force discloses nature’s intentions, but the Cartesian analysis of force is mathematically correct. True to Bilﬁnger’s rule, Kant negotiated between the Leibnizian and Cartesian claims and found himself committed to combining metaphysical laws and mathematical rules. What should such a coupling look like? In Kant’s account, F mv2 is a spurious formula (according to the claims in section II of the Living Forces) because Descartes, not Leibniz, was right about the mathematical conception of force. But vis viva exists anyway because Leibniz, not Descartes, was right about the real constitution of force. To resolve this tension, a uniﬁcation is needed. Kant sought it by enriching general philosophical principles so that

On the Way toward the Precritical Project 65

they would apply both mathematically and metaphysically. The principle of continuity is such an example.25 In Kant’s treatment, the principle of continuity explains that there is only one quantity of force on the mathematical level, and it explains that two distinct types of force are nonetheless present on the metaphysical level. In its mathematical sense, continuity implies for Kant the rejection of Leibniz’s twofold quantiﬁcation of force as both mv (the quantity of the vis mortua of a body at rest) and mv2 (the quantity of the vis viva of a body in motion). In the Leibnizian scheme, Kant argues, motion is the condition of a body possessing a force quantiﬁable as mv2 (#23, I 33). The problem with this scheme is that when a body with vis mortua is at rest at time t1 and moves with vis viva at t2, then one could imagine t1 and t2 as points on a line such that there is always a point in between, as Leibniz himself had acknowledged in his correspondence with Des Bosses.26 But what happens at this intermediate point when the body is on the verge of moving but does not move? The continuity of the time intervals implies a continuity between rest and motion that precludes the discontinuous switch from vis mortua to vis viva contained in the Leibnizian scheme (#26, I 37). The further one traces an intermediate time-point back to t1, the more the vis viva of the moving body will be subject to the conditions for vis mortua, until vis viva collapses into vis mortua (#25, I 35–6). Depending on one’s starting point on this continuous scale, it follows that either the quantity of vis viva is reducible to the quantity of vis mortua, or that there must be vis viva already in a body at rest (cf. ibid.; also #25 note, I 36–7). The lesson, for Kant, is that you cannot get to vis viva from vis mortua by means of mathematical continuity. Thus, a mathematical demonstration and quantiﬁcation of vis viva is impossible, and there is no such thing as mv2 in nature (#28, I 40). Mathematical continuity explains why vis viva, as mv2, is not a mechanical quantity, and metaphysical continuity explains why vis viva, as living force, still subsists as a quality. The principle of continuity, metaphysically understood, implies that the two force-types are the boundary conditions of viviﬁcation (#121–123). Since a body exerting vis mortua will acquire vis viva in a ﬁnite lapse of time, there must be inﬁnitely many intermediate stages between the two force-types (#122, I 145). An inﬁnitely small vis mortua transforms continuously and incrementally into the ﬁnitely large vis viva (I 145– 6). The qualitative difference between dead pressure and living force derives from a phase transition within a certain time interval. Metaphysical continuity is at the bottom of the viviﬁcation that establishes vis viva and vis mortua as distinct force-types at opposite ends of a continuous dynamic spectrum. Mathematical continuity leads, negatively, to the quantitative collapse of vis viva to vis mortua; metaphysical continuity leads, positively, to the qualitative transformation from vis mortua to vis viva. Therefore, it is not the case, as has been asserted by Friedman (1992b), that the principle of continuity has only a mathematical sense for Kant.27 On the whole, Kant’s employment of the principle of continuity is highly problematic. The metaphysical explanation of viviﬁcation through continuity just replaces one concept with another; Kant plays with words but fails to

66 The 1740s: Kant’s Starting Point

furnish any evidence. The mathematical collapse of living force into the quantity of motion presupposes that the starting point of the continuous series is rest involving mv, but such an implicit priority of rest over motion resurrects pre-Galilean assumptions. Kant would realize his mistake a decade later. In a lecture announcement with the title New Theory of Motion and Rest (1758), he would argue for the essential relativity and thus kinematic interchangeability of motion and rest. The concepts of motion and rest make sense only in respect to certain reference frames, but what is motion and what is rest depends on which particular inertial frame is assumed (II 16–19). Kant would note there that the principle of continuity was a beautiful and correct rule of reasoning in logic, but it could not be applied to physical contexts. The priority of rest over motion implied by the principle of continuity presupposes the ‘‘common notion of motion and rest’’ (I 22)—that is, the pre-Galilean assumptions that motion and rest are fundamentally different and that there is such a thing as absolute rest. Since this ‘‘common notion’’ is wrong, the principle of continuity in any of its physical applications is not only false, but also unnecessary, considering the new, relativistic doctrine of motion and rest (I 21, 23–5). In any case, the principle of continuity, as Kant had employed it in the Living Forces, failed to achieve the desired union of quantitative and qualitative approaches. But the more fundamental defect of any type of uniﬁcation in this setting is not that it would not work, but that it would remain pointless. Kant’s conception of mathematics destroyed any rationale for a uniﬁcation. Given that there is such a ‘‘great difference’’ (#98, I 107) between objects studied by the philosophy of nature and mathematical concepts, there does not appear to be any need to utilize mathematics in the philosophical investigation of force in nature. Within the philosophy of nature mathematics seems irrelevant, and the structure of the Living Forces revealed as much when one considers that its culmination, Kant’s synthetic theory of dynamics, was couched in words, not in formulas. As long as Kant maintained that ontological features of mathematical bodies differed significantly from ontological features of natural bodies, the quantiﬁcation of a natural phenomenon simply could not tell us much about that phenomenon. Despite Kant’s intentions, there was ultimately no difference between his and Crusius’s position.

3.3 Anti-Newtonian Implications The physics in the Principia was explicitly and emphatically a mathematical physics. After deﬁning absolute, accelerative, and motive forces in deﬁnitions 6–8 in the preliminary lesson to his work, Newton wrote, For I here design only to give a mathematical notion of those forces, without considering their physical causes and seats. . . . I likewise call attractions and impulses, in the same sense, accelerative, and motive; and use the words at-

On the Way toward the Precritical Project 67 traction, impulse, or propensity of any sort towards a centre, promiscuously and indifferently, one for another; considering those forces not physically, but mathematically: wherefore the reader is not to imagine that by those words I anywhere take upon me to deﬁne the kind, or the manner of any action, the causes or the physical reason thereof, or that I attribute forces, in a true and physical sense, to certain centres (which are only mathematical points); when at any time I happen to speak of centres as attracting, or as endued with attractive powers. (M 1:5–6; cf. also K 1:45–46)

Newton’s restriction to mathematical description was a characteristic feature of his approach in the Principia. Newton’s famous declaration at the conclusion of his work echoed his earlier restriction: But hitherto I have not been able to discover the cause of those properties of gravity from phenomena, and I frame no hypotheses; for whatever is not deduced from the phenomena is to be called an hypothesis; and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy. (M 2:547; cf. also K 2:764)

It follows, and Newton explicated this in rules 3–4 of book III (M 2: 398/400, K 2:552/555), that the phenomena are both the warrant and restriction of natural philosophy. We must exclude investigations into causes because they go beyond what is observable and quantiﬁable in the phenomena. For the same reason, we must exclude inquiries into essences. Although universal gravitation explains the motions of celestial objects, Newton’s own methodological restrictions prevented him from afﬁrming that gravity is essential to bodies (scholium to rule 3; cf. M 2:400, K 2:555). The objects of Newton’s inquiries were empirical phenomena, not causes or essences. Mathematical constructions served to illuminate the empirical phenomena by describing their physical structures. Evidently, the Newtonian philosophy of nature assumed the possibility of the physical application of mathematics. How eighteenth-century thinkers regarded the possibility of this application determined their regard for Newton. Crusius’s and Kant’s views illustrate this point. While Newton’s Principia presupposed a theoretical conﬂation of mathematical and real objects, Crusius’s Natu¨rliche Begebenheiten presupposed their ontological demarcation. As a result, Crusius’s physics, intended as an account of real objects, turned out to be a nonmathematical philosophy of nature. Crusius could accept Newtonian quantitative physics only as an abstraction, not as an accurate representation of nature (C 4.1:536; #21). He rejected universal gravitation as a description of an actual physical force and failed to jump on the Newtonian bandwagon. Kant’s case was more complicated. The divide between mathematics and reality in the Living Forces was a half-hearted boundary, and deliberately so, because that was the only way how Kant thought he could achieve a balance between the reality of vis viva and the validity of the quantity of motion. Corresponding to his lukewarm permission to use quantitative approaches in dynamics, a mixture of sympathy and reluctance

68 The 1740s: Kant’s Starting Point

characterized his attitude toward Newtonian physics. Because mathematics, in Kant’s view, partially described physical structures, Kant took Newton’s arguments into account just like the arguments of the Cartesians. But the consistently mathematical character of Newton’s approach prohibited its fundamental signiﬁcance for the Living Forces. Since Kant divorced bodies in mathematics from bodies in nature, arguing that features of the one are not necessarily features of the other, a mathematical approach to physical phenomena like Newton’s could inevitably have only limited worth. Just as mathematics has some, but not much, use for Kant’s description of natural objects, Newton’s science had some value, but not much, in illuminating the structure of nature. Consequently, although Newton’s fame was well established by the 1740s, it is not surprising that Newton remained conspicuously absent from the otherwise detailed surveys of the physical literature in the Living Forces.28 While Kant discussed Leibniz and his followers on almost every page and mentioned Descartes and the Cartesians almost as frequently, there are few references to Newton in the whole book—two to Newton, one to the principle of inertia, one to ‘‘Newton’s disciples,’’ and three to Jurin, a Newtonian philosopher of nature.29 Newton retained the Cartesian quantity of motion in the Principia (cf. def 2; M 1:1, K 1:40), and yet, Kant consistently referred to Descartes not to Newton when discussing the quantity of motion. He included Newton among those ‘‘great men’’ whom he no longer wanted to fear if truth turned out to be at odds with their views (I 7). Kant rejected the cornerstones of Newtonian physics, the laws of motion and Newton’s famous claim in the Opticks that ‘‘motion is much more apt to be lost than got, and is always upon the Decay.’’30 Essentially, his repudiations of Newton derived from his Leibnizian commitment to vis viva. There is no loss of motion in Leibniz’s dynamics, Kant explained, because God conserves the same quantity of force in the world. According to Newton, however, God does not, but compensates for the continuous loss of motion from the universe by infusing new motion in the world (#48). Kant ﬁrst ﬂirted with Newton’s idea (#50), and then rejected it as a ‘‘desperate excuse’’ and endorsed Leibniz’s position (# 50, I 59–60). Against Newton’s laws of motion in general, he claimed that a body at rest can set another body in motion (#51, I 60), that a perpetual motion is possible (#97–8, I 105–7), and that a small action can evoke a greater reaction (ibid.). Against the ﬁrst law in particular, he argued that it is invalid for small and great velocities (I 155), and that its validity in the intermediate range of speed is only superﬁcial because a full explanation of motions at intermediate velocities requires the metaphysical theory of viviﬁcation (I 156–7). Kant dismissed the law of inertia in its general form and replaced it in the Living Forces with his own new law of dynamics (#132, I 154–5).31 An apparent endorsement of the third law of motion by Kant turned out to be anything but. He employed what seems to be Newton’s law of the equality of action and reaction in order to refute the Leibnizian-Wolfﬁan proofs of the physical applicability of mv2 to the motion of elastic bodies

On the Way toward the Precritical Project 69

(#37–9). Not shy about praising himself, Kant found his own refutation elegant because the proofs (Schlu¨sse) are refuted by the systems (Lehrgeba¨ude) in which they originate—it is Wolff ’s law of equality of action and reaction that delivers the coup de grce to the Leibnizian-Wolfﬁan proofs (#40, I 50). Ignorant of the actual origin of the law, Kant identiﬁed it not with Newton’s third law of motion but with Wolff ’s law of interaction in the Cosmologia generalis #346 (W II.4, 252). While enumerating the various effects of the essential force, Kant surmised that the three-dimensionality of space derives from the law according to which the strength of the effect of substantive forces stands in an inverse proportion to the square of their distances (#10, I 10). As we have seen in chapter 2, it remains unclear whether the explicit reference to the inverse square is an implict reference to Newton’s inverse square law. If it were indeed intended as such, then Kant’s idea of a dynamic development of space would involve a fusion of Newton’s inverse square law and Leibniz’s relational space. Hence, if the three-dimensionality of space derived from an essential force of substances whose strength obeys this inverse square law, and if Kant indeed had Newton in mind here, then this would mean that Kant equated Leibniz’s vis viva with Newton’s force of gravity. Such an equation would contradict both Leibniz, who saw in gravity an instance of vis mortua, and Newton, who rejected the possibility of a vis viva.32 Moreover, Kant’s actual characterizations of living force do not sustain this reading; he likened gravitation to dead pressure in #15–18 and argued in #139 that the phenomenon of gravity neither proves nor disproves living force. The only clear sympathy for any Newtonian notion revealed in the Living Forces pertains to action at a distance (#143, I 164). But Kant did not understand its implications. The presence of action at a distance presupposes the possibility of empty space, while Kant’s own discussion of movement of space presupposes the existence of a resisting ether ﬁlling space.33 It would be an understatement to say that Kant in 1740 was not yet the Newtonian he would become in the next decade. Many commentators (Adickes, 1924a; Marty, 1980; Friedman, 1992b; Laywine, 1993) maintain that Kant had been a Newtonian throughout his philosophical career, from the very beginning to the very end.34 I contend that Kant’s actual appraisals of Newton in the Living Forces do not bear this out. This treatise was still light years away from the celebration of Newton in the Universal Natural History. In the 1740s, Kant either rejected Newtonian ideas out of hand, or he accepted them with severe qualiﬁcations. In part, Kant’s relative indifference to Newton was rooted in ignorance. He was not aware of the fundamental discrepancies between Newtonian physics and Cartesian mechanics. He portrayed the issue of force as a bone of contention between the Leibnizians and Cartesians, and characteristically lumped the Newtonians and the Cartesians together as the opponents of vis viva.35 Just as Kant’s account of mathematics ﬂuctuated between the exclusion of mathematics from nature and the endorsement of its value, his attitude toward Newtonian physics wavered between rejection and acceptance.

70 The 1740s: Kant’s Starting Point

In many respects, the Living Forces prepared the ground for the labors of the next decade. But it did so mostly in a negative and dialectic fashion. The continuity from the 1740s to the 1750s consisted in Kant transforming questionable and vague stipulations into systematic and precise claims he believed he could justify. But the crucial difference between these two decades of Kant’s early philosophizing was the changing assessment of Newton. In the 1740s, Newtonian physics was more the target of objections than anything else and possessed only marginal signiﬁcance for Kant. In the 1750s, a dramatic turnaround would occur, and Newtonian physics would become the celebrated centerpiece of Kant’s reﬂections on nature. Thus, Kant’s philosophy of the 1740s was tied to his philosophy of the 1750s through a continuity of issues but not through a continuity of theories. In the 1750s, when Kant transformed his earlier stipulations into systematic claims, they acquired different predications. His new philosophical orientation revealed a need to reexamine earlier stipulations and to ﬁnd better solutions to the problems that Kant’s ﬁrst book addressed but failed to master. Ultimately, what had remained of the Living Forces was nothing but a catalogue of questions.

II

THE

1750S

-0 T H E P R E C R I T I C A L P RO J E C T

Superior beings, when of late they saw A mortal Man unfold all Nature’s law, Admir’d such wisdom in an earthly shape And shew’d a Newton as we shew an Ape. Could he, whose rules the rapid Comet bind, Describe or ﬁx one movement of his Mind? Who saw its ﬁres here rise, and there descend, Explain his own beginnings, or his end? Pope An Essay on Man (1734) The cosmos evokes a quiet amazement through its immeasurable size and through the inﬁnite diversity and beauty that shine forth from all of its sides. It stirs the imagination to contemplate all of this perfection. But for reason there is a different delight, namely to consider how so much splendor, so much grandeur, ﬂows from a single universal rule with an eternal and right order. Kant Universal Natural History II.7 (1755)

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F O U R

The Conversion to Newton

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4.1 The Lesser Works of the Second Decade Kant left the university without a degree when his father died in 1746. He looked for a job and ended up earning his living as a private tutor in various rural estates. After nine years in the countryside, he came back to Ko¨nigsberg with the intention of completing his academic studies. When he returned to the university in 1754, a period of stunning productivity began. Within two years he had composed a master’s thesis, a doctoral dissertation, a habilitationsschrift (a postdoctoral thesis required for a professor), and had, on the side, managed to have one book and half a dozen papers published. He wrote on an extraordinarily wide scope of topics, ranging from monsoons to ontology. Contrary to what one might expect, this ﬂurry of activity resulted in several sound scientiﬁc insights, sophisticated philosophical theories, and surprisingly lucky guesses that anticipated future scientiﬁc discoveries. In the summer of 1754, Kant authored the Spin Cycle essay and the Aging Earth essay. These two articles appeared in a Ko¨nigsberg weekly. The one, printed in two issues in June, was on possible variations in the speed of the Earth’s rotation around its axis; the other, printed in a six-part series in August and September, was on the geological signs of the aging of the earth.1 During the same time, he worked on his second book, which he 73

74 The 1750s: The Precritical Project

published anonymously under the title Universal Natural History and Theory of the Heavens in March 1755. But Kant had bad luck with the manuscript. His publisher Peterson went bankrupt just when the book was at the press; most of the already printed copies were impounded on behalf of the creditors and ended up in a warehouse which eventually burnt down. As a result, this ambitious and farsighted work remained just as unknown as the earlier Living Forces.2 Unfazed by this setback, Kant composed a Latin treatise, the Brief Outline of Certain Meditations on Fire (‘‘Meditationum quarundam de igne succincta delineatio’’). In May 1755, he defended On Fire as his magisterarbeit or M.A. thesis, not as his dissertation as has been occasionally asserted (Cassirer, 1981; Ho¨ffe, 1994).3 After earning the master’s, Kant set his sights on obtaining the doctoral degree. The fruit of his doctoral work was the important New Elucidation of the First Principles of Metaphysical Knowledge (‘‘Principium primorum cognitionis metaphysicae nova dilucidatio’’). Some commentators claim that this inquiry into ontological principles was Kant’s professorial thesis or habilitationschrift (Schmucker, 1980; Ho¨ffe, 1994).4 In fact, it won Kant the doctorate in September 1755 and earned him the venia legendi, the permission to teach at the university as a lecturer or privatdozent. The university hired Kant as a lecturer in the fall term of 1755, a position that he kept for more than a decade until he accepted a job at the local palace library in 1766. (He had to wait one and a half decades after his habilitation before he attained a professorhip in 1770.) After he was hired as a lecturer he wanted to apply for a professorship—a post that had remained vacant for four years since the premature death of its prior holder Martin Knutzen. To qualify for the professorhip in mathematics and philosophy at his alma mater, Kant needed to write a third Latin thesis after On Fire and New Elucidation. In the winter of 1755/6, he explored the possibility of combining qualitative, metaphysical approaches with a quantitative, geometrical perspective in terms of a ‘‘physical monadology.’’ In April 1756, he defended the Joint Use of Metaphysics and Geometry in Natural Philosophy, the First Example of which Contains the Physical Monadology (‘‘Metaphysicae cum geometria iunctae usus in philosophia naturali, cuius specimen I. [primum] continet monadologiam physicam’’). This substantial tract, which served as his professorial thesis, qualiﬁed him for the position. But political happenstance defeated academic merit; the Prussian government decided not to ﬁll the late Knutzen’s post and rejected Kant’s application. Parallel to these scholarly efforts, Kant penned some popular pieces on the Lisbon earthquake. It must be remembered that this earthquake (actually, a seaquake) was not just a human catastrophe, but also a truly extraordinary event on both scientiﬁc and metaphysical levels. It was the biggest earthquake recorded in Western history. On 1 November 1755, the quake occurred in a submerged geological formation called the East Atlantic rise to the south of the Azores islands offshore of Portugal. The seismic tremors were felt all over the continent, and the sudden rise and fall of the coastal waters were observed as far away as Scotland and Sweden. The casualty of the quake was Lisbon, one of the cultural centers of eighteenth-century

The Conversion to Newton 75

Europe. A series of tsunamis rolled toward the Portugese coastline, overwhelming Lisbon with waves cresting at 12 meters (40 ft) above high tide level. The city was instantly destroyed, and in the subsequent chaos ﬁres broke out that merged into a ﬁrestorm incinerating the rubble, causing the death of 70,000 people. The destruction of Lisbon left the philosophical world shaken. Biblical analogies failed as possible explanations. Lisbon was not Sodom. The catastrophe occurred in a Roman Catholic city that was a repository of Christian art and civilization on a religious holiday—All Saint’s Day (Allerheiligen for Kant)—during church service. The victims who died were mostly worshipers crushed by collapsing church spires. However, those who chose to sin on this festive day survived; the town brothels at the eastern outskirts of the city were spared. Overnight, Leibniz’s theodicy was turned into a bad joke. In 1756, Voltaire attacked Leibniz in his Poe`me sur le de´sastre de Lisbonne, and in 1759, he let his Candide remark, ‘‘if this is the best of all possible worlds, then I do not want to know how the worst looks like.’’5 Kant wrote three articles in response to the Lisbon catastrophe.6 The ﬁrst article, an essay on the causes of earthquakes, appeared in 1756 in two January issues of the Ko¨nigsberg weekly. Kant’s theory of the cause of earthquakes showed some similarities to Leibniz’s Protogaea, a natural history published posthumously in 1749. Leibniz had argued that the surface of the earth contracted into a solid crust covering immense ‘‘bubbles’’ (bullae) or caverns ﬁlled with gases and moisture when the originally ﬁery earth cooled off.7 Similarly, Kant assumed that the earth’s crust covers gigantic caves whose ducts and passages follow the course of mountain ridges (I 419–20). The iron, sulfur, and water in these hollows form combustible gaseous mixtures which cause earthquakes when ignited (I 422). The second essay on earthquakes, a lengthy journalistic report of the history of the Lisbon event, was published by Hartung as a small booklet in February 1756. Kant repeated the main points of his earlier newspaper article and added a speculation about the origin of the caves that differed from Leibniz’s hypothesis: the caverns, according to Kant, were the result of the retreat of the primeval ocean that had once submerged all land (I 433). The third essay, a sequel to the aforegoing tracts, was printed in the local newsmagazine in April 1756. There, Kant repudiated the view that earthquakes are caused by invidious conjunctions of the planets and stars. The three papers revealed that he was more interested in the scientiﬁc side of the event, in the question of how it happened, than in the metaphysical problem of why it happened. He had already asserted in the earlier Universal Natural History that the cosmic evolution of nature toward self-perfection may involve local destructions. Hence, the Lisbon earthquake did not challenge his cosmogony in the same way as it did Leibniz’s theodicy. Such catastrophes, Kant insinuated in the ﬁrst earthquake paper, do not have a divine cause; as terrible as they were, earthquakes were accidents (I 420). In the second essay, in a provocatively titled section, ‘‘On the Use of Earthquakes,’’ he enumerated the beneﬁcient side-effects of the hypothetical cave

76 The 1750s: The Precritical Project

gases. The heat produced by their combustion warms up aquifers and produces thermal springs. It raises the temperatures on earth, making it habitable (I 456–7). The emission of these sulfuric gases into the atmosphere enriches the soil, and it ‘‘puriﬁes’’ the air from ‘‘animal emanations’’ (I 457). The purpose of earthquakes is something we simply do not know. We should not arrogantly assume that we understand God’s intentions, he emphasized; to look at the Lisbon earthquake as a divine punishment is nothing but a naive and misguided anthropocentrism (I 459–60). The Earthquake Papers contain a mixture of true insights and false assumptions. But a superior methodological approach distinguished Kant’s assertions from the guesses of his contemporaries. Instead of appealing to theological fantasies, or indulging in astrological superstitions, Kant searched for the facts and advanced empirically testable claims. Modern seismology has solved the mystery of earthquakes. In 1912, Alfred Wegener published his hypothesis of continental drift, and its later reﬁnement to the theory of plate tectonics explained earthquakes through the transverse movements of continental plates along their fault lines. Deepseated tectonic forces compress rocks and deform them. The elastic strain continues to build up until the rock breaks; the stored energy, suddenly released, pushes the failure surfaces past each other in opposite directions. The radiating seismic wave energy manifests itself as an earthquake. Most earthquakes are of this kind, but some happen for different reasons. Not only plate drift, but also volcanic eruptions can lead to the accumulation of elastic strains in the bedrock. The kinetic energy of a meteorite impact may cause earthquakes as well, even if the impact is not on the ground but on the upper layers of the atmosphere (as in the 1908 Tunguska event). Although Kant’s seismological hypothesis does not apply to the majority of cases, it is true that occasional destructions of caverns generate rock motions that result in small earthquakes. It is also true that underground hollows can contain combustible gaseous mixtures (for instance, deposits of natural gas). But Kant’s association of gas explosions and collapsing caves is not generally correct. The type of earthquake stipulated by him usually occurs when the cave roof breaks in, and this tends to happen when the cave has grown too large to support the weight resting above it, or when a gaseous or liquid deposit, such as an aquifer, shrinks, drains off, or is being depleted, eliminating the internal pressure that stabilized the hollow and propped up its ceiling. A similar mixture of right and wrong characterizes Kant’s speculations on the origin of caves. The details of his association of caves and water are mistaken because subterranean hollows are not the remnants of a vanished primeval sea. Moreover, prehistoric earth was never completely inundated by a global ocean, although ancient seas covered much of what is now dry land. But overall, Kant was still on the right track, because grottoes are usually formed by the erosive forces of water. They typically exist in limestone formations that have been scooped out by the ﬂow of carbonated groundwater. On the other hand, Kant erred—completely and unambigu-

The Conversion to Newton 77

ously—in attributing beneﬁcial effects to sulfuric emissions. Sulfuric gases such as sulfur dioxide (SO2), which can be released through seismic and volcanic events, bind with hydrogen in the atmosphere and enrich cloud droplets with sulfuric acid (H2SO4). The acidic precipitation can alter the pH value of soil and water beyond the tolerance limit of many organisms. The continuous and large-scale sulfuric emissions through industry and other human activities in the twentieth century have damaged forests, reduced biodiversity, and sterilized lakes. Kant genuinely solved scientiﬁc puzzles in other work done at that time. Although we normally do not think of Kant when we think of meteorology, he wrote two papers that contributed to the ﬁeld. In April 1756, the same month in which the third of the Earthquake Papers appeared, he announced his lectures for the summer in the traditional form, by way of a brief scholarly tract. This was the New Remarks towards an Elucidation of the Theory of Winds. A second lecture announcement followed in April 1757, with the title, Whether the West Winds in our Regions Are Humid because They Have Traversed a Great Ocean.8 In the Theory of Winds, the more important of the two meteorology papers, Kant stated a discovery which he ﬁrst mentioned in the Universal Natural History (I 223–4): the direction of coastal winds has to do with the thermal expansion of the air. During the day, the sun heats the land more than the sea, the air above the land expands and rises, the surface air pressure falls, and a surface wind starts blowing toward the land. At night, the air cools quicker above the land than above the sea; the air above the land contracts and falls, the surface air pressure rises, and the surface wind now begins blowing toward the sea (I 492–4). The same essay also contains a number of additional discoveries, concerning the origin of the trade winds, the equatorial passat, and the monsoon. Because of the spherical shape of the earth and its diurnal west-east rotation, points at the equator undergo a greater west-east movement than points in higher latitudes on the same longitude. This phenomenon applies to the earth’s surface, as well as to the air column resting above it, and it causes a corresponding deﬂection of a wind that blows perpendicular to the earth’s rotational direction. In the northern hemisphere, a north wind will turn into a northeastern and a south wind into a southwestern wind; in the southern hemisphere, a north wind will turn into a northwestern and a south wind into a southeastern wind. Because of the earth’s rotation, the trade winds, which blow from the subtropics toward the tropics, will turn into northeastern winds north of the equator and southeastern winds south of the equator (I 494–6). For the same reason, the equatorial passat is a steady east wind, blowing from east to west (I 496–8). At the end of summer, the wind direction changes, particularly in the northern hemisphere. Southwesterly monsoons then replace the northeasterly trade winds. Nobody had been able to unlock the mystery of the seasonal occurrence of the monsoon before Kant. He hit on the right solution by combining the two explanations of the coastal and trade winds. In the

78 The 1750s: The Precritical Project

northern hemisphere, in summer, the sun heats up the landmass of south Asia more than the equatorial sea. The resulting thermal expansion over the land creates a high pressure zone over the sea. After the autumn equinox, the balance shifts, the solar radiation weakens in the northern hemisphere, the landmass begins cooling off, and the air above it contracts. Monsoon winds start blowing from the oceanic high pressure zone into the now chillier coastal regions. Because of the rotational deﬂection, and corresponding to the deﬂection of the reversely blowing trade winds, this south wind coming from the equator turns into a southwestern wind. It picks up moisture over the sea and blows toward the northeasterly landmass. Arriving at the chillier coastal regions, the wind cools off; the moisture precipitates over the land; and the monsoon has arrived (I 499–500). The Theory of Winds is a remarkable paper, all the more so because its author produced his ﬁndings by theoretical deliberations alone, without doing either ﬁeld work or experiments. But not all of Kant’s insights were genuine ﬁrsts. George Hadley had discovered the reason of the trade winds a decade earlier in his Concerning the Cause of the General Trade-Winds (1735). Johann A. Segner identiﬁed the mechanism that determines the direction of the coastal winds in his Einleitung in die Naturlehre (1754), a book that had appeared two years before the Theory of Winds. Kant cites James Jurin, Barenius, Peter van Musschenbroek, and especially Edme Mariotte (the remarkable physicist who explained the celestial coronae, discovered the eye’s blind spot, and articulated the gas law of the same name), but he does not refer to either Hadley or Segner. It is likely that Kant came up with his results independently and was unaware that others had already published the right solutions. His theory of the monsoon, however, qualiﬁes as a genuine discovery. It was historically the ﬁrst correct account of the cause of this phenomenon.9 Only months after he started teaching in the summer term of 1756, Kant was forced to abandon his research ambitions. His work load as an instructor was excruciating; he had to teach between sixteen and twenty hours per week. Most of these classes required individual preparation; the West Winds lecture announcement of 1757 lists a program of courses ranging from natural philosophy to mathematics to logic to metaphysics (I 501–2). It seems that Kant did not particularly mind, at least not publicly. His presentations were known for their lively and enthusiastic style, and as a teacher he was a great success with the students. Nevertheless, these never-ending obligations soon impeded his scholarly productivity. For the next seven years, Kant published almost nothing. In the remainder of the 1750s, he managed to write just three short essays, and he wrote them only because he felt obliged to do so. His professional duties required him to advertise his courses in the form of a published essay on any given topic at least once a year. These advertisements consisted of a brief tract explaining a phenomenon or demonstrating a thesis, followed by a postcript which contained the courses scheduled for the upcoming term. Three course announcements were printed from 1757 to 1759: the already mentioned West Winds (April 1757), the New

The Conversion to Newton 79

Theory of Motion and Rest (April 1758), and the Attempt at Some Reﬂections on Optimism (April 1759). That was all; Kant was busy teaching. The next time he would be able to sit down and write would be in the next decade.10

4.2 The Spin Cycle Essay and the Theory of Tides The most important precritical works in the 1750s were the Universal Natural History, the New Elucidation, and the Physical Monadology. The Spin Cycle essay (1754), which preceded them, was only a short paper, but it prepared the ground for the philosophical innovations Kant made in those subsequent works. The essay shows how far Kant had come since the student piece of the 1740s, and it reveals a complete change of mind compared to the stance adopted in the Living Forces. The arguments in the Spin Cycle essay proceed exclusively from Newtonian considerations; no other natural philosopher is even mentioned in the published version of the essay. Newton had become Kant’s scientiﬁc reference point.11 The importance of Kant’s conversion cannot be underestimated. He would never waver from his commitment to Newtonian physics for the rest of his life. Not only would this commitment contribute later to his characterization of nature in the Critique of Pure Reason (1781) and inspire a whole treatise of its own, the Metaphysical Foundations of Natural Science (1786), but it also made, in the 1750s, Kant’s precritical project of a uniﬁed and comprehensive philosophy of nature both possible and necessary. Having discovered with Newtonian physics a theory that could serve as a universal account of physical nature, Kant had acquired one of the two components for the envisioned synthesis that the precritical project was about. The second component, metaphysics, involved general assumptions: the unity of nature and the purposiveness of its development, the possibility of freedom, and the presence of God. Here, Kant was on his own. No Newton of metaphysics was available to Kant. He had to construct new theories because he realized that the demonstrations furnished by the rationalists, the Wolfﬁans, and the pietists were at best a hodge-podge of plausible and implausible ideas. Newton’s scientiﬁc description of the motions of the bodies in the solar system was the most compelling account of cosmic mechanisms. Through the unconditional acceptance of Newton, Kant’s paradigm of knowledge had become the celestial mechanics. This new paradigm was as liberating as it was threatening, for to promote Newtonian physics to a paradigm suggests that mechanism is the ideal form of knowledge. What will this do to our metaphysical assumptions? If mechanism is the new standard for our explanations, then whatever we can explain we will have to explain mechanistically. Inevitably, the world would then emerge as a closed deterministic system whose parts and processes are in their totality governed by empirical laws. Can there be a higher purpose in such a world? Can there be freedom? Can there be a God? All of a sudden, the assumptions of purpose, freedom, and God become questionable, and as questions they become urgent. This was the ﬂip-side of the liberating conversion to Newtonian physics. Its enor-

80 The 1750s: The Precritical Project

mous explanatory and predictive power prompted Kant to accept it as the new model of nature. His acceptance left him no choice but to reconcile Newtonian physics with the very assumptions of purpose, freedom, and God that it now threatened to destroy. Kant was in awe of Newton’s theory of universal gravitation. In the Spin Cycle essay, he described attraction as ‘‘nature’s universal engine,’’ by means of which Newton unpacked the secrets of nature in a manner that was ‘‘as clear as it is indubitable’’ (I 186). He announced, at the end of the essay, his forthcoming Universal Natural History under the revealing tentative title, ‘‘Cosmogony, or the attempt to deduce the origin of the cosmos, the constitution of the heavenly bodies, and the causes of their motions, from the general laws of motion of matter according to Newton’s theory’’ (I 191).12 A ‘‘cosmogony’’ (Kosmogonie) is the account of the birth and formation of the cosmos. For Kant, only superlatives were adequate in assessing Newton’s achievement. In the third of his Earthquake Papers, in 1756, Kant declared the theory of universal gravitation as human reason’s most successful attempt at understanding nature (I 468). The Spin Cycle essay, which marks the Newtonian conversion, is an investigation of the rotational velocity of the earth. Is this speed constant or decelerating? Under what circumstances would the earth’s rotation slow down? The terrestrial spin cycle would lengthen and its rotational speed decrease if space were ﬁlled with some resisting material. We could imagine that the friction of such a resisting material would impede and ultimately exhaust the axial rotation of the earth. But such a scenario is merely hypothetical. We do not need to worry about the earth being slowed down by some cosmic matter, Kant thinks, because Newton had convincingly shown that celestial bodies, including the earth, move with free and unhindered motion through space (I 186). The only external factor that inﬂuences the motion of the earth consists of the gravitational attraction of the moon and the sun (I 186). The topic of the essay, the axial rotation of the earth, almost begs to be approached through the Cartesian vortex theory. Kant’s approach is different. He thinks that the vortex theory is false and that questions pertaining to terrestrial rotation must be resolved by means of Newton’s theory of universal gravitation. Vortices require an ether, a cosmic medium that can propagate as well as resist, but such a cosmic medium does not exist because, as Kant believes now, space is empty. Kant articulates this new view with old words: space is ﬁlled with an ‘‘inﬁnitely small resisting’’ matter that allows free and unimpeded motion (I 186). In the Living Forces, Kant had claimed that space was ‘‘inﬁnitely subtle’’ (I 29), ﬁlled with matter, ‘‘but with inﬁnitely thin, and accordingly inﬁnitely weakly resisting matter’’ (I 115). Although the words are similar in the Living Forces and the Spin Cycle essay, they express greatly different views. Kant’s conversion to a frictionless and, for all practical purposes, empty space corresponds to his denial of the resistance of particles dispersed in space. In the Living Forces, the ‘‘inﬁnitely

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weak’’ resistance of spatial matter was dynamically relevant; by the time of the Spin Cycle essay, it had become inconsequential. Kant had argued in the Living Forces that it takes more force for a faster body than for a slower body of equal size (#17) or mass (#104) to traverse the same space. This assertion was an important weapon in the defense of vis viva. Kant integrated this claim in an argument that concerns, as he put it, ‘‘the nature of motion according to the concepts of metaphysics,’’ and that, as he added in a footnote, is a proof of Leibniz’s opinion which ‘‘is really correct, as long as it is in some way qualiﬁed’’ (I 29). Suppose a body A moves with a speed of 2 units and a body B moves with a speed of 1 unit. Both A and B travel along the same path. In an inﬁnite amount of time, A will traverse twice the space of B. But because A moves twice as fast as B, A hits the ‘‘inﬁnitely small masses of space’’ with twice the speed of B. How can we measure the forces involved? Force is measurable by the sum of all occurring effects (#17), and here, two effects occur—the traversal of a distance deﬁned in terms of the quantity of spatial moleculae, and the manifestation of a force deﬁned in terms of the intensity of the impact with which the moving body hits the spatial moleculae. According to Kant, each of these effects is proportional to the speed of the moving body. The total effect (the quantity of the actual force, metaphysically understood) is proportional to the product of these two component effects (that is, to the square of the speeds). If A moves with twice the speed of B, then the force FA will be four times as large as the force FB. The dynamically relevant resistance of the ‘‘inﬁnitely small masses of space’’ in the Living Forces demonstrated for Kant the existence of a vis viva proportional to the square of velocity. He associated the concept of an inﬁnitely weakly resisting spatial matter with a spatial plenum. Considering the goal of the Living Forces, this association makes perfect sense, for both Leibniz and Descartes agreed that space is not empty (either because of Leibniz’s principle of plenitude or because of Descartes’s ether theory), and Kant’s reconciliatory arguments reﬂected this common ground in the controversy. The spatial plenum, for Kant, had an ‘‘inﬁnitely weak resistance’’ in the sense of a genuine but small resistance—genuine, because it served as the determining factor of force, but small, because it permitted eternal motion. The Spin Cycle essay, however, reveals Kant’s subsequent realization that the earlier conjunction of free motion and spatial resistance is selfcontradictory. If a body could move forever through space, then space would be devoid of resistance, ruling out the measurement of the force of a moving body through the length and velocity of the body’s spatial traversal; on the other hand, if we actually could measure force in this way, then space would have a resistance, implying that the unimpeded motion of bodies through space could not be constant. In this essay, Kant opted for a Newtonian void. He used ‘‘inﬁnitely small resistance’’ in the Spin Cycle essay in the scientiﬁcally orthodox way, referring physically to a vanishing quanitity and mathematically to zero. A body traversing space may still meet with particles on

82 The 1750s: The Precritical Project

its trajectory, but neither the quantity of the particles encountered nor the intensity of their impacts are indicative of the forces involved. He now considered these factors negligible. Cosmic space may be ﬁlled with some remnants of matter or gaseous traces, but for the purpose of mathematical and kinematic simpliﬁcation, we can treat this diffuse impurity of a mostly empty space as if it were a void. The terminological transition regarding the inﬁnite, with its implications for space, motion, and force, reﬂected the growing inﬂuence of Newton on Kant. Philosophically and literally, Descartes and Leibniz had dropped out of the picture.13 How did Kant now tackle the question of the earth’s rotational cycle? According to Newton’s principle of inertia, the motion of a body will continue unless an external force acts on it. There are external forces acting upon the motion of the earth, but they do not consist in a possible resistance of space, but rather in the combined effect of lunar and solar gravitational attraction. The evident effect of solar gravitational attraction is the orbital motion of the earth. A less obvious effect, of primarily lunar and secondarily solar gravitation, is the tidal motion of the earth’s oceans.14 Newton laid the ground for his theory of the tides in the corollaries to a proposition in book I of the Principia (bk.I, prop. 66, cor. 18–22). The general context of proposition 66 is the three-body problem (bk. I, prop. 65 9), which involves the questions of how the motions of three bodies under mutual attraction can be calculated, and how perturbations effected by a distant third body will change the elements of a Kepler orbit. The insights Newton gained while trying to get a grip on the three body problem became the basis of the lunar theory that he announced in book II (prop. 35: scholium) and developed in book III (prop. 17, 21–23, 26–35). He summarized his theory of tides in proposition 24 (theorem 19): ‘‘The ﬂux and reﬂux of the sea arise from the actions of the sun and moon.’’ In the subsequent scholium (K 2:613–18, M 2:435–40), Newton explained what he had in mind.15 The tidal action of one gravitational body on another consists of the effect of equal bulges at antipodal points of the attracting body. The gravitational effect of the sun turns out to be about only one half (actually .44) of the moon, because the greater mass of the sun is more than compensated for by the sun’s greater distance to the earth. The oceanic bulges caused by the moon and the sun are carried, independently, by friction with the changing positions of the moon and sun. Thus, the kinematics of the oceanic tides needs to take into account the orbital motion of the moon about the earth and of the earth about the sun, both coupled with the rotation of the earth. A high tide occurs when a particular location on earth is carried past the gravitationally generated oceanic bulge. Spring tides occur when the moon and the sun are aligned such that their gravitational forces are directly added, causing the strong high tides at the new and the full moon phase. The weaker neap tides happen at the ﬁrst and last quarters of the moon when the moon and the sun are at different positions. Newton’s account was the basis of Kant’s argument. Given that the axial rotation of the earth, like any motion, can be inﬂuenced by external actions,

The Conversion to Newton 83

the question arises whether the lunar and solar gravitational attractions that generate terrestrial tides can also inﬂuence the earth’s rotation. If the earth were a perfectly solid body, Kant argued, then its rotation would continue forever. But any signiﬁcant amount of liquid on earth will be subject to lunar and solar gravitation and thus rise and fall in a tidal movement. Since the gravitation of the moon is the primary force acting on the oceanic bulges, the tidal motions are largely synchronized with the lunar revolution. In other words, the tides rise on the regions of earth that are directly below and directly opposed to the position of the moon in the sky. But although the tidal motions are synchronized with the lunar revolution, the lunar revolution is not synchronized with the terrestrial rotation: the moon completes one orbit per month, whereas the earth revolves around its axis in a day. This difference is crucial. The ever-changing directions of the cyclic water currents involved in the rise and fall of the tides counteract the neverchanging direction of the rotation of the earth. It must follow, Kant inferred, that these tidal movements retard the terrestrial spin cycle (I 187, 189). In the remainder of the Spin Cycle essay, Kant dealt with two questions this inference raises. What will the end of the spin deceleration look like? And, when will this ﬁnal stage occur? Because the moon impedes the terrestrial rotation through the asynchronous swelling of the tides, this retarding effect will cease when the swelling of the tides has become synchronous with the motion of the moon. The lunar retardation will not lead to a complete halt of the terrestrial rotation, but will force the earth’s spin cycle to fall in harmony with the moon’s revolutions. When the earth spins around its axis in the same pace as the moon revolves around the earth, the deceleration of the rotational speed will end, leaving the remaining velocity constant. Thus, in the far future, Kant surmised, the earth will always face the same side to the moon, and the terrestrial day will eventually last a whole month (I 190). According to Kant’s calculations, this ﬁnal stage will happen in two million years (I 188). Kant’s calculation was wrong, but his general theory was correct. The rotational speed of the earth is indeed decelerating for the reasons described, and as we know now, the ﬁnal month-long earth day will occur ﬁve billion years in the future.16 Not only was he right in suspecting the retardation of the terrestrial rotation, but he also succeeded in identifying the actual cause of the retardation which involved a new application of Newton’s theory of the tides. Kant discovered the cause of the deceleration in the asynchronity of lunar revolution and terrestrial rotation, together with the retarding friction caused by the oceanic tides. In the nineteenth century, the German scientist Robert von Mayer (known as the ﬁrst to articulate the law of the conservation of energy) veriﬁed Kant’s prediction of the spin retardation in his Dynamik des Himmels (1848), without being aware of Kant’s previous work on the issue. The insight that the earth is slowing down received further conﬁrmations through the work of French and British physicists and became general scientiﬁc knowledge in the second half of the nineteenth century.17

84 The 1750s: The Precritical Project

Typical of so many precritical texts, the Spin Cycle essay remained completely unknown. It appeared once in a local newspaper, the Wo¨chentlichen Ko¨nigsbergischen Frag-und Anzeigungs-Nachrichten, and was subsequently forgotten, suffering the usual fate of newspaper articles. The Spin Cycle essay was not reprinted during Kant’s lifetime. The aging Kant resented all the efforts of his youth, and the Spin Cycle essay was no exception. It fell into the very oblivion that the critical Kant desired for his whole precritical oeuvre. We can only speculate why the old Kant extended his rejection to encompass this marvelous little paper. Maybe he associated irritating memories with it. The Prussian Royal Academy of Sciences had announced the problem of the earth’s rotation as its prize question for 1754.18 Deeming his own reﬂection too insigniﬁcant to merit submission, he did not enter the competition and merely wrote his ideas up for a newspaper commentary on the academy’s question. This modesty must have hurt, because Kant’s humble newspaper article was right on the mark, whereas the erudite essay that won the trophy was both inferior and wrong. In 1756, a Jesuit scholar, P. Frisi, from the University of Pisa, received the prize for arguing against the possibility of a spin retardation.

4.3 On Fire and the Puzzle of the Ether The Brief Sketch of Certain Meditations on Fire (‘‘Meditationum quarundam de igne succincta delineatio’’; 1755) is a largely speculative account of combustion, thermal changes, and chemical reactions. Since ﬁre has to do with the thinning of bodies and their structural dissolution, Kant wanted ﬁrst to discuss the cohesion of matter and the nature of ﬂuids (I 371). He accordingly concerned himself with the nature of solid and liquid bodies in section I and developed a theory of heat, ﬁre, and cold in section II. On Fire is neither scientiﬁcally sound nor philosophically important. What is interesting in this magisterarbeit is the question which it raises about Kant’s Newtonian conversion. Having accepted Newtonian physics as his scientiﬁc platform, Kant now constructed a theory of ﬁre that used the ether as its pivotal explanatory hypothesis. The ether seems to belong to pre-Newtonian physics; it has its natural home in the Cartesian vortex theory. Yet, Kant did not seem to think that he had overstepped the bounds of a solid philosophy of nature in doing so. Evoking Newton, Kant began his tract with a methodological statement to the effect that his investigative strategy is guided by geometry and experience (I 371). How was it possible for Kant to be a Newtonian and to endorse the ether? Kant’s overall views on the ether were as subtle and ﬂuid as the ether itself. After endorsing the ether as a cosmic medium in the Living Forces, he rejected the cosmic ether in the Spin Cycle essay. On Fire involved a consideration of the ether as a molecular medium. This type of ether permeates the interstices of bodies. Solid as well as liquid bodies consist of particles that are not in immediate contact but coalesce by means of an ethereal,

The Conversion to Newton 85

elastic, and mediating matter (I 372, section I, proposition 3). Kant used this assumption for explaining physical state transitions and the elasticity of bodies. The molecular ether, labeled ‘‘materia elastica,’’ ‘‘materia ignis,’’ and ‘‘aer elasticus,’’ is the carrier of warmth and light among the atomistically conceived particles of matter. ‘‘Fiery matter’’ is an aspect of this elastic matter, and its wavelike and vibrating motion among the molecules manifests itself externally as heat (I 376, sect. II, prop. 7). The molecular ether, compressed by the force of attraction into the interstices of the bodies, is the substance of heat and light (I 377, sect. II, prop. 8). Kant dismissed On Fire only a year later. In the Physical Monadology (1756), he chose not to explain physical state changes through an elastic ether. This was not so much a rejection of the ether, but rather the resolution of its mystery. He concluded the Physical Monadology with the claim that the bodily elements themselves generate an elastic medium and force (I 486). The theory of dynamic matter which Kant developed in this treatise involved the assumption of active simple substances equipped with attractive and repulsive forces. Their interplay generates elastic and permeating force ﬁelds. The ether is thus revealed as a phenomenon; it is not a primitive component of nature, but can be reduced to a side-effect of substantial forces. The advantage of the theory in the Physical Monadology was that it made the addition of the molecular ether as an auxiliary hypothesis unnecesssary. This remained Kant’s deﬁnitive view on the subject during the precritical period.19 The ether returned in the critical philosophy. The early Kant had constructed the physical monadology in order to show that it was possible, as well as useful, to unify metaphysics with the exact sciences. Through the critical turn, metaphysical theories of any kind had become problematic. This robbed the physical monadology of its explanatory power and jeopardized it as a substitute for the ether. Apparently, the molecular ether could not be eliminated so easily after all. In the Metaphysical Foundations of Natural Science (1786), in the chapters on Dynamics and Phenomenology, Kant ﬂirted with the possibility of an ether that functions both as a cosmic air permeating the universe (IV 534, 564), and as a wa¨rmestoff, a ‘‘caloric matter,’’ ﬁlling the interstices of bodies (IV 532).20 At the end of his life, Kant threw caution to the wind and dramatically resurrected cosmic and molecular ether in the sheets of the Opus Postumum. There the ether expanded into an unlikely material basis of the transcendental turn, and Kant offered an a priori demonstration that presupposed, in all earnestness, the existence of the ether for the validity of the critical account of cognition.21 As David Hume realized, the concept of cosmic ether had a great advantage; hypothetically but common-sensically, it explains gravity in terms of an underlying mechanism.22 Without the cosmic ether, universal gravitation would be strictly an action at a distance. But is this plausible? Characterizing universal gravitation as an action at a distance or as a stringless pull moves gravity into the vicinity of occult powers. Newton himself clearly perceived this difﬁculty. He wrote to Richard Bentley (25 February 1692/3),

86 The 1750s: The Precritical Project It is inconceivable that inanimate brute matter should, without the meditation of something else which is not material, operate upon and affect other matter without mutual contact.23

The ether was the sine qua non of a successful mechanical philosophy.24 The early Newton endorsed a material ether just as Kant did in the On Fire treatise. In the Questiones quaedam philosophiae (1644), Newton argued that attraction is just apparent and actually due to an invisible mechanism, namely, a descending etherial shower. In the Hypothesis Explaining the Properties of Light (1675), he sketched a mechanical system of nature whose centerpiece was the hypothesis of the ether. The ether, in this account, explained gravity as well as electrical attraction, cohesion, and the elasticity of bodies, heat, and optical phenomena. Chapter 2 of the unpublished paper De aere et aether (written around 1674) contains an explanation of the forces of repulsion which act at a distance by means of ethereal mechanisms.25 Newton changed his mind about the ether when he wrote his main works. The Principia and the Opticks represent the rejection of a mechanical philosophy that involves only motions and bodies and thus invites the ether hypothesis. Instead of a kinematics of the ether, these works advance a dynamics of forces. Newton added forces to the ontology of nature that are capable of acting over a distance (cf. Opticks, query 1, p. 339). If action at a distance was only an illusion and actually action propagated through a material ether, then the ethereal ﬂuid would be dynamically relevant and possess resistance of its own. In book II of the Principia (concluding scholium to section 6; K 1:461–3, M 1:325–6), Newton described an ingenious experiment to determine the resistance of the ether. He installed a pendulum whose bob was a wooden box and compared the oscillations when the box was empty with the oscillations when the box was ﬁlled with metal and its greater weight compensated for. Because the presence or absence of a cargo does not affect the outer shape of the box, the box would encounter the same air resistance on its external surface in either case. However, a dynamically relevant ether permeating the internal parts of matter would have a resistance relevant on the internal parts of the bob; here, the presence or absence of the cargo would make a difference. If an ether existed, a pendulum with a box ﬁlled with metal as its bob would encounter more resistance to its internal parts, because it would contain more internal matter. Newton compared the number of oscillations of the pendulum in both cases and calculated the resistance on the surface of the bob to be 5,000 times as great as the resistance on the internal parts of the bob. The upshot of this result was that an ether resistance is negligible. If there is an ether, its resistance is too small to matter for physics. In book III of the Principia, Newton summed up his result: The celestial regions being perfectly void of air and exhalations, the planets and comets meeting no sensible resistance in those spaces will continue their motions through them for an immense tract of time. (prop. 10; K 2:586, M 2: 419)

The Conversion to Newton 87

But despite such reservations, Newton’s views of the ether remained complex. In the ﬁnal paragraph of the Principia, Newton wrote: And now we might add something concerning a certain most subtle spirit which pervades and lies hid in all gross bodies; by the force and action of which spirit the particles of bodies attract one another at near distances, and cohere, if contiguous; and electric bodies operate to greater distances, as well repelling as attracting the neighboring corpuscles; and light is emitted, reﬂected, refracted, inﬂected, and heats bodies; and all sensation is excited, and the members of animal bodies move . . . by the vibrations of this spirit. (Scholium Generale; K 2:764–5, M 2:547)

Evidently, the ‘‘most subtle spirit’’ is the ether. But it is the molecular ether Newton speaks of—an ether explaining cohesion, electricity, magnetism, optical phenomena, and physiological effects—not an ether that ﬁlls cosmic space. Magnetic and electric attraction acting over short distances are one thing, universal gravitation acting over large distances is another. The ‘‘most subtle spirit which pervades and lies hid in all gross bodies’’ does not explain gravitational action at a distance, nor does it attempt to. The molecular ether belongs to a different category, and even this ethereal ﬂuid is merely a speculation, as Newton’s next sentence illustrates: But these are things that cannot be explained in a few words, nor are we furnished with that sufﬁciency of experiments which is required to an accurate determination and demonstration of the laws by which this electric and elastic spirit operates.

We can distinguish the early from the late Newton, and we can differentiate in Newton’s mature view the denial of the cosmic ether from the sympathy for the molecular ether. But the puzzle of the ether in the Newtonian model persists. It becomes dramatically relevant in the Opticks. When Newton prepared the second English edition of the Opticks, he added eight new Queries (q. 17–24) that seemed to put the view of the Principia in jeopardy. Not only is this ‘‘Aether’’ the explanation of sensory perception (q. 23; 353) and animal motion (q. 24; 353–4), but its ‘‘Vibrations [are] propagated from the point of Incidence to great distance’’ (q. 17; 348) and ‘‘readily pervade all Bodies,’’ as well as expand ‘‘through all the Heavens’’ (q. 18; 349). The ‘‘Aethereal Medium’’ passes out of ‘‘compact and dense Bodies into empty Spaces’’ (q. 20; 350), such that it is ‘‘much rarer within the dense Bodies of the Sun, Stars, Planets, and Comets than in the empty celestial Spaces between them’’ (q. 21; 350). The ‘‘elastick force of this Medium . . . may sufﬁce to impel Bodies from the denser parts of the Medium towards the rarer, with all that power which we call Gravity’’ (q. 21; 351). The characterization of the cosmic ether in the Queries are couched in terms of questions. In fact, the full phrases, from which these quotations are taken, end without exception in question marks. Hence, the author of the

88 The 1750s: The Precritical Project

Opticks does not contradict the author of the Principia. Newton adds another thought: the ether, which possibly permeates the cosmos according to the Queries of the Opticks, might be capable of propagating gravity, while not resisting the motion of projectiles, because it is composed of particles repelling each other (q. 21; 352). But this speculation does not solve the problem of action at a distance. An ether composed of repelling particles merely raises the assumption of action at a distance to another level; that is, the interaction of separated, distant celestial bodies translates into the interaction of equally separated tiny particles.26 Although the ether remained a vexing mystery for both Newton and Kant, it turns out that Kant’s attitude toward the ether—the rejection of a cosmic material ether in 1754 and the temporary acceptance of a molecular ether in 1755—was not inconsistent with his endorsement of the Newtonian model. Kant’s changing views would have been at variance with the Newtonian model if they entailed a deﬁnitive and conclusive claim regarding the reality of the ether. But Newton neither ruled out the ether categorically nor defended it systematically. Although he had made his well-known statements regarding a spatial void, he had left the question of the ether simply open. In both the Principia and the Opticks, he argued that a cosmic ether, if it existed, was devoid of signiﬁcant resistance, suggesting a model of physical nature that involved empty space. Following Newton, Kant endorsed in the Spin Cycle essay the claim of action at a distance that universal gravitation working through empty space entails. The Newtonianism of the Spin Cycle essay remains unchanged in the treatise On Fire. Both of Newton’s main works raise the possibility of a molecular-electric ether. Kant’s theory of ﬁre, based on the hypothesis of an ethereal materia ignis, is not at odds with the claims of the Principia and the Opticks. There is, of course, one difference between the assessments of the ether by the two thinkers. On Fire does not reiterate the Opticks but rather transforms into a theory what had been merely speculative remarks in Newton’s work. Similarly, the Spin Cycle essay does not repeat the claims of the Principia but pushes them to new conclusions. These creative transformations and constructions are characteristic of Kant’s approach to Newton. Both On Fire and Spin Cycle reveal that his conversion resulted in considerably more than just uninspired commentaries on Newton. Kant’s Newtonianism typically involved the application of the accepted theories to new phenomena (as in the Spin Cycle essay), and the expansion of the accepted claims into new theories (as in the On Fire thesis). Kant did not merely follow in the footsteps of his master, but passed him by, attempting the philosophical completion of the work that Newton had begun.

4.4 Nonquantitative Physics in the Universal Natural History Kant’s conversion to Newton in the early 1750s amounted to a genuine switch of allegiances. Instead of emerging as a third authority next to Des-

The Conversion to Newton 89

cartes and Leibniz, Newton and his physics pushed Cartesian kinematics and Leibnizian dynamics aside. The conversion was more than a passive celebration of the new paradigm, for Kant applied Newton’s celestial mechanics to novel issues and expanded its explanatory power beyond its former conﬁnes. Kant’s goal was to complete what Newton had begun—to generalize the Principia into an explanatory model of all inanimate nature and to support this model with a systematic and plausible metaphysical framework. Before his conversion, Kant had advocated an ontological division of mathematical concepts and natural entities according to which quantitative descriptions fail to capture the inner workings of the world. Endorsing the Newtonian model of nature implied a rejection of this division, for the Principia is a long and sustained argument in support of the power of the exact sciences to elucidate physical structures. By becoming a Newtonian, Kant embraced the claim that physical nature can and should be described mathematically. The Universal Natural History and Theory of the Heavens (1755), written at the time of On Fire, was his ﬁrst truly great philosophical contribution to the Newtonian model. In the Principia, Newton had attempted to explain the local motions of the planetary system at its current time. In the Universal Natural History, Kant used these explanations for the sake of illuminating nature as such. He intended to investigate the cosmos as a spatial whole, in which the planetary system and even the Milky Way are only parts, and as a temporal whole, in which the present state of the cosmos is a mere interval in the world’s development from beginning to end. The basis of this Newtonian extrapolation was universal gravitation, the ‘‘single general rule,’’ as Kant calls it, that uniﬁes the universe and generates its order (I 306). What remains odd about this conversion, however, is that Kant’s endeavor of completing and expanding Newton’s mathematical model of nature remained nonmathematical throughout. Although the previous, pietist wall between mathematical concepts and natural entities had come down, and Kant had discarded his earlier reservations about the physical applicability of mathematics, his extrapolation of the Newtonian model in the Universal Natural History was entirely qualitative. This book was not meant to be a popular introduction. If it had been, Kant’s nonmathematical approach would have made perfect sense. Instead, he intended it to be a genuine research contribution; he wanted to apply and universalize Newton’s ‘‘Mathematical Principles’’ in this peculiar, nonmathematical fashion. Why did he not follow in the quantitative footsteps of his master? One reason might have been that Kant was never good at mathematics, as Adickes (1924b) pointed out.27 That Kant was more a philosopher than a scientist is certainly true. Another reason motivating his peculiar approach could have been the limited data avaliable on the subject matter. Krafft (1971) suggests the ‘‘thin’’ empirical basis as the main reason for the nonquantitative contents of the Universal Natural History.28 The data needed for a systematic quantiﬁcation of the subjects investigated were too limited; although two-thirds of the book concern empirically accessible objects (such as the densities of the planets

90 The 1750s: The Precritical Project

or the rings of Saturn), the observational techniques of the time effectively precluded the gathering of precise information. Newton, whose observational situation was similar to Kant’s, chose to pass over these issues in silence. But if Kant lacked the skill for a quantitative investigation, and if the data was insufﬁcient anyway, why did he write this book at all? What did he hope to achieve with a purely qualitative cosmology? Part of the answer has to do with the characteristic direction of Kant’s inquiry. In the titles of various chapters of the Universal Natural History, he declared his intention to investigate the causes of the celestial objects. Newton had scoffed at such projects; causal investigations, he maintained, should not be the business of ‘‘experimental philosophy.’’ For Kant, however, experimental philosophy (or natural science, the term he used) was just one part of natural philosophy; metaphysics was the other part. A year later, he noted in the Physical Monadology that natural science (scientia naturalis) should not undertake anything without the assent of experience and the mediation of geometry. But this path of discovery is limited, he argued, because it only leads to laws, not to causes. Identifying the latter is the task of metaphysics (metaphysica). In doing so, metaphysics penetrates deeper than science into the physical objects (I 475). These remarks suggests a division of labor between Newton and Kant: the scientiﬁc identiﬁcation of laws had been the focus of the Principia; the metaphysical determination of their causes would be the focus of the Universal Natural History. Of course, Kant’s distinction in the Physical Monadology, between the sciences identifying laws, and metaphysics identifying causes, is not quite right when framed so generally. One merely needs to recall the Spin Cycle essay, the Earthquake papers, and the Theory of Winds. The Spin Cycle essay contains the identiﬁcation of the cause of the deceleration of the earth’s rotation. The Earthquake papers, in particular the ﬁrst, amounts to a proposal intended to explain why earthquakes occur. The Theory of Winds involves causal explanations of various meteorological phenomena. Each and every one of these articles is scientiﬁc in character, involving reasoning about empirically veriﬁable mechanisms, while concerning causal inquiries as well. Nonetheless, the distinction between science dealing with laws and metaphysics dealing with causes is useful if sufﬁciently qualiﬁed. Not causal inquiries as such, but causal inquiries of a speciﬁc kind distinguish metaphysical investigations from scientiﬁc ones. Some causes admit a mathematical description (as the ones pertaining to variations in the terrestrial spin cycle) or at least an empirical examination (such as the causes of earthquakes and wind patterns). Moreover, laws of nature that can be expressed in quantitative terms may involve causal explanations, and Newton had evidently investigated how certain factors have certain effects. Causal inquiries of this sort fall in the fray of science. But other types of causal inquiries, neither mathematical nor empirical in kind, concerning the ‘‘why’’ rather than the ‘‘how’’ of causation, are outside the purview of science. This is a basic difference between the Principia and the Universal Natural History. Whereas Newton had investigated the ‘‘how’’ of causation, Kant was interested in the ‘‘why’’; he in-

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tended to discover ultimate origins and overall designs instead of sheer effects. In doing so, he pursued a different goal, namely, the identiﬁcation of the rationes essendi ac ﬁendi and causae ﬁnales—the causal factors of being, becoming, and purpose.29 Mathematics is of no help in the pursuit of such causes, and Kant admitted this already in the Living Forces (#62, I 70). The contribution which he hoped to make with the Universal Natural History was an expansion of Newtonian physics from an account of the present solar system to a theory of the universe from beginning to end. Searching for the origin of the universe means to look for its essential cause. Tracing its development and organization means to look for its ﬁnal causes. Mathematics cannot assist in either of these quests. This is why Kant could extrapolate from Newton’s celestial mechanics a qualitative cosmogony without falling victim to a deep incoherence. The qualitative approach is appropriate for the construction of a cosmogony, because its focus on time involves the identiﬁcation of metaphysical causes. But the Universal Natural History, despite its title, is not only about the history, but also about the structure of the cosmos. Why should mathematics be required for the investigation of the local space in Newton’s celestial mechanics and yet be unnecessary for the exploration of deep space in Kant’s cosmology? The relations of stars and galaxies involve efﬁcient causes just as the relations of the planets and the sun do. Efﬁcient causes belong to the domain of science, because the relevant factors are in principle observable and quantiﬁable. But the cosmology of the Universal Natural History is just as nonquantitative as the cosmogony.30 Kant’s qualitative approach to cosmology is deliberate and for a speciﬁc reason. Insisting that geometric exactitude and mathematical infallibility could not be demanded of such an investigation (I 236), he argued that it is perfectly sufﬁcient to ground the cosmological system in ‘‘analogies and conformities according to the rules of plausibility and common-sense (einer richtigen Denkungsart)’’ (I 235).31 The ‘‘guiding thread of analogy and reasonable plausibility’’ (I 235) was Kant’s methodological standard for the philosophical completion of the celestial mechanics. Newton could apply quantitative methods for surveying the restricted segment of nature that was the object of his inquiry. Expanding this model of the planetary system to the sweep of the galaxies is a different matter. Since the cosmos is inﬁnite and immeasurable, only God would be able to map out its structure with mathematical precision (cf. I 256, 309–10 note, 315). A human investigation of the cosmos, according to Kant, must therefore remain content with analogical reasoning.32 The argument in support of analogies suggests that a quantitative cosmology is impossible. That only God could fathom the cosmos with mathematical precision is plausible if we understand, like Kant, ‘‘mathematical precision’’ in the sense of a rigorous, deductive exactitude. It becomes implausible, of course, if we understand ‘‘mathematical precision’’ in the larger sense of a quantitative approach in general. The choice between analogies and mathematics, and the decision for the former make sense only as long

92 The 1750s: The Precritical Project

as the exact sciences are nothing but geometry, algebra, and calculus. Mathematics at mid-century already included some statistical and probabilistic devices, but their application to astronomical phenomena had to wait for another ﬁfty years. The earliest systematic work on statistics (then called ‘‘political arithmetics’’) dates from the seventeenth century. John Graunt’s Natural and Political Observations . . . upon the Bills of Mortality (1662) and Sir William Petty’s Political Arithmetic (written 1676, published 1690) were the ﬁrst monographs on the subject. Probability theory had its modest beginnings in the Liber de ludo alea (wr.1525, p. 1663), penned by the renaissance man and gambler Jerome Cardan. In the middle of the seventeenth century, Blaise Pascal and Pierre de Fermat discussed the theory in an exchange of letters, and Huygens published the ﬁrst treatise on probability, De rationciniis in ludo aleae, shortly thereafter (1657). Jacques Bernoulli improved the mathematics further in his inﬂuential Ars conjectandi (1713). At the time of the Universal Natural History, statistics and the theory of probability existed as nascent sciences, but their application to celestial mechanics required more theoretical advances. Joseph de Lagrange (1736– 1813) and in particular, Pierre Simon de Laplace (1749–1827) would perform this task toward the end of the eighteenth century. Laplace’s relevant works, the Exposition du syste`me du monde (1798), the Traite´ de la me´canique ce´leste (5 vols., 1799–1825), and especially the The´orie analytique des probabilite´s (1812), changed the face of Newton’s celestial mechanics. By the nineteenth century, a quantitative cosmology, utilizing statistics and the theory of probability, had become a reality. Qualitative cosmologies had become obsolete. But although Kant was eventually proven wrong by the future progress of mathematical astronomy, he should not be blamed for his mistake. Historically, his assessment is understandable. The judgment that only God can describe the cosmos mathematically while we are left with analogies was a realistic assessment of the formal tools that were available when Kant wrote the Universal Natural History. Interestingly, Kant insisted that the human limitation to analogies does not handicap our comprehension of the universe. God could do better, but it really does not matter. Analogies are not a makeshift method, chosen because nothing better is at hand, but are in fact superb cognitive devices entirely up to the task of illuminating the cosmos in its totality. For Kant, the analogical method derives its power to generate the expansion of the Newtonian model from the rules that governed the construction of the model itself. According to the regula philosophandi that Newton put at the beginning of book III of the Principia, ‘‘we are to admit no more causes of natural things than such as are both true and sufﬁcient to explain their appearance.’’ Moreover, ‘‘to the same natural effects we must, as far as possible, assign the same causes,’’ and most important, ‘‘the qualities of bodies . . . which are found to belong to all bodies within the reach of our experiments, are to be esteemed the universal qualities of all bodies whatsoever’’ (rules 1–3, K 2:550–5/M 2:398–400).33

The Conversion to Newton 93

As Newton put it, we are not ‘‘to recede from the analogy of Nature, which is wont to be simple, and always consonant to itself ’’ (K 2:553/M 2: 398). The macrocosm is structurally simple. Its characteristic features are uniformity, internal consistency, and harmony.34 If we accept Newton’s model as an explanation of the workings of nature in our region of space, and if we accept, on Newtonian grounds, the basic uniformity of physical nature, then it follows that analogies will work. They are not questionable gimmicks of a speculative metaphysics but efﬁcient and scientiﬁcally informed tools for determining the structure of the cosmos (cf. also I 229). This, then, is the other part of the answer to the question of Kant’s characteristic approach. In his cosmogony, he dispensed with mathematics because of the qualitative character of the causes he was looking for, and in his cosmology, he utilized analogies for the expansion of the model of nature because of the spatial uniformity of the macrocosm. Although the direction of the cosmogonical inquiry and the constitution of the cosmological subject-matter solve the puzzle of Kant’s nonquantitative philosophy of nature, one oddity remains that deserves discussion. Toward the end of the introduction to the Universal Natural History, Kant explains the divergence of planetary orbits from circular paths with the curious claim that ‘‘nothing is exactly weighed out in nature’’ (I 246). Surely, for the reasons stated, the investigation of the macrocosm cannot be mathematically precise. But does this mean that the macrocosm is not mathematically precise? Kant asserts that ‘‘nothing is exactly weighed out in nature’’ before stating that planetary orbits are ‘‘only roughly circular’’ (I 246).35 There are two ways in which one can understand the ‘‘rough’’ circularity of planetary orbits. An orbit can be roughly circular because the orbiting body describes an ellipsis with a small eccentricity, or because the body wobbles on its curvilinear trajectory due to gravitational perturbations. Kant concerns himself with the ‘‘elliptic’’ sense of the rough circularity of planetary orbits in a passage where he describes orbital ellipses as differing from circles so slightly that, for all practical purposes, one can refer to them as circles (I 245–6; cf. also I 266–9). Empirically, he is quite right about this. For instance, the elliptic eccentricity of the orbit of Mars is so slight that a representation on a sheet of paper would look perfectly circular. Its departure from a circle would remain within the width of the drawn line, even if the line were drawn by a ﬁne pen. (The Martian orbit is by no means exceptional; in fact, Mars has a ‘‘large’’ eccentricity as compared to Earth’s.)36 Mathematically, Kant’s view is not problematic either. A circle and an ellipse are not that different. Both are conical sections, and a circle is an ellipse in which the two foci are identical and whose eccentricity is zero. Newton had used the mathematical afﬁnity of circles and ellipses to his advantage because it had simpliﬁed his derivation of the inverse-square law from Kepler’s harmonic law.37 Since Kant knew that ellipses could be precisely determined, the ‘‘rough’’ circularity of the orbits, in this sense, could not suggest the claim of nature being intrinsically fuzzy.

94 The 1750s: The Precritical Project

The second, ‘‘perturbational’’ sense of orbital circularity is a theme in the Principia. Gravitational perturbations affect curvilinear orbits of masses. Not only do the lunar and planetary paths diverge from pure circles in terms of their elliptic eccentricity, but also the resulting orbital ellipses are not precisely ellipses. Planets wobble. They do so because the mutual attractions of planets and sun cause disturbances in each other’s curvilinear motions (bk. III, prop. 5, cor. 3; K 2:571, M 2:410). Perturbations also play a role in Newton’s lunar theory, and here mathematic exactitude becomes an issue in the guise of the three-body problem. The moon wobbles because it is in the middle of an unpredictable tug-of-war affected by the twofold gravitational pull of sun and earth. Sun and earth are not isolated but exert mutual gravitational pulls on each other, hence, the two causes of the lunar perturbations are engaged in causal interactions of their own. As a result, the mathematical analysis of the lunar perturbations becomes vastly complicated; so complicated, in fact, that the three-body problem has no general analytic solution. Mathematics can merely approximate the dynamic situation of moon, earth, and sun and the resulting lunar perturbations without being able to generate reliable predictions of the perturbations in detail. The complexities of lunar perturbations make things more complicated, but they do not make them fuzzy. We fail to succeed in our mathematical descriptions because human mathematics is limited, not because such descriptions are impossible in principle. The lack of mathematical exactitude is not due to an intrinsic nonquantiﬁability of celestial motions. Kant was perfectly aware of this. While investigating the hazy shape of the ecliptic plane of the solar system, he observed that the ecliptic plane is not a mathematically exact ﬁgure because of the small discrepancies of the individual orbital planes from their general alignment. Kant argued that the lack of precision in such macroscopic physical processes arises from the plurality of circumstances that mutually interfere with each other and thus prevent measured regularities (I 269). The sheer number of factors inﬂuencing macroscopic motions make them appear imprecise, and these multiple dynamic causes lead to a kinematic complexity in which perturbations, aberrations, divergences, and discrepancies from idealized mathematical models become evident and inevitable. But each of the causal factors would emerge as a quantiﬁable efﬁcient cause if one could consider them individually and in isolation. In short, the quantitative approach characteristic of Newtonian physics was legitimate but limited. A nonmathematical approach guided by analogies was better suited for an investigation with the sweeping breadth of a universal theory of the heavens.38 The combination of observation and mathematics was the key to the Principia’s success, and Kant hoped the combination of observation and analogy would be the key to the success of the Universal Natural History. In short, a dramatic change occurred in the 1750s: Kant matured from being a student of philosophy to being a philosopher in his own right. Two interconnected aspects characterized the arrival of this new stage. First, Newton moved to the foreground of Kant’s thought and became the domi-

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nant ﬁgure in his philosophy of nature. Second, the conversion to the Newtonian description of physical nature made it necessary to justify basic metaphysical assumptions—in particular, the assumptions of purpose and freedom—which a Newtonian model of nature as a mechanistic and deterministic system threatened to undermine. Thus, the Newtonian conversion transformed Kant’s earlier interest in the harmony of qualitative and quantitative perspectives into a pressing need—the need to protect metaphysics from the scepticist impact of science, to reconcile metaphysical desiderata with Newtonian physics. With Kant’s conversion to Newton, the precritical project had begun. The Spin Cycle essay signaled Kant’s break with the amalgam of Leibnizian and Cartesian ideas that he had advocated in the Living Forces. The way in which Kant investigated the fate of the earth’s rotation in the Spin Cycle essay revealed that he now unconditionally accepted Newtonian physics as the new scientiﬁc paradigm. The On Fire treatise, written a year after the Spin Cycle essay, showed Kant was more than just a disciple content with tagging along after his master. Kant admired Newton, yet he was also an independent thinker, as the construction of an ether-theory of ﬁre not based on Newtonian claims illustrated. The defense of the analogical method in the Universal Natural History was a further example of the combination of Newtonianism and speculative originality that would characterize Kant’s thought from the 1750s to the end of the precritical period. But most important, the defense of the analogical method gave Kant’s philosophical explorations of nature their speciﬁc direction. The envisioned reconciliation of science with metaphysics, triggered by the Newtonian threat to metaphysical desiderata, would have to take the form of constructing a model of reality that incorporated quantiﬁable as well as qualitative components. The implicit claim of the defense of the analogical method was that purely qualitative investigations of nature are valid, useful, and compatible with Newtonian premises. This defense was the ﬁrst step toward turning the precritical project into a reality.

F I V E

The Universal Natural History The Purposiveness of Nature

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5.1 The Rejection of Traditional Teleologies The Universal Natural History and Theory of the Heavens (1755) was the most remarkable achievement during Kant’s second precritical decade. Ameriks (1982) locates this work in the ‘‘empiricist’’ period of Kant’s thought, a period which supposedly begins with the Living Forces and ends, after the Universal Natural History, with the New Elucidation (1755).1 There is some merit to this classiﬁcation, because both the Living Forces and the Universal Natural History exhibit a focus on physical topics, and because, in both works, ‘‘the soul is regarded as located in the world and, like everything else, as interacting with material things and fully dependent on them.’’2 But Ameriks’s classiﬁcation is too general for our purposes. It fails to acknowledge the two major events that occurred after Kant’s debut in the 1740s and that characterized his publications in the 1750s: the conversion to Newton and the resulting need for the precritical project. In the years leading up to the Universal Natural History, Kant discarded Leibnizian and Cartesian approaches for the sake of Newtonian physics. The latter involves a model of nature whose mechanistic and deterministic presuppositions threaten to undermine the metaphysical desiderata of purpose, freedom, and God. Unwilling to accept a deterministic world-machine without provisions, Kant had to articulate new accounts of purpose, freedom, and God that would supplement and 96

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qualify the Newtonian model of nature. This endeavor of a comprehensive philosophy of nature, with its complex tasks of constructing new justiﬁcations of metaphysical desiderata and of revising Newton when necessary, became the precritical project—Kant’s central philosophical venture before his turn to the Critique of Pure Reason. The Universal Natural History has been described by Beck (1969) and Shea (1986) as the work in which Kant ‘‘out-Newtoned’’ Newton.3 Yet, the enthusiastic embrace of Newtonianism turned Kant neither into an experimental researcher walking in Newton’s footsteps, nor into a sycophantic commentator paraphrasing Newton’s work. Instead, he integrated Newtonian physics into a general system of nature. He enriched Newton’s physical force as an external action on a body affecting a change of motion with a quasi-Leibnizian, metaphysical understanding of force as an immanent property of a substance responsible for its future development. While the physical aspect of force explained the kinematic structure of the universe, its metaphysical aspect allowed an explanation of the purposive organization of nature along Newtonian lines. Kant was the ﬁrst to realize, in contrast to the Wolfﬁans, Pietists, and Physico-theologians, that a teleology unifying metaphysical desiderata with Newtonian nature must employ ﬁnal means congruous with the physical processes. The Universal Natural History is about the origin and organization of the cosmos. Kant pursued two speciﬁc goals in the book: to outline a cosmology of the structure of the universe and to devise a cosmogony of its formation. Of course, it is hard to imagine a venture involving greater philosophical ambition than this. But since Kant limited this endeavor to the identiﬁcation of the mechanical patterns of nature responsible for its genesis and systematicity, he thought that the venture of the Universal Natural History was more viable than one might expect. The complexity of the universe is beyond human imagination, but its homogenous lawfulness is accessible. As Kant puts it, the spherical form of the celestial bodies is geometrically simple, the motions of these bodies are ‘‘unmixed,’’ and the space in which they travel is empty (I 229). The mechanics of the universe are not complicated he contends; the organic structure of a little caterpillar is inﬁnitely more involved and convoluted than the mechanical structure of the whole cosmos (I 230). Thus, Kant thought that a mechanical explanation of the universe was feasible. But is such an explanation legitimate considering the conservative metaphysical presuppositions of the age? After all, to say, with Voltaire, ‘‘give me matter, I shall build a world with it’’ (I 229, 230) might open the door to materialism and undermine the cause of religion.4 But Kant thought he could dismiss this worry. In his view, a mechanical, scientiﬁc perspective is not opposed to theology; what seem to be arguments for freethinkers, he claimed, are actually weapons against them (I 225). Even if one proceeds from the explicit assumption that the organization of nature has a divine cause, then it will still be more plausible to assume that God’s creation is well organized and capable of generating order by its own laws (I 225) than

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to suppose that it is structurally deﬁcient and in need of an ‘‘external hand’’ for the regularity of its processes (I 223). Kant insisted to assume this is plausible on theological grounds: the best testimony of God’s magniﬁcence is that his creation is not inadequate and that it possesses sufﬁcient perfection to develop mechanically on its own (I 222). So Kant contended that the contradiction between mechanics and theology is an illusion. This set the tone for the book and showed how it ﬁt into the precritical project. Having embraced the Newtonian model of nature with the Spin Cycle essay (1754), Kant tried to reconcile physics with a divinely inspired purpose in the Universal Natural History, with freedom in the New Elucidation (1755), and with God in the Only Possible Argument (1763). The Universal Natural History has often been misunderstood as a scientiﬁc cosmology based on Kant’s rejection of teleology, for example, by Tonelli (1959b), Schneider (1966), or Shea (1986).5 In fact, however, Kant rejected the teleologies of his contemporaries only to construct his own. He assigned a crucial function to teleology; it is the bridge between the celestial mechanics and the assumptions of God and purpose. In his conception, teleology connects science and metaphysics and, by doing so, strengthens both. The new teleology of the Universal Natural History was intended to resolve tensions within Newtonian science and to avoid the difﬁculties of other teleologies that had failed to justify the desiderata of God and purpose. Thomas Aquinas’s dogma in the Summa Theologica I.23, that God organizes all things in nature toward an end, was the platform for the teleological discussions that ensued in Germany in the early eigtheenth century. Since divine ends guide the processes of nature, nature does not subsist in complete isolation from God after its creation. Nature is beautiful, harmonious, and useful for humans, because its organization reﬂects the benevolence of its omnipotent creator. Teleologies of nature were attempts at explaining that God remained present to his creatures, that the world was not left to its own devices, and that the divinely inspired processes of creation are benevolent and purposive rather than blind and random. How would God instill this benevolent purposiveness in nature? The most straightforward (but, as Kant realized, also the most problematic) strategy would be that God imposed his will on nature when he deemed ﬁt, thus interfering with nature while disrupting its course. The pietists—P. J. Spener, A. H. Francke, F. Buddeus, A. Ru¨diger, J. Lange, and A. Hoffmann—had no qualms about supernatural interferences and readily acknowledged the possibility of miracles. Joachim Lange argued that the very conception of a divine being entailed that God would act outside and above the created processes of nature.6 Although divine interferences would violate the laws of nature, this did not bother the pietists. In their view, any conﬂict between a theological description of God’s acts and a scientiﬁc model of nature must be the fault of science. Theology is the explication of truths contained in the Bible, and science errs when contradicting biblical tenets. One does not need to defend theology; from the pietist point of view, it is sufﬁcient to ridicule the sciences when they challenge

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theological dogma.7 Franz Buddeus declared the sciences to be subject to the authority of faith and considered an independent, quantitative scientiﬁc research program impermissible.8 Andreas Ru¨diger rejected the employment of mathematical methods in the scientiﬁc study of nature, and Christian August Crusius, as we have seen earlier, was mired in this antiquantitative conception of science to such an extent that it prevented him from accepting Newtonian physics as a literal description of nature.9 Despite his pietist background, and despite his continuing sympathies for this brand of lutheran faith, Kant had little tolerance for the philosophical views of the pietist theologians. In his view, theology should never set itself at variance with science. If it did, Kant argued, it would only lose, relinquishing the better reasons to the freethinkers and atheists (I 222).10 The pietist position was also unacceptable for Christian Wolff (as was Wolff ’s position for the pietists).11 Wolff rejected the antiscientiﬁc stance of the pietists, but, like them, he was willing to believe in miracles. Both the pietists and Wolff agreed (and Kant with them) that the world represents the divine act in its unfolding according to God’s plan. Divine acts spring from God’s free will and are thus contingent. Because divine acts are contingent, Wolff concluded that the world ought to be contingent as well. The contingency of the world is theologically desirable and is warranted by the constant possibility that miracles may happen at any time. He maintained in the Deutsche Teleologie (1723) that the structural contingency of nature corresponds to the possibility of miraculous means for achieving the telos of revelation (W I.7:7–8 #9). Thus, miracles are not only ﬁnal vehicles of God’s teleological ordering, but are also essential warrants of the causal structure of a world that allows for spontaneous causation and thus for freedom. Wolff declared the ultimate purpose of nature to be God’s revelation of his magniﬁcence to humans.12 According to the Deutsche Teleologie, God reveals his magniﬁcence by engineering a marvelous usefulness of natural things (W I.7:96 #66). However, an agreeable design alone does not sufﬁce, because humans may be content with the fortuitous arrangment without recognizing its cause in the divine designer. In order to bring the revelation fully about, and in order to generate the awe essential to the recognition of a divine cause, humans must be confronted with supernatural events and divine intervention, as Wolff argued in the Cosmologia Generalis (1731; W II.4:397 #510). Along with fortuitous design, miracles are the means of realizing God’s revelatory end. Wolff ’s willingness to invite miracles into nature, as a means serving God’s revelatory end, and as the warrants of freedom, forced him to face a subtle but serious ontological problem. There is a fundamental difference in the causation of a supernatural occurrence and a natural event. The former happens on the basis of God’s will; the latter happens as a regular effect of prior natural events. By granting miracles a place in a theory of nature, an ontological problem arises that consists of the copresence of two incompatible types of causation in one and the same world. The traditional tenet, reiterated by Wolff, that both miracles and the world are causally contingent,

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does not solve the problem for the contingency of miracles and the contingency of the world are not the same. Miracles are contingent in that they simply happen regardless of the circumstances. The world is contingent in this manner as regards its overall existence, but what happens in the world does not happen regardless of the circumstances. God freely chose to create the world; he could have created a different one or none at all. But as soon as this particular world has been created, its events depend on each other in ways that are not contingent. To be sure, Wolff permits the possibility of spontaneous causation in the world such that humans, as creatures within it, can act freely. At the same time, he acknowledges the signiﬁcance of natural laws that govern empirical nature. To the extent that the world’s processes are describable by laws, the world’s processes are wholly deterministic, despite the overall existential contingency of the creation. Perhaps it is still possible to allow for a copresence of spontaneously caused free acts and deterministically occurring natural processes by allocating them to different spheres of the world, the one intelligible, the other sensible. But this escape route is not open for miracles. They do not happen in the intelligible realm of morally relevant freedom; they happen in the sensible realm of physical nature. How is it possible that some events, such as natural processes, obey a deterministic causation, and that others, such as a miraculous interference, follow from a spontaneous causation, while being part of the same world? Wolff was not lukewarm in his acknowledgment of natural laws. In fact, his conception of empirical nature is wholly deterministic. Empirical nature possesses the feature of a ‘‘hypothetical necessity’’; that is, of a mechanistic causal organization in which posterior events occur because of prior events, and in which prior events determine posterior events. All events in nature are linked over time. This continuous and universal causal web of all things is the nexus rerum. It constitutes the causal structure of the world from the beginning of creation to its end and uniquely deﬁnes this world. But as we have seen, a miracle is the contingent event par excellence. When miracles occur, truly foreign incidents invade the previously regular deterministic chain of events. The very irregularity of a miraculous event causes so much ontological stress that the chain breaks. After the miracle things reconnect as it were. The immediate effects of the supernatural occurrence become the ﬁrst links of a newly forged causal chain and serve as the causes of subsequent events that are once again natural. But the problem of the copresence of the two incompatible types of causation resurfaces here in that the causal chain that governs the world’s present and future after the miraculous incident is different from the causal chain that would have governed the world’s present and future if the miraculous incident had not occurred. Miracles cannot have an impact on the creation without affecting the nexus rerum. But since the causal chain of all things, the nexus rerum, is what deﬁnes this world, the miraculous alteration of the causal patterns of nature threatens to generate a new world with a different nexus rerum. Miracles cause ontological havoc, and Wolff was keenly aware of it.

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How could the causal chaos that a miracle threatens to trigger be avoided? Wolff saw only one way out. In the Deutsche Metaphysik (1719) and in the Cosmologia Generalis (1731), he argued that a second miracle must occur in the wake of the ﬁrst. Whereas the ﬁrst miracle expresses God’s immediate intentions, the second one does the service of an ontological cleaning crew. Because God’s initial revelatory miracle damages the causal order, Wolff argues, God needs to follow up with a miraculum restitutionis.13 This ‘‘miracle of restitution’’ patches things up and smoothes over the disruption of the causal nexus. Wolff understood that the very irregularity of miracles endangers the structural interconnectedness of nature. But the introduction of a miracle of restitution, as an ad hoc device for restoring the causal order disturbed by the ﬁrst miracle, shows the impossibility of harmonizing miracles and nature. A reconciliation that resorts to a miracle in its own right offers no rational solution to the causal problem caused by divine intervention. The appeal to a miraculous restoration of deterministic processes dramatically revealed the depth of Wolff ’s failure to resolve the conﬂict between theology and science. Kant knew this. He was convinced that an acceptable teleology of nature must reject supernatural vehicles and conform to the model of nature described by science. The lesson he drew from Wolff ’s account is that a teleology spanning metaphysical desiderata with a Newtonian conception of physical nature must employ ﬁnal means congruous with the physical processes of nature. Wolff ’s teleology cannot be salvaged by simply abandoning the supernatural. In addition to the miraculous ﬁnal means, Wolff argued for natural ﬁnal means which manifest themselves in the design of nature, and which generate the marvelous utility of nature for humans, thus bringing about the telos of a divine revelation. The difﬁculty with this ‘‘natural’’ side of the Wolfﬁan teleology is that it evokes an extreme anthropocentrism. The revelatory telos involves a network of subordinate tele of natural objects that are tantamount to the utility of these objects to human interests. All subordinate ends that God imposed on nature work ultimately in man’s favor. In the Deutsche Teleologie, Wolff enthusiastically engaged in the task of explaining whatever came to his mind in this anthropocentric manner. Why do stars emit light? For the purpose of making nocturnal journeys more convenient (W I.7:50 #33). Why does the sun shine? So that people can go about their business conveniently during the day (W I.7:74 #47).14 It is no wonder that Voltaire gleefully made fun of such arguments.15 Kant rejected the teleological anthropocentrism in the Universal Natural History, and he reiterated his rejection in the later Only Possible Argument for a Demonstration of the Existence of God (1763). As he noted in the Universal Natural History, it is an exaggeration to suppose that the whole cosmos has been organized for the mere purpose of human interests. An intelligent louse might as well imagine that the tender scalp it dwells on and the forests of hair it inhabits have been created just for the sake of its own well-being— from a louse’s point of view, things certainly look that way (I 353–4). In the

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Only Possible Argument, he remarked that many different purposes can be identiﬁed for all sorts of natural phenomena. To pick out the human uses as the relevant ones is arbitrary. Kant realized that there is insufﬁcient evidence to warrant the claim that nature exists only for the sake of man (II 131).16 The physico-theologians (the third major group of metaphysicians next to the pietists and the Leibnizian-Wolfﬁan School Philosophers) agreed with Wolff on divine revelation as the ultimate telos of nature, but they disagreed, for the most part, with Wolff ’s radical anthropocentrism.17 In their view, the subordinate tele of nature consist in the purposive arrangement of nature for nature’s own sake. Thus, the physico-theologians avoided Wolff ’s problem of anthropocentrism by insisting that the beauty and harmony of nature, and not its utility to humans, reveal God’s magniﬁcence. Beauty and harmony not only disclose God’s greatness but also his presence and are thus signs of his existence. What is characteristic about the physico-theological arguments is that they involve demonstrations of God’s existence from the speciﬁc design of natural objects and not from the overall design of nature. Because of the joint effect of God’s benevolence, omnipotence, and omniscience on his creation, beauty and harmony ought to be found everywhere in nature, and thus it ought to be possible to deduce God’s existence from the purposive arrangement of even the most ordinary aspects of the creation. This focus on particularities became quite popular and turned out to be one prominent form of the argument from design. In the Dialogues Concerning Natural Religion (wr. 1750–76, publ. posth. 1779), David Hume critically examined both forms, discussing arguments from the overall design of nature, as well as arguments from the speciﬁc design of natural objects.18 Although the physico-theologians avoided Wolff ’s problems, their arguments invited other difﬁculties. In the wake of William Derham’s Physicotheology (1714) and of Bernhard Nieuwentyt’s Het regt gebruik der Werelt beschowingen (1715), religious metaphysicians published teleological tracts professing to prove God’s existence from physico-theological considerations.19 Pretty much every natural phenomenon was subjected with exacting fastidiousness to theological scrutiny, resulting in hardly a dearth of exotic tracts. As regards elementary manifestations of God’s power, there were J. A. Fabricius’s Pyrotheologie (1732), a physico-theology of ﬁre; F. C. Lesser’s Lithotheologie (1735), a physico-theology of rocks; J. A. Fabricius’s Hydrotheologie (1735), a physico-theology of water; B. H. Heinsius’s Chionotheologie (1735), a physico-theology of snow; P. Ahlwardt’s Brontotheologie (1746), a physicotheology of thunder; and M. Preu’s Seismotheologie (1772), a physicotheology of earthquakes. As regards the derivation of God’s existence from the purposive arrangement of plants, there were general compendia such as B. de Rohr’s Phytotheologie (1740), as well as speciﬁc treatments of the subject, such as J. D. Denso’s Chortotheologie (1741), a physico-theology of grass. Religious contemplations of the animal kingdom abounded, ranging from such high-ﬂying attempts as J. H. Zorn’s Petinotheologie (1742/3), a physicotheology of birds, to more pedestrian entomological endeavors such as C. M.

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Seidel’s Bombyco-Theologie (1718), a physico-theology of silkworms (there is a subtle beauty to the fact that a certain Seidel writes on caterpillars secreting Seide). Seidel’s tract preceded F. C. Lesser’s Insectotheologie (1738), a physico-theology of insects, and A. G. Schirach’s Melittotheologie (1767), a physico-theology of bees. Lowly creatures were no match to these intrepid thinkers, as C. H. Rappold’s Locusta-Theologie (1730), a physico-theology of locusts, and E. L. Rathlef ’s Akridotheologie (1748), a physico-theology of grasshoppers, forcefully illustrate. The study of the watery realms resulted in works such as F. C. Lesser’s Testaceotheologie (1744), a physico-theology of mussels and snails; J. G. O. Richter’s Ichthyotheologie (1754), a physicotheology of ﬁsh; and last but not least, F. Menz’s Rana-Theologie (1724), a physico-theology that derived God’s existence, of all things, from tadpoles.20 Kant respected these valiant efforts but was not enthusiastic about them. He emphasized in the Universal Natural History that he would repudiate his ‘‘mechanical’’ characterization of nature if he were convinced that it undermined theological arguments (I 222)—a point he made even more forcefully in the preparatory drafts to the book (cf. XXIII 12). But he also insisted that theological arguments are valuable only if they are grounded in natural science. Kant’s expression of sympathy toward the religious vantage point was limited to theological arguments concerned with the harmony of the Weltbau, the overall constitution of the cosmos (I 222). Theological arguments derived from speciﬁc aspects of nature, which were the characteristic focus of the physico-theologians, were passed over in silence. In the Only Possible Argument, he discussed such arguments in a section entitled ‘‘Insufﬁciency of the Standard Method of Physico-theology.’’ His critique in the 1760s explicated the demand of the Universal Natural History that physicotheology conform to science.21 According to the Only Possible Argument, the weakness of physico-theology consists in its characterization of harmonious and beautiful arrangements in nature as sheer coincidences engineered by God (II 118). This popular portrayal is false (many harmonious arrangements follow necessarily, and not coincidentally, from the lawful organization of nature, Kant claims), and this portrayal sets itself at odds with science: as soon as harmonious aspects are shown to be necessary results of a lawful natural organization, the physico-theological accounts are revealed as groundless speculations (II 118–9). In the section, ‘‘Improved Method of Physico-Theology,’’ Kant identiﬁes yet another problem of physico-theology, namely, its fallacious conﬂation of ‘‘use’’ and ‘‘purpose.’’ A natural object or phenomenon can have many different uses, but the fact that nature contains ‘‘innumerable examples of the extended usefulness of one and the same thing for multiple employments’’ does not warrant our immediate identiﬁcation of these uses with the teleological purposes of the thing (II 131). Whereas a purpose stands in necessary unity with the object, a use can be ‘‘a nicely ﬁtting side-effect’’ that stands in necessary unity with an altogether different context of laws that has nothing to do with the object proper (II 136). Of course, the difference between purpose and use challenges not only

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the speculative zest of the physico-theologians, but also the relentless anthropocentrism characteristic of Wolff ’s teleology. That a thing is useful to humans does not mean that usefulness must be its purpose. Alluding to the banalities of the Deutsche Teleologie, Kant notes that Greenlanders certainly beneﬁt from Northern Lights in winter (they do not have to sit entirely in the dark), but to identify this beneﬁt as the telos of Northern Lights would simply be mistaken (II 136). Not only nonnatural ﬁnal means such as miracles, but also nonnatural ﬁnal ends such as human interests must be ruled out; a teleology can be congruent with a Newtonian model of physical nature only if its means and ends are somehow integrated in the physical structure of nature. What about Newton’s own teleology? Despite his well-known disparaging remarks on speculation and metaphysics, Newton developed a teleological theory in the context of his model of physical nature. Teleological reasoning appeared frequently in the form of auxiliary explanations—Newton appealed to teleology whenever he was unable to derive a physical phenomenon from his celestial mechanics. God was Newton’s answer when physics failed him. Newton was puzzled by the apparent incongruity of several observations. Nature seems to exhibit an orderly design that merits the label of a ‘‘celestial mechanics,’’ but then again, nature also seems to exhibit an entropic tendency that threatens this order. The observation of the regularity of celestial motions conﬂicts with the observations of bodily collisions. The regularity of celestial motions suggests the conservation of motion, but bodily collisions, Newton thought, invariably involve a loss of motion. Motion is lost when two bodies collide and rebound with less than their initial velocities.22 To explain the continuing regularity of motions in the face of the observation of bodily collisions, Newton supposed that God periodically infuses nature with new motion to keep the world machine from running down.23 His teleology combined his religious faith with an explanation of the physical puzzle. In the ‘‘Scholium Generale,’’ Newton accepted the notion of ﬁnal causes and viewed them as ways in which God makes himself known (K 2: 763, M 2:546). God designs nature, and nature’s design, in turn, shows it could only have proceeded from the ‘‘consilio & dominio entis intelligentis & potentis’’—from the counsel and dominion of an intelligent and powerful being (K 2:760, M 2:544). Another problem that puzzled Newton concerned the planetary perturbations. The sun holds the planets in its gravitational grip and forces them to orbit around a common center, but since the planets are masses they exert gravitational attraction on each other as well. Their gravitational forces cause perturbations in each other’s orbits, blurring the precise mechanical dance of the planets around the sun. The solar system becomes more fragile than one would like it to be, because in a dynamic system irregularities do not go away on their own but are bound to increase. If left to its own devices, Newton suspected, the solar system would eventually be destroyed by these perturbations. Nonetheless, the solar system appears to be stable enough, although no mechanical means is in sight to account for this stability. Once

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again, Newton tentatively resolved this puzzle by appealing to the hand of God: God’s periodic readjustments ensure the continuing harmony of the system.24 The third inexplicable phenomenon Newton observed was the ecliptic plane. If the law of universal gravitation were the only reason for the arrangement of planetary orbits around the sun, these orbits would be random. Instead, they are all clustered around one plane. Why? Newton could not discover any mechanical reason for the coplanar orbits and surmised in the Opticks that ‘‘such a wonderful Uniformity in the Planetary System must be allowed the Effect of Choice’’ (q. 31, 402).25 According to Newton, God periodically invades the system of the world from the outside. God infuses new motion whenever some is lost, he corrects perturbations when they get too big, and he ﬂattens the solar system into a plane. The hand of God is visible in the workings of nature, and God’s interferences ensure the future harmonious workings of the natural order. Nature is like a watch, and from time to time, God needs to wind it up. As in the teleologies of the pietists, Wolff, and the physico-theologians, divine design occurs in Newton’s model through external interferences. But means and ends are different in Newton. Although the ﬁnal vehicle is an external divine act, it is not a genuine miracle in Wolff ’s sense; it is not a truly extraordinary event. Newton’s ﬁnal means, the hand of God, rather resembles Wolff ’s miraculum restitutionis; its effect is to restore the mechanical causal nexus of nature instead of wreaking havoc on it. Newton’s ﬁnal end, the telos of the general natural ordering, differs from Wolff ’s general purpose of nature in that the ﬁnal ordering does not occur for the sake of human beings but for the sake of nature. The primary end of Newton’s teleology is the preservation of the lawful organization of nature. Kant realized that neither God nor nature are particularly well treated in Newton’s account. Newtonian nature has an entropic tendency; if left to its own devices it would only break down. Given that God is omnipotent and omniscient, could we not expect something better from God’s creation? Moreover, although Newton shows how God concerns himself with his creation by means of periodic necessary adjustments, such a concern does not seem to be very digniﬁed. The role Newton assigns to God is, on the whole, a rather bad career move for a god, for the originally supreme creator is now supposed to make himself useful as nature’s handyman. If the world were created as an omniscient, omnipotent, and benevolent creator had intended, then external interferences after the fact would not be required. Both in the Universal Natural History (I 332–3) and in the Only Possible Argument (II 107– 8, 142), he assessed Newton’s hand of God as an indication that Newtonian nature is insufﬁcient in its own lawful ordering. Kant’s suspicion, informed by metaphysical considerations, was that the universe not only works, but also that it works much better than Newton supposed. A creator with truly divine qualities would have created a ﬂawless universe rather than a mechanical lemon. Taking this teleology of nature seriously suggested for Kant that God lacked the very qualities that deﬁned him.

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Another problem that Kant perceived in this teleology is that Newton’s model of nature reveals a lack of harmony among its parts, for the entropic tendency of physical nature must be counteracted by an antientropic teleological reconstruction. God’s interferences mend the gradually arising irregularities and fuel new motion into the mechanistic system. Teleology, so construed, works against the mechanical tendency of the world. This deﬁciency indicates a split that goes through Newton’s ontology of processes. In his public views, Newton presupposed that two irreducible and incommensurate types of processes occur—entropic mechanical processes intrinsic to the natural system and antientropic divine acts extrinsic to the system.26 He was not interested in ontology, so for him this difﬁculty of his public views, if he noticed it at all, could not have been of great concern. But it mattered for Kant. Since the precritical philosophy of the 1750s stood under the sign of a great synthesis of metaphysics and science, it needed a uniﬁed ontology and thus a uniﬁed account of processes. Newton’s failure was, in a way, the opposite of the failure of the metaphysicians. The pietists, Wolff, and physico-theologians established a relationship between God and nature that supported the claims of metaphysics, but the ﬁnal means and ends they advocated were not acceptable to science. Newton constructed ﬁnal means and ends in support of his science, but the resulting God-nature relationship (with a downgraded God and a deﬁcient nature) was not acceptable to the tenets of metaphysics. Confronted with the difﬁculties that botched the teleologies of his predecessors, Kant had to start completely afresh.

5.2 Perfection as the Telos of Nature Kant regarded Newton as having perfected the ‘‘mathematical half ’’ of natural philosophy, and he hoped to furnish with the Universal Natural History an account of the ‘‘physical half ’’ of natural philosophy (I 230). The ‘‘physical half ’’ consists partly of speciﬁc investigations of the planets, moons, comets, and the sun, and partly of a teleological cosmogony to explain the origin and organization of the cosmos. The marriage of Newton’s quantitative model of nature with the new teleology in the Universal Natural History constituted the physical completion of Newtonian mechanics that Kant had intended. The notion of the perfectibility of the world is the focal point of the teleological cosmology. Kant explicated this notion in the Attempt at Some Observations on Optimism (1759). He summarized the main elements of the cosmogony once more in the Only Possible Argument (1763). There, he integrated them in an argument from design. The rather lengthy summary was essentially a recapitulation of the salient points of the Universal Natural History. Kant did not usually repeat himself, but he must have felt the urge to restate his views once more because the copies of the Universal Natural History, locked up in a warehouse because of the bankruptcy of the publisher, had failed to reach the public. The Only Possible Argument was indeed the next opportunity that presented itself because intense teaching commit-

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ments had prevented Kant from pursuing his own philosophical interests until the early 1760s. When he found the time to resume his research, he began where he had left off earlier. Despite the comparatively large time span that separates the composition of the two books, we can regard the Universal Natural History and the Only Possible Argument as belonging to the same stretch of Kant’s precritical development.27 Kant believed that the teleological vantage point and the mechanistic representation of nature can mutually support each other such that both perspectives come out stronger. In the Universal Natural History, he assumed the divine imposition of goals occurred in terms of ﬁnal processes immanent to nature instead of external divine interferences. In identifying the causal vehicle of purposive events with the efﬁcient causation of physical processes, Kant killed two birds with one stone. He integrated mechanics into a physicotheological context, thus providing a metaphysical vindication of Newton, and he ﬂeshed out physico-theology by means of mechanics, thus furnishing a mechanistic defense of a physico-theology in which God emerged as the creator of a self-sufﬁcient and perfectly engineered nature. The perfectly engineered nature, a leitmotif of the Universal Natural History, was a Kantian echo of Leibniz’s doctrine of the best of all possible worlds. As Kant explained it in the Optimism essay, the Leibnizian doctrine is closely tied to teleology because it presupposes that this world is the best (II 35). Since the world is perfect, everything it contains contributes to perfection (II 32). Against Newton’s conception of a world riddled with internal ﬂaws, Kant insisted that the organization of nature must be appropriate to God’s dignity (II 34). Following Newton, Kant thought of physical nature as a system of motions and bodies; following Leibniz, he thought of the world as perfect. This prompted Kant to construct an improved version of the Newtonian model that represented physical nature not just as a mechanical system, but as a ﬂawless mechanical system. Considering Newton’s and Leibniz’s bilious relationship because of the unfortunate priority dispute, there is a certain irony in the fact that a Leibnizian idea turned out to be Kant’s motive for improving the Newtonian model.28 Paradoxically, Kant’s twofold allegiance to the Newtonian model of physical nature and to the Leibnizian doctrine of the best of all possible worlds implied an approach that bore little resemblance to those of his predecessors. In contrast to the pietists and Wolff, Kant did not assign any teleological function to miracles. Divine interferences were not necessary for the purposive unfolding of nature. In contrast to the physico-theologians, he did not seek to demonstrate God’s existence from the design of particular natural entities. Moreover, in contrast to Newton’s claims about nature’s increasing irregularities, Kant insisted that nature exhibits a tendency toward greater self-organization. Moreover, the idea of unifying teleology and mechanics— the idea that is central to the venture of the Universal Natural History—may have been inspired by Leibniz’s parallel interests in teleology and mechanics. Nevertheless, it is not indebted to it. Leibniz had kept teleology and mechanics apart by assigning them to distinct ontological territories. Mechan-

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ics, for Leibniz, had concerned the phenomena; teleology, in terms of monadic entelechies, had concerned the substances.29 The immanent cosmogony of the Universal Natural History was an implicit repudiation of Leibniz’s separation. Kant dismissed anthropocentric teleologies in the Universal Natural History and in the Only Possible Argument (I 351–60; II 131–6),30 asserting that it makes little sense to assume the purpose of nature is God’s revelation to humans because they are not the center of the universe (II 96–7, 102, 127– 30). The actual telos of nature, he claimed, is different. An overarching striving is visible in nature, a striving toward perfection, which indicates that the purpose of nature is nature’s perfection (I 223, 263, 332). Not only is it the case that the world is perfect, but also, in a teleological sense, the world ought to be perfect.31 Nature strives to realize its goal from the very beginning; even in its simplest and sheerest state matter has the urge to develop itself into a ‘‘more perfect’’ constitution (I 228, 262–3, 314). This, then, is the major difference between Kant’s teleology and the approaches of his predecessors. The ultimate aim of ﬁnal means is neither the revelation of divine magniﬁcence to humans, nor the smooth operation of mechanical systems. For Kant, the overarching telos is the perfection of nature. The idea that perfection is the ﬁnal goal of nature may seem curious at best and incoherent at worst. It seems to contradict the Leibnizian view that nature is perfect, which Kant endorsed. For, if Leibniz was right, such a teleology would appear to be unnecessary. And, if Kant’s teleology was necessary, his acceptance of Leibniz’s view would not seem to make sense. Put differently, if nature is perfect, a progression toward this goal will not be needed because the goal has been realized all along, and if nature progresses toward perfection, then the mere fact of its progression means the aim has not been reached and nature is not perfect. But these puzzles arise only if one means an ultimate state of completion with the term ‘‘perfection,’’ or if one equates ‘‘perfect’’ with ‘‘the best.’’ When attributing these senses to perfection, one would accordingly be inclined to say nature is either perfect (complete, the best), or imperfect (incomplete, not the best), but never ‘‘more’’ perfect. However, this equivocation of ‘‘perfect’’ with ‘‘best’’ or ‘‘complete,’’ although certainly plausible today, was absent from the philosophical vocabulary of the eighteenth century. Kant, as well as Leibniz and the School Philosophers, employed ‘‘perfection’’ in a different sense. In the terminology of the day, ‘‘perfect’’ is perfectus, whereas ‘‘best’’ (as in ‘‘the best of all possible worlds’’) is perfectissimus or optimus.32 Kant’s use of the term follows the received tradition initiated by the Church Fathers. Augustine had declared in De natura boni (404 C.E.) that goodness is real but evil is not (#2, 6), and that God resides in the realm of being and goodness (#10). These remarks were the basis of the Augustinian doctrine that evil, as the opposite of the good that is tantamount to being, must be a privation of being (#15, 17, 34). With this doctrine, Augustine attacked the Manichean polarity of good and evil, rejected Origen’s divorce of God from the sphere of being and goodness, and pushed for the view that

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being and goodness exist in degrees (#1, 8, 12, 17). The highest degree of being, the ens realissimum, and the highest degree of goodness, the summum bonum, converge and are identical with God (it was not a coincidence that Kant employed the same terminology). Being and goodness diminish below the divine zenith through the descent of the ladder of creatures from angels to humans to beasts, until being and goodness dissolve at the nadir into nothing, or, what is the same, into evil. The Augustinian nature partakes in degrees of reality and in degrees of goodness.33 In his inﬂuential Metaphysica (1739), the textbook Kant would use in his lectures, Alexander Gottlieb Baumgarten reiterated the Augustinean equivalence of being and the good and tied both terms to the notion of perfection. Baumgarten deﬁned perfection as an agreement (consensus) of a manifold: If several things taken together simultaneously constitute a sufﬁcient reason, then they agree (consentiunt); the agreement itself is perfection, and the one thing, in which they agree, is the determining ground of perfection, or the focus of perfection. (#94, p. 26).34

Because Baumgarten claimed that each being comprised essential features (essentialia) that exhibited a causal harmony of the being’s essence with its attributes, he concluded that omne ens est perfectum transcendentaliter, each being is essentially perfect (#99). Since perfection is equivalent to the good, he further infers that omne ens est bonum transcendentaliter, each being is essentially good (#100). Thus, the ontological concepts ‘‘reality,’’ ‘‘goodness,’’ and ‘‘perfection’’ are synonymous. On 3 October 1714, Wolff asked Leibniz in a letter for a deﬁnition of perfection (AG 230). Leibniz acceeded to the request in the winter of 1714/ 15, deﬁning perfection ‘‘as the degree of positive reality . . . or afﬁrmative intelligibility’’ (ibid.). In a subsequent letter, on 18 May 1715, he offered another deﬁnition of the term: Perfection is the harmony of things, or the state where everything is worthy of being observed, that is, the state of agreement . . . in variety; you can even say that it is the degree of contemplatibility. Indeed, order, regularity, and harmony come to the same thing. (AG 233–4)

In the conceptual trajectory from Augustine to Leibniz to Baumgarten, perfection carries the connotations of reality, goodness, order, and harmony. All of these attributes allow gradations—things can possess and exhibit a greater or lesser degree of any of these features. Hence, the things in the world can be more or less perfect. Their degrees of perfection are at various distances from God’s absolute degree of perfection. Similarly, Kant wrote in the Optimism essay that entities exist in a continuous progression of degrees of reality (II 31–2). God embodies the summit of reality, and the range beneath the summit constitutes the world (II 33). Perfection is deﬁned in terms of this concept of reality, which comprises a

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gradation of being and goodness (II 30). Accordingly, perfection is not simply a highest state, but a dynamic progression admitting of degrees.35 In the Optimism essay (II 30–1), Kant remarked that God (as the ultimate state of being and goodness) is absolutely perfect, whereas nature is relatively perfect in terms of its evolution toward this ultimate state. According to the Universal Natural History, the telos of nature is the approximation of God through nature’s self-organization into a state of perfection. This state, according to the Optimism essay, is an absolute as regards nature’s potential and penultimate compared to God. The basic material building blocks of nature are not inert blobs of stuff, but active centers of force driven by a striving to ‘‘unfold’’ themselves (Auswickelung; I 226). The more extensive this unfolding of matter is, the higher the attained degree of perfection will be. In the Universal Natural History, Kant characterizes ‘‘perfection of nature’’ by a variety of attributes: order (I 226), diversity (I 306), beauty (I 306), fertility (I 314–17), abundance (I 338), and wealth (I 352). The telos of nature is its perfection. In other words, a maximum of order conjoined with a maximum of diversity and fertility. The triplet order-diversity-fertility generates harmony and beauty in the cosmos. Kant’s theory of teleology is certainly a unique creation, but his characterization of perfection, the telos of his theory, remains quite traditional. The associations of wealth (understood as a greater amount of being), harmony, and order evoke Leibniz’s earlier reﬂections on the concept. The associations of beauty, fertility, and diversity echo Baumgarten’s views. Beauty is deﬁned as the ‘‘perfection of the phenomena’’ in the Metaphysica (#662, p. 248). In the Aesthetica (1750), Baumgarten connects a cognitive category to both beauty and perfection that he calls ubertas (#22, p. 9) and which has the twofold sense of ‘‘fertility’’ and ‘‘diversity.’’36 In the Living Forces, Kant had advanced the view that the level of harmony and perfection of the world is proportional to its degree of interconnectedness (#11, I 25). In the Universal Natural History, he developed this view further, illustrating the natural interconnectedness with the metaphor Kette der Natur, the ‘‘chain of nature’’ (e.g., I 308, 365). This expression, modeled on Alexander Pope’s ‘‘the chain of being,’’37 marks nature’s march toward the telos of perfection, from nature’s inception in homogeneous chaos to its goal-state of order and diversity. The formerly lofty theological telos of traditional teleologies deﬂated in Kant’s cosmogony to the self-organization of physical structure. In contrast to all earlier teleologies except Newton’s, Kant identiﬁed the goal-state and purpose of the ﬁnal evolution as something immanent to the cosmos.

5.3 Newtonian Forces as Final Vehicles That Kant selected the Newtonian forces of attraction and repulsion as the vehicles for nature’s unfolding toward perfection was, paradoxically, his point of departure from Newton. The integration of Newtonian physics into Kant’s teleology implied the rejection of Newton’s teleology. Newton’s ﬁnal vehicles

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were extrinsic to nature, whereas Kant’s Newtonian ﬁnal vehicles were immanent to nature. Against Newton’s appeal to a ‘‘hand of God,’’ Kant asserted in the Universal Natural History that the development of nature does not require supernatural interferences (I 222–5). A constitution of the universe in need of miracles would lack stability and permanence, and this would ultimately question the dignity of God as the creator of nature (I 311). This view sharpened into a criticism of miracles in the Only Possible Argument. Appealing to miracles in teleology is the ‘‘least philosophical’’ method of physico-theology, because taking miracles for granted ignores the fact that the burden of proof rests on the claim for, and not against miracles (II 134–5). The resemblance between these passages in the Only Possible Argument and Hume’s similar but less civil remarks on miracles in the Enquiry Concerning Human Understanding (1748) is probably not a coincidence. Hume roundly condemned miracles as violations of the laws of nature and declared that, ‘‘because a ﬁrm and unalterable experience has established these laws, . . . there is here a direct and full proof . . . against the existence of any miracle.’’38 Kant encountered Hume’s work after publishing the Universal Natural History and before writing the Only Possible Argument. In the wake of this encounter, Kant showed considerably less patience with the supernatural.39 The ‘‘hand of God’’ implied for Kant a model of nature lacking the very organization prescribed by the mechanical principles of Newtonian physics (I 332–3; II 107–8, 142). In contrast to the Leibnizian-Wolfﬁan School Philosophy, Kant regarded the conﬂict between science and theology as a pseudoproblem and rejected the possibility of a competition between physical processes and external supernatural interferences. As he argued in the Universal Natural History, God imposes his ends on nature in conformity with nature’s causal ordering and generates a ﬁnal unfolding that occurs mechanically (I 224–5). That God created the laws of nature indicated to Kant that God viewed the laws as having a function, for if they did not, their creation would have been pointless (I 223).40 In Kant’s view, the laws of nature bind matter and compel matter to generate independent and necessarily beautiful connections (I 228). God has put a ‘‘secret art’’ into the forces of nature to execute an evolution from an initial chaos to a more perfect cosmic constitution (I 229). Are matter and forces the same here? Kant’s notion of an essential striving (I 226) was not simply a Newtonian force riding on a distinct and compliant matter. For Newton, matter was passive; for Kant, this passivity was an illusion, for matter actually contained an urge to organize itself (I 263).41 In a sense, then, matter and force run together in Kant’s account. Matter transforms into an active substrate of nature, and force (in the Principia a shorthand expression for the observed regularity of mechanical phenomena) reiﬁes into the inner essence of matter.42 Like the ‘‘chain of nature’’ that originated in the idea of a natural interconnectedness, Kant’s concept of a dynamic matter is a further elaboration of an idea in the Living Forces. There, Kant had described force as the essence, ‘‘entelechy,’’ or the immanent basic component of material bodies (#1, I 17; #124, I 148). Now, with the employment

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of a Newtonian force for his own purposes, Kant found the immanent, ﬁnal means to explain the systematic and mechanical formation of the cosmos. According to Kant, the starting point for the formation of the universe was, unsurprisingly, its divine creation. But God did not create an organized cosmos; he merely provided ‘‘basic matter’’ (Grundmaterie; I 310) as building blocks for nature’s self-organization. Initially, nature was chaos, a general and random scattering of basic matter throughout space (I 226, 263). The initial state of created nature lasted only a moment because material elements have essential gravitational forces to set each other in motion (I 264). The gravitational effects triggered the second phase of nature in which the homogeneously dispersed elements coalesced into lumps. Gravity generated the formation of clumps of matter, dispersed elements ‘‘of a denser kind’’ accreted and collected lighter elements in their wake, and regions with a higher density of mass attracted surrounding masses (I 225, 264). The accretion of masses prepared a third phase in nature’s self-organization: a second force intrinsic to matter began to have effects, the force of repulsion ‘‘modiﬁed’’ the motions of the particles that resulted from the second phase, eventually generating a ‘‘well-ordered whole’’ (I 225–6). The self-organization of matter involves two primary or primitive forces, attraction and repulsion (I 234). Kant’s conception of a ‘‘Newtonian’’ force of repulsion has led to some difﬁculties. Some commentators (such as Werkmeister, 1980) argue that Kant’s second organizing force of the cosmos, next to attraction, was the centrifugal force. Others (such as Shea, 1986) argue there is no repulsive force in the system of the Principia and that Kant merely attributed it to Newton.43 In fact, Kant derived both attraction and repulsion from the Newtonian philosophy of nature. The former is Newton’s force of gravity, the latter a molecular repulsion (I 235), which manifests itself, Kant thinks, in such phenomena as elasticity and gaseous dispersion (I 265).44 In other words, Kant likened repulsive force to elasticity, and he did not equate it with centrifugal force. Centrifugal force, both for Newton and for Kant, results from the angular velocity relative to the inertial frames; it arises from the inertial resistance of an orbiting mass against the constant deviation of its rectilinear motion to a curvilinear motion. Centrifugal force is a derivative (we would say ﬁctitious) force, not a primitive force, and thus different from repulsion. As regards the Newtonian roots of Kant’s repulsive force, one can make the case that Kant’s conception of a repulsive force based on elasticity and dispersion concurred with Newton’s own tentative interpretations of these phenomena. The early Newton wrote about repulsive force in De aere et aether (around 1674) and added repulsive and attractive forces to the ontology of nature after his dismissal of the kinetic philosophy.45 He explained in query 31 of the Opticks the homogeneous dispersion of salt dissolved in water through the repulsive forces of the parts of salt that hold the parts apart from each other at regular distances (p. 387–8). In the projected book IV to the Opticks, Newton stated as ‘‘hypothesis 2’’ that, as all the great motions in the world depend upon a certain kind of force (wch in this earth we call gravity) whereby great bodies attract one another at great

The Universal Natural History 113 distances: so all the little motions in ye world depend upon certain kinds of forces whereby minute bodies attract or dispell one another at little distances.46

For Kant, the modiﬁcation of motion through repulsion consisted in the deﬂection of material particles from their linear path toward a gravitational center. Collisions were inevitable in the dynamic concentration of accreting masses. Repulsive forces allowed the colliding particles to bounce back instead of being mashed together. The particles rebounded at different angles, veering off their original trajectories (I 245). The resulting ‘‘lateral motions’’ (Seitenbewegungen) of the impacted particles caused the condensing particle cloud to spin around its core. Ultimately, rotating groups of worlds emerged that revolved around a common center of gravity which, in a sense, is the hub of the universe (I 311–12). If one compares Kant’s account of repulsion with Newton’s own remarks, then it is evident that a conception of repulsion as dispelling the accreting particles into lateral motions, causing the particles of a protostar to rotate, remains completely in the spirit of Newton’s own speculations.

5.4 Kant’s Nebular Hypothesis Because a ‘‘single universal rule’’ guides the evolution of the cosmos (I 306), Kant argues that the formation of the solar system mirrored the formation of the cosmos and that the formation of our solar system was the same as the formation of other planetary systems everywhere. The third phase in the universe’s evolution resulted in a rotating cosmic cloud, and in what we might call the fourth phase of cosmic evolution, the processes of gravitational accretion and lateral repulsion repeated themselves on ever smaller scales. The cosmic cloud precipitated out into smaller lumps—the germs of future galaxies—that began to rotate around their own centers of gravities while continuing to participate in the overall cosmic orbital motion. In the continuing process of condensation, the spinning galactic bubbles spawned smaller gravitational knots, one of them being the seed of the solar system (I 250). The fourth phase of the cosmic evolution resulted in the birth of the solar system whose initial state was a cloud of randomly and homogeneously distributed matter particles. Gravitational forces acting on the particles caused them to accrete into a uniform sphere of matter. Attractive and repulsive forces applied to the primordial sphere of matter and set it spinning. The ensuing centrifugal forces made the equator of the matter ball bulge out, ﬂattening the ball into a rotating disc. The resulting spinning elliptic bands of matter condensed into worlds by means of gravitational attraction leading to the solar system in its present state (I 264–6). Perhaps the only difference between the genesis of the solar system and the evolution of the cosmos concerns the formation of planets. Kant argued that gravitational attraction did not initiate the growth of the planets because this force is too weak and acts too slowly with respect to ‘‘a little particle (Partikelchen) of such exceptional delicacy’’ (I 267–8 note). Instead, Kant surmised, the natural cohesion of elements generated a condensing

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protoplanet, and as its mass grew, gravitational forces increasingly overshadowed the cohesive powers and eventually completed the formation of the planet. Kant’s account of the development of the solar system became known as the Nebularhypothese. Contrary to the belief of earlier scholars (e.g., Adickes, 1924a), Kant’s nebular hypothesis turned out to be essentially correct and was conﬁrmed almost two hundred years after its original formulation by the astrophysicists C. F. v. Weizsa¨cker and J. G. Kuiper in 1944.47 The nebular hypothesis exempliﬁed Kant’s envisioned union of Newtonian mechanics and immanent teleology. The mechanical forces acting on matter are sufﬁcient to account for the well-ordered organization of the solar system. Whereas Newton thought it necessary to summon the hand of God in order to explain the arrangement of planets around an ecliptic plane extending from the sun’s equator, Kant showed that mere physical forces alone are the ﬁnal vehicles responsible for the ecliptic arrangement. Kant developed this hypothesis at length only in the Universal Natural History, the work that failed to reach the public in signiﬁcant numbers. Although he reiterated it in the Only Possible Argument (II 144–7), the recapitulation is vague and abbreviated, and it lacks the clarity and force of the original theory. That Kant tucked it away in the text as a mere example of an acceptable employment of the physico-theological method did not help. The summary in the Only Possible Argument was insufﬁcient to change the fact that the cosmogonical hypothesis remained unknown. A generation later, Pierre-Simon de Laplace published conjectures resembling Kant’s hypothesis in his Exposition du syste`me du monde (1796).48 Laplace, who was unaware of Kant’s early work, developed a theory that repeated the outlines of Kant’s hypothesis. Like Kant, Laplace deduced the formation of the solar system from one mechanical cause, described its initial state as a cloud of matter, and identiﬁed attraction and repulsion as the forces responsible for the self-organization of the solar system. Laplace’s account, in the ‘‘Note VII et Dernie`re’’ of the Exposition du syste`me du monde, was more restricted and considerably shorter than Kant’s in the Universal Natural History. In addition to its brevity, there were also a number of speciﬁc differences that distinguished the Laplacian hypothesis from Kant’s. Kant proposed a uniform cosmogony to explain an analogous formation of the solar system and to the birth of the universe. The nebular hypothesis, in its original Kantian form, applied to both. Laplace restricted his version of the nebular hypothesis to the solar system, and the ‘‘KantianLaplacian hypothesis,’’ as it became known in the nineteenth century, referred essentially to Laplace’s limited version of Kant’s more general hypothesis. In addition to this difference in scope, numerous details of the formation of the solar system separate the two accounts: Kant explained the rotation of the primary cloud through the force of repulsion, whereas Laplace took the rotational movement as a given fact. Kant was concerned with all the elements of the solar system including the comets which Laplace ignored. Kant identiﬁed dust, Laplace gas as the primary matter. Finally, Kant

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believed the formation of planets stemmed from condensation processes similar to the ones occurring in the sun, while Laplace suspected that the formation of planets had come about through the expulsion of matter clumps from the rotating sun. As regards this last contrast, Kant turned out be right; his idea was conﬁrmed in Weizsa¨cker’s and Kuiper’s theory of turbulences.49 In one signiﬁcant respect, however, Laplace’s version of the nebular hypothesis was superior to Kant’s. Laplace correctly supposed that the solar system was hotter in its earlier stages than in its present stage. Kant’s precritical cosmogony, by contrast, stipulated a ‘‘cold’’ formation. That the condensation of matter generates heat is something Kant would realize only much later, in the essay On Volcanoes on the Moon (1785), which led him to revise his cosmogony accordingly (VIII 72, 74–5). In any case, when the Universal Natural History became accessible to a wider public in several editions in the last three years of the century,50 thus shortly after Laplace’s publication of the Exposition du syste`me du monde, the cosmogonical hypothesis of the origin of the solar system became known as the ‘‘Kant-LaplaceHypothesis,’’ a label coined by Arthur Schopenhauer in 1818.51 In Kant’s account, the same forces that acted on the formation of the cosmos and the solar system were responsible for the formation of the Milky Way. Attraction induced the galactic cloud to condensate, repulsion set it spinning, and the ensuing centrifugal forces caused the galactic equator to bulge out (I 250). Kant suspected that we cannot perceive the galactic rotation. The rotation remains invisible either because the orbital velocity of the ﬁxed stars was too slow, or because the distance separating our point of observation from the objects observed was too vast (I 251–2). He was well aware that the spin of a rotating mass generates centrifugal forces whose vector is perpendicular to the rotational axis. He accordingly asserted that the Milky Way was compressed into a disk—regardless of the fact that it appears, from our vantage point, as an unbroken ribbon in the sky (I 249). Once again, Kant was right—William Herschel, the discoverer of Uranus, conﬁrmed the disklike structure of the Milky Way in 1811. Five years before Kant wrote his book, the English natural philosopher Thomas Wright suggested the idea of a disklike Milky Way in his Original Theory or New Hypothesis of the Universe founded upon the Laws of Nature and solving by Mathematical Principles the general Phaenomena of the visible Creation, and particularly the Via Lactea (1750). Kant probably got the idea from reading Wright. But as several commentators have rightly pointed out (Hoskin, 1970; Hetterington, 1973), the lion-share of the credit for this idea should go to Kant. He defended and elaborated his proposal, integrating it into the correct Newtonian framework, whereas Wright merely mentioned the idea without further comment.52 The disklike structure of the Milky Way is reminiscient of the ecliptic plane of the solar system. In the Universal Natural History, the similarity is not coincidental. A commentator (Shea, 1986) argues that the similarity is due to the Milky Way belonging to the solar system as its extension. But this is not quite right. As Kant described it (I 248–50), the similarity does

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not stem from a simple homogeneity of the solar system and the cosmos. Instead, it derives from a grandiose cosmic structure that reiterates itself on ever greater levels of magnitude.53 The cosmic reiteration reveals itself in the analogies between solar system and galactic system: ﬁrst, the stars in the Milky Way are clustered around an eclipsis just like the planets in the solar systems. (The stars are not simply dispersed within the galaxies, as Thomas Wright had assumed.) Second, the disklike Milky Way rotates around its gravitational hub, just as the solar system does. And ﬁnally, the Milky Way is a systematic composite like the solar system. While the components of the solar system are individual bodies, the components of the galaxy are individual solar systems. The Milky Way is a ‘‘system of ﬁxed stars,’’ and we can conceive of it, Kant writes, as the solar system in inﬁnite magniﬁcation (I 250). Kant thought extragalactic nebulae could be explained though analogy to the Milky Way. Thomas Wright had advanced this idea in Original Theory or New Hypothesis of the Universe. Nebulae appear in the telescope as ‘‘cloudy stars,’’ and Wright had speculated they were actually ‘‘knots of stars’’ (7th letter, p. 65).54 Kant knew about Wright’s book through a review in a German magazine,55 and he integrated Wright’s idea in his cosmogony. Cloudy stars (neblichte Sterne), Kant argued, are not stars but systems of stars. In fact, they are other galaxies seen from afar (I 255–6). Of course, at the time of the Universal Natural History, this was just an educated guess because of the insufﬁcient resolution of the available telescopes. In the 1920s, Heber Curtis resurrected the Wright-Kant hypothesis that nebulae were extragalactic star clusters and became the leading defender of the ‘‘island universe’’ theory (a term inspired by the Universal Natural History). In 1924, Edwin Hubble succeeded in verifying that nebulae are clusters of stars outside of the Milky Way through his observations of M 31, the Andromeda galaxy.56 Although Kant’s interpretation of cloudy stars as ‘‘island universes’’ was merely a speculation, it was a good one. Not only for the trivial reason that it turned out to be correct, but also because it was more sophisticated than other eighteenth-century explanations of cloudy stars. Maupertuis regarded them as giant suns; Halley believed them to be pure light (conﬁrming, in his opinion, that the creation of light preceded the creation of suns); and Derham, utterly innocent of any scientiﬁc inkling, thought they were luminous openings in the curtain of the night. Kant not only incorporated the correct idea into his own cosmogony, but also succeeded in modernizing it. In Wright’s view, cloudy stars were simply clusters of stars; in Kant’s account, these clusters of stars were dynamic systems obeying the same rules as all other macrocosmic phenomena of the universe, and mirroring the structure of any celestial system regardless of its magnitude. According to Kant, the universe as a whole obeys Newton’s law of universal gravitation. The universe obeys it through space, as the fundamental principle of cosmology, as well as through time, as the single general rule of cosmogony or the evolution of the cosmos. The accretion of material

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spheres from the original, randomly dispersed matter dust led to the generation of the sun and planets which together formed the solar system. The generation of other solar systems like ours led to the formation of the Milky Way; as planets orbit a sun in a solar system, solar systems orbit a common galactic center. Our Milky Way is one of many similarly constituted island universes. All of these galaxies, Kant supposed, might form an immense megasystem revolving around a common cosmic point, the gravitational center of the universe (I 255, 311). As we know nowadays, these speculations were not that far off. The hypothesis that planets exist in other solar systems has been repeatedly conﬁrmed through a surprising number of recent discoveries; and the claim that individual galaxies, including the Milky Way, are in the grip of overarching gravitational forces has been proven as well (the so-called local galactic group, to which the Milky Way belongs, moves toward an as-yet unidentiﬁed ‘‘great attractor’’). Kant took Pope’s ‘‘chain of being’’ to the extreme. Creation as a whole is an interconnected system of subsystems, and each link in the chain of nature that is a systemic composite on one level is a component of a greater system at a larger level (I 255–6, 307). The universe has a reiterative structure, repeating the organization of the solar system on two higher orders of magnitude, on the level of the galactic system (I 251, 307), and on the level of the cosmic system of extragalactic nebulae (I 253–6, 308–9). Cosmogony and cosmology run together in the Universal Natural History. The cosmogony is not the history of past events, and the cosmology is not the account of the present structure. The cosmogony applies to the past, present, and future, because the evolution of the universe is an ongoing process. We can imagine Kant’s conception of the cosmic development as a dynamic explosion of organizing forces that occurred at the point where the random scattering of basic matter was originally at its densest. Since this primal ‘‘big bang,’’ the shockwave of the initial explosion has been rolling through the boundless cloud of randomly scattered particles. It leaves a continuously enlarging bubble of organized cosmic structures in its wake. Because Kant assumes that the universe has no limit in space (cf. I 247, 255, 306), the evolution of the universe, once begun, will continue without reaching an end in time (I 309). The creation continues to happen; an inﬁnite cosmos implies an eternal self-organization.

5.5 Life in the Cosmos and Humans as Links in the Chain of Nature Within the expanding bubble of the structured cosmos, the self-organization of nature continues on the organic level, resulting in ever-increasing fertility and diversity. In section III of the Universal Natural History, ‘‘Of the Inhabitants of the Stars,’’ Kant threw the caution announced in the preface to the wind and brought the mechanical cosmogony to its logical conclusion. In the preface, he had presented himself as being extremely reluctant to deduce the organization of organic nature from mechanic causes (I 230).

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Now, at the conclusion, he suggests such a deduction anyway. The mechanical evolution of the cosmos, he thought, would eventually lead to the evolution of life and even to the evolution of rationality. In this sense, then, mind depends on matter, and Kant even goes so far as to claim that the composition of material elements will determine the level of rationality in the living being. In Kant’s opinion, the construction of a reiterated cosmos on the basis of analogies in sections I and II of the Universal Natural History was not just a plausible hypothesis, but essentially a certain and correct theory, and he repeatedly revealed the depth of his conviction (I 263, 277, 334, 341–2, 344). In section III, where he turned to organic nature in general and to intelligent life in the cosmos in particular, he adopted a more cautious, but still conﬁdent stance. The arguments advanced, he claimed, only seem to be speculative. In actuality they are well founded and probable (I 351). Since nature strives for a self-perfection that reveals itself in a maximum of order, diversity, and fertility, it must follow that nature, in realizing its telos, will be teeming with life. In the Entretiens sur la pluralite´ des mondes habite´s (1686), Bernard Le Boyer de Fontenelle had written about the cosmos, ‘‘tout est vivant, tout est anime´,’’ everything is alive, everything is animated.57 Kant did not think his teleology required him to embrace the claim that all planets are inhabited; nonetheless, he found it implausible to assume that most planets are devoid of life (I 352, 354). Deserted regions exist in the cosmos; comets, for instance, are in all likelihood not suited for organic life. But on the whole, nature is rich, and this wealth reveals itself in the production and sustenance of life. Thus, a planet that is uninhabited now will be inhabited in the future, because the perfection of a planet lies in the organic nature it supports. The telos of a planet is to carry life (I 353). What kind of life? Ultimately, Kant argued, the purpose of planets is to allow the evolution of intelligent life. Although intelligent life-forms are more complex than primitive organisms, the degree of complexity is not directly proportional to the degree of intrinsic value. Interestingly, and in contrast to the ratiocentrism of the critical period, the precritical Kant rejected the idea that rational life is more valuable than nonrational, mere organic life. Within the inﬁnity of creation, all organisms are equally necessary, and an insect is just as important as the most sublime being on the cosmic scale (I 354). Setting himself at variance with the theological tradition, Kant doubted not only that humankind is the purpose of creation, but also that it is the crown of creation. A theme running throughout the whole precritical period was Kant’s rejection of the theological dogma that humans are in an important sense distinct from the remainder of the creation. Kant did not subscribe to a Cartesian dualism of a mental substance that thinks without being extended and a material substance that is extended without thought. He even suggested in the later Prize Essay (1764) that it cannot be proven that the soul is not of material nature (II 293). Although the soul does not consist of matter, he continued there, it may be some sort of energy or force commensurate with the material framework of nature. The price of Descartes’s

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dualism was the nagging problem of mind-body interaction, and in order to avoid similar difﬁculties, Kant hesitated to create an ontological divide between the human soul and physical nature. In the Universal Natural History, Kant described human beings as material entities. The ‘‘coarseness’’ of matter puts limits on the capabilities of the human brain, and this constrains and restricts the intellectual and rational performance of humans (I 356). Certainly, there is an ‘‘inﬁnite distance’’ between body and mind, but the mind is dependent on the body for the power of rationality is linked to the constitution of matter (I 335). These speculations on the cosmic role of human beings and the constitution of the human mind had a negative thrust because they denied the theological dogma of human superiority and the Cartesian tenet of a mindbody dualism. But, in addition, they carried a positive thrust as claims in support of the model of nature whose construction was the goal of the precritical project. Kant’s envisioned uniﬁcation of science and metaphysics involved a marriage of quantitative and qualitative aspects of reality in the same ontological domain. Because quantitative aspects of reality concern sensible matter, and qualitative aspects of reality involve the intelligible, their ontological union has consequences for the status of human beings as well as for the status of the mind. If the sensible and the intelligible pertain to the same domain, then empirical nature and rational beings are connected closely enough that both a theological anthropocentrism and a Cartesian dualism must become problematic. The marriage of the sensible and the intelligible that was characteristic of the precritical project is incompatible with both a biblical dualism between man and nature, which pits the human ruler, created in the image of God, against the brute beasts of material nature, and a Cartesian dualism that divorces the res cogitans from the res extensa. The characterization of human beings as middle rungs on the ladder of creatures; the contention that a creature’s rationality is proportional to the degree of coarseness of its constitutive matter; the admission that the human soul may be of material nature—all of these seemingly separate claims are connected through the logic of the unifying enterprise of the precritical project. At the same time, the mere effort of unifying mind and matter in the way suggested does not warrant the conclusion that Kant successfully performs the task of furnishing a solid alternative to Cartesian dualism. Bringing the mental and the material together, through the dependency of intellect and character on the material constituents of their embodiment, and through the possibility of human freedom within a deterministic physical reality, remains largely on the level of promissory notes. The brief and superﬁcial remarks in the Universal Natural History do not sufﬁce to substantiate and justify these assertions. As Ameriks (1982) rightly points out, the Universal Natural History treats the issue of mind-body interaction as unproblematic, but its theory of mind remains much too simple to defend the claims advanced.58 In any event, Kant thought rationality depended on matter. This idea implied for him the more speciﬁc (and curious!) view that the level of rationality depended on the type of matter. The extent of the material imped-

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iment of the mind hinges on the particular ‘‘coarseness’’ of the matter involved. The ‘‘coarseness’’ of matter (Grobheit der Materie) is proportional to the ‘‘inﬂexibility’’ of the ﬁbers (Unbiegsamkeit der Fasern) and the ‘‘inertia’’ of the ﬂuids (Tra¨gheit der Sa¨fte) of the intelligent organism (I 356). As the further argument makes clear, the coarseness of matter, in turn, is proportional to its mass and density. The matter constituting planets which sustain life is not the same everywhere. Because the force of gravity is directly proportional to the quantity of mass, as Newton found out,59 Kant believed he could conclude that heavier particles fall deeper than lighter particles toward the center of gravity (I 270). While consisting of distinct elements of varying density, matter was originally homogeneously dispersed in the protosolar system. A heterogeneous mass of elements accreted in one place and eventually formed the gravitational center of the particle cloud. The remaining elements began to orbit this center, and their density (or mass since Kant equated the two notions) determined the height of their orbit. On the basis of Newton’s law of universal gravitation (gravitation is directly proportional to mass and inversely proportional to distance), Kant formulated his ‘‘static law,’’ as he called it, that the heights of the matters in the cosmos are inversely proportional to their densities (I 270). The ‘‘static law’’ described the differentiation of matter after the formation of the central gravitational mass in the solar system, and thus, the ‘‘static law’’ did not apply to the material constitution of the central body. The sun consists of elements of varying density and contains the greatest mass of all bodies in the solar system. The matter dispersed in the solar cloud differentiated according to the density of its elementary components because the density determines the height at which the particles pulled toward the gravitational center are laterally deﬂected into orbital trajectories. Denser elements, deﬂected later, formed lower orbits; lighter elements, deﬂected sooner, formed higher orbits. The revolving orbital particle bands accreted into planets, and as a result, the average planetary density decreases with the distance from the sun (I 277). It was already known at Newton’s time that the density of the planets varies and decreases with the planet’s distance from the sun.60 Nonetheless, Kant’s ‘‘static law’’ is a questionable generalization of this fact because, as we know now, this decrease does not happen in a precise and linear way, and there is not an exact inverse proportion of material density and distance from the gravitational center. In section III of the Universal Natural History, Kant combined his ‘‘static law’’ of the proportionality of material density and solar proximity with the idea of the proportionality of material density and rational impediments. He inferred from the inverse relation between planetary density and orbital height that the farther intelligent life-forms are from the sun, the less matter inhibits the unfolding of rationality (I 358). Fontenelle had argued in the Entretiens that heat, hence, the proximity to the sun, has a positive effect on organic activity (4ieme soir, 2:78–9). He had painted a picture of planetary citizens ranging from the small, sun-blackened, and heat-frazzled Mercurians

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crazily dashing about, to the ponderous and somber sages on Saturn, smart but glum, who coolly pursue their affairs (2:94–5). Like Fontenelle, Kant believed that heat affects organic but not intellectual activity. As ﬁre keeps matter in a state of excitation, and as life embodies this state, life has a necessary relationship to ﬁre (I 358). Following Fontenelle, Kant speculated that true intelligences are to be found in the outer planets. But unlike his predecessor, Kant did not link their increased sophistication with the ambient chill more amenable to thought. Instead, he connected it with the rarefaction of matter in the outer reaches of the solar system (I 359). Because the stronger solar radiation excites even the dense elements of the inner planets, life might be possible there, but the emergence of true intelligence requires matter of a lighter and ﬁner kind.61 The curious considerations of material density, orbital distance, and rational sophistication explain why Kant thought humans occupied the ‘‘middle rung’’ on the cosmic ladder of creatures. Since the earth is situated between the inner and the outer planets, Kant’s reﬂections on the relation of solar distance and increased intelligence imply that humans are superior to some planetary citizens and inferior to others. Moreover, the universe is vast, it is teeming with life, and it is more than likely that other regions of the cosmos are populated by other intelligences of varying degrees of sophistication. This consideration reinforced Kant’s repudiation of anthropocentrism. Anthropocentrism is untenable on epistemic grounds because it derives from a speculative perspectivism. But it is also unwarranted on ontological grounds, because man’s ‘‘intermediate’’ material constitution prevents him from being the pinnacle of creation. Shell (1996) suggests that man’s rational mediocrity is derived from the human struggle between sexual and intellectual maturity in the Universal Natural History, but as the above description of Kant’s lines of argumentation have made clear, there is no evidence whatsoever for such a reading.62 According to Kant, man proceeded on the intermediate course (Mittelstraße; I 366) between wisdom and irrationality (I 365), a conclusion that inﬂuenced his student Johann Gottfried Herder.63 The cosmic mediocrity of humans is no fault of their own but results from their halfway position between the inner solid planets whose material density is heavy and the outer gas giants whose material density is light.

5.6 Human Species, Race, and Kant’s Alleged Racism According to the premises of Kant’s teleological cosmogony, the hierarchical differentiation of cosmic intelligences based on the density of the locally prevailing matter determines the intermediate rank of the human species. Does the differentiation of the intelligible, as a hierarchy of rationality, continue within the human species as well? And if so, in what manner? In section III of the Universal Natural History, Kant explains the ranking of intelligences on the planets of the solar system in the following way:

122 The 1750s: The Precritical Project On the one side, we saw thinking creatures (denkende Gescho¨pfe), who would admire a Greenlander or a Hottentot as a Newton; on the other side, we saw thinking creatures who would marvel at Newton as an ape. (I 359–60)

Right after this passage, Kant quotes the verses from Alexander Pope’s Essay on Man (wr. 1730–32, publ. 1733–34) that inspired him to make this comparison: Superior beings, when of late they saw A mortal Man unfold all Nature’s law, Admir’d such wisdom in an earthly shape, And shew’d a Newton as we shew an Ape.64 Kant’s use of ‘‘Newton’’ as a symbol of intellectual superiority and of ‘‘Greenlander’’ and ‘‘Hottentot’’ as symbols of intellectual inferiority raises questions. Kant’s symbols of intellectual inferiority were non-European ethnic groups subordinated to the European colonists. The ‘‘Greenlanders’’ are the native Inuit of Greenland, which was ﬁrst colonized by Icelandic seafarers and became a Danish possession in 1721. The ‘‘Hottentots’’ are the KhoiKhoin,65 the original inhabitants of South Africa, which was ﬁrst claimed by the United Dutch East India Company in 1652, became a Dutch colony after the founding of two inland settlements in 1679 and 1687, and fell to the British crown in 1795. As the third symbol of intellectual inferiority, Kant borrowed the ‘‘Ape’’ from Pope’s verses, thus implicitly equating primates, Inuits, and Khoi-Khoin. Hence, not only the philosophical question of a further differentiation of rationality within the human species arises here, but also the darker, more troublesome question of whether this differentiation occurred along racial lines. In other words, does the precritical cosmogony entail racism? If this unpalatable passage of the Universal Natural History was isolated in Kant’s writings, a benevolent reading as an unintentional clumsiness might be plausible. But what is insinuated here is elaborated elsewhere. In the Observations on the Beautiful and the Sublime (1764), Kant characterized Africans as vain, chatty, and devoid of talents (II 253). He took black skin as a ‘‘distinct proof ’’ of stupidity (II 254–5) and further remarked, The negroes of Africa have naturally no feeling that rises above the ridiculous (das La¨ppische). (II 253)66

In the Lectures on Physical Geography, written sometime between 1756 and 1760,67 Kant declared, The greatest perfection of humankind ﬁnds its embodiment in the white race. Already the yellow Indians possess less talent. Far lower are the Negroes; the lowest are some American tribes. (IX 316)

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Any hierarchical differentiation of human races is by deﬁnition racism. It has been argued (Firla, 1994; Firla-Forkl, 1994) that Kant’s attitude was a personal prejudice, a twisting of available facts for the sake of conforming to a preconceived standard.68 But the actual situation was more complex. It is not the case that Kant encountered neutral data and forced them on to a Procrustean bed of racist bias. Kant’s two most relevant anthropological sources were Peter Kolb’s Caput Bonae Spei Hodiernum, das ist Vollsta¨ndige Beschreibung des africanischen Vorgebu¨rges der Guten Hoffnung (1719) and George Louis Leclerc Buffon’s enormous, forty-four-volume Histoire Naturelle Ge´ne´rale et Particulie`re, which appeared in Germany in condensed form as the Allgemeine Historie der Natur (1752). Neither of these sources was free of bias. Kolb ﬁltered the information about African customs and traditions through his own frequently negative judgment and coined the rather derogatory term ‘‘Buschma¨nner’’ (bushmen) for the San people of Namibia; Buffon came up with the invidious hierarchy of races that Kant adopted in the Lectures on Physical Geography.69 Nor is it the case that Kant’s attitude was an isolated prejudice. His judgments reﬂected the prevailing views of the time. Racist remarks similar to Kant’s can be found in Fontenelle, Helve´tius, Hume, Lessing, Maupertuis, Regnard, Rousseau, Sulzer, Wieland, and Voltaire.70 The reason for this widespread and entrenched racism was the assertion of values implicit in the European Enlightenment. Philosophical anthropologists presented their standards of evaluation as universal, necessary, and rational standards, but in reality, these standards derived from the particular preferences characterizing the Age of Enlightenment. Eighteenth-century European culture was the measure of all things. Any society that was different was inferior by implication, and the degree of its difference from the European standard determined the degree of its inferiority. This was the consensus of the age, and it was not challenged until Johann Gottfried Herder revealed the arbitrariness of this ethnocentrism with his Auch eine Philosophie der Geschichte der Menschheit (1774).71 Kant’s racism was fueled by slanted data and was part of the zeitgeist—as a promulgator of the European Enlightenment with racist leanings, Kant was a child of his time. What is interesting for our purposes, however, is that a closer examination of the Universal Natural History reveals a contradiction between racism and cosmogony. Kant’s prejudice was at odds with central assumptions of the Universal Natural History; the bias did not mesh with the components of Kant’s system of nature. Humans occupy a middle rung on the ladder of rational creatures, and although one might think a racist hierarchy of human intelligences could conceivably be the internal differentiation of this middle rung, other considerations in the Universal Natural History rule this out. With Kant’s ‘‘static law,’’ gravitational and repulsive forces caused a staggered arrangement of elements of varying density, and the resulting orbiting bands of elements of similar density eventually accreted to planets. Hence, the density of matter differs from planet to planet, but must be the same within each particular planet. With Kant’s remarks in section III, the

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density of matter determines the complexity of the mind and thus the degree of rationality. Together with the ‘‘static law,’’ this implies a hierarchy of intelligences in the solar system (provided that other planets are populated as well), but it precludes a hierarchy of intelligences on the same planet. The racist bias we ﬁnd in Kant was not a consequence of the positions to which he committed himself with the teleological cosmogony; on the contrary, the premises of the teleological cosmogony preclude the very hierarchical differentiation of human races that is the essence of the bias. Thus, the conception of the cosmos, in the Universal Natural History, the Optimism essay, and the Only Possible Argument, remains independent from a racial hierarchy of rationality. Racist opinions inﬂuenced Kant’s classroom remarks, in the Lectures on Physical Geography, they inﬂuenced a nonacademic, popular essay, the Observations, and they persisted in his critical works, but they were not an integral part of the precritical project of a uniﬁed philosophy of nature. Thus, Kant’s racist opinions reveal the deﬁciencies of the man, but not the failings of his philosophy. With that said, let us return to the cosmogony.

5.7 The Cosmic Whole: The Cyclical Universe The present cosmos is a constantly expanding sphere of organized matter differentiated into planets orbiting suns within galactic nebula. When matter reaches a certain level of self-organization, decay sets in. Here, Newton’s statement in the Opticks, that ‘‘Motion is much more apt to be lost than got, and is always upon the Decay’’ (398), enters the cosmogony of the Universal Natural History. Newton referred to the constant and ubiquitous loss of motion in mechanical systems, but Kant interprets it to mean that this entropic tendency of nature is not universal but emerges in time at a certain stage of material complexity and in space at the center of the ordered universe. Because nature strives uniformly for ever greater self-perfection, the organized matter within the expanding sphere of the formed universe continues to differentiate itself into greater diversity and fecundity. At a certain stage of material complexity, entropic processes start that lead to the dissolution of the formerly organized physical structures. The oldest regions at the center of the expanding sphere are affected ﬁrst. Thus, Kant claims the decay begins at the center of the universe and generates a second sphere of entropy, following in the wake of the sphere of organization and expanding within (I 319). Loss of motion leads to destruction and eventual chaos (ibid.). As nature organizes itself, so nature will fall apart. However, the chaos within the entropic sphere is physically identical with the chaos at the inception of the universe. It accordingly contains the very dynamic and kinematic factors that caused its organization. Thus, Kant argues that nature will restore itself from the new chaos (I 320). It spawns another organizational sphere within the expanding entropic sphere; renewed organization follows in the wake of chaos, and the evolution of the cosmos as a whole can be likened to a ‘‘Pho¨nix der Natur,’’ a phoenix of nature (I 321).

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At ﬁrst sight, the phoenix-motive inspired by Newton’s loss of motion seems to stand at odds with Kant’s teleology of nature. How can the entropic bent of organized matter be reconciled with the declared progression of nature toward ever greater perfection? Kant thought he could reconcile the two divergent tendencies. Although chaos follows in the wake of organization, the initial sphere of organization keeps on expanding. The outer boundary of the universe, constantly pushed further, is the receding chaos of the not yet created and primordial nature. The inner boundary of the universe, constantly pushed deeper into the organized creation, is the expanding chaos at its center. Hence, Kant concludes that the circumference of the organized universe is always growing (I 319–20). Since the velocity of expansion of the successive spheres is presumably constant, and the outer expansion sweeps up exponentially more space than the inner expansion, the moving organized region will get bigger and bigger. There is no outer limit to organization since space, with its homogeneously dispersed matter particles, is inﬁnite. Phoenix and perfection are in harmony because they depend on one’s perspective. From a vantage point outside the organized cosmos, the universe constantly increases in volume, order, and diversity. From a vantage point at a certain point inside the organized cosmos, nature appears as a cyclical universe, a never-ending surf of waves of chaos and order. The sweeping grandeur of the cosmos as Kant portrays it in the Universal Natural History is nothing but amazing. Kant knew what he was talking about when, later in life, he began the conclusion of his Critique of Practical Reason (1788) with the words, Two things ﬁll the mind with ever new and increasing admiration and awe, the oftener and more steadily we reﬂect on them: the starry heavens above me and the moral law within me.72

A modern appraisal of Kant’s theory of the cosmos reveals both weaknesses and strengths. His account of the solar system contains a series of ﬂaws: there are more planets than the ones known at his time; material density does decrease with increased distance from the sun, but not as regularly as the ‘‘static law’’ predicts; the size of the orbiting bodies does not increase with distance and the comets are not bigger than Jupiter; the actual rotational velocity of Saturn does not match Kant’s calculations, and the moons of Saturn neither orbit randomly nor all in one direction.73 In addition to these speciﬁcs, his general conception of science is, of course, dated. Above all, his idea of material entelechies endowed with a causal power has become scientiﬁcally meaningless. In contrast to his conception, the aim of modern science is not to reveal the intelligible character of the universe, but to catalogue the regularities the causal sequences reﬂect.74 On the other hand, Kant’s theory of the universe also contains a series of correct insights, the nebular hypothesis of the formation of the solar system, the identiﬁcation of the Milky Way as a rotating and disk-shaped galaxy, and the improvements on Wright’s idea about galactic nebula. That

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Kant was able to anticipate future discoveries was not just luck and coincidence. The systematic temporal and spatial extension of the celestial mechanics into a cosmogonical cosmology put him on the right track. In doing so, he succeeded in giving the Newtonian model greater consistency than it had when leaving Newton’s own hands. These improvements, in turn, were possible because Kant integrated the model into a coherent metaphysical context. Kant’s teleology, the glue binding mechanics and metaphysics together, was better than all of the rival theories of his contemporaries and immediate predecessors, and it turned out to be far-sighted. It had scientiﬁc value in that the underlying assumptions of the immanent teleology (the cosmos is uniform; it evolves through its own devices; it forms a systematic, selfreplicating whole) yielded considerable predictive rewards. Ultimately, it was this very set of teleological assumptions that allowed Kant to have such success with his cosmological conjectures. Nothing, in fact, could be further from the truth than the claim of Tonelli (1959b), Schneider (1966), and Shea (1986) that the Universal Natural History amounted to a general rejection of teleology for the sake of science. Moreover, Kant’s teleology of the Universal Natural History had metaphysical value in that its central proposition—ﬁnal means and goal-states are immanent to the goal-directed system—ensured its survival. The precritical claim of the immanence of means and ends has become the sine qua non of any modern conception of teleology, be it in the philosophy of biology (Ayala, 1970; Mayr, 1982; Ruse, 1986; Bedau, 1992; Kitcher, 1993; Dawkins, 1995),75 or in the current environmental philosophies (Attﬁeld, 1981, 1983, 1995; Rodman, 1983; Taylor, 1994).76 By all accounts, the Universal Natural History was a milestone. The young Kant had left the eclecticism of the 1740s behind and emerged as a distinct thinker in his own right. The Universal Natural History was a programmatic statement of his commitment to Newtonian science. As the later Critique of Pure Reason (1781) and the Metaphysical Foundations of Natural Science (1786) amply testify, the Newtonian model would remain Kant’s paradigmatic description of empirical reality. With the precritical cosmology, the young Kant also made a compelling case against the very anthropocentrism that would later become characteristic of his critical thought.77 In the Universal Natural History, Kant integrated humans into nature, as a part of his overall attempt of linking the sensible and the intelligible in nature, and of marrying the scientiﬁc and metaphysical approaches. What had been a vague idea in the Living Forces, and had prepared itself with the Spin Cycle essay, had now been transformed into a well-deﬁned, intricate, and richly textured philosophy of nature. The precritical project was now in full bloom. Although the project would eventually end in a grandiose failure, Kant succeeded with the Universal Natural History in improving Newtonian mechanics and in constructing the most elegant metaphysics of nature of his time. The theories Kant developed in this book continued to reverberate throughout philosophy. His views on the structure of the cosmos anticipated Johann Heinrich Lam-

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bert’s; the idea of the nebular hypothesis anticipated the work of PierreSimon de Laplace; the reﬂections on the evolution of nature inspired Johann Gottfried Herder’s theory of an evolution of humanity; and his views on the organization of nature reappeared at the end of the nineteenth century through Ernst Haeckel and the vitalists.78

S I X

The New Elucidation The Struggle for Freedom

-0

6.1 The Precritical Project, Ontology, and the Consistency of Nature After the Universal Natural History and Theory of the Heavens, Kant wrote the New Elucidation of the First Principles of Metaphysical Cognition (1755). This treatise was quite short compared to Kant’s second book; the Universal Natural History, numbering a respectable 266 pages in the Peterson edition, was seven times as long. The New Elucidation was published by J. H. Hartung in Ko¨nigsberg and appeared as a modest booklet of 38 pages in 1755.1 Despite the difference in size, both are equally rich works. Each of them was a crucial step toward the realization of the precritical project—the synthesis of the Newtonian model with the general assumptions of a rational and speculative metaphysics. With the Universal Natural History, Kant had attempted to combine physics and purpose. Now, with the New Elucidation, he tried to reconcile physics and freedom. At the heart of the New Elucidation was an investigation of causality. Because his precritical project involved the reconciliation of the aspects of reality described by science and metaphysics, Kant needed to concern himself with the relation between the deterministic processes modeled by science and the free actions stipulated by metaphysics. Their envisioned harmony meant that reality should be explicated as a uniﬁed whole. For the New 128

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Elucidation, this implied that the analysis of causal structures of freedom and determinism had to proceed along compatibilist lines. Nature is allencompassing as well as consistent. Because both physical bodies and rational beings are elements of the same world according to Kant, deterministic processes and free actions must both be part of a consistent whole. At ﬁrst glance, it seems as if the issues investigated in the New Elucidation had little to do with the subject matter of the Universal Natural History. The abrupt shift from cosmology to ontology appears to substantiate Cassirer’s charge of Kant’s erratic development—that the budding philosopher merely jumped from one topic to the next.2 In fact, this shift was not erratic but necessary. What connected the two works was Kant’s sustained vision of constructing a comprehensive philosophy of nature. In the Universal Natural History, Kant tried to fuse the Newtonian model of physical reality with the teleological hypothesis of nature’s purposive development. But the harmony of science and metaphysics which resulted from Kant’s peculiar blend of teleology, cosmogony, and cosmology, had remained only on the surface of phenomena. The deterministic processes of the cosmos, which obey Newton’s ‘‘single universal rule,’’ are subject to an intersubstantial causation that evokes the theory of physical inﬂux. The ﬁnal unfolding of the cosmos, which heeds the telos of material entelechies, is subject to an intrasubstantial causation that is reminiscent of Leibnizian preestablished harmony. Finally, the morally relevant actions of the intelligences populating the cosmos are subject to a spontaneous causation that signals the freedom of these beings. (By deﬁnition, a free action is the spontaneous effect of the agent performing it—an action is free only if the agent is its complete, immediate, and ultimate cause.) The efﬁcient intersubstantial causation of physical inﬂux, the ﬁnal intrasubstantial causation of material entelechies, and the free spontaneous causation of rational activity are three different accounts of causal events. They seem to stand side by side in the Universal Natural History. Because Kant did not concern himself with their differences there, the book raises the question of the compatibility of these accounts. If nature is truly as consistent as he had hoped, then it ought to be possible to deduce the coherence of these kinds of causation from one uniﬁed principle of causality. This issue connects the Universal Natural History with the New Elucidation. The aim of the latter work was to provide the needed causal deduction and to describe the fundamental fabric of nature. Accordingly, in section I of the New Elucidation, Kant asserted that the structure of reality is consistent; in section II, he argued that its types of causation are compatible; and in section III, he hoped to show that the world forms a coherent whole. Kant furnished with the New Elucidation the required ontological sequel to the cosmology of the Universal Natural History. The main difﬁculty, Kant thought, consisted of harmonizing the efﬁcient causation represented by physical inﬂux with the spontaneous causation of freedom. There is a fundamental asymmetry between these two causal species. According to the efﬁcient causation that characterizes physical processes, the causal chains that connect objects with each other are continu-

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ous and unlimited in time. Free, spontaneous activity, on the other hand, originates in the agent. The causal chain that characterizes free activity has a concrete beginning—in contrast to the continuous chains of efﬁcient causation, spontaneous causation starts with the free choice of a rational being. On the other hand, the reconciliation of the efﬁcient causation of physical inﬂux with the ﬁnal causation of nature’s teleological development was not a big problem. Because Leibniz’s preestablished harmony ruled out the intersubstantial causation that physical inﬂux presupposed, the reconciliation of efﬁcient and ﬁnal causation would have been an issue if Kant analyzed ﬁnal causation in terms of the preestablished harmony. But he did not. He avoided this quandary by diverging from Leibniz. Although the active matter of the Universal Natural History is reminiscent of Leibniz’s monadic entelechies, Kant did not subscribe to a strong preestablished harmony of monads that solely permitted an intrasubstantial causation while prohibiting interaction between substances. As the Living Forces had already made clear, he was persuaded by the possibility of the intersubstantial causation the theory of physical inﬂux suggested. The only fashion in which Leibniz’s doctrine had been relevant for Kant in the Living Forces (e.g., #1, I 17) was in terms of the weaker assumption that substances are genuine entelechies and the wellsprings of their own changes. In the Universal Natural History, the Leibnizian entelechies were superseded by Kant’s own conception of an essentially active matter (e.g., I 224–26), which allowed the teleological unfolding of nature according to its own laws. He explained the causal structure of the teleologically active matter in the following way: . . . Such an unfolding of nature is not something extraordinary in nature, but is necessarily brought about by nature’s essential striving. This is the most magniﬁcient testimony of nature’s dependence on that Original Being which carries within itself the source of the essences and of their ﬁrst laws of development. (I 226)

The cause of both matter and its essential striving is God; the entelechy is accordingly an effect that produces other effects through its own unfolding. God was the maker and programmer of the material entelechies. God’s activation of the teleological program of matter has caused the unfolding of nature. When running through its teleological program, the active matter employs physical forces and is regulated by natural laws. Teleology, so constructed, thus invites a physical determinism. Matter, as Kant put it in the Universal Natural History, ‘‘has no freedom to diverge from this plan of perfection’’ (I 228). There was no need for any further ontological investigation of teleology in the New Elucidation. Kant considered his conception of ﬁnal causation as unproblematic, and it is understandable why he thought so. After all, ﬁnal causation emerged neither as a supernatural hand of God disrupting the causal sequence nor as a retroactive power of a telos radiating backward in time from a future goal toward a present unfolding. The evolution of nature

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toward a well-ordered complexity occurs through natural causal factors that can be identiﬁed by science. For Kant, it must have seemed that he had already accomplished the reconciliation of ﬁnal and physical processes. But what he had not yet accomplished, and what he needed to accomplish in order to advance the precritical project, was the reconciliation of the efﬁcient causation of physical processes with the altogether different causal structure of freedom. This additional step was the goal of the New Elucidation. During the summer of 1755, Kant prepared for the doctoral examination at the Universita¨t Ko¨nigsberg. The degree required him to write and publicly defend—in Latin—a dissertation.3 On 27 September 1755, Kant was tested on the New Elucidation, which he had submitted as his thesis. The rigorosum took place in front of the philosophical faculty, with a respondens or friendly commentator, the theology student Christoph Abraham Borchart, and two opponentes or critics who were students from the law school.4 Apparently, everything went well and that particular morning went by without incident. Kant received his doctorate, became a member of the faculty, and was now allowed to teach his own courses. Kant would have had a far more difﬁcult time if he had tried to convince the conservative academic authorities of the Universal Natural History.5 Odds were that the examination board did not even know he was the author of the anonymously published book which asserted the primacy of science over religion and described a minimalistic God acting only by means of the laws of nature.6 That Kant passed the exam without a hitch may have been because his dissertation looked to the unsuspecting eye like a conventional study of a traditional topic. He argued, not very surprisingly, that physical events are determined and that rational agents act freely, that regular physical events coexist with spontaneous freedom, and that God is important as the cause of interaction. Kant chose to call his dissertation A New Elucidation of the First Principles of Metaphysical Cognition. What are these ‘‘ﬁrst principles’’? The School Philosophers—whose views prevailed in Ko¨nigsberg at the time of Kant’s doctoral defense 7—championed certain ontological axioms. Christian Wolff identiﬁed the principles of contradiction and sufﬁcient reason as the foundational laws in the beginning of the Deutsche Metaphysik (1719). Later in the text, he added, apparently as an afterthought, Leibniz’s principle of the identity of indiscernibles to this pair of fundamentals.8 Georg Bernhard Bilﬁnger followed his teacher in the Dilucidationes philosophicae (1725), joining merely the principle of identity to the three rules advanced by Wolff.9 When Wolff returned to this topic with his Ontologia (1730), he suggested a ranking of the principles. The most important principles, according to the Ontologia, are the principles of contradiction and sufﬁcient reason.10 In addition, there is a number of secondary principles, such as the principii individuationis, essendi, ﬁendi, and the principii internum ac externum. They concern aspects of the principle of sufﬁcient reason and are merely of derivative signiﬁcance.11 Friedrich Christian Baumeister, in the Philosophia deﬁnitiva (1738)— a popular textbook which went through numerous printings—paraphrased

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the contents of the Ontologia and repeated Wolff ’s characterization of the principles of ontology.12 In the Institutiones metaphysicae (1738), Baumeister restated the same ideas once more and added the familiar principles of individuation and indiscernibles to the fray.13 Alexander Baumgarten, a more innovative thinker than Baumeister, identiﬁed six major ontological axioms in the Metaphysica (1739): the principles of contradiction, excluded middle, identity, sufﬁcient reason, effect, and reciprocity.14 Johann Christoph Gottsched, in his inﬂuential Erste Gru¨nde der gesammten Weltweisheit (1733–4), asserted that only two genuine ontological axioms exist, the principle of contradiction and the principle of sufﬁcient reason (#213, p. 117). Johann Peter Reusch, in the Systema metaphysicum (1735), identiﬁed the principle of contradiction as the ﬁrst major ontological axiom, discussed corollary principles such as the principle of the excluded middle, and viewed the principle of sufﬁcient reason as the second major axiom.15 Gottlieb Canz, in the Philosophia fundamentalis (1744), populated his ontology with teeming hordes of principles. This was more a terminological quirk than a philosophical revision. Canz simply liked to use the word principium and employed it frequently. His essential ontological axioms, however, were in line with the tenets of the School Philosophy: contradiction, sufﬁcient reason, and a number of derivatives.16 Andreas Bo¨hm, in his Metaphysica (1755), and Johann Franz Coing, in his Institutiones Philosophicae (1765), repeated the familiar list of principles and their corollaries without providing anything new.17 All of these prolix tomes were verbose variations on the same well-trodden theme. There are two major principles, contradiction and sufﬁcient reason. The former principle is the ‘‘erster Grund’’ (Wolff), the ‘‘principium absolute primum’’ (Baumeister, Baumgarten), the ‘‘erste Grundwahrheit’’ (Gottsched), the ‘‘fons omnis certitudinis’’ (Reusch), the ‘‘veritas absolute prima’’ (Bo¨hm), or the ‘‘primum principium’’ (Coing)—in short, the principle of contradiction is the ﬁrst law of ontology.18 In light of the tracts of the School Philosophers, Kant’s proposal looked like an exercise in conventionality to the unsuspecting eye. Like all the treatises mentioned above, the New Elucidation included a list of fundamental principles. The list had the usual length. Kant identiﬁed ﬁve axioms. The principles were familiar, too. The principle of contradiction was here as well as a principle of causality. The principle of contradiction preceded the principle of causality, and the principle of causality preceded a couple of derivative principles. But a number of differences reveals that Kant did not toe the Leibnizian-Wolfﬁan line and that his arguments undermined instead of supported the canonical view. For one thing, the principle of contradiction, which Kant articulated as the thesis, ‘‘it is impossible that the same thing should simultaneously be and not be’’ (I 391:1–2),19 raised a question. Kant claimed that a logical and metaphysical primitive should consist of simple terms (I 390:33–36). But ‘‘impossible,’’ the central term in the principle of contradiction, is a complex concept. In addition, the principle of contradiction contains the word ‘‘not.’’

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It would be paradoxical, he argued, if the fundamental rule of all truth involved a negation (I 391:11–14). Breaking with the Leibnizian-Wolfﬁan tradition, Kant discarded the principle of contradiction as the ﬁrst axiom. True propositions, he asserted, express both afﬁrmative and negative contents. Because one can derive neither a negation from an afﬁrmation nor an afﬁrmation from a negation, the basis of all true propositions must represent both. In other words, the fundamental rule must be a complex axiom containing both an afﬁrmative and a negative proposition. Breaking with the tradition once more, Kant concluded there is no simple ﬁrst principle of truth (I 388:12–13). Instead, he proposed a compound principle of identity as the foundation of all truths. According to Kant, the principle of identity consisted of a rule of afﬁrmative identity, ‘‘whatever is, is,’’ and a rule of negative identity, ‘‘whatever is not, is not’’ (I 389:3–6). Once again, this amounted to a break with the tradition, for the canonical view had been that the principium identitatis is a simple axiom, which Baumgarten had articulated as the proposition that ‘‘each possible object A is A’’ (Metaph., #8, p. 4). A twin principle of identity was Kant’s ﬁrst axiom. The second axiom, derivable from the ﬁrst, was the principle of contradiction. The third axiom was a law of causality. But in contrast to the School Philosophers (and in line with the pietists), Kant chose to call this third law the principium rationis determinantis, the principle of determining reason, which he explicated as the thesis that ‘‘nothing is true without a determining reason’’ (I 393:23). Its corollaries were a principle of succession (‘‘substances change only in so far as they are connected with other substances’’) and a principle of coexistence (‘‘ﬁnite substances are related with each other because of the divine understanding’’). Neither of these derivative principles appeared in the canonical texts of the Leibnizian-Wolfﬁan philosophy. Already this brief glance at the contents of Kant’s dissertation reveals that its author had his own opinions and refused to close rank and ﬁle with the likes of Reusch, Canz, Bo¨hm, or Coing.20 Kant characterized his ﬁve axioms as principles of knowledge (I 387) and as ﬁrst links in the chain of truth (I 391). The New Elucidation apparently concerned matters of logic and epistemology. But ‘‘cognition’’ and ‘‘truth’’ were not just logico-epistemic categories in this context. Metaphysical knowledge concerned the being of the world. Thus, the ﬁve principles not only purported to describe the structure of true propositions, but also the structure of states of affairs in the world. The principles of identity and contradiction (in section I of the New Elucidation) had only implicit ontological relevance. The ontological level became more visible with the principle of determining reason (in section II). Determining reason served in Kant’s view as a ground of knowing and as a ground of being—that is, it functioned both as a logical condition of true propositions (I 393:28–32), and as a causal law of existence (I 396:8–11). With the principles of succession and coexistence (in section III), the ontological relevance of the laws moved to the foreground. If Kant in the begin-

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ning of the treatise talked about truth, he was in the end concerned with substances, their changes, and their relationships to each other and to God— in other words, with the subject-matter of ontology. Being differs from knowledge, and ontology from cognition. How could these disparate categories be lumped together? Kant deﬁned truth as a notional identity between the subject and the predicate of a proposition (I 389: 10–14). As he remarks, it is . . . agreed that there is no need for an antecedently determining ground to establish a truth: the identity which exists between the predicate and the subject is sufﬁcient for the purpose. (WM 18; I 396:38–397:1)21

Kant’s view of truth echoed Leibniz’s intensional conception of truth and anticipated Moses Mendelssohn’s concurring view. For Leibniz, the mark of a true proposition was the containment of the predicate in the subject.22 For Mendelssohn, the predicate of a true proposition was an explication of its subject.23 Although Kant’s deﬁnition seemed to suggest that truth was exclusively a matter of logical relations, truth, for him, pertained to the elements of syntax, as well as to the elements of the world: Possibility is only deﬁnable in terms of there not being a conﬂict between certain combined concepts; thus the concept of possibility is the product of a comparison. But in every comparison the things which are to be compared must be available for comparison. . . . This being the case, it follows that nothing can be conceived as possible unless whatever is real in every possible concept exists and indeed exists absolutely necessarily. . . . Furthermore, it is necessary that this entire reality should be united together in a single being. For suppose that . . . the material of all possible concepts were to be found distributed among a number of existent things; it would follow that each of these things would have its existence limited in a certain way. . . . This being the case, it follows that the realities which are limited in this way will exist contingently. (WM 15–16; I 395:7–19)

Something is possible (as a round ball is possible) and not impossible (as a square circle is impossible) if there is no logical conﬂict between the ideas combined. Such a possible concept is intelligible. As Reuscher (1977) points out, the intelligible element of the concept, the realium, possesses a thoughtindependent existence, either as an absolute existence (belonging to the divine necessary being) or as a contingent existence (subsisting as an object in the world).24 A true proposition, which is the combination of a subject with an identical predicate, conveys an idea that corresponds either to a contingent object or to a necessary property of God.25 The way in which Kant interpreted his own deﬁnition of truth shows him sliding from one view, according to which truth consists in a predicate-containment, to another, according to which it consists in an object-correspondence. As Reuscher put it, Kant’s truth-identity of subject and predicate consisted of

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the involvement of the realia in the subject with the realia of the predicate, hence, ‘‘when it is notionally so, it is true, i.e. existentially so.’’26 That Kant was juggling two views of truth in the New Elucidation without addressing the question of their coherence was a weakness of his theory. The underlying assumption, however, was both simple and plausible: metaphysical knowledge is knowledge of reality. Metaphysical propositions involve logical structures, which, in turn, reﬂect the ontological structures of real states of affairs. Accordingly, the principles of metaphysical cognition are both logically and ontologically relevant. The principle of contradiction, ‘‘it is impossible that the same thing should simultaneously be and not be,’’ expresses the logical truth (p ∧ p),but it also expresses an ontological fact: a thing either exists in the world or it does not; it cannot exist and not exist at the same time. But it is curious that the New Elucidation involved a correspondence conception of truth as well as a coherential conception of truth. It would appear that truth consists either of a correspondence to an external object or of an internal coherence between subject and predicate. How can it be both? Are there perhaps distinct kinds of truth, depending on the kinds of propositions? It is doubtful that Kant had a good answer, but then again, he was not the only one with the problem. The combination of object-correspondence and predicate-containment was characteristic of the philosophical establishment of the age. In his Philosophia rationalis sive Logica (1728), Christian Wolff proposed the ‘‘determinability of the predicate through the subject’’ as a criterion of truth (#524, p. 397), while, at the same time, deﬁning truth as the ‘‘conformity of our judgment with the object or represented entity.’’27 Thus, on the one hand, truth consisted of a ‘‘necessary nexus’’ of predicate and subject; on the other hand, it amounted to the correspondence of propositions and things. A third sense of truth emerged in the Ontologia, where Wolff characterized truth as a property of the things themselves.28 Following this reiﬁcation of truth, Baumgarten could take truth as an internal feature of objects and deﬁne ‘‘objective certainty’’ as the knowability of the truth within the things (Meta., #93, p.26).29 The School Philosophers naively blended these various conceptions into a potpourri view, with the result that any principle that governs the structure of reality also governs the structure of cognition. Illustrating this ontologico-epistemic conﬂation, the subtitle to Coing’s Institutiones Philosophicae runs, ‘‘On God, the Human Soul, the World, and the First Principles of Human Knowledge.’’ Kant followed the School Philosophers in their multilevel conception of truth. He endorsed the fundamental principles of the New Elucidation as axioms of an undifferentiated logical, epistemic, and ontological relevance. This endorsement revealed the young Kant as a metaphysical realist, and it signaled the hope which fueled the precritical project: the world is knowable, and the construction of a comprehensive model of the world is feasible. This was the reason for Kant’s twofold view of truth. The correspondence conception implies that a mind-independent reality exists that can be known by reason. That we can know things in this way means that we can accurately

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cognize reality. The coherence conception implies that true propositions are not just tautological transformations of one another, but also that one propositional truth entails further truth. Knowledge can be generated by aprioristic and conceptual means alone. Based on the tacitly assumed isomorphism of conceptual and ontological structures, Kant thought he could determine ontologically relevant truths on the basis of logical principles. In the New Elucidation and elsewhere in the metaphysical literature of the age, the principles governing truth apply to cognition as well as to reality; they are, at the same time, logical laws of knowledge and metaphysical laws of nature. In any event, the twofold function of Kant’s ﬁve principles was an assertion that the faculty present at the defense of the New Elucidation would have accepted without protest. The double employment of the ﬁrst principles was the standard operating procedure of the metaphysical establishment.30 Ten years later, when composing the Dreams of the Spirit-Seer, sweeping assumptions like these, with the epistemic optimism they imply, would come back to haunt Kant. But at least for now, during his rigorosum on that particular September morning, he could get by with stipulating that principles of metaphysical cognition simultaneously serve as ontological axioms. In section I of the New Elucidation, Kant advanced three claims: there is no ﬁrst and universal principle of all truths (proposition 1); the principle of identity has an afﬁrmative and a negative aspect (proposition 2); and the principle of identity comes before the principle of contradiction in the hierarchy of truths (proposition 3). In a text written some years later, The False Subtlety of the Four Syllogistic Figures (1762)—a rather ironic critique of syllogistic logic and, in a sense, a postscript to section I of the New Elucidation—Kant framed a general rule of rational inference: whatever contradicts a feature of a thing, contradicts the thing itself (II 49). This inferential rule holds because there is an order to the world. The world, as well as any object that it contains, is consistent with itself. Kant further commented on this idea in his third book, the Only Possible Argument of a Demonstration of God’s Existence (1763). There, he declared that anything self-contradictory is intrinsically impossible (II 77). What is impossible cannot exist, thus, what is self-contradictory cannot be part of the world, and what is part of the world must be possible and consistent with itself. Such talk about the consistency of nature was nothing new. Thinkers of all stripes embraced this idea. Despite the growing rift between metaphysics and science in the eighteenth century, the common ground of the metaphysicians and the experimental philosophers was a consensus about the fundamentally regular structure of nature. As Newton put it in the Principia: we are not ‘‘to recede from the analogy of Nature, which is wont to be simple, and always consonant to itself ’’ (book III, rule 3; M 398). Any contradictions that arise in the descriptions of nature are the fault of the model and not the fault of nature. Although Newton was not interested in ontological issues, he considered it to be trivially true that the celestial whole of bodies and forces forms a system whose laws, once identiﬁed, hold true without exceptions.31

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Leibniz agreed: responding to John Toland’s Christianity not Mysterious (1696), he argued that God is nature’s highest reason and that the divine revelation does not contain anything intrinsically absurd. If things appear absurd to us, this is only because we are too limited to see them in their proper perspective.32 In denying any real ‘‘absurdity’’ in nature, Leibniz endorsed the idea of nature’s consistency. Wolff ’s conception of nature was similar to Leibniz’s. Wolff ’s nature possessed the principal attributes of order and verity; in his characterization, order and verity were inseparable from consistency.33 Pietist philosophers joined in the chorus of consistency. Franz Buddeus argued that physics shows us the created world which reveals God’s existence, and that this discipline merely explicates the natural phenomena already described in the Bible, which, of course, is devoid of contradictions.34 Crusius, a more intelligent thinker than Buddeus, identiﬁed nature in his main work, the Metaphysik (1745), as the system of ﬁnite and connected things (#360, C 2:657). In the Natu¨rliche Begebenheiten (1749), he deﬁned the systematicity of nature in terms of consistency, declaring that whatever contradicts an orderly and wisely organized world cannot be assumed in physics (#35, C 4.1:562).35 Like everybody else, Crusius considered the law of contradiction to be the most general ontological axiom (Met. #13, C 2: 23). He proposed two further rules, the principium inseparabilium and the principium inconiungibilium, as he labeled them in the Epistola ad Hardenberg (C 4.1:351). The former asserts that what cannot be separated in thought is not separated in reality; the latter asserts that what cannot be combined in thought is not combined in reality. Crusius thought that all marks of possible and real entities were summarized in these three principles. This triplet of fundamentals constituted the ontological foundation of the unity and systematicity of nature, although the individual axioms did not depend on each other and are not derivable from each other (Met. #14, p. 26). For Crusius, this triplet determined the uniﬁed consistency of nature. Wolff and his followers had suggested two principles, contradiction and sufﬁcient reason. Crusius had countered with three principles, contradiction, inseparabilium, and inconiungibilium. Kant, ﬁnally, suggested three principles— identity, contradiction, and determining reason—followed by a pair of corollary principles: succession and coexistence. Was it Newton who had inspired Kant’s set? A curious symmetry holds between Kant’s foundation of metaphysics and Newton’s foundation of mechanics. Like Kant, Newton had proposed three laws—of inertia, acceleration, and interaction. And like Kant, Newton had formulated a pair of corollaries: the parallelogram law of forces and the law of the lever.36 The upshot of section I of the New Elucidation was that the world has a consistent structure. This sounds trivial, and it certainly was a most conventional position, but by taking this result seriously, Kant had now deﬁned the platform on which the model of nature was to be constructed. That he developed his synthesis of physics and freedom on the basis of nature’s consistency showed his dissatisfaction with the easy escape-routes of dualism

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and reductivism—Kant endorsed the veracity of both lawful physical processes and free activity, and he perceived them as occurring in the same world. He had to take up the thorny issue of reconciling physical necessity with free activity, because rational beings and natural processes appeared to him to be integral parts of the same universe. There was no way around the copresence of determinism and freedom. The alternative—reducing the one to the other—would have catastrophic consequences for the envisioned philosophy of nature. The reduction of deterministic efﬁcient causation to free spontaneous causation would be tantamount to sacriﬁcing the Newtonian model, for, if natural processes only appeared to be deterministic without being so, physics would describe only how things seem to be, not how they are. Moreover, to reduce spontaneous causation to deterministic causation would be equivalent to sacriﬁcing freedom and morality. Rational beings who only seem to act freely without doing so cannot not be held accountable for their actions, and the concepts of morality would be inapplicable to such agents. This, then, constituted Kant’s problem: on the one hand, both types of causation must be assumed in order to avoid absurdities. On the other hand, the world is equipped with a consistency that does not allow a diametrical opposition between the mutually exclusive types of causation. Since they cannot be reconciled on the same level, the only hope of harmonizing them lies in showing that the types of causation are consonant implications of one and the same principle of causality. Kant needed to go down into the basement of his precritical house and deal with its ontological plumbing. Because of all this, the ﬁrst principles of metaphysical cognition required a new elucidation.

6.2 The Mineﬁeld of Causality: Leibniz, Wolff, and Crusius The laws of identity and contradiction govern the consistency of nature at a point in time. The principle of determining reason controls the consistency of nature over a period of time. Thus, the principle of determining reason is the condition of consistency applied to processes (the succession of events). The consistency of processes is that anything that occurs has a reason for its occurrence. Consistency of nature over time is nothing but the constancy of causality, and the principle of determining reason ﬁlls the gap left by identity and contradiction. The principle of determining reason, the topic of section II of the New Elucidation, is the statement, ‘‘nothing is true without a determining reason.’’ Kant deﬁned ‘‘determining’’ as the positing of a predicate while excluding its opposite, and ‘‘reason’’ as what determines a subject in relation to a predicate (I 391:34–36). Determining-by-a-reason ﬁrst occurs as a causal determination of real objects (which are concrete things with a speciﬁc set of properties). This determination makes their existence possible. A causal nexus of events determines the thing’s properties, which, in turn, constitute the existential makeup of the thing. This ﬁrst type of determining reason is a causal mechanism that is the ‘‘antecedent’’ ground for the thing’s exis-

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tence. Kant called this ontological determination the ratio cur vel ﬁendi—the reason why, or the reason of becoming (I 392:5). In addition, the concrete and existing thing can be conceptualized as the subject in a proposition. When that happens, the thing, now in its propositional translation, is causally determined once more, ‘‘consequent’’ to the thing’s existence. Any proposition that takes the thing as its subject and predicates something of it, involves a cognitive speciﬁcation of the subject in relation to its predicate. This cognitive determination makes knowledge possible—without causality, no knowledge. Kant called this second type the ratio quod vel cognoscendi, the ground that, or the ground of knowing (I 392: 6). Hence, the ground of the things of nature splits up into an antecedent ontological determination of the object as a concrete and existing thing endowed with properties, and into a consequent cognitive determination of the object as a propositional subject linked to information predicated of it. This is a complex account. Kant formulated it in response to Leibniz, Wolff, and Crusius. Kant was well aware that their proposals suffered from problems. In constructing his theory in the New Elucidation, he cautiously weaved his way through a philosophical mineﬁeld, trying to avoid the dangers lurking at every turn.

-0 Leibniz called the law of causality the principle of sufﬁcient reason, which ﬁgured prominently in his metaphysics.37 Put simply, it asserts that there is nothing without a reason.38 Leibniz claimed that the principle of causation can be derived from ‘‘primary truths’’ (AG 31), and in a way, Kant agreed with him. Although Kant conceived of his version of the law of causality as an autonomous principle, he deemed it possible because of the principle of contradiction, which, in turn, was possible because of the twin principles of identity.39 Leibniz argued in De rerum originatione radicali (1697) that we cannot ﬁnd in any natural object a sufﬁcient reason for its existence. The ratio exsistendi of natural objects lies in God (G 7:302). Kant agreed. The ultimate origin of things is God. Without God, the things in nature would not be possible and could not exist (I 395:29–30). Kant furnished a simple, but effective argument for why things are not endowed with a ground for their existence: an existing thing is the effect of its ground of existence, but since an effect always comes after the cause, the existing thing must come after the ground of its existence and can therefore not be identical with it (I 394:10– 16). Although Leibniz and Kant concurred in this regard, each meant something else when claiming that things originate in God and cannot be their own causes. Leibniz insisted that we cannot ﬁnd the reason for the existence of a particular thing in any contingent thing whatsoever. It is impossible that one contingent thing is capable of causing another. Leibniz stated in

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the Principes de la nature et de la grace (1714) that the principle of sufﬁcient reason is outside the worldly series of contingent things (#8, G 6:598). Sufﬁcient reason and the divine prima causa are the same.40 Prior to the existence of things, God had established a harmony of their individual future causal developments. This preestablished harmony is so thoroughgoing and precise that things give the semblance of interaction. The doctrine of the preestablished harmony, whose elements Leibniz advanced in several essays in 1676, and which he systematically presented in the Discourse de la me´taphysique (1686), involves three claims: (1) each state of a substance is caused by something internal to the substance; (2) the states of distinct substances match each other perfectly; and (3) distinct substances do not interact.41 This is a curious doctrine, but Leibniz had good reasons for proposing it. Descartes’s famous mind-body distinction in the sixth of his Meditationes (1629) had raised the notorious problem of interaction. How can souls and bodies interact if they possess mutually exclusive properties? Thoughts may lead to other thoughts, and solids may push other solids, but how do solids lead to thoughts, or thoughts push solids? Given the undeniable differences of soul and body, the followers of Descartes had doubted the possibility of interaction. What appears as interaction is actually God’s intervention—that is, God’s activity of synchronizing mental changes with their corresponding bodily changes and vice versa, whenever these changes occur. Leibniz agreed with the occasionalists that interaction is problematic. But as he explained in the Systeme nouveau (1695), if miraculous interventions in each and every instance account for the guise of mindbody interaction, then one invokes a deus ex machina to save the appearances (G 4:483; AG 143)—which means that the occasionalist account is a pretty bad explanation. Because neither a direct interaction nor a divine occasion can explain the evident harmony of body and soul, there is only one choice left—a choice that has, as Leibniz thought, ‘‘very great advantages and rather considerable beauty’’ (G 4:484; AG 143): That is, we must say that God originally created the soul (and any other real unity) in such a way that everything must arise for it from its own depths, through a perfect spontaneity relative to itself, and yet with a perfect conformity relative to external things. (Leibniz’s emphasis; AG 143; cf. G 4:484)

We may disagree with Leibniz on the beauty of his choice, but we must grant him the advantages that he speaks of. As long as one is unwilling to pay the price of an ontological monism (the price of the forced reduction of one class of objects to the other despite their glaring differences), then one remains confronted with the difﬁculty of making sense of the apparent interaction of two absolutely disparate entities. An occasionalist resolution is unappealing because it resorts to the miracle of God’s continuous interventions. Moreover, the occasionalist God, constantly busy intervening everywhere, is extremely overworked, which raises the question of whether this is a digniﬁed condition for the creator of the world to be in. The only other

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alternative is a preestablished harmony between bodies and souls, set up by God at the moment of creation in order to ensure their perfect synchronicity and the ﬂawless appearance of interaction. A preestablished harmony is a more plausible resolution of the problem of mind-body interaction than the occasionalist hypothesis. But why should one assume, in addition, that such a harmony must obtain among all substances? Leibniz’s ‘‘two kingdoms’’ of ﬁnal and efﬁcient causes (G 7:344) suggest a pre-established harmony of souls and bodies, but they do not suggest similar harmonies among souls or among bodies. Yet, Leibniz felt compelled to generalize the preestablished harmony into an account of all substances. His motive was a straightforward theological consideration. Because God is an omnipotent, omniscient, and benevolent being, it follows that God, when he created the world, must have created the best of all possible worlds. The best world exhibits ‘‘the most perfect of harmonies’’ (G 6:44). Harmony is regularity in diversity. The most perfect of harmonies means that the greatest possible regularity governs the greatest possible diversity. The most perfect of harmonies accordingly requires that the world has the greatest possible amount of substances (monads), and that another world with more substances is inconceivable. Thus, God created the greatest collection of monads. How could their greatest possible degree of regularity be ensured? Two options present themselves. Either the substances sort out irregularities through interacting with each other, eventually generating regularity among themselves, or they and all their future changes are in perfect regularity from the start. The second alternative ensures the greatest possible degree of regularity. Accordingly, the world contains the most perfect of harmonies because it is ﬁlled with monads (Leibniz’s principle of plenitude) that are programmed ab initio to realize their successive states in perfect synchronicity. How does this doctrine affect the freedom of rational agents? One may be tempted to think that the preestablished harmony provided an excellent basis of freedom. Freedom means that nothing and nobody except myself is the cause of my action. In the Foundations of the Metaphysics of Morals (1785), Kant would later distinguish the autonomy of the will, the supreme principle of morality, from heteronomy, the source of all spurious principles of morality (IV 440–41). Autonomy is a key feature of freedom. I am free if I can follow my own maxims and am not forced to obey foreign conditions. Leibniz disallowed essential causal interaction between natural objects, and in doing so he effectively averted the danger of determinism from the start. Hence, it seems that freedom reigns triumphant in the preestablished harmony. But the triumph of freedom is illusory. It is true that the rejection of interaction entails the elimination of heteronomy, if we understand by heteronomy that one soul’s law has no control over the acts of another. Leibniz’s preestablished harmony permits the autonomy of souls, but this is not enough. Autonomy is a necessary condition but not a sufﬁcient condition of freedom. To be free is more than just proceeding according to one’s in-

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ternal necessity. In addition to being autonomous, a soul must have a choice whether to follow its inner law or not. The preestablished harmony does not allow such choices. Like all monads, souls are necessitated by their private law of development, and in this sense, souls are autonomous but not free. Kant recognized this shortcoming in Leibniz’s doctrine. As he put it later in the Critique of Practical Reason (1788), if our freedom was just the kind of autonomy that Leibniz suggested, then it would be indistinguishable from the ‘‘freedom of a turn-spit,’’ which moves on its own once it has been wound up (V 97). A further problem of the preestablished harmony is that the kind of determinism it entails is not the kind of determinism that matches the Newtonian model of nature. Leibniz’s doctrine implies the determinism of intrasubstantial causation. Newton’s model presupposes the determinism of intersubstantial causation. Because, in Leibniz’s doctrine, things only appear to interact without actually doing so, a theory such as Newton’s that presupposes interaction among bodies and forces will not describe the actual structure of nature.42 This was one more reason for Kant not to accept the preestablished harmony in an unmitigated form. Hence, when Kant claimed that the reason for the existence of things could not be found in the things, he meant something quite different than Leibniz. What Kant denied, with Leibniz, was the idea that a thing could be the cause of itself; what he asserted, contrary to Leibniz, was that a thing could be caused by another. He located the determining reason within the worldly series of contingent things, associated it with antecedent efﬁcient causes in nature, and asserted the reality of interaction in the ﬁrst corollary to the principle of determining reason, the principle of succession (I 410: 18–20). This was Kant’s fundamental disagreement with Leibniz, a disagreement that deﬁned, in a nutshell, the precritical project.43

-0 Wolff ’s views on causality and interaction were situated halfway between those of Leibniz and Kant. Impressed by Newton’s laws of motion, Wolff formulated a set of laws that resembled them.44 Although he rejected the claim of action at a distance that Newtonian gravitation seemed to suggest, he still took the possibility of interaction seriously.45 Wolff ’s philosophical system (the doctrine to which Kant reacted) was a reading of his works codiﬁed positively by defenders such as Gottsched and Baumgarten, and negatively by opponents such as Lange and Crusius. It involved a position on causality that combined the preestablished harmony with the reality of interaction. But Wolff ’s system was not the same as Wolff ’s philosophy; it amounted to a snapshot of his views at a comparatively early stage of his career. In his actual development, Wolff explored three different views on causality and interaction between 1719 and the 1730s.

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In the Deutsche Metaphysik (1719), Wolff argued that simple things (the elementary substances and ultimate components of the things in nature) are coordinated in a preestablished harmony, whereas the things in nature (the complex composites consisting of substances) causally interact and constitute a nexus rerum. This combination of a preestablished harmony with an interactive causality was perceived as the characteristic trait of the Wolfﬁan ‘‘system.’’ But Wolff changed his mind in the Anmerkungen zur Deutschen Metaphysik (1724) ﬁve years later. He decided to abandon the preestablished harmony of simple things. Causal interaction reigns throughout, he now argued; a nexus elementorum prevails in nature just as a nexus rerum. In the Anmerkungen, he limited the relevance of the preestablished harmony to the mind-body problem. Again ten years later, in the Psychologia rationalis (1734), Wolff changed his mind once more. He despaired of the mind-body problem and abandoned this last holdout of the preestablished harmony. Wolff ’s initial combination of the preestablished harmony with a realistic account of interaction had sparked the Pietismusstreit, a vicious debate with pietist theologians who faulted Wolff for his Leibnizian sympathies. Intimidated by the charges of atheism and heresy (which precipitated a political intrigue and eventually forced him to ﬂee Prussia), Wolff wished to appease his critics.46 He published in the 1720s and ’30s a whole series of writings that minimized the relevance of the preestablished harmony. But these commentaries did not receive the same attention as the Deutsche Metaphysik. For better or worse, this early work had become the canonical text of the School Philosophy. According to this canonical text, Wolff rejected Leibniz’s extranatural location of the sufﬁcient reason. He opted, like Kant after him, for the opposite: the sufﬁcient reason determines things within nature in such a way that they genuinely interact. He derived the law of causality from the principle of contradiction47 and thought that the principle of sufﬁcient reason applied to the existence of things. According to Wolff, the application of sufﬁcient reason to the existence of things makes intelligible why anything is.48 Composite things have their ground in each other (Dt. Meta. #543, p. 331), which means that bodies are mutually dependent on the physical plane.49 Their connectedness and interdependence reveals a ‘‘natural necessity’’ (Dt. Meta. #575, p. 352). Wolff ’s natural necessity is the same as Leibniz’s hypothetical necessity, a necessity arising through the determination of events by prior conditions.50 By contrast, a ‘‘geometric necessity’’ applies to simple things, to the substantial essences of composite bodies subject to natural necessity. The geometric necessity is Wolff ’s correlate to Leibniz’s preestablished harmony, and it represents the monolinear determination of the substances (Dt. Meta. #575, p. 353). Geometric necessity governs the level of the simple things. According to Wolff ’s early view in 1719, a simple thing is just like Leibniz’s monad and shares the same causal autonomy. (In 1724, he would abandon this equation of simple thing and monad; cf. Anmerkungen #215, p. 368–71.) God

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grounded a monolinear causal sequence of antecedent and subsequent causal states within the simple thing; other objects do not impose conditions on the simple thing. Because the soul is a simple thing as well, geometric necessity is the key to the freedom of the soul. The soul is subject to the same type of causal determination as the elementary components of bodies are. As a result, the mind or the soul is not dependent on any foreign cause. Its own antecedent states, which ultimately originate in God, are wholly responsible for its present state. Accordingly, Wolff argued, the soul is free. But as we have seen, monolinear determination is not freedom; it is merely an autonomy that necessitates itself. The pietists attacked Wolff on precisely these grounds and argued that the thesis of geometric necessity entails an invidious determinism.51 The stipulation that the soul is a simple thing was a smart metaphysical move that safeguarded the immortality of the soul. This move had already been prepared by Descartes. Before Descartes, theology had been heavily oriented to Aristotelianism. Aristotle had conceived of the soul as the form of the body (De Anima, 412a17–21), which suggested that the soul existed in conjunction with the body and not apart from it. As Cottingham (1992) points out, many theologians were tempted to assert that personal immortality was a doctrine that had to be based on faith alone.52 (Although this was a philosophical problem for Roman Catholic scholasticism, it must be remembered that this was not a religious problem for followers of the Bible in general. Contrary to the view introduced by Augustine into Christianity, that humans are immortal and fully conscious immediately after death, the Bible—in Genesis 3:19 and John 5:25—states that humans are naturally mortal, that death destroys them, and that there will be no humans in heaven or hell until after the Resurrection and Judgment.) Descartes’s dualism supplied the ﬁrst solid argument on behalf of the continuous and automatic immortality of the soul. Because body and soul are independent of each other, the soul’s existence is not tied to the body’s existence. As Descartes put it in the synopsis to the Meditationes, ‘‘the decay of the body does not imply the destruction of the mind, and [these arguments] are hence enough to give mortals the hope of an after-life’’ (AT 7:13; Cott. 2:10). That the soul is not corporeally extended means, as he noted in the Passions de l’aˆme (1649), ‘‘that one cannot in any way conceive of a half or a third of a soul.’’53 The soul has no spatial parts. Out of these Cartesian origins grew the tradition that the soul is not only devoid of spatial parts, but also devoid of parts altogether. The lack of parts ensures the soul’s immortality. By comparison, the ﬂesh is mortal because it has parts. When these parts become unstuck from each other, the ﬂesh corrupts, and decay sets in. Any composite, by its very nature, can fall apart—a compound entity is a corruptible entity. Because the soul is devoid of parts, there is nothing that can become naturally unstuck. Moreover, the soul not only has no parts, it also is not a part. Therefore, when the body dies, the soul, not being an element of the body, will not die with it. God

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could conceivably annihilate souls, but death has no sway over the soul. The soul’s simplicity entails its immortality. Kant adhered to this tradition during his precritical period and favorably discussed the conception of the soul as a simple substance in the False Subtlety essay (1762; cf. II 51). Since this conception is a cornerstone of rational psychology, Kant would later regularly mention it in his metaphysics classes. In the student transcripts known as L1, L2, Dohna, Ko¨nigsberg2, and Ko¨nigsberg3 (which stem from courses Kant taught after the collapse of the precritical project), this conception is explained with what Ameriks (1982) calls the ‘‘unity argument’’: I am aware of a unity of distinct thoughts; such a unity could not be had if the thoughts were grounded in distinct substances; therefore I am a simple being.54 Kant would dissect and refute the unity argument in the Critique of Pure Reason. There, in the analysis of the Second Paralogism (A351–A362), he would contend that the simplicity I derive from the unity of my thoughts is a mere logical unity (A355). The logical simplicity, by means of which I represent myself, does not entail that I know the actual simplicity of myself (A356). Consequently, the conception of the soul as a simple substance, which can neither be inferred from concepts nor from experience (A352–3), remains a synthetic a priori proposition (B410).55 As it turned out, this very conception of the soul got Wolff into trouble, but not for the reasons that the critical Kant would identify. The perceived culprit was not the stipulation of the soul’s simplicity as such, but the connection of the soul to a geometric necessity by means of its simplicity. In Wolff ’s system, the soul is a simple thing subject to the monolinear causation of the preestablished harmony. Joachim Lange, the most rabid of the pietist enemies, devoted much of his professional energies to destroying Wolff ’s philosophical reputation. In his Caussa Dei et religionis naturalis adversus atheismum (1727), Lange noticed that the copresence of natural necessity and geometric necessity involved an illicit coupling of two distinct notions of causality (p. 124). Lange scolded Wolff for having proposed an absurd conglomerate of ‘‘idealistic’’ and ‘‘materialistic’’ systems—idealism, in Lange’s terminology, being the thesis of the pre-established harmony, materialism being the thesis of a mechanistic nexus rerum. The fact of such an untenable conglomerate was bad enough, but worse, in Lange’s view, were its theological ramiﬁcations. If one approached Wolff ’s system from the side of the bodies, from the ‘‘materialistic’’ part of the conglomerate, then it would be evident, Lange argued, that the interactive nexus rerum generated a deterministic system of nature in which there was no place for God (Caussa, p. 10, pp. 362–9). Hence, Wolff ’s materialism entailed atheism and thus undermined religion. If one approached Wolff ’s system from the side of the minds, from the idealistic part of the conglomerate, another problem would arise, Lange maintained, that was just as serious. If the soul is like a Leibnizian monad without windows, then the soul cannot causally interact with its own body (Caussa, p. 68, p. 399). The preestablished harmony between body and soul does not explain mind-body interaction; it does away with it

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(Caussa, p. 346). Therefore, any decent pietist must attack Wolff ’s appropriation of the preestablished harmony (Caussa, p. 3–5). Lange certainly had a point there. According to the Bible, humans are sinners. Sins occur if evil thoughts are put into practice, or, if one succumbs to a temptation of the ﬂesh. Lying in cold blood, which violates the Eighth Commandment, presupposes that the mind can inﬂuence the body. Yielding to carnal pleasures, which violates the Sixth Commandment, presupposes that the body can inﬂuence the mind. Cutting the link between body and soul means that souls cannot sin. Even worse, it makes God, as the divine sufﬁcient reason, responsible for our sins. Hence, Lange concluded that the idealism of Wolff ’s system entailed heresy and thus undermined religion once more. Wolff ’s account, more than Leibniz’s, was a forerunner to the New Elucidation, in that it exempliﬁed a possible combination of freedom with physical processes. The juxtaposition of natural necessity with geometric necessity, and the nonreduction of either type of causation that it implied, must have looked attractive to Kant. Nonetheless, the pietists were right in claiming that Wolff forcibly mated two contradictory types of causation. Even if one granted that geometric necessity and natural necessity were the ontological correlates to freedom and determinism (which, for the reasons stated, is problematic anyway), the puzzle remained of how geometric and natural necessity can coexist. Wolff ended up with two distinct classes of entities, simples and composites, corresponding to two incommensurate forms of causation. This is just what Kant needed to avoid.56

-0 Crusius criticized Wolff ’s account for neglecting the distinction of the logicoepistemic and the ontological aspects of sufﬁcient reason. These two aspects are the ground of being and the ground of knowing, which Crusius differentiated in his treatise on causality, the Dissertatio philosophica de usu et limitibus principii rationis determinantis, vulgo sufﬁcientis (1750), or De Usu for short.57 He labeled them the principium essendi and the principium cognoscendi (246, #36–7).58 Kant, by separating an a priori ontological ratio cur vel ﬁendi from an a posteriori cognitive ratio quod vel cognoscendi, heeded Crusius’s critique of Wolff ’s theory. Aside from the distinction of the grounds of knowing and being, it was also necessary, Crusius believed, to probe the depths of the grounds of being. The ontological aspect of causality needed to be clariﬁed. Wolff ’s employment of ‘‘sufﬁcient reason’’ was confused, and the principium essendi required a new description. A sufﬁcient reason is that one, whereby one understands why something is rather than not, and why something happens in one way rather than in another (De Usu, #41, p. 252).59 According to Crusius, whatever comes to exist is generated by some other thing that possesses a faculty sufﬁcient for its generation, and that has played a constitutive rather than

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an inhibitive role in the causal act (ibid., #20, p. 227). Like Lange, the pietist Crusius had no tolerance for a preestablished harmony and endorsed an interactive causality (Ethik, #30–35). Any contingent event requires a sufﬁcient reason in order to come about.60 But in order to accommodate the contrast between contingent events such as physical processes that are determined and contingent events such as rational actions that are free, Crusius differentiated the principium essendi itself. Despite Benden’s (1973) remarks to the contrary, Crusius proposed to label the sufﬁcient reason for free action ‘‘sufﬁcient causation’’ and the sufﬁcient reason for physical processes ‘‘determining causation’’ (De Usu #26, p. 232).61 Free activity is governed by the principium rationis sufﬁcientis. Physical processes stand under the authority of the principium rationis determinantis.62 Once again, Kant’s terminology in the New Elucidation reveals Crusius’s inﬂuence. But in contrast to the earlier distinction between logico-epistemic and ontological aspects of causality, Kant’s employment of these terms had little to do with how Crusius deﬁned them. Whereas Crusius referred with ‘‘determining reason’’ to physical processes and with ‘‘sufﬁcient reason’’ to freedom, Kant used ‘‘determining reason’’ as a label for the principle of causality, which applies to both free and deterministic events, and ‘‘sufﬁcient reason’’ as a label for the conception of causality proposed by the LeibnizianWolfﬁan School. Despite his stipulation of two subprinciples of ontological causation, Crusius did not advocate a categorial distinction between causal species as Wolff did. On the contrary, Crusius’s point against Wolff was that inventing such causal species would sidestep the problem of free will without resolving it. The resolution of the problem of free will must acknowledge that causality is always the same. An irreconcilable difference between free activity and physical processes cannot be allowed; both are real, and both derive, ultimately, from a homogeneous law of causality. In this regard, Crusius and Kant perfectly agreed. Crusius proposed to resolve the issue in the following way: free activity and physical processes can coexist because they manifest the underlying law of causality in terms of different mechanisms. That is, both free activity and physical processes are caused, and the cause sufﬁciently accounts for its effect in either case. But the causal mechanism of free activity is reﬂexive, whereas the causal mechanism of physical processes is transitive. In other words, the cause of a contingent physical thing is always another thing (Met. #31, p. 49), but the cause of a free action lies in the free activity itself. In the Ethik (1744), Crusius deﬁned freedom as the power of the will to determine itself to its own activities (#39, p. 45). Since the will has causal power and is consequently its own sufﬁcient reason, it is, by deﬁnition, responsible for the totality of the aspects of the effected activity. Thus, freedom is the ‘‘complete inner activity’’ of the will (Eth. #41, p. 49 and #43, p. 54–5). Spontaneity and autonomy characterize freedom; determination and heteronomy characterize physical processes. Kant had mixed feelings about this analysis. Crusius had pin-pointed crucial faults of the Wolfﬁan account. He also had correctly brought out the

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difference between the ontological and cognitive aspects of causality. Furthermore, Crusius had succeeded in making a big leap beyond Leibniz and Wolff. As long as the mind was conceived as a monad subject to monolinear causation, the mind was unfree and bound by the divine program. Autonomy, as the mere absence of heteronomy, is insufﬁcient to ground freedom. Crusius had insisted on spontaneity in addition to autonomy, meeting all the requirements of freedom. Nonetheless, his leap fell short of a solution. The central issue—the compatibility of the two types of causation—was still unaccounted for. Crusius contended that freedom lies in self-determination. But if the cause of the free will is identical with the very same free will, then the free will turns out to be both its own cause and its own effect. This is impossible— both experience and logic tell us that causes precede effects, that effects succeed causes, and that therefore, a cause and its effect cannot happen simultaneously. Kant stated in the New Elucidation: ‘‘To say that something has the ground of its existence within itself is absurd’’ (I 394:10–11). The sequential nature of causality is axiomatic. Moreover, even if one ignores this problem of self-causation and grants the results of Crusius’s analysis, the central problem of the compatibility of the two types of causation will remain. If (as Crusius argued) the causation of physical processes is sequential such that the cause of a thing is always another thing, but the causation of free will is reﬂexive such that the cause of the will is the same will, then there will be two separate kinds of causation. Because they involve essentially different structures, they fail to be compatible with each other. Newtonian physics can be reconciled with the metaphysical assumption of freedom only if neither of the corresponding types of causation is reduced to the other. Leibniz failed to furnish the desired solution, because he reduced the interactive causation of physics to a mere phenomenon and diminished the free causation of the will to a mere self-necessitation. Wolff ’s account of causality was a step toward Kant’s own project, because Wolff assumed that both free activity and physical processes corresponded to a particular type of causation. Although Wolff did not explain interaction away as Leibniz did, he followed his predecessor in diminishing freedom. Moreover, as Crusius had rightly observed, Wolff was incapable of deriving the geometric necessity of freedom and the natural necessity of physical processes from a uniﬁed foundation. Crusius went beyond Wolff by at least providing an explanation of how both freedom and physical processes could originate in one principle of causality. But Crusius’s explanation violated an axiomatic feature of causality as such. None of the three theories of causality worked. Still, Kant thought Crusius’s strategy had come quite close to a solution. Crusius had proposed that the two types of causation embody two distinct causal mechanisms, represented by two corresponding ontological subprinciples, and that each of these subprinciples is a derivation from a uniﬁed law of causality. If there is a way of reconciling physics and freedom, then this must be it. Somehow, it must be possible to show that efﬁcient and spontaneous causation are distinct while derivable from the same basic law.

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6.3 Physical Processes and Physical Inﬂux To explain free will presupposes that we know its opposite. The analysis of the causation of physical processes thus represents one side of Kant’s inquiry. Kant asserted in proposition 8 of the New Elucidation that everything that exists contingently requires an antecedent reason determining its existence (I 396:8–9). Interaction governs the occurrence and determination of natural objects and physical processes. Consider two bodies A and B, and imagine they collide such that A ends up pushing B. When that happens, A impresses a force on B. In doing so, A affects a change of B. Because of A’s impact, B will be pushed to a different location. Having received a new force and a new spatial location (which, according to Kant, belongs to the determinations of the body because he rejected Leibniz’s law of the identity of the indiscernibles), the ontological result of A’s interaction with B is that B absorbs a change in its properties and obtains a new determination of its own reality (I 407:8–9 and I 407:note). Kant’s example is the causal schema of a physical process. Physical processes involve interaction. Interaction makes changes possible. Changes constitute the ﬂow of time, and thus interaction makes time possible. This prompted Kant to propose, as the fourth axiom of his ontology, the principle of succession:63 No change can happen to substances except in so far as they are connected with other substances; their reciprocal dependency on each other determines their reciprocal changes of state. (I 410:18–20; WM 37)

The principle of succession implies that an isolated substance will remain immutable. Substances devoid of causal connections could exist but would be frozen in time. Just as a substance cannot be a cause of itself, it does not have the power to affect a change in itself. Because nature involves change and exists in time, the ontology of nature requires a principle of succession that accounts for change and time. The three laws of motion in Newton’s celestial mechanics describe the physical aspects of the world. In Newton’s words: 1. Every body continues in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed upon it. (law of inertia, Principia, M 1:13) 2. The change of motion is proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed. (law of acceleration, Principia, M 1:13) 3. To every action there is always opposed an equal reaction; or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts. (law of interaction, Principia, M 1: 13)

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Laywine (1993) observed that Kant’s principle of succession seems to be three distinct principles in one: (1) no substance has the power to affect change in itself; (2) all change in a substance must be the effect of a connection with, or the action of, some other substance; (3) change of state in substances is mutual; that is, equal and opposite. Hence, the principle of succession ‘‘seems to stand in a peculiar relation,’’ as Laywine put it, to Newton’s laws of motion.64 The correspondence of the principle of succession to the laws of motion is not surprising, because Newton’s laws describe the mechanical patterns of bodies in nature whose ontological explication is Kant’s axiom. By employing terms such as ‘‘rest,’’ ‘‘right line,’’ ‘‘change of motion,’’ and ‘‘direction,’’ Newton’s laws presuppose the conditions of space and time. Kant’s principle of succession articulates the condition of time and thus furnishes a partial foundation of Newton’s laws. The other part of the foundation, space, is spelled out by the principle of coexistence, the ﬁfth and ﬁnal of Kant’s axioms.65 Considering this foundational relation of Kant’s principles to Newton’s laws, the New Elucidation foreshadowed the later Metaphysical Foundations of Natural Science (1786) and its transcendental underpinning of Newtonian physics. The law of succession reveals Kant’s opposition to the preestablished harmony in the physical realm (cf. I 412:6–10 and 415:25–33). Interaction is an essential feature of nature. Moreover, interaction constitutes the necessity which characterizes physical processes. Free actions, like physical processes, are governed by the principle of determining reason. Neither actions nor processes reside in a causal void, and both are effects that are determined by their causes. Freedom does not contradict determination but determinism.66 Because of the subtlety of the various causal attributes, a brief clariﬁcation is in order. A physical process is determined by prior conditions, and it is deterministic in that it has a predictable outcome. The necessity of the present state of a physical process is relative to a prior state. Hence, physical processes can be said to possess relative necessity. A free action, by comparison, is determined by a volition, but it is not deterministic because its course cannot be predicted beforehand. Because it does not depend on any prior states, except a volition, it could be regarded as being necessary relative to the volition. But a free action does not possess relative necessity like a physical process because the volition of a free act is spontaneous. Because the world and its parts have been created by and are ontologically dependent on a divine act of choice, physical processes and free actions are contingent. God, who created the world, does not depend on anything. God is free. Nor is God necessitated by anything. God is not contingent. Moreover, according to the tradition, it is impossible that God does not exist. God is absolutely necessary. Hence, according to the jargon of eighteenth-century metaphysics, (1) physical processes are determined, contingent, deterministic, and relatively necessary; (2) free actions are determined, contingent, and spontaneous; and (3) God is free/spontaneous and absolutely necessary.

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What happens, ontogically, when the things in the world appear to interact? Traditionally, there are three options for how to account for interaction: occasionalism, preestablished harmony, and physical inﬂux. Perhaps the ﬁrst to suggest the trichotomy of options was Pierre Bayle in his Dictionnaire historique et critique (1697).67 The trichotomy appears in the entry on Hieronymus Rorarius, who, as Bayle related, had written a book that defends the claim that animals are more rational than humans—a book, in Bayle’s words, that ‘‘deserves to be read’’ (p. 213). The major part of the entry was a lengthy discussion on the putative rationality of animals. The reﬂections on the ‘‘actions of the beasts’’ prompted Bayle to discuss causation of action in general. There he enumerated the three theories (cf. p. 245). After Bayle, Bilﬁnger described this trichotomy in the De harmonia animae et corporis humani maximi praestabilita (1723); Wolff repeated it in his Psychologia rationalis (1734); Baumgarten reiterated it in the Metaphysica ﬁve years later, and by the time of the New Elucidation, the triplet of possible causal hypotheses had become common academic knowledge. Occasionalism denies interaction among substances, and it denies substances a causal power of changing their inner states. God governs each individual causal event and acts on its occasion. God ensures the succession of inner states within individual substances, and the synchronicity of corresponding alterations among substances.68 Whereas an occasionalist God is constantly active, a God creating a preestablished harmony is active only at the inception of nature. Preestablished harmony denies interaction among substances but allows them a causal power of changing their inner states. This causal power is qualiﬁed in that it depends on the substances’ inner laws, which the substances cannot oppose. God governs the overall sequence of causal events, ensuring the synchronicity between substances. In contrast to both occasionalism and pre-established harmony, physical inﬂux assumes that interaction exists and pertains to the fundamental fabric of reality. Not God, but substances do all the work; they have the power to interact and to change their inner states. By formulating the law of succession, Kant aligned his ontology with the hypothesis of physical inﬂux. Physical inﬂux originated with the Disputationes Metaphysicae (1597) of the Spanish scholastic philosopher Francisco Sua´rez. In the seventeenth century, it remained popular with the Aristotelian-Scholastic philosophers who dominated the German universities in the generation before the LeibnizianWolfﬁan School Philosophers. Leibniz rejected physical inﬂux, convinced that it conﬂicted with the law of conservation.69 The School Philosophers were split over physical inﬂux. Wolff thought it implied an obscure and unintelligible transfer of being between the interacting substances.70 Gottsched was more sympathetic to physical inﬂux and argued that physical inﬂux should be taken as a ﬁgurative expression, not as a literal ﬂux of being.71 Leonhard Euler tried to transform the ﬁgurative expression of physical inﬂux into a concrete account. Euler had succeeded Maupertuis as the president of the Berlin Academy, he was a leading champion of Newtonianism in Germany and a critic of Leibniz and the Wolfﬁans. The key to Euler’s

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inﬂuxionist account of interaction in his Gedanken von den Elementen der Ko¨rper (1746) was a deliberate conﬂation of inertia with impenetrability (cf. #19). He interpreted Newton’s vis inertia as a vis impenetrabilis, equating the former with a resistance to penetration. Euler reasoned that the possibility of interaction requires that bodies are in contact which in turn presupposes they are impenetrable. Otherwise, bodies would penetrate each other and fail to interact. Not a transfer of being happens in the moment of interaction, as Wolff thought, but a transfer of force between bodies that are impenetrable and thus in contact. Euler’s explanation required the assumption of an ether. As a Newtonian, Euler regarded universal gravitation as an example of interaction. As an inﬂuxionist, Euler reasoned that the gravitationally interacting celestial bodies must be in contact. Accordingly, gravitational interaction cannot be a literal action at a distance. A cosmic medium must bridge the distance of the seemingly isolated celestial bodies to propagate the transfer of force and establish the required contact. This cosmic medium is, of course, the ether. By announcing the principle of succession that serves as the ontological foundation of the celestial mechanics, Kant moved into Euler’s vicinity. Just like Euler, he thought that Newtonian mechanics required an inﬂuxionist underpinning. But unlike Euler, he did not construct a speciﬁc theory that explicated the details of physical inﬂux. For Kant, physical inﬂux remained a hypothesis presupposed by the law of succession. Physical inﬂux was a given. It was the ontological pendant of universal gravitation, and like universal gravitation, it is impossible to explain it any further. By avoiding Euler’s route, Kant took action at a distance at face value. Thus, there was no need of resurrecting the ether, which he had rejected as a cosmic medium in the Spin Cycle essay and limited to a molecular medium in the master’s thesis On Fire. The central claim of the hypothesis of physical inﬂux is that interaction is real—even on the level of ontology. Interaction is not an empirical appearance but an irreducible ontological primitive. The ﬁfth axiom of Kant’s ontology, the principle of coexistence, spells this out: Finite substances do not, in virtue of their existence alone, stand in a relationship with each other, nor are they linked together by any interaction at all, except in so far as the common principle of their existence, namely the divine understanding, maintains them in a state of harmony in their reciprocal relations. (I 412:36–37–413:1–2; WM 40)

At ﬁrst glance, the principle of coexistence appears to be at odds with Kant’s inﬂuxionist commitment. It seems that Kant drops interaction for the sake of a preestablished harmony of substances maintained by a divine understanding. A closer look reveals that this is not the case. In the demonstration of the principle, he asserts that ‘‘individual substances have a separate existence’’ (WM 40; I 413:3–4). That a substance can exist in isolation

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means that interaction is not an essential property of substances. As he explains, If . . . nothing further than this [positing of the separate existence of individual substances] were admitted, no substance would stand in relation to any other substance, and there would be no interaction at all between substances. (WM 40; cf. I 413:9–10)

This claim, of course, follows from the principle of succession. The notion of substance does not entail the notion of relation of which interaction is a special kind. Clearly, ‘‘the co-existence of the substances of the universe is not sufﬁcient to establish a connection between them’’ (WM 41; cf. I 413: 22–23). Substances could exist without interaction, but, as Kant had already pointed out (410:27–28), nothing would then happen. There would be no change, and the substances would be as ﬁxed as ﬂies trapped in amber. Thus, the exact opposite of a preestablished harmony is asserted here. Leibniz’s doctrine means that substances not only exist without interaction, but they also change. But for Kant, the scenario of hermit substances implies the absence of physical processes. But there are processes, and hence, change and interaction must be part of the world: . . . since, nonetheless, all the things in the universe are found to be reciprocally connected with each other . . . it has to be admitted that this relation depends on a communality of cause, namely on God, the universal principle of beings. . . . [T]he self-same scheme of the divine understanding, which gives existence, also established the relations of things to each other, by conceiving their existences as correlated with each other. It is most clearly apparent from this that the universal interaction of all things is to be ascribed to the concept alone of this divine idea. (WM 41; cf. I 413:13–15, 17–20)

God created the substances and established their relations. Because their relations are not substantial properties but exist nonetheless, they are ontological primitives just like the substances themselves. The same divine ground is responsible for both, and an ontological parity of substance and interaction results. Substances stand in an interactive community not because of their essences but because God sustains the schema of interaction as a feature belonging to their community. The principle of succession supplied the ontological basis to the laws of motion, and the principle of coexistence furnished the ontological ground of the law of universal gravitation. Had Kant conceived of interaction as an ontological derivative and tied it to substance, he would have ended up in Euler’s corner. Then, interaction would have depended on the properties or the arrangement of substances, such as their inertial impenetrability and their immediate and ether-mediated contact. By tying interaction to God,

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Kant could permit Newton’s universal gravitation, together with the action at a distance it involves, without requiring Euler’s assumptions. Moreover, the stipulation of interaction as an ontological primitive sustained by God diplomatically avoided the theological ramiﬁcations of the mind-body problem. Kant could deﬂect the pietist critique because he did not need to analyze mind-body interaction as a mere phenomenon of coordinated changes internal to a monadic substance. In his account, souls sin through their bodies and are indeed responsible for their actions. God does not pull the strings of the bodies in synchronicity with the ideas of the souls. What the souls then decide to do through their bodies is their problem, not God’s. The divine being merely warrants the possibility of intersubstantial interaction while leaving speciﬁc interactions to the substances. The divine schema of the physical inﬂux constituted for Kant the rerum harmonia universalis, a general harmony of all things (I 415:24), be they physical events, or mind and body.

6.4 The Struggle for Freedom The Universal Natural History and the New Elucidation brought determinism to light that was only implicit in Newton’s philosophy of nature. In the Universal Natural History, Kant went far beyond Newton in the way he minimized God’s inﬂuence on the workings of nature. Kant emphasized the cosmogonical efﬁcacy of mechanical interactions. He solemnly demanded, ‘‘give me matter and I shall build a world with it!,’’ and defended this call with the predictable structure of physical nature (I 229–30). In the New Elucidation, he advanced ontological principles to the effect that events are determined by relevant factors, and that natural bodies form a system of regular interactions through physical processes.72 Determinism is an asset for a philosophy of nature. It permits one to understand physical nature not only in speciﬁc cases, but also in its overall constitution. This advantage found a powerful statement by Pierre-Simon de Laplace in the The´orie analytique des probabilite´s (1812): Thus we should conceive of the present state of the universe as the effect of its prior state and as the cause of the state that will follow. An intelligence who knew all the forces that animate nature and the situation of the things that compose the universe at a given time, and who was great enough to analyze all this data, would subsume the motions of the largest bodies of the universe and the motions of the lightest atoms under the same formula. Nothing would be uncertain to such an intelligence, and the future, like the past, would be evident to its eye. The human mind, in the perfection it has given to astronomy, is a faint echo (une faible esquisse) of such an intelligence. The discoveries in mechanics and geometry, together with those of universal gravitation, have brought the human mind within reach of summarizing the past and future states of the world-system in the same analytic expressions. Although the human mind will always remain inﬁnitely far from such an intel-

The New Elucidation 155 ligence, all his efforts in the search for truth are bringing it incessantly closer to the intelligence we mentioned.73

Determinism is vital for explaining the physical world, but it becomes a problem when it leaks into the metaphysics of free action. Julien Offray de la Mettrie’s L’homme machine (1748) and Baron Paul Henry Thiry d’Holbach’s Systeˆme de la nature (1770) were notorious examples. La Mettrie extrapolated his theory of humans from the empirically accessible segment of the world (p. 97).74 Nature is governed by laws that make it predictable and uniform (p. 123, p. 147). There is only one, a ‘‘diversely modiﬁed’’ substance in the world, la Mettrie believed (p. 151). This prompted him to argue for an ‘‘analogie du re`gne animal et ve´ge´tal, de l’homme a` la plante,’’ an analogy of the animal and plant kingdoms that holds from man to plant (p. 147). D’Holbach explored the implications of la Mettrie’s view. In the Systeˆme de la nature, d’Holbach treated nature as a system governed by constant and invariant laws (p. 14, p. 21).75 Everything is causally interconnected (p. 52). The interconnectedness which springs from mechanical and material causes generates a relative necessity that eliminates chance (p. 51, p. 66). Because freedom presupposes chance, and chance does not exist, freedom is an illusion (p. 75). D’Holbach thought it is acceptable to speak of humans having choices that are made between motives the will acts upon (p. 194–5, p. 197). But such choices are psychological impressions. They are not matter-of-fact. D’Holbach insisted that the chosen actions are unfree because their causes— intellectual motives—are formed in the soul by senses that are fully subject to material causes (p. 197–9, p. 187–8). What is worrisome about d’Holbach’s blatant repudiation of freedom is that his analysis of human action resembles Kant’s. Both thinkers regarded the motive as having something to do with the cause of action. Both asserted that the will causes an action when it acts on the motive. And both thought that the motive can be the effect of an external material cause. In d’Holbach’s account, the existence of a causal link of intellectual motives to prior material causes effectively dispels the possibility of freedom. Intellectual motives were not sheltered anymore from physical processes, and the determinism of the latter destroyed the spontaneity of the former. How could Kant respond to this challenge? He needed to show that a link between the physical world and intellectual motives, if it existed, would not threaten freedom. He had to prove not only that the source of action is within us— d’Holbach admitted this as well—but also that the source of action, or at least a vital part of it, begins with us. Not just any proof would do. The demonstration Kant wanted had to accord with the presuppositions of the precritical project, that free and necessary actions are harmoniously copresent in a coherent world, and that their distinct but compatible causations follow from a uniﬁed principle. The struggle for freedom took place in a passage of the New Elucidation entitled ‘‘Refutation of Objections’’ (I 400–405). There, Kant insisted that the

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causation of free actions differs from the causation of physical processes only in terms of the causal mode (I 400:30–36). The principle of determining reason governs both kinds of causation, hence, both originate in the same ontological ground (I 400:12). Their difference consists neither in their being mutually exclusive species (as in Wolff) nor in their involving inconsistent structures (as in Crusius). Instead, they differ in the way that events are determined. External stimuli and impulses determine events in a deterministic nexus; spontaneous inclinations of the will determine events in a free nexus (I 400:36–38). Kant explained: But the way in which the certainty of [the] actions [of intelligent beings] is determined by their grounds gives us all the room we need to afﬁrm that they bear the characteristic mark of freedom. For such actions are called forth by nothing other than motives of the understanding applied to the will, whereas in the case of brute animals or physico-mechanical actions everything is necessitated in conformity with external stimuli and impulses and without there being any spontaneous inclination of the will. (WM 23–4; I 400:36–39)

Because causation, no matter what mode, obeys the principle of determining reason, all occurrences, free as well as necessary ones, share the same structure. They require antecedent reasons, occur in the right sequence, cannot be self-caused, and maintain the proportionality of cause and effect.76 In these respects, the efﬁcient causation of physical processes and the spontaneous causation of free action are identical. The only difference concerns their manner of determination: external impulses cause physical events, and inclinations of the will cause free actions. In a dialogue which Kant inserted in the ‘‘Refutation of Objections,’’ Caius, Kant’s d’Holbachian opponent, remarks that whenever he feels guilty about the sordid things he has done during his life, he consoles himself with the fact that he ‘‘was bound by the connected series of grounds which have determined each other from the very beginning of the world’’ (WM 24; I 401:22–28). Titius, Kant’s mouthpiece, roundly rejects Caius’s consolation. The series of grounds does not let Caius off the hook. His actions were free because he liked to act on these grounds (I 402:3–6). What made Caius’s actions free, Titius adds, is that, at any given juncture, the series of interconnected grounds furnishes motives for the performance of the action which are equally attractive in both directions: you readily adopted one of them because acting thus rather than otherwise was more pleasurable to you. (WM 25; I 402:4–6)

Against Caius’s insistence that ‘‘the totality of grounds’’ had him ‘‘incline in one particular direction,’’ Titius asks him to consider ‘‘whether it is not the case that the spontaneous inclination of your will, according to the attractions of the object, is not required if there is to be a complete ground of action’’ (WM 25; I 402:7–9). In this sense, freedom is spontaneity. And

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spontaneity, Titius adds, ‘‘is action which issues from an inner principle’’ (WM 25; I 402:12). The point, Titius elaborates, is that even if prior grounds furnished motives for the evil you have done, you decided to choose freely among them: Hence, no matter how much the state of things prior to the free acts has been determined by some ground, and no matter to what degree the intelligent being is entangled in a connected series of circumstances . . . nonetheless, this futurition is determined by grounds which are so constituted that voluntary inclination towards what is base is the hinge upon which everything turns. . . . [M]ortals commit sins voluntarily and as a result of an inmost state of mind, for the chain of antecedent grounds does not hurry them along or sweep them away against their will; it attracts them. (WM 28, 29; I 404:10–14, 37–39)

Excepting the element of spontaneity, there is no difference between intellectual motives and physical processes. Both are links in parallel causal series whose ultimate ground is God. In contrast to Wolff ’s account that left a gap between the geometric necessity of intellectual motives and the natural necessity of physical processes, Kant’s proposal connects the two. A motive can be caused by a prior motive, but it can also be the effect of an external impulse and thus of a physical event. Substances cannot change themselves according to the law of succession, and this includes immaterial substances such as the soul. The soul is subject to inner changes through its ‘‘internal sense’’ (I 411:35). The inner changes of the soul, which cannot arise in isolation, require the presence of other things outside the soul with whom the soul is engaged in a ‘‘mutual nexus’’ (I 411:34–37). Since there are genuine, inﬂuxionist interactions between material and spiritual substances, a physical event can determine an intellectual motive. In this (and only this) sense, Caius had it right. The motives confronting his will had been the terminal links of deterministic chains of antecedent grounds strung from the world to the mind. So far, so good. Intellectual motives are determined with necessity. Where is freedom? Evidently, the deterministically generated motive cannot be the wellspring of the spontaneity constitutive of freedom. Indeed, imagining this was just the mistake that Caius had made. Motives do not let him off the hook. He chose freely among them. As Titius reminds him, the cause of the free action is the spontaneous inclination of the will and not the motive. Kant has now approached the problem of freedom from two directions. Before the inception of freedom, prior to the performance of the action, there has been a series of external impulses that eventually produced motives in the mind. After the inception of freedom, during the performance of the action, the effect of the spontaneous inclination of the will becomes visible. At this stage in the analysis, the relevant features of efﬁcient as well as spontaneous causation are preserved. The sequence of efﬁcient causation begins with physical events, continues with external impulses, and ends with intellectual motives. The sequence of spontaneous causation begins with the inclination of the will and ends with the performed action.

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To complete the analysis requires us to show how the end of the efﬁcient series relates to the start of the spontaneous series. How do motive and inclination of the will connect? Caius—and d’Holbach, for that matter— replied that the motive determines the inclination of the will. The inclination of the will, in their view, was just another effect, just another link in the deterministic chain of efﬁcient causation. This is how Caius hoped to console himself whenever his conscience stirred. If Caius was right, freedom would collapse to its opposite, necessity, and d’Holbach’s view would carry the day. Titius—Kant—retorted that there is a causal breach between the motive and the inclination of the will. The intellectual motive is linked to the external series (which closes Wolff ’s gap), but the motive is not linked, in the same fashion, to the inclination of the will (thus opening up another gap). The motive is the effect of an impulse, but the will is not the effect of the motive. The motive does not necessitate the will. Instead, the will inclines itself toward the motive that it selects. The will embraces a particular motive, and when that happens, the resulting combination of will and motive precipitates the action. D’Holbach and Kant agree in that the motive has something to do with the causation of the action. But its particular role is clearly different in the two accounts. D’Holbach’s motive determines the action through the mediation of the will. In d’Holbach’s account, the motive is the master, and the will is its servant. Kant’s motive, on the other hand, offers itself to the will, the will latches on to it, and then the will, guided by the motive, determines the action. In Kant’s account, the will is the master, and the motive is its servant. In Kant’s account, the existence of the motive contributes to the occurrence of the action in a partial and insufﬁcient manner. The motive underdetermines the action. It does not have the force to necessitate the will to perform the action. Certainly, a motive may tempt the will and exert some inﬂuence over it—but the will is in charge; the will has always the power to resist the temptation. As Kant has Titius explain, the spontaneity of the will of rational beings consists in their power of self-determination (I 404: 7–10). Rational beings have the ability to choose, and it is therefore up to them toward which motive they wish to incline their will. The explication of the spontaneity of the will in terms of a power of selfdetermination pushes Kant’s analysis dangerously close to Crusius’s proposal. There, the notion of self-determination involved a fatal ﬂaw: Crusius’s will was its own cause and thus set itself at variance with the sequential form of causation. How can the trap of self-causation be avoided? The only solution would be to split the will up into discrete components, each playing a speciﬁc causal role. In the New Elucidation, the only candidates for such components would be the intellectual motive and the inclination of the will. If both pertained to the overall phenomenon of willing in a way that avoided the Crusian trap, then the motive, as the one component of willing, would be a cause, and the inclination, as the other component of willing, would be the effect. Seen in this light, one discrete component of the will causes another and thus the will does not cause itself. But such a solution is in-

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acceptable. It rescues Kant from the Crusian trap only to throw him to the wolves of d’Holbach’s determinism. Moreover, such an internal differentiation of the phenomenon of willing is contradicted by Kant’s own characterizations of motive and inclination. Kant distinguishes motive and inclination of the will; the former is the result of external impulses, and the latter involves a characteristic ‘‘spontaneity,’’ ‘‘power of self-determination,’’ or ‘‘inner principle.’’ The motive is a passive temptation. The will is the active cause of the action. Moreover, because the will involves the power of self-determination, the will causes itself. Therein consists the spontaneity of free causation. The will moves toward a particular direction. As Kant explains (I 404:37–39), its motion is not impelled by the motives. Instead, the motives attract the will, and the will either resists this attraction or gravitates toward it. The account of the New Elucidation preserves both rational freedom and physical necessity. Kant had successfully avoided reducing the one to the other. But did he succeed to derive them from a common ground? As in Crusius’s ontology, a fundamental asymmetry divorces spontaneous from efﬁcient causation in the New Elucidation. Kant’s assurance to the contrary, the difference of the two types of causation is not over their modes—external impulses in the one case, and intellectual motives in the other—which it should have been if both kinds of causation were to remain derivable from a common ground. The intellectual motive is not an integral part of spontaneous causation; it is neither the ultimate cause of the action nor the primary impulse necessitating the will. Instead of being the foundation of spontaneous causation, the intellectual motive is the last link of the chain of efﬁcient causation. Thus, it cannot be the mode of freedom. The two kinds of causation differ in terms of their structure. In spontaneous causation, the cause is not an effect of another cause; instead, the cause determines itself. In efﬁcient causation, the cause is always an effect of another cause and never determines itself. Kant was able to show how the determinism of physical processes results from the principle of determining reason, but he failed to derive the freedom of rational agents from the same axiom. What freedom is remains a mystery. Kant could only say that in freedom, the will freely chooses among the motives present to the mind. Characterizations of this sort beg the question. This asymmetry of spontaneous and efﬁcient causation reveals that Kant’s lengthy and exhausting struggle for freedom ended in defeat. He hoped to reconcile freedom and determinism within a consistent universe and declared that efﬁcient and spontaneous causation do not differ in the type of causal nexus (400:30–36). Their general structures were supposed to be the same; they had to be the same given Kant’s own premises. But as it turned out, their structures remained dissimilar. The New Elucidation was the attempt at providing an ontological underpinning to the Universal Natural History. Proceeding from the hypothesis of physical inﬂux, Kant wanted to explain the causal structure of the physical processes, which are the objects of Newtonian science and the ﬁnal means

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of the unfolding of the cosmos. In the Universal Natural History, Kant’s project of marrying Newton and metaphysics had brought about the union of natural science and teleology. In the New Elucidation, he hoped to bring natural science together with freedom, the metaphysical presupposition of ethics. The unwavering commitment to an ontologically coherent model of reality deﬁned Kant’s task and raised the central question of the New Elucidation: How does the efﬁcient causation of deterministic nature cohere with the spontaneous causation of rational volition? The only path that Kant could pursue in tackling this question was to derive both species of causation from one and the same principle of determining reason. The Leibnizian escape-route of a preestablished harmony was closed to him, because it was ill-matched to both Newtonian science and the metaphysical desideratum of human freedom. In embracing physical inﬂux instead, Kant produced an ontology of physical causation that was leaner and tighter than the alternatives suggested by Wolff, Crusius, and Euler. The price of this ontology, however, was that determinism reared its ugly head again. The envisioned marriage of science and metaphysics required an ontology that justiﬁed not only the soundness of Newton’s enterprise, but also the possibility of freedom. In trying to contain the threat of determinism while demonstrating its compatibility with free will, Kant set himself up for disaster. No magical peace accord between free will and determinism presented itself. Later in life, with the Critique of Pure Reason, he would denounce the task of the New Elucidation as an impossibility. The conﬂict between free will and the laws of nature cannot be resolved, and any theoretical examination of this matter will remain stuck in an antinomy of opposed transcendental ideas (cf. A445/B473–A451/B479). Only a practical resolution can get us out of this antinomy, the critical Kant would argue (A797/B825– A800/B828). Of course, this critical solution is nothing but a dressed-up postulate: we are supposed to assume, for the purpose of the possibility of morality, that free will exists, despite the empirical reality and its deterministic laws. On the theoretical level, Kant was never able to go beyond the antinomy that he confronted in the New Elucidation for the ﬁrst time. But it would be years before he publicly acknowledged his failure. Instead of referring to his own tract on the matter, he would note in the Prize Essay (1763) that a valid deduction of freedom was still extant (II 282). In the 1750s, though, Kant felt still conﬁdent. The forced marriage of spontaneous and efﬁcient causation had led to anything but matrimonial bliss, but for the time being, the precritical project continued.

S E V E N

The Physical Monadology and the Elements of Nature

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7.1. The Problem of Inﬁnite Divisibility In the winter semester 1755, Kant started working as a privatdozent or adjunct instructor. He was now thirty-one years old. His former teacher Martin Knutzen had died ﬁve years ago. Kant wanted to apply for Knutzen’s vacant post, but in order to be eligible for the professorship he needed to write yet another Latin dissertation. Frederick the Great, king of Prussia since 1740, and successor to the throne of the soldier king Frederick William I, had initiated the academic tradition requiring a professor to have earned three degrees: the master’s, the doctorate, and the professorial habilitation. Each degree involved a public defense of a thesis. Kant had defended On Fire as his master’s thesis in May 1755 and the New Elucidation as his doctoral thesis in September 1755. Now he needed to compose a tract that could pass muster as his professorial thesis. For this purpose Kant wrote The Joint Use of Metaphysics and Geometry in Natural Philosophy, the First Example of which Contains the Physical Monadology. He submitted it to the faculty on 23 March 1756 and successfully defended it on 10 April.1 The Physical Monadology appeared as a slim booklet of 16 pages with Hartung in 1756. From a practical point of view, Kant’s labors on the Physical Monadology turned out to be in vain. His application was rejected, and he had to wait another fourteen years before achieving the desired professorship. In fact, 161

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everybody’s application was rejected because the government decided to abolish Knutzen’s chair. The king’s attention was engaged elsewhere. Diplomatic relations to Austria were deteriorating, and the Berlin government started preparations for war. Academic positions that could be eliminated were eliminated. Prussia cut down spending on its universities in order to pool its ﬁnancial resources in the military. In August 1756, Frederick the Great’s army invaded Saxony and started the Seven Years War. Initial military defeats in East Prussia resulted in the Russian occupation of Ko¨nigsberg from 1758 to 1762.2 It was not a coincidence that the title of Kant’s work is reminiscient of Leibniz’s Monadologie. In 1714, the year before his death, Leibniz was asked by Nicolas Remond, a counselor to the Duke of Orleans, to summarize his philosophy of nature. Leibniz responded with the E´claircissement sur les monades, which became known as the Monadologie. He sent the tract off as a personal missive; it reached a wider audience only years later. A German translation was published in 1720, a Latin edition in 1721, and the original French version appeared in 1740.3 In Germany, the Monadologie was celebrated; in France, it failed to challenge Newtonianism as the heir to the Cartesian legacy. Whereas Descartes and Newton viewed bodies as real things, Leibniz took them as phenomena. And while Descartes and Newton made appeals to corpuscles (the one to explain physical effects, the other to account for optical phenomena), Leibniz’s monadology was a theory of forcecenters which reduced everything to energy.4 Thus, Newtonian physics revealed afﬁnities to Cartesianism which Leibnizian dynamics lacked, and this helped Newtonianism to replace Cartesian mechanics as the new paradigm of natural philosophy in France. The Monadologie was effectively cut out of the loop. Its leading French critic was Pierre L. M. de Maupertuis, the ﬁrst of the philosophes who, in the 1730s, defended the Principia against Cartesian mechanics. Convinced that the properties of components corresponded to the properties of the composites, Maupertuis became an outspoken advocate of a form of corpuscular ‘‘atomism.’’5 If a body is extended and solid, so must be its parts. Accordingly, bodily parts must be extended and solid atoms and cannot be unextended and monadic wellsprings of force.6 Frederick the Great invited Maupertuis with several other French philosophers to come to Berlin. At the king’s behest, Maupertuis chaired the newly reconstituted Prussian Academy of Sciences in 1744. One of the responsibilities of the academy president was to select a topic of current scientiﬁc and philosophical interest for a biannual international prize question. This was the opportunity Maupertuis had been looking for. Now he could render a blow to Leibniz’s system. So in 1745, he announced an essay competition on the Monadologie. When all submissions were in, the philosophers of the academy selected as ﬁnalists one essay arguing for the monads and another arguing against them. But when it came to choosing a winner, the vote was a tie. The philosophy section of the academy was evenly divided between the supporters of Leibniz who defended the monads (such as Christian Wolff, Justin Henri Samuel Formey, Samuel Ko¨rber, Jakob Friedrich Mu¨ller, and

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Johann Friedrich Stiebritz), and the disciples of Newton, who rejected them (such as Leonard Euler and Johann Heinrich Justi). Maupertuis refused to split the prize. With the support of Euler—his eventual successor as president of the academy—he pressed for a vote from all members of the academy. Adding the votes of the Newtonian academicians from the mathematics and science sections tipped the scales; the scheme worked, and in 1747, Justi’s essay against monads won the trophy.7 By the time Kant labored over the Physical Monadology, the rigged contest was long over. He was attracted to the question because the competition had failed to settle the debate. The prize question over monadology concerned the question of the composition of matter. As Pierre Bayle had explained in the entry on Zeno of Elea in the Dictionnaire historique et critique (1697), there are three possible compositions of matter: that it consists of mathematical points, that it consists of atoms, and that it consists of particles that are divisible to inﬁnity.8 The Greek philosopher Epicurus had maintained that there are atomic elements that are solid and indivisible. Atoms cannot be split up. With the rise of Christian theology, this claim was questioned in light of God’s stipulated omnipotence. God can do anything, and He can surely split atoms. Pierre Gassendi, one of the last modern defenders of Epicurus’s claim, granted the theological objection to atomism but insisted that atoms cannot be naturally divided.9 Not supernatural divisibility, but natural divisibility was the issue.10 Are atoms then naturally divisible? Descartes reasoned in the Principia philosophiae that they must be. Because the deﬁning property of a body is extension, any part of a body, or any body no matter how small, is extended as well. Extended bodies can always be divided. No matter how ﬁnely a body is sliced, thinner sections are always possible—a last division of a body cannot be achieved.11 Descartes’s conception of the body necessarily entailed the rejection of indivisible atoms and the acceptance of an inﬁnitely divisible matter. To assume that the smallest identiﬁable units of matter are extended ‘‘atoms’’ or particles implies that they are not only divisible, but divisible to inﬁnity. The majority of natural philosophers agreed. As a result, the term ‘‘atom,’’ if it is to be used at all, must signify a divisible corporeal corpuscle, which of course had little to do with the ancient conception according to which iτοµο had been indivisible by deﬁnition.12 Most modern ‘‘atomists,’’ the Cartesians as well as the Newtonians (including Maupertuis and Euler), embraced the view of the inﬁnite divisibility of matter.13 Accordingly, Bayle’s trichotomy—indivisible points, indivisible atoms, and divisible particles—contracted to a dichotomy: indivisible monadic points and divisible corporeal corpuscles. Monads are unextended and indivisible and are therefore the ultimate constituents of matter. Logically, it is of course correct to argue that the properties of a whole are not necessarily the properties of its parts, and thus, there is no a priori reason to assume that the components of an extended composite must be extended as well. In fact, to argue, on logical grounds, for the assumption that the properties of the whole are necessarily the properties of the parts would fall prey to the fallacy of division.14 Thus,

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it is possible that an extended whole consists of unextended parts. But this does not protect the hypothesis of monadic point-entities from a serious metaphysical difﬁculty. Points cannot be divided any further because by definition they lack extension (the prerequisite of divisibility). The difﬁculty arises when one considers composition instead of division. Although it seems intuitively acceptable to say that the division of matter stops at unextended points, it is implausible to say that the composition of matter begins with unextended points. How many points ﬁt into a body? Unextended components, no matter how many there are, cannot combined make up an extended composite. However, the metaphysical difﬁculty just described arises only if one assumes that parts and wholes are equally real—that the extended corporeal composite is ontologically on par with the monadic points that are supposed to ﬁll it. Leibniz did not worry about this difﬁculty because he did not proceed from this assumption. For him, the extended whole did not possess genuine reality; only the monadic parts did (Monadologie #3, AG 213; cf. G 6:607). Their reality was fundamental because they were the entelechies of things and the building-blocks of the universe (Mon. #18–19, 62, 66). Extended wholes, on the other hand, presupposed space. Whether space was real or not depends on whether space had an independent existence. If it did, then space could persist in the absence of things—if there was an ‘‘absolute’’ space so understood, then it could be empty. But this consequence, the possibility of a void, violated several principles Leibniz regarded as truths (the laws of sufﬁcient reason, of plenitude, and of the identity of indiscernibles). Hence, Leibniz rejected the void and concluded that space did not have an independent existence.15 Space could not be ‘‘absolute’’; its existence had to rest on something else. According to Leibniz, space hinged on and came about through the motion of bodies. The motion of a body, as a change of position, could be described as a relation. Space, deﬁned through the motions of bodies, had to be their relational framework.16 Because it was essentially a derivative network of relations, space turned out to be an ideal entity.17 This did not mean for Leibniz that space was a chimera. Space was real in that it involved divine attributes and substantial forces.18 But the reality of this ideal space was limited for it needed other created entities for its existence; it was real merely in a derivative sense.19 Since space was the necessary condition of extension which, in turn, was the necessary condition of extended wholes or bodies, bodies were only ideal, too. Hence, it did not matter that monadic parts could not combined make up an extended whole for an extended whole, compared to a monadic part, was just an appearance anyway. In this way, Leibniz escaped from the metaphysical difﬁculty. However, the escape route from the metaphysical difﬁculty was not entirely free of difﬁculties of its own. The kind of reasoning just described conﬂates several distinct senses of the concept of an absolute space. Whether and how an absolute space involves a void (and whether and how the alleged impossibility of a void indicates the impossibility of an absolute space) depends on how one deﬁnes ‘‘absolute space.’’ In the eighteenth century, this

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notion was burdened by conceptual ambiguities. In the proper sense of the term, an absolute space is the ultimate reference frame for inertial motion. This is the conception of space Newton employed in the Principia. Absolute space, so conceived, is different from a presumed space that exists ‘‘absolutely’’—that is, a space that exists independently of objects. Space in this second sense would belong to the ontological furniture of the world. If it was real, then it would exist originally, and not as a derivative of the relation of objects. Such a space would exist like a substance. This substantive space is the conception of space that Leibniz rejected, as in the paper On Copernicanism and the Relativity of Motion (1686). However, how he rejected this conception there introduced a further ambiguity. He remarked, ‘‘space without matter is something imaginary’’ (AG 91). Is ‘‘space without matter’’ substantive space, empty space, or both? Empty space concerns the thesis that there are spaces that are unoccupied by bodies, either within the universe or beyond its edges. It is not difﬁcult to see that empty space is distinct from both substantive space and absolute space. If an empty space existed, then this would demonstrate that space existed just like a substance does. Hence, the claim of the reality of an empty space entails the claim of the reality of a substantive space. But a substantive space is not necessarily empty. One could envision a world in which space served as an original receptacle of bodies, and yet all the space there is was occupied by bodies. Hence, the claim of the reality of a substantive space does not entail the claim of the reality of an empty space; it merely entails the claim of the possibility of an empty space. Furthermore, the relation of empty space to absolute space lacks the ontological connotations that characterize the relation of empty space to substantive space. The conception of an absolute space, the reference frame for inertial motion, entails the assertion of a void as a heuristic device of an explanatory model. Related to these conceptual ambiguities of an ‘‘absolute’’ space is the issue of absolute motion. Absolute motion can be characterized in terms of displacements within an inertial frame of reference. But it is also possible to defend absolute motion without defending absolute space. Kant’s changing views on this issue illustrate this. In the essay Motion and Rest (1758), he rejected absolute space and thought that this implied the rejection of absolute motion. Because there is no logical limit on the size of the reference frame adopted, he concluded that there is no ultimate reference frame for inertial motion. What appears as motion in one reference frame can be rest in another, and therefore, absolute motion does not exist (II 16–17). In the Directions in Space (1768), he did not retract the rejection of absolute motion, but he retracted the rejection of absolute space.20 Now he thought that an ultimate spatial frame of reference with an absolute directionality existed because this was the only way to explain the existence of incongruent counterparts (II 382–383). So, in the 1750s, Kant rejected absolute motion because he rejected absolute space. In the 1760s, he rejected absolute motion but now defended absolute space. Finally, in the 1780s, he embraced the opposite view. Following Huygens, he defended absolute motion while re-

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jecting absolute space (IV 482). Kant’s arguments for his mature view show that it was possible to substantiate a useful concept of absolute motion without appealing to an inertial frame of reference. In the Metaphysical Foundations of Natural Science (1786), he argued that there can be absolute motions without absolute space because the inertial forces characteristic of absolute motion can be analyzed simply in terms of the relative motions of the parts of the ‘‘absolutely’’ moving body with respect to one another. As he explained (IV 556–557), an absolute circular motion could be distinguished from a merely relative one by the fact that the parts of the absolutely rotating body exhibit a tendency to move away from one another, rather than the fact that they are changing places in a supposed absolute space.21 So much for the conceptual clariﬁcation of absolute space, its relation to absolute motion, and the ambiguities that clouded the debates on the composition of matter. Let us now return to the issue at hand. Leibniz thought that he could avoid the metaphysical difﬁculty of extended wholes involving unextended parts by reducing the former to the latter. Substances, the unextended parts of the extended wholes, are ‘‘more’’ real than space and extension because they constitute them. This reduction settled for Leibniz the question of the inﬁnite divisibility of matter. Matter was not inﬁnitely divisible because divisibility presupposed spatial extension which was merely the effect of the substances constituting matter. Accordingly, spatial divisibility could not double back and threaten the substances with an inﬁnite divisibility. By downgrading the reality of space, Leibniz avoided the problem of inﬁnite divisibility. But Kant faced the metaphysical difﬁculty because he assumed both the reality of substance and the reality of space. A monad ‘‘ﬁlls’’ (implet) space according to proposition 5 of the Physical Monadology (I 480:2; WM 56).22 Kant observed that this statement had until now prevented the union of the claims of metaphysics regarding substance and the claims of geometry regarding space (I 480:14–21).23 Nonetheless, that space was inﬁnitely divisible was just as true as that monads were not inﬁnitely divisible. Neither geometry nor metaphysics were in error, he thought. Since a monad was a substance precisely because it was not inﬁnitely divisible, it followed that space, being inﬁnitely divisible, was not a substance. Space, as Kant saw it, was a phenomenon of the external relations of the substances (I 480:27– 8). This seems to be exactly what Leibniz said.24 In fact, Kant agreed with Leibniz that space is a composite system generated by component substances. As he wrote in the Universal Natural History, attraction is doubtless a property of matter that is just as pervasive as the coexistence of matter which constitutes space by connecting substances through mutual dependencies. Or, to put this point more precisely, attraction is just this very general relationship which uniﬁes the parts of nature to one space. Hence it spans the whole extension of space into all reaches of its inﬁnity. (I 308)

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For Kant, the force of attraction constituted space by generating dynamic relations among substances. Leibniz had assumed that there is space if there are relations. But—as Leibniz had further assumed—this space is merely ideal because substances do not interact and any relations are only apparent. According to the quoted passage from the Universal Natural History, Kant agreed with Leibniz that dynamic relations generate space. But he disagreed with him over the alleged ideality of the relative space. The principle of coexistence in the New Elucidation expressed Kant’s conviction that substances do interact and that relation is just as real as the substances are. Thus, Kant’s relational characterization of space did not bring him to the Leibnizian conclusion of an ideal relative space. In the ontology of the New Elucidation, space had emerged as the sum of the real interactions (I 414: 10). Substances relate with one another because God is the divine schema of their interaction. The relations that are constitutive of space depend directly on God instead of being properties of substances. Space is a relational network whose existence is independent of the existence of the substances. In light of Kant’s ontological claims, relative space is a substantive space. It is tempting, however, to suppose that Kant adopted the Leibnizian view after all because he dubbed space as a ‘‘certain appearance of the external relation of substances’’ in the Physical Monadology (I 480:27–28; WM 57).25 On the basis of this characterization, one might think that the ontological claims of 1755 did not bear on the mondological theory of 1756, and that Kant’s conception of space involved a transition from a substantive relative space in 1755 to an ideal relative space in 1756. But Kant’s endeavors—both the speciﬁc task of the Physical Monadology and his overall precritical project—effectively precluded such a transition. He had no choice but to assume the reality of both substance and space. The full title of the Physical Monadology (‘‘The Joint Use of Metaphysics and Geometry in Natural Philosophy, the First Example of which Contains the Physical Monadology’’) advertised what the treatise was about. Kant intended to show that geometry and metaphysics can be combined to generate new insights. The intention of a joint use of geometry and metaphysics in the Physical Monadology advanced the precritical project—the synthesis of quantitative-scientiﬁc and qualitativemetaphysical perspectives for the sake of obtaining a philosophy of nature that has great explanatory power. Moreover, this intention bore directly on the ontological status of space and substance. Geometry asserted the reality of space, and metaphysics asserted the reality of substance. With his theory of physical monads, Kant hoped to resolve the puzzle of the composition of matter by utilizing both geometric space and metaphysical substance without reducing the reality of either one. Had Kant endorsed an ideal relative space instead of a substantive relative space, he would have sabotaged the task of the Physical Monadology. A reconciliation of the Newtonian account of nature with the assumptions of metaphysics requires the irreducibility of either side. To give up on the reality of substance would make laws about substances meaningless— had Kant done this, there would have been no point in writing the New

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Elucidation. But to renounce the reality of space and relation would deﬂate Newton’s model of bodies, interactions, and motions in space to an account of a mere phenomenon. Had Kant done that, then he would have had no reason to write the Universal Natural History. Because he wanted to show there that Newtonian physics is not only a useful theoretical model but a profoundly correct description of nature, he inﬂated Newton’s heuristic claim of an absolute space to an ontological claim of a substantive space. The fundamental challenge of Kant’s synthetic project was to show that both physical and metaphysical entities were the ontological furniture of the same room of reality—space, bodies, and forces existed alongside monads, purpose, and freedom.

7.2 The Activity of Matter Geometry asserts the reality of space, and metaphysics asserts the reality of substance. In the preface to the Physical Monadology, Kant raised the question of how geometry and metaphysics can be brought together (I 475). The obstacle to their reconciliation was not just that these two disciplines differ, but that they squarely contradicted each other on a number of points. For example, geometry afﬁrmed, but metaphysics denied, that space was inﬁnitely divisible, that there was empty space, and that innate forces such as universal gravitation acted at a distance.26 Kant intended to resolve these conﬂicts and explain the nature of bodies by deducing repulsive and attractive forces ‘‘from the inner nature of elements and their original properties’’ (I 476). The fabric of the universe consists of extended bodies that are in space and attract each other. The force of repulsion cannot cause the phenomenon of attraction, and the force of attraction cannot cause the phenomena of extension and space, hence, both must be assumed as fundamental principles. Attraction and repulsion are the two immanent moving forces that constitute the ground of all material activity (I 476). The Physical Monadology, containing Kant’s theory of harmonizing metaphysical substance and geometric space, is structured more geometrico around thirteen propositions. Proposition 1 is the deﬁnition of a monad: it can exist independently and does not subsist as a plurality of parts (I 477:5–7). Proposition 2 is Kant’s central metaphysical thesis: bodies consist of monads (I 477:8). Proposition 3 is a claim from geometry: space is inﬁnitely divisible (I 478:1–3). Proposition 4 involves a basic logical fact: an inﬁnitely divisible composite does not consist of simple parts (I 479:14–15). Proposition 5 brings metaphysics and geometry together: a monad is in space and it ﬁlls space (I 480:1–3). Propositions 6 and 7 explain that a monad can exist in space because it determines space through its sphere of force-activity (I 480: 36–39; I 481:9–11). In the remainder, Kant ﬂeshes out the physical aspects of the monadology (which explains the label, ‘‘physical monadology’’). Propositions 8 and 9 are about the force of impenetrability: the former identiﬁes impenetrability as the force whereby a monad ﬁlls space (I 482:4–6), and the latter involves a deﬁnition of contact based on the dynamic conception

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of impenetrability (I 483:11–12). Proposition 10 links the monadology to attraction and repulsion: these two forces combined constitute the spatial volume of bodies (I 483:31–33). Propositions 11 and 12 explain inertia as a third fundamental property of the monad: the force of inertia has a deﬁnite quantity (I 485:15–16), and its variations determine the speciﬁc densities of masses (I 486:5–7). The conclusion of the Physical Monadology, proposition 13, explains elasticity and action at a distance through the ether, and ether through the properties of the monad (I 486:36–38).27 The metaphysical cornerstone of the physical monadology is the theorem that bodies consist of monads (prop. 2). Because bodies consist of parts (partes) that can exist independently, their composition (compositio) into a body is nothing but the relation of the parts. Since a relation is not an essential property, the composition is a contingent feature of the parts. If a body was annihilated, the composition of parts would not be anymore, but the parts themselves would still exist. But parts that can exist independently of composition are simple, and thus, Kant concluded, bodies consist of monads (I 477:16–17). Kant knew about Euler’s work (he referred ﬁrst to him in On Fire, I 378), and although he did not mention Euler in the Physical Monadology, he tried to come to terms with Euler’s central objection against monads. In his anonymously published tract against monads, the Gedanken von den Elementen der Ko¨rper (1746), Euler had argued that matter must be inﬁnitely divisible because it is in an inﬁnitely divisible space, which effectively rules out the existence of monads. That bodies are composites does not entail that they must be composed of simple parts such as monads.28 Kant’s argument for his metaphysical cornerstone was intended to head off Euler’s objection, but for all practical purposes it remained unsuccessful. For one thing, by taking for granted that bodies have independently existing parts, Kant begged the question. This premise allowed him to identify the composition of parts into a body as a relational, contingent property, but only by presupposing what needs to be proven. Furthermore, by demonstrating, against Euler, the existence of monads from the fact of composition, Kant could not avoid confounding two different meanings of the term.29 Having initially characterized composition as interconnectedness (as an attribute of the body consisting in the interrelatedness of its parts), he went on to state that particles existing outside of this composition have no composition, characterizing composition as divisibility (as an attribute of the parts). Because Kant wrongly equated the interconnectedness of the parts of a body with the divisibility of the parts themselves, the conclusion, that the parts are simple, does not follow. At best, we can say that Kant took in the Physical Monadology the existence of simple parts to be axiomatic.30 The geometric cornerstone of the physical monadology is the theorem that space is inﬁnitely divisible (prop. 3). Kant furnished two slightly different versions of the same geometric demonstration and acknowledged that this proof has been employed by many physicists (I 478:35–36).31 Kant employed the proof, which had been ﬁrst introduced by Jacques Rohault, in order to show the inﬁnite divisibility of space. The proof, as Kant used it, can be

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summarized thus: Suppose there are two parallel lines l1 and l2, and a third line that intersects them at right angle in the points a on l1 and b on l2. Suppose further that there is a point c on l1 and another point d on l2 such that a line cd intersects line ab at point x. The greater the distance between b and d on l2, the closer x will be to a. If the distance between b and d on l2 is inﬁnite, then x will be inﬁnitely close to a, which means that the line cd intersects line ab inﬁnitely close to a. Hence, a line on a geometric plane is inﬁnitely divisible, and therefore, geometric space is inﬁnitely divisible. Because space is inﬁnitely divisible, its division will never arrive at an indivisible end-point. This is true of any composite structured in this manner, and accordingly Kant asserted that an inﬁnitely divisible composite does not consist of simple parts (prop. 4). How can such a continuum be ﬁlled? Monads ﬁll space, Kant claimed (prop. 5), but they do so differently than one might assume. Our common understanding of a particle ﬁlling space is the straightforward conception of the atomists: an extended composite consists of smaller extended components, and these smaller components ﬁll space by their extended solidity. They literally occupy a space. Kant granted the Cartesian argument that such corpuscles are impossible if they are to be conceived as indivisible atoms. If they occupied space, they could be separated further. Hence, if monads ﬁll space, they will not do so in a straightforward corpuscular fashion; they do not occupy space by a plurality of parts. Moreover, since both geometry and metaphysics are right in their basic claims that space is inﬁnitely divisible while monads are not, it cannot be that indivisible monads literally ﬁlled an inﬁnitely divisible space. Monads are pointal entities; they have zero size, and thus there is an important sense in which monads do not ﬁll space. Yet monads are the simple substances of material things. How is this possible? It is important to see that Kant thought that there are two ways a body can ﬁll space: by the ‘‘plurality of its parts’’ and by exerting a force. Monads do not ﬁll space in the ﬁrst way, but they do so in the second way. Kant declared monads determine space through the spheres of their activity (sphaerae activitatum) (I 481:36–39). Monads ‘‘ﬁll’’ space by exerting a repulsive force that acts at a distance to prevent any other body from approaching beyond a certain boundary. The space determined by the monad through its sphere of activity is the circumference of its outer presence. These spheres of activity or monadic force ﬁelds are, in Kant’s words, the extensive magnitudes (quantitates extensivae) of the monads. Kant thought that he could kill two birds with one stone: have the monads occupy space as the simple elements of extended matter, and let the monads remain indivisible. Monads ﬁll the spatially extended matter through their force ﬁelds. A physical line involves an inﬁnite number of spatial intervals, but it comprises only a ﬁnite number of monads, for each of the line’s monads occupies a deﬁnite place through their spheres of activity. These ﬁnitely many monads are not divisible any further. Monads could be divisible if they involved either a plurality of parts or a plurality of essential properties. However, because the monad’s force ﬁeld radiates from the monad

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and therefore surrounds it instead of dwelling inside it, the force ﬁeld is not a part of the monad. Hence, the monad does not involve a plurality of parts and is accordingly not subject to a division of this sort. Furthermore, because the monad’s force ﬁeld is the extensive magnitude of the monad and the outer determination of the pointal entity at its center, the force ﬁeld is an accidental property of the monad (I 482:2–3). Hence, the monad does not involve a plurality of essential properties and is not subject of a division of that kind either. The account of the monad’s force ﬁeld was burdened by a greater problem with divisibility than Kant realized. He maintained that it is impossible to break a monad into two. Because the extensive magnitude belongs to the monad and is sustained by it, it is equally impossible to subject the extensive magnitude of the monad to division. The ‘‘space’’ the monad occupies might be geometrically bisectable, but that the extensive magnitude of the monad itself should be divided into two, separably movable, and mutually repelling spheres cannot be. Nonetheless, the sphere of activity of the monad is an extensive magnitude in a literal sense: it has extension. Hence, it must be subject to division, despite Kant’s remarks to the contrary. The force ﬁeld is spatially describable in a literal way: it has a center, it has a threedimensional volume, and it has an external, shell-like boundary. These properties of the force ﬁeld are the spatial segments of the monad’s extensive magnitude. This entails that the monad is naturally divisible.32 The argument that the monad could not be divided because the force ﬁeld was neither a literal part nor an essential property begged the question. Kant’s problem was that the sphere of activity can be sliced up into smaller segments simply because the sphere of activity is an extensive magnitude. Later, in the Metaphysical Foundations of Natural Science, Kant would take repulsive force to act only in contact and so from every point within the volume of a body (IV 499, 511–512). There, he would also identify the problem of his earlier view (IV 521–523) and assert that matter (not just space!) ‘‘is divisible to inﬁnity, and indeed into parts each of which is again matter’’ (Ellington, p. 49; IV 503). Kant’s critical view of repulsion would allow for a division of any given body into smaller spheres and thus avoid the difﬁculty that undermined the conception of the monadic force ﬁeld in the Physical Monadology.33 Space, Kant argued, is linked with substance via force. The sphaera activitatis is the dynamic link between the unextended monad and the extension of space. A monad ﬁlls space through its impenetrability—in fact, this is the only way a thing can genuinely ﬁll space (a brick ﬁlls space because of its impenetrability, but a ghost does not). Other monads cannot vie for the space which a particular monad occupies because the monad has a resistance (renitentia) to others (I 482:4–15). Impenetrability results from resistance, and resistance is a force. As Kant saw it, monads in contact with each other exert their forces of impenetrability on each other (I 483:11–12). Contact consists of the reciprocal affection of force. In Kant’s view, contact does not require material solidity and touch, as the Cartesian mechanics presupposed.

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Instead, contact requires forces. Impenetrability means that one substance repels another. Hence, impenetrability is analyzable in terms of the force of repulsion; the vis impenetrabilis is the vis repulsiva (I 484:1). But this force alone cannot explain how monads can cohere to form a body, Kant thought. Thus, a second force is necessary, a force of attraction that keeps repulsion at bay and allows a dynamic equilibrium. The two forces of attraction and repulsion are fundamental to Kant’s theory. Not only do they govern the intermonadic relations, but they also circumscribe the sphere of the monad. Repulsion and attraction determine the volume of a monad and the limit of its extension (I 483:31–33). Attraction controls repulsion for the sake of the possibility of the intermonadic relationships that ensure the composition of material bodies. Therefore, attraction is stronger than repulsion. But to some extent, repulsion must overcome attraction for the sake of preserving the impenetrability of the individual monads. Therefore, repulsion is stronger than attraction. Kant could allow both inferences because he argued that the quantities of the two forces decrease at different rates. Newton had demonstrated with the inversesquare law that attraction decreases with the square of the distance. In Kant’s account, attraction overcomes repulsion over the distances involved in the intermonadic relationships, and the rate of decrease of the attractive force must accordingly be smaller than the rate of decrease of the repulsive force. Because spherical spaces are in proportion to the cube of their radii (and also because, as he put it, the ‘‘force diffused throughout a larger sphere is diminished in a ratio which is the inverse of the volume of their spaces’’; WM 62, I 484:30–31), Kant stipulated that repulsion decreases with the cube of the distance (I 484:32–33). Both forces radiate from the monadic center in all directions. The impenetrability of the monad indicates that repulsion is stronger than attraction at the center. The cohesion of monads with each other indicates that attraction is stronger than repulsion somewhat farther away. Since the stronger repulsion diminishes quicker than the weaker attraction, repulsion and attraction are equal at a certain distance from the center. The balance of the two forces at this distance constitutes the limit of the monad’s impenetrability and determines the spatial extension of the dynamic sphere of the monad (I 484:40–485:1–4). Force was Kant’s key to the presumed solution of the problem of inﬁnite divisibility. Space is inﬁnitely divisible. The monad is not, yet it ﬁlls space because its dynamic sphere of activity determines its extension. The matter of a body becomes a grid of equidistant monadic force-centers that cohere to a body through their repulsive and attractive forces. Although Kant’s solution of the problem of material composition failed because of the aforementioned difﬁculties, the characterization of attractive and repulsive forces remains interesting. The way Kant explicated the relation of force and substance makes one wonder whatever had happened to the living forces. If there was a subject-matter that positively cried out for the reintroduction of vis viva, then this was it. Yet, the term was not even

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mentioned in the Physical Monadology. Living forces and the issues that surround them, such as the conservation of force in kinematic situations, had completely dropped out of the picture. By 1756, the fundamental force of the monadic substances was not vis viva anymore. Vis repulsiva and vis attractiva had taken its position. Although the discussions in the True Estimation of Living Forces had prepared the ground for the precritical project, they had done so only negatively: the tract had been full of problems, and these problems needed to be solved. Because they had concerned the fundamental assumptions of Kant’s ﬁrst book, the renewed attempt at solving these problems proceeded from entirely different presuppositions. As the Physical Monadology highlights Kant’s intellectual distance in the 1750s from his ﬁrst false start, so does it illustrate the importance of his Newtonian conversion. Kant had applied Newtonian concepts to the macrostructure of the world in the Universal Natural History. Now, in the Physical Monadology, he applied them to the microstructure of nature. Furthermore, this dissertation was not just about microphysics, but rather about the intended merger of scientiﬁc and metaphysical perspectives. In this regard, the Physical Monadology serves as a beautiful illustration of the continuing precritical project. Here, Kant connected Newtonian concepts to a Leibnizian theory. The merger of Newton’s forces and Leibniz’s monads was supposed to answer a central question of philosophy of nature—the question of the composition of matter. Because Kant would never waver from his conversion to Newton, it is not surprising to ﬁnd parallels between his discussion of the material microstructure in 1756 and his return to these issues in 1786. In the Metaphysical Foundations of Natural Science, Kant would continue to defend his thesis of a fundamental force pair of attraction and repulsion, arguing that both jointly determine the existence of matter (IV 508–509). His arguments for the necessity of both forces recapitulated claims of the Physical Monadology—if there was only attractive force, matter would coalesce to a mathematical point and space would be empty (IV 511), and if there was only repulsive force, matter would disperse itself to inﬁnity (IV 508). There is a dynamic balance between these two forces determined by their speciﬁc rates of decrease (IV 522).34 After the characterization of the forces of attraction and repulsion, Kant concerned himself in the Physical Monadology with inertia. He asserted that it has a deﬁnite quantity in each monad (I 485:15–16). Obviously, the inertia of a body is the sum of the inertial forces of its constitutive monads. Since the mass of a body can differ (two bodies of the same volume can have different masses), he supposed that the inertial forces of the monads can differ as well: not only do monads have deﬁnite quantities of inertia, but they also possess distinct quantities of inertia. The difference in monadic inertia determines the different speciﬁc densities of bodies (I 486:5–7). Inertia, for Kant, is a moving force (vis motrix; I 485:28). Does the characterization of inertia as a moving force mean that there are three instead of two fundamental forces—that there are not just attraction and repulsion, but attraction, repulsion, and inertia? Whereas impen-

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etrability and universal gravitation are reducible to either repulsion or attraction, inertia is distinct from either. The oddities surrounding the status of inertia can be traced back to Newton. In the Principia, Newton had deﬁned inertia as a materiae vis insita, as an innate force of matter (def. 3, K 1:40; M 1:2). But right after this deﬁnition, Newton had remarked that inertia differed from the inactivity of mass only in our manner of conceiving it (ibid.).35 That Kant called inertia as a vis motrix is at variance with his earlier claims in the Universal Natural History that there are two forces (I 243–5).36 There is nothing wrong with saying that inertia is just another expression of the monad, but for the sake of consistency, it would have been better to characterize these expressions as attractive and repulsive forces, and as mass, whose property is inertia. Perhaps Kant’s talk about inertia as a force was just in deference to a terminological convention, and its signiﬁcance should not be overstated. In any event, not long after the Physical Monadology, Kant abandoned this conventional conception of inertia. In Motion and Rest (1758), he returned to the original pair of primitive forces and rejected the characterization of inertia as a force (II 19–21).37 As a conclusion to his treatise, Kant stated that monads have a perfectly elastic force and constitute an original elastic medium (I 486:36–38). Since forces have a certain degree of intensity, the force of one monad can temporarily overcome the repulsive force of another and penetrate into its sphere of activity (I 487:1–5). Because the repulsive force of a monad is inﬁnitely large at the center, the sphere of activity can never be completely penetrated. Monads can be squeezed together, but they cannot be crushed. If the foreign force ceases, the sphere of activity will rebound. This solves the puzzle of the ether. In On Fire, Kant had tried to account for combustion and chemical transformation with a theory that merged atom and ether (I 372). But he had not gotten very far with it. On Fire had ascribed a versatility to the ether that remained implausible for lack of further explanation: its cohesion causes the attraction of particles and the solidity of bodies (I 373); its vibrations propagate heat, ﬁre, and light (I 376–7); and its elastic mediation of the atomistic corpuscles is the reason for the mechanics of ﬂuids (I 372). The problem with On Fire was that the ether appeared there next to mass and force as a mysterious new category that could neither be veriﬁed nor pinned down. In the Physical Monadology, Kant lifted the mystery of the ether. The ether was revealed as a determinate and derivative manifestation of the elementary attractive and repulsive forces.

7.3 The Joint Use of Metaphysics and Science Kant wanted to show with the Physical Monadology that the problem of inﬁnite divisibility was solvable. A simple substance may be an indivisible point-entity, but its forces can still structure space, determine a dynamic sphere, and thus make the monad an ultimate physical component of matter. He intended to save the belief that a body consists of simple parts by constructing a dynamic theory of matter. As a result, the topic of the Physical

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Monadology was anything but an arcane scholastic puzzle. By trying to explain the composition of matter, he wrestled with the question of how forces and matter form the grid of the universe. The Universal Natural History had only scratched the surface of this question. There, Kant had merely assumed that matter is active, without elucidating it further (I 226–8, 263–4). This was the basis of Kant’s teleological constructions and cosmological speculations. As the explanation of this central assumption, the Physical Monadology joined the New Elucidation as the theoretical underpinning of the Universal Natural History. Both of Kant’s previous works had focused on certain well-deﬁned segments of nature—the Universal Natural History on nature’s macroscopic cosmic constitution, and the New Elucidation on nature’s fundamental ontological structure. To proceed with the construction of a comprehensive model of nature, Kant had to engineer a bridge that joined the topics of his previous inquiries. He needed to connect the purposive and physical development of the cosmos with the formal structures of causal processes. By explaining the cosmogonical assumption that matter is active, Kant intended to demonstrate how attractive and repulsive forces govern all of nature (the macrocosm as well as the microcosm). Having shown in the Universal Natural History how attraction and repulsion organize celestial objects, solar systems, and galaxies, he wanted to show with the Physical Monadology how attraction and repulsion shape bodies and determine space. That attraction and repulsion manage to have these effects in Kant’s account evokes the principles of succession and coexistence of the New Elucidation. According to these principles, substances are subject to processes and stand in a community of interactive reciprocity. The New Elucidation had provided an analysis of interaction only in the abstract. To become relevant for a philosophy of nature, this analysis needed to be translated into the concrete. The Physical Monadology ﬂeshed out the abstract community of reciprocally interacting substances as the physical community of monads that constitute material bodies through their interactive forces. Physical monads were the link between cosmos and causality. The bridge spanning the teleological-cosmological unfolding and the set of ontological laws was the dynamic microstructure of nature. The theory of active matter of the Physical Monadology allowed one to travel in Kant’s precritical philosophy from cosmogony to ontology and back, and because of the unifying function of this theory, the Universal Natural History and the New Eludication had become parts of an emerging system. Kant’s precritical project involved two levels, the one being the construction of the system of nature, the other being the synthesis of the vantage points of natural science and metaphysics. The Physical Monadology was important for the precritical project on both counts. On the systematic level, the resolution of the puzzle of the composition of matter became the link that coupled the previous investigations of nature together. On the synthetic level, the full title of the work, The Joint Use of Metaphysics and Geometry in Natural Philosophy, the First Example of which Contains the Physical Monadol-

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ogy, revealed already the relevance of the treatise. The physical monadology was merely an example to illustrate a more general point. Not only is it feasible to reconcile natural science and metaphysics, but it is also useful— we should reconcile the two perspectives if we wish to make any progress in the investigation of nature and if we hope to solve as yet intractable problems. A joint use of science and metaphysics will explain the constitution of matter, the existence of simple substances, the phenomenon of elasticity, and the hypothesis of the ether. Not bad for a sixteen-page tract! ‘‘Metaphysics’’ and ‘‘geometry’’ represent the two opposing vantage points in the philosophy of nature. Metaphysics is the philosophical inquiry into causes, the qualitative endeavor of understanding the structure of the world. Geometry is part of mathematics which, in turn, is essential to the scientiﬁc description of events and the laws that govern them. In the preface to the Physical Monadology, Kant wrote: Clear-headed philosophers, who seriously engage in the investigations of nature, unanimously agree, indeed, that punctilious care must be taken lest anything concocted with rashness or with a certain arbitrariness of conjecture should insinuate itself into natural science, or lest anything be vainly undertaken in it without the support of experience and without the mediation of geometry. . . . And certainly, if we follow this sound path, we can exhibit the laws of nature though not the origin and causes of these laws. For those who only hunt out the phenomena of nature are always that far removed from the deeper understanding of the ﬁrst causes. Nor will they ever attain knowledge of the nature itself of bodies, any more than those who persuade themselves that, by climbing higher and higher up the pinnacles of a mountain they will at last be able to reach out and touch the heavens with their hands. Metaphysics, therefore, which many say may be properly absent from physics is, in fact, its only support; it alone provides illumination. (WM 51; I 475:2–6, 12– 19)

Scientiﬁc investigations can identify laws of nature through geometry and experience but cannot determine their causes. The consensus which Kant described, that conjectures have no place in natural science, was the legacy of Newton’s famous dictum, hypotheses non ﬁngo, I feign no hypotheses.38 That one should not endeavor anything without the support of observation mirrors his fourth rule of reasoning in philosophy.39 That one should not endeavor anything without the mediation of ‘‘geometry’’ reﬂects Newton’s approach in general.40 After all, the Principia were the Principia mathematica of natural philosophy, and Newton’s inital deﬁnitions of the quantity of matter (def. 1, K 1:39, M 1:1), the quantity of motion (def. 2, K 1:40, M 1: 1), and the quantities of force (defs. 6–8, K 1:43–4, M 1:4) had set the tone for subsequent investigation. Newton would have emphatically agreed with the self-imposed limitation of natural science that Kant observed. Newton had spelled out the limitation in a polemic against Leibniz, the Account of the Book Entituled Commercium Epistolicum (1714/5): philosophers are to argue ‘‘from Phaenomena and Experiments to the Causes thereof, and thence to the Causes of those Causes,’’ but the causal investigation goes only so far

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as the empirical data allows because ‘‘it is not the Business of Experimental Philosophy to teach the Causes of things any further than they can be proved by Experiments.’’41 While Kant’s sketch of natural science reﬂected Newton’s own position, his conception of metaphysics followed Leibniz. In a letter to the Countess Elisabeth (1678), Leibniz had likened metaphysics to logic in being an ‘‘art d’inventer’’ and to theology in being a ‘‘theologie naturelle’’ (G 4:292). As both an art of invention and as a natural theology, metaphysics is a nonempirical and rational ﬁeld of investigation. In the essay On Body and Force: Against the Cartesians (editor’s title, 1702), Leibniz had identiﬁed the subjectmatter of metaphysical investigation as a concern with cause and effect (G 4:395; AG 252)—a deﬁnition he had repeated in the third letter to Samuel Clarke (1715; G 7:363, #7). In the Principes de la nature et de la Grace (1714), he had portrayed metaphysics as the domain of ‘‘why’’ questions (G 4:602, #7). For both Leibniz and Kant, metaphysics was the nonempirical and rational investigation into the underlying causes of nature. However, as much as Newton and Leibniz would have endorsed Kant’s respective characterizations of natural science and metaphysics, they would have had little tolerance for Kant’s vision of reconciling them. That Kant so easily distinguished scientia naturalis (I 475:4–5) from metaphysics would have probably troubled Leibniz’s self-described followers. If physics is a natural science, what will this make metaphysics? Does this mean that metaphysics is not a science? Surely, it must be the rational science that meets physics on equal terms! But Kant just referred to it as a philosophia transcendentalis (I 475:23–24). Metaphysics is a transcendental philosophy. ‘‘Science’’ is a title reserved for physics. As the next batch of Kant’s philosophical productions will forcefully illustrate, this choice of words is not coincidental. By comparison, Baumgarten deﬁned metaphysics as the science of the ﬁrst principles in human knowledge (Metaphysica, #1, p. 1) and identiﬁed the branches of metaphysics—ontology, cosmology, psychology, and natural theology—as sciences in their own right (cf. ibid., #4, p. 2; #351, p. 110; #501, p. 173; #800, p. 329). On the other hand, Kant’s conviction that metaphysics alone provided illumination to physics (I 475:18–19) would have provoked the natural scientists, and it would have been anathema particularly to Newton. The man who declared not to feign hypotheses had no patience with those who did. Referring to himself in the third person, Newton added a ﬁnal word to the Account of the Book Entituled Commercium Epistolicum that quivered with indignation:42 And after all this, one would wonder that Mr. Newton should be reﬂected upon for not explaining the Causes of Gravity and other Attractions by Hypotheses; as if it were a Crime to content himself with Certainties and let Uncertainties alone. (313/223)

Comparing himself, as a scientist, to Leibniz, Newton had nothing nice to say about his rival:

178 The 1750s: The Precritical Project [T]he one [Newton] proceeds upon the Evidence arising from Experiments and Phaenomena, and stops where such Evidence is wanting; the other [Leibniz] is taken up with Hypotheses, and propounds them, not to be examined by Experiments, but to be believed without Examination. (314/224)

For Newton, the extent of observation had determined the extent of legitimate causal investigations. Since metaphysics in Leibniz’s description had been a causal investigation beyond the reach of observation, metaphysics was for Newton nothing but untested and untestable speculation. Kant disagreed. In his view, the conservative limitation of natural science is also the reason why Newton’s approach alone was insufﬁcient to describe the structure of nature, and why a more daring metaphysical investigation into the underlying causes is necessary. In response to Newton’s limitation of natural science to geometry and observation, Kant remarked in the preface to the Physical Monadology: Certainly, nothing can be thought more useful to philosophy, or more beneﬁcial to it, than this counsel. However, hardly any mortal can advance with a ﬁrm step along the straight line of truth without here and there turning aside in one direction or another. For this reason there have been some who have observed this law to such a degree that, in searching out the truth, they have not ventured to commit themselves to the deep sea but have considered it better to hug the coast, only admitting what is immediately revealed by the testimony of the senses. (WM 51; I 475)

Kant left the shoreline of natural science behind and set sail to head out into the ocean of metaphysics. The Physical Monadology was the keystone to the ediﬁce of the precritical project erected in the 1750s. In the following decade, Kant would write two more works devoted to his project, the Only Possible Argument, in which he would argue for God’s existence for both physical and metaphysical reasons, and the Prize Essay, in which he would construct one uniﬁed methodology for physical and metaphysical investigations. But in a sense, the Physical Monadology represents already a closure of sorts. Now, despite the various problems and inconsistencies that ailed it, the system of nature was complete. Subsequent additions concerned God and method, issues that were outside and beyond the system. Furthermore, the Physical Monadology was the last work in Kant’s life that revealed him inspired by a metaphysical exuberance. The 1750s, when he found Newton and created his philosophy of nature, was a time of great optimism. This would change forever with the next decade. The difﬁculties that had been glossed over in the previous tracts would catch up with him. Kant realized in retrospect that some of his earlier arguments, so easily advanced, presupposed claims whose demonstration would be arduous at best and hopeless at worst. The encounter with David Hume did not help. In 1759, Kant exchanged several letters with his former friend, Johann Georg Hamann, the author of the Socratic Memorabilia (1759), and tried to win him back to

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reason after the latter had become obsessively religious. Hamann directed Kant’s attention to Hume, the ‘‘Attic philosopher’’ (X 15). Although it would take still many years before the Scottish sceptic awakened him from his dogmatic slumber, Kant’s sleep had become restless almost immediately. The Only Possible Argument (1763), which is in many respects the most ambitious of Kant’s metaphysical works, is also the onset of the crisis. It contains a strange, dark echo of the metaphor of a sea voyage that Kant employed in the beginning of the Physical Monadology. Now, metaphysics had become a ‘‘bleak ocean without shore and lighthouses,’’ and on his voyage through uncharted waters, Kant had become a sailor afraid to get lost, in need of checks at every landfall, in order to ﬁnd out whether hidden currents had diverted his course (II 66).

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III

THE

1760S

-0 CLIMAX AND CRISIS

I have the fate to be in love with metaphysics, although I can hardly ﬂatter myself to have received favors from her. Kant Dreams of a Spirit-Seer (1766) II 367 A certain Mr Schredenberg in Stockholm, who performs miraculous things that are most unbelievable in our sceptical age, and who wrote eight volumes full of nonsense that he calls Arcana coelestia, is the spiritseer, whose fantasies Mr Kant sought to illuminate through metaphysical hypotheses that Kant calls Dreams. The witty profundity that the little work is written with occasionally leaves the reader in doubt about whether Mr Kant wished to ridicule metaphysics or whether he intended to praise clairvoyance. Yet it contains important reﬂections, some innovative thoughts on the nature of the soul, as well as several objections to popular systems that would merit a more serious presentation. Mendelssohn Review of Dreams of a Spirit-Seer (1767)

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E I G H T

The Only Possible Argument The Culmination of the Precritical Project

-0

8.1 Steps on the Way: From 1757 to 1762 Kant’s philosophical activity reached its ﬁrst peak in the inspired years of 1754 to 1756. He composed little in the six years that followed. But by the year 1762, he was working simultaneously on several manuscripts. The renewed productivity would last until 1766. Thus, we ﬁnd in Kant’s intellectual evolution two periods of intense effort, one in the 1750s, and the other in the 1760s. Each phase involved dramatic developments. The ﬁrst period of activity (1754–1756), initiated by the sudden and vehement conversion to Newtonianism, had marked the promising beginning of the precritical project. Kant had discovered a philosophical framework in which the general application of the ideal of the Living Forces, the synthesis of scientiﬁcquantitative and metaphysical-qualitative perspectives, ﬁnally seemed possible. In the second period of activity (1762–1766), he completed the remaining tasks posed by the precritical project, but instead of being satisﬁed with his achievements, he was tormented by self-doubt until he decided to destroy everything. The harvest of the 1750s had been a model of nature harmonizing metaphysical assumptions with Newtonian science. In his second period of activity, in the 1760s, Kant turned to second-order questions. He felt that he needed to show how this model of nature related to God, and how the 183

184 The 1760s: Climax and Crisis

investigations that grounded the model could achieve certainty. With the Only Possible Argument (1763), he tried to meet the ﬁrst demand by constructing a rational theology. With the Prize Essay (1764), he hoped to perform the second task by proposing a new investigative program. During all these years, he was living a regular and peaceful existence as the Herr Magister in homely Ko¨nigsberg. But this tranquil, friendly, and uneventful life was only the public surface; underneath and in private, Kant was ﬁghting a losing battle against wrenching questions. While he struggled with the challenges of supplementing the precritical project theologically and methodologically, he began to have second thoughts. In the 1750s, he had constructed several key segments of the future uniﬁed philosophy of nature— the cosmological expansion of Newtonian physics, the ontological foundation of freedom and necessity, and the dynamic microstructure of reality. In the 1760s, he added two more parts to the envisioned whole—a bridge from nature to God, and a Newtonian methodology reconciling the strategies of metaphysics and science. All of these ventures were daring and bold. But as the 1760s proceeded, Kant started to have misgivings about their worth. He discovered ﬂaws in the theories advanced earlier that were marring their integrity and weakened their explanatory power. He also began to proceed with a hesitant, circumspect caution in the investigations that were his current concern—a caution that had not been visible in the previous years. In the mid-1760s, Kant’s growing doubts about the precritical project came out into the open. He published a treatise, the Dreams of a Spirit-Seer (1766), which was intended as a satire on the exploits of a clairvoyant. Evidently aimed at an easy target, the mockery was not terribly interesting in itself. But the ridicule backﬁred: while deconstructing the clairvoyant’s visions, Kant realized that his own exploits had not been much better. Was there really anthing that clearly distinguished his own speculations from fantasy? Unable to give a convincing answer, he admitted defeat. The precritical project fell apart, and Kant abandoned the grand plan of a uniﬁed philosophy of nature. In the four years that followed the crisis marked by the Dreams, Kant wrote little. A short essay on the Directions in Space (1768), in which he broke for good with a Leibnizian conception of relative space, was the only work that he published during this time. Eventually, he picked up the pieces and moved into a different direction. If metaphysics and science cannot be married through a uniﬁed philosophy of nature, then so be it. Apparently, it is better to consider reality as comprising two incommensurable spheres— a ‘‘sensible world’’ described by natural science, and an ‘‘intelligible world’’ explored by metaphysics. This move, made in Concerning the Forms and Principles of the Sensible and Intelligible World (1770), a treatise usually known as the Inaugural Dissertation, was Kant’s ﬁrst big step toward the critical philosophy. Thus, after the collapse of the precritical project, he embarked with the Inaugural Dissertation on the path that would lead to the Critique of Pure Reason.

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Since 1755, Kant had been teaching at the Herzog Albrecht University in Ko¨nigsberg. In 1765, he was able to reduce his course load because he had found a full-time job as a librarian, and in 1770, he secured the desired professorship in logic and metaphysics.1 The outward circumstances of Kant’s life during these years are quickly told. The Seven Years War, which had started in 1756, had initially not gone too well for the Prussian state. By 1757, the armies of Frederick the Great were on the retreat. The Austrians and French were pushing north into Saxony, the Swedes had conquered Pomerania, and the tsarina’s forces were marching through East Prussia. Ko¨nigsberg never became a battleground, but it ended up as a spoil of war. The university fell under military jurisdiction, and the academic affairs were administered by a Russian ofﬁcer, Lt.-General Nicolaus von Korff. The Russians were by and large friendly, the change of the local government was a peaceful transition, and Kant minded his own business. Semester after semester, he offered a variety of philosophy classes which were well attended and popular. Kant lived and lectured in the house of Professor Kypke, an older colleague and friend. In 1758, Kypke died, which made his professorship for metaphysics and logic available. Kant applied for the vacant position with a missive to the Russian empress Elisabeth, indicating his interest, emphasizing his competence, and closing with a prostration: ‘‘I am dying of deepest devotion: your honorable imperial majesty’s most extremely subservient servant Immanuel Kant.’’2 Yet he was turned down as he had been in 1756, when he had hoped to be considered for the late Martin Knutzen’s position. Another privatdozent, a certain Buck, had seniority in the department and was awarded Kypke’s former post. Kant’s daily grind as an untenured teacher continued. From 1756, Kant’s philosophical productivity had been on the wane, and the six years that followed the inspired period in the mid-1750s were largely a dry spell. Burdened by the yoke of his teaching commitments, he was able to bring merely three small lecture advertisements to the printer: the West Winds argument, the Motion and Rest paper, and the Optimism essay. A necrologue on a deceased student, the Thoughts on the Premature Death of Johann Friedrich von Funk, followed in 1760. Then the trickle of writings dried up until 1762. The ﬁrst of the three lecture advertisements announced a course in physical geography. Its appendix concerned the question of the title, Whether the West Winds in Our Regions Are Humid because They Have Traversed a Great Sea (1757).3 Kant’s earlier Theory of Winds (1756) contained an essentially correct explanation of the trade and passat winds through the axial rotation of the earth. By comparison to the Theory of the Winds, the West Winds essay was a failure. Kant was not aware of the actual causes of evaporation from the oceans and moisture absorption of the atmosphere, and he did not know that humidity levels in the air depended on air temperature and pressure. He doubted that winds pick up moisture whenever they traverse oceans (II 12) and mistakenly assumed that the humidity of the air depends on the

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wind direction such that westerly sea winds are humid while easterly sea winds are dry (II 11). The second advertisement was the New Theory of Motion and Rest (1758). In contrast to the West Winds advertisement, this was a rich essay and full of interesting ideas. Kant’s reﬂections involved the principle of continuity, the law of inertia, and the conception of space. In respect to each theme, Motion and Rest marked a further development of Kant’s thoughts. He had employed the principle of continuity in the Living Forces in order to unify quantitative (Cartesian) and qualitative (Leibnizian) approaches to force. There, he had argued that the principle of continuity, if used to derive force mathematically, would preclude the possibility of two distinct quantities because a continuous dynamic spectrum holds between a body at rest and a body in motion such that the conditions of the latter are reducible to the conditions of the former (I 33–40). He had furthermore argued that the same principle, taken in its metaphysical sense, would establish two distinct qualities of force (vis viva and vis mortua) as the boundary conditions of the process of ‘‘viviﬁcation’’ (I 145–146). With Motion and Rest, Kant dismissed all of this as misguided speculation. The principle of continuity, he now asserted, was a ‘‘helpful hypothesis,’’ but, as a hypothesis, it was an assumption, not a principle, and thus an ‘‘arbitrary law’’ (II 21). Continuity is only relevant within the limits of logic, but it cannot be applied to physical issues. Its earlier application to physics had rested on an essential distinction between motion and rest such that motion, but not rest, required for its preservation the incessant activity of a ‘‘living’’ force. But because what counts as motion or rest actually depends on the inertial frame selected, a modern, Newtonian perspective eliminates their absolute distinction and thus the application of continuity presupposing it (II 23–25). In fact, Motion and Rest contained Kant’s ﬁrst correct interpretations of the principle of inertia. Although the Newtonian conversion that occurred with the Spin Cycle essay (1754) was a comparatively sudden event, the full comprehension of the implications of this conversion would take considerably longer. Before the conversion, Kant had supposed that the ‘‘intension’’ that conserves the free motion of a body is a constantly acting force measurable by the body’s velocity (I 141–144). After the conversion, in the Spin Cycle essay, he realized that free motion is a state, just like rest is, and does not require a constantly acting force.4 Two years later, in the Physical Monadology (1756), he would think of the inertial force as a force of nature or a vis motrix, and he would come to understand that inertia is measurable by mass, not velocity (I 485). In Motion and Rest, ﬁnally, he recognized that there is no empirical proof for inertia as a ‘‘force’’ of nature. Rather, inertia, like gravitational force, is a shorthand expression of an empirical law whose cause is unknown and should accordingly not be stipulated (II 20). With these three consecutive steps (motion is a state, inertia is measurable by mass, and the law of inertia refers to an empirical phenomenon not to an essential force), Kant arrived at the modern notion of inertia.

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Motion and Rest raised the question of the connection between inertia and absolute space. Kant maintained in this paper that motion and rest can only be understood in relation to one another (II 16–17). Absolute motion is impossible. Although he did not explicitly deny absolute space, his categorical rejection of absolute motion seemed to imply it. In the New Elucidation (1755), Kant had accepted the Leibnizian idea that space is a relational network while at the same time insisting that these relations are fundamentally, and not merely phenomenally, real (I 414). In the Physical Monadology, he had thus been able to accept a geometric space that can exist independently of matter, such that gravitational forces may act through a void (I 475). The fruit of these investigations had been that he could entertain an ‘‘absolute’’ space in the sense of a substantive space—that is, that space exists independent of extended objects and their spatial relations. What had remained open was the question of whether such space is absolute in Newton’s speciﬁc sense, such that it exists as an independent and privileged inertial frame. Motion and Rest is an answer to this question: space is substantive and thus not merely a Leibnizian, relational construct, but it does not exist as a privileged frame of reference. Motion and rest are intelligible only in relation to other objects, none of which can be identiﬁed as being truly immovable. But if absolute space has to be ruled out as a privileged frame of reference, and if we can perceive only relative motions, what can tell us that inertial motions, speciﬁed as uniform and rectilinear motions, really exist? If some inertial motions are uniform and rectilinear, what will they refer to? Newtonian inertia, it seems, calls for Newton’s absolute space. In a later text, Concerning the Ultimate Foundation of the Distinction of Directions in Space (1768), Kant would realize, albeit for a different reason, that absolute space should not be thrown out.5 In that paper, composed after the Dreams of a Spirit-Seer and before the Inaugural Dissertation, he would argue that the positions of spatial parts that are related to each other presuppose a spatial continuum (Gegend) according to which their places are ordered (II 377). The spatial continuum consists of the relation of this system of places to an ‘‘absolute space’’ (ibid.). It needs to be shown that absolute space possesses an autonomous reality, independent of the being of all matter, and as the ﬁrst ground of the possibility of the composition of matter (II 378). An indication of this autonomous reality of absolute space, Kant believed, can be found in the fact that bodies have their own internal order in a three-dimensional continuum. Two bodies may be entirely equal in terms of extension, proportion, and position of their parts, and still differ as regards the directionality of the order of parts, as in the case of hair whorls, hands, or snail shells (II 380). If space were relative, consisting only of the relationship of the objects ﬁlling it, then spatial objects similar in size and equal in form (such as a right and left hand) would be congruent. That they exist as incongruent counterparts instead indicates that directionality is a fundamental quality of space. Directionality cannot be explained through the relation and position of the parts of an object, but only through the

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relation of the parts to a general absolute space (II 382–383). It is not the relations of objects that makes space possible; space makes possible the relations of objects. Although absolute space is not an empirical object, it is a fundamental concept that grounds all empirical sensation (II 383). Kant would conclude in the Directions in Space that the existence of incongruent counterparts entails the existence of an absolute space.6 After the scientiﬁc issues of Motion and Rest, Kant returned to metaphysics. The third of the three lecture advertisements was the Attempt at Some Reﬂections on Optimism (1759). In fact, Kant not only reﬂected on the metaphysical optimism contained in Leibniz’s Theodice´e (1710) and in Pope’s Essay of Man (1733–1734), but he also tried to defend it. He maintained that metaphysical optimism follows ‘‘naturally’’ from ‘‘an acceptable’’ conception of God—that God would choose to create only the best of all possible worlds (II 587).7 In the Optimism essay, Kant argued that the sequence of worlds differs from a numerical sequence in that there is not an inﬁnite progression of always better worlds, which would logically rule out ‘‘the’’ best world (II 588). He drew there the conceptual distinction between absolute and relative perfection relevant for his immanent teleology of nature (II 588–589) and established an ontological connection between goodness and reality (II 589– 591). Kant wrote the Optimism essay during the controversy that followed in the wake of the prize question for 1755 of the Prussian Royal Academy which had asked to examine Alexander Pope’s dictum that everything is good.8 Only ﬁve years after its composition, Kant would reject the Optimism essay and his own earlier defense of the Leibnizian conception of evil as the mere absence of good. (The claimed proportionality of reality, relative perfection, and goodness had implied that evil is nothing.) He would maintain in the Negative Quantities (1764) that the quantity of reality is distinct from the level of perfection (II 198), and that evil is not nothing but subsists as a negative quantity, and as such emerges as something substantial (II 182– 183). Around the time of the third lecture advertisement, Kant was thinking of putting together a schoolbook on Newtonian physics, and hoped to enlist his friend Johann Georg Hamann for a collaboration on the project. Hamann, however, was both inebriated by a newfound religiosity and irritated by Kant’s insistence on saving him for the enlightenment. Hamann responded in late 1759 with two sarcastic letters. He ridiculed Kant’s ambition of writing a Kinderphysik (‘‘Children’s Physics’’) and suggested that he base the exposition of physics on the Biblical account of the creation (X 20–23). Recognizing that Hamann had become a hopeless fundamentalist and needed to be written off as a loss for the cause of reason, Kant reacted with frosty silence and dropped the idea.9 Meanwhile, the Seven Years War was drawing to a close. The tsarina Elisabeth died in January 1762, and the tide of war turned. Elisabeth’s nephew, tsar Peter III, mounted the Russian throne and negotiated a rather astonishing peace treaty with Prussia in May 1762. Peter withdrew his sol-

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diers from Ko¨nigsberg as well as from the other conquered territories. In a surprise move, the tsar formed a military alliance with Frederick the Great that pitted the tsarist armies against their former allies.10 Relieved of the pressure in the east, the Prussian government diverted its regiments, thwarted the military campaigns of Austria and France, and victoriously concluded the Seven Years War in February 1763. Parallel to these events, Kant experienced another burst of productivity, and now, his second period of intense activity began. After half a decade of turning out very little (the lecture advertisements and the necrologue had added up to measly thirty-two pages),11 Kant wrote in quick succession two substantial critiques of philosophical logic (False Subtlety and Negative Quantities), a book on rational theology (Only Possible Argument), an important programmatic treatise on the methodology of metaphysics (Prize Essay), and a popular treatise on aesthetics (Observations on the Beautiful and the Sublime). The season of renewed creativity began sometime in spring or summer 1762, when Kant sat down to work on his third book, the Only Possible Argument in Support of a Demonstration of the Existence of God, which was, as the author tells us, ‘‘the fruits of lengthy reﬂection’’ (II 66; WM 112).12 At the end of the summer, his attention was diverted by his discovery of JeanJacques Rousseau (1712–1778), whose name, together with Hume’s, he had ﬁrst encountered in Hamann’s letters in 1759.13 Rousseau had published two of his greatest works in 1762, the Contract social ou principes du droit politique, and L’Emile ou de l’e´ducation. The Social Contract had arrived in Ko¨nigsberg in the same summer; Emile, immediately condemned by the Paris parliament, became available in the East Prussian bookstores a year later.14 These works, as well as the Discours sur les arts et les sciences (1750), which was the prize essay honored by the Academy in Dijon that had established Rousseau’s philosophical reputation, challenged the practical and moral value of theoretical knowledge. Reading Rousseau left a big impression on Kant.15 Rousseau’s doubts of the worth of knowledge, together with Hume’s doubts of its validity, added to Kant’s growing reservations about the LeibnizianWolfﬁan School Philosophy.16 He interrupted his labor on the almost complete manuscript of the Only Possible Argument and composed in October 1762 a critique of the logic of the School Philosophy which he entitled The False Subtlety of the Four Syllogistic Figures. With this essay, Kant launched a volley of arguments against the ediﬁce of logical rationalism, characterizing it as a ‘‘colossus, who hides his head in the clouds of antiquity, and whose feet are feet of clay’’ (II 57; WM 101). While the bookseller Kanter in Ko¨nigsberg was printing in November 1762 the False Subtlety as a tract of thirty-ﬁve pages, Kant returned to the manuscript that had been sitting on his desk and put the ﬁnishing touches on the Only Possible Argument. He rushed through the galleys in a great hurry and brought it in December to the publisher together with an apologetic preface, in which he admitted that ‘‘a variety of commitments’’ had prevented him from devoting the necessary time to the manuscript (II 66; WM 112). The commitment that stood in the way of more extensive revisions

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of the just ﬁnished book was an incident that dated from the previous year. In June 1761, the Berlin Academy had announced a prize question that concerned the certainty of metaphysical demonstrations.17 Such a topic would naturally catch Kant’s fancy; this issue was not only relevant, but indeed central to his general pursuit of the precritical project. What added, in late 1762, urgency to interest was that Kant had now become aware of Rousseau’s and Hume’s sceptical views on the subject. Urged on by their doubts, the certainty of metaphysical demonstrations had become a serious question on a personal level. The deadline for the receipt of submissions was 31 December 1762. Now that the Seven Years War had ended for the citizens of Ko¨nigsberg with the conclusive return of the territory to Prussia in August, and that Kant had delivered the Only Possible Argument to the publisher in December, nothing prevented him from entering the competition in Berlin. He quickly penned his answer to the prize question and entitled it the Inquiry Concerning the Distinctiveness of the Principles of Natural Theology and Morals (known as the Prize Essay, even though it did not win the prize). He completed the text in the nick of time, and it reached Johann Heinrich Samuel Formey, the secretary of the academy on the day of the deadline. When Kant dropped the Prize Essay in the mail, his publisher Kanter had completed the printing of the Only Possible Argument. The book appeared in December 1762 with the imprimatur January 1763.

8.2 The Two Proofs and the Only Possible Argument—or: One ‘‘Beweisgrund,’’ but Two ‘‘Beweise’’ In the Universal Natural History, Kant had argued for the compatibility of the Newtonian model with natural purpose. In the New Elucidation, he had wanted to establish the compatibility of the Newtonian model with moral freedom. In the Physical Monadology, he had defended the thus uniﬁed philosophy of nature by illustrating the merits of combining quantitative and qualitative approaches with a new theory of matter. Kant’s primary focus in the 1750s had been the construction of a system of nature. The notion of God had remained in the background but had been relevant nonetheless. The Universal Natural History presupposed God as the warrant of teleology who ensures nature’s purpose of self-perfection and the unfolding of this purpose through natural laws. The New Elucidation required God as the schema of the interaction of substances. Both of these works involved considerations aimed at establishing God’s existence; the Universal Natural History included scattered remarks that prepared the ground for an argument from design, and the New Elucidation contained an ontological argument in outline form. The Physical Monadology did not explicitly evoke God but tacitly presupposed God as the creator of an interactive and dynamic matter. Although God was present in all of these works in various ways and to varying degrees, the very lack of unity called for another and more focused examination. What was still needed was a sustained and systematic inquiry

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into the very assumption of God’s existence. Above all, this required space, for the strength of any demonstration depends on the conceptual clariﬁcation of its terms and the logical precision of its steps. But none of the earlier works had put the topic sufﬁciently in the foreground to allow a meticulously constructed, page-and chapter-consuming proof. One pay-off of such a examination would be a compelling illustration of the comprehensive unity of Kant’s model of reality. Because God is an assumption of metaphysics, it should be possible to construct a metaphysical defense of God’s existence based on a priori considerations. And because God is the source of the physical world described by the natural sciences, it should equally well be possible to make a case for God’s existence based on empirical considerations. The inquiry that was supposed to achieve all this was The Only Possible Argument in Support of a Demonstration of the Existence of God (1763). The Only Possible Argument, a book of 205 pages in its original edition, consists of three parts; the ﬁrst is devoted to the construction of an ontological argument a priori, the second to the construction of a physicotheological argument a posteriori (an argument from design), and the third to a general appraisal of these two proofs. Part I carries the title, ‘‘In Which Is Furnished the Argument in Support of a Demonstration of the Existence of God’’ (II 70; WM 116). According to its heading, part I is supposed to deliver the ‘argument’ (Beweisgrund) of God’s existence. Over four sections, Kant carefully constructs an ontological proof in part I. General considerations about existence (Dasein) lead to the analysis of the inner possibility presupposed by existence; an elaboration of necessary existence follows; and ﬁnally, the conclusion is established that the necessarily existing being is God. The title of part II runs, ‘‘Concerning the Extensive Usefulness Peculiar to this Mode of Proof in Particular,’’ (II 93; WM 137). But instead of discussing the usefulness of the ontological argument just developed in part II, Kant constructs there an a posteriori demonstration based on the unity of natural objects. This demonstration amounts to a probabilistic argument from design. Kant refers to it either as a physico-theological argument or as a cosmological argument. In the eight sections of part II, he distinguishes ways in which natural objects depend on God; he reﬂects on the order and the perfection of nature; he criticizes current physico-theology and proposes improvements; he summarizes the cosmogony of the Universal Natural History; and he reﬂects on the self-sufﬁciency of God. Part III, ﬁnally, ‘‘In Which It Is Shown That There Is No Other Possible Argument In Support of a Demonstration of the Existence of God Save That Which Has Been Adduced’’ (II 155; WM 195) is a review and the conclusion. In Kant’s view, the new ontological argument is a successful alternative to Descartes’s invalid proof of God’s existence. Moreover, the new argument from design, Kant thinks, is a successful alternative to Leibniz’s ﬂawed argument from the contingency of the world. The physico-theological proof is ‘‘at once powerful and very beautiful’’ (II 155; WM 201), but it lacks, being a merely probabilistic argument, the rigor desired of a deductive demonstration. Although there are, as Kant grants, ‘‘two possible proofs of the existence of God’’ (II 159; WM

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199), there ‘‘is not more than a single demonstration of the existence of God possible’’ (II 162; WM 201). What shall we make of Kant’s curious distinction of proof and demonstration at the end of the book? How many viable arguments for God’s existence are there—one or two? The structure of the Only Possible Argument presents the reader with a puzzle. The contents seem to be at odds with the title of the book as well as with the headings of the parts. The title announces that there is only one (einzig) argument in support of God’s existence, but the book contains two proofs instead of one—the ontological argument of part I, and the physico-theological argument of part II. Furthermore, the title of part II concerns the ‘‘usefulness peculiar to this mode of proof (Beweisart) in particular’’ (II 93; WM 127). The proof established in part I is an ontological argument. Given the title of part II, one would expect that Kant discusses the usefulness of the argument next. But he does not do this. Instead, he constructs an altogether different proof which proceeds from nature instead of from concepts, and which involves an inductive instead of a deductive inference. Why does a book that purports to present one possible argument contain two? If it were the case that the ontological argument was identical with this allegedly only possible argument, why would Kant bother to write part II? Some commentators, such as Beiser (1992), have read part II as a refutation of physico-theology for the sake of establishing the primacy of ontology.18 But the structure and contents of part II do not support this interpretation. Part II contains a critique of common physico-theology, a proposal for remedying its faults, and the construction of a novel physico-theological argument Kant deems superior to the traditional empirical alternatives. All this is puzzling.19 In this second part of the book, Kant restates many of the ideas developed already in the Universal Natural History. He surveys three ways of inferring God’s existence from physical effects. Such inferences could be prompted by the perception of miracles, by the perception of nature’s contingent order, or by the perception of the necessary unity of nature (II 116; WM 157– 158). Although miracles appear to give the most compelling testimony of divine intervention, their occurrence requires proof, and such proofs are still wanting. Hence, arguments based on supernatural interventions represent ‘‘that mode of judging where the philosophy is still concealed’’ (II 134; WM 175). This leaves two more ways, namely, to infer God’s existence from nature’s contingent order or from nature’s necessary order. But arguments based on nature’s contingent order suffer from a weakness: they ignore the possibility that God does not need to reveal Himself in contrived or peculiar arrangements, and that God can work instead by means of the necessary natural processes which he had created in the ﬁrst place. It would be better for rational theology to acknowledge the descriptions of nature generated by science. As Kant already argued in the preface to the Universal Natural History, religion would only lose if its claims ignored or contradicted scientiﬁc descriptions (cf. I 222–228). Resuming the same thread in the Only Possible Argument, he warns that a conﬂict between physico-theology and

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mechanical explanations of nature would lead to dangerous (and ultimately invincible) objections to physico-theology (II 118). That, in turn, would force religion to oppose science, denounce it as a heresy, and try to silence it (II 119–122). In the end, an antimechanical physico-theology based only on contingent events would not even help God’s cause because it would merely entail a demiurge responsible for artiﬁcial arrangements in nature, not a supreme creator of nature’s mechanical development (II 122–123).20 Just as he did in the Universal Natural History, Kant opts in part II of the Only Possible Argument for the third and only viable physico-theological strategy: to infer God’s existence from nature’s necessary unity (II 116). This is why he begins section 1 of part II with a reﬂection on nature’s unity. A unity is visible in the fundamental aspects of nature such as space (cf. II 93–96) and the laws of motion (II 96–100). Since all things in nature depend on God, natural laws depend on God as well and are the divine vehicles for organizing the purposive order of nature. Because the good lies solely in the achievement of nature’s purposes, and not in the particular means of achieving it, physico-theology ﬁnds the best testimony for God in the mechanical harmony of nature rather than in alleged divine interventions (II 108–109). In the following sections of part II, Kant recapitulates the main themes of the cosmology of the Universal Natural History. The basic description of the universe and its origin remains largely the same.21 One aspect noticeably absent from this reiteration is the ‘‘static law’’ of the Universal Natural History: the idea that gravitational and repulsive forces cause a staggered arrangement of elements of varying density such that the closer a planet is to the sun, the denser will be its mass (I 270–271). Kant rejects this hypothesis in the Only Possible Argument (II 142). That Kant dropped the static law implied his greater awareness of the fact that the planetary system is not as meticulously symmetrical and harmonious in its structures and proportions as he originally assumed. But a messier universe does not undermine God’s design. On the contrary, Kant interprets this to his advantage, strengthening the case against extrinsic teleologies and supernatural inferences in the natural order. The fact of such imperfections in nature is evidence that the ‘‘hand of God’’ does not adjust things from the outside and that the adherents of miracle- and contingency-based physico-theologies are mistaken (II 142–144; WM 182–184). Thus, physico-theology, when done correctly, reveals God’s existence through the observable, purposive, and natural arrangement of the cosmos.22 In this sense, Kant’s argument from design is a ‘‘cosmological’’ argument (II 160; WM 199)—a label that Kant uses, and which he continues to use in the ﬁrst Critique (A629/B657–A630/B658). There are accordingly two ways to prove God’s existence: either through an ontological argument, an abstract and conceptual demonstration that proceeds a priori from the notion of possibility, or through a physico-theological argument, a concrete and inductive demonstration that proceeds from the observation of the existing cosmos (II 155–156). Kant ends up with two distinct arguments for

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the existence of God, a metaphysical demonstration of a necessary being, and a ‘‘Newtonian’’ argument for God that proceeds from the mechanical organization of physical nature. Hence, there are two distinct demonstrations in the Only Possible Argument. Why does Kant pursue this twofold route? Other commentators, such as Schmucker (1980) and Gebler (1990), who acknowledge the presence of a twofold route, remain puzzled by it.23 I suspect that Kant’s peculiar strategy was motivated by the overall thrust of the precritical project which he had pursued in the decade leading up to the Only Possible Argument. After all, the project did not only involve the construction of a comprehensive model of nature containing qualitative and quantitative aspects, but also the reconciliation of metaphysical postulates with Newtonian science. It ﬁts nicely into the thrust of the project, as involving metaphysics and science, that Kant is able to construct proofs based on either aspect of the project. That the ontological argument involves metaphysics is evident. That the physicotheological proof is supposed to involve science is, of course, far less obvious, but this is how Kant conceives of it. Referring to part II in the preface of the Only Possible Argument, he remarks: It might seem that the periodic occurrence of fairly detailed physical explanations in a work would be damaging to the unity which one must observe in reﬂecting upon one’s subject. However, since my intention in these cases has been especially focused on the method of using natural science [Naturwissenschaft] to attain cognition of God, I could scarcely have achieved this purpose without deploying such examples. (WM 114, cf. II 68; my emphasis)

By showing that a priori considerations of metaphysics and a posteriori surveys of mechanical nature will lead to God, Kant hopes to make a persuasive case for the comprehensive unity of his project. The very unity of the project forces Kant to take a further step. The precritical project is not just about the preservation of either side; it is about their reconciliation. Given that the reconciliation of metaphysics and science is a constant theme of the precritical philosophy up to this point, it should, in accordance with this article of faith, be possible to reconcile the two divergent paths to God’s existence. And this is precisely what Kant sets out to do. He intends to show that the physico-theological and the ontological arguments cohere in their claims such that the consideration of the one will necessary lead to the consideration of the other. The physico-theological argument points to the ontological argument, and the ontological argument points to the physicotheological argument. The physico-theological argument must proceed from the necessary unity of nature. This unity is the result of the natural laws that govern physical processes. Because the laws of nature are part of nature itself, and they are responsible for the purposive organization of nature, the purposive organization that reveals God’s existence is already embedded in the natural things as such. The ground for the purposive organization lies

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in the essence of the things themselves, in their own potential, and thus, in their own possibility. Speaking of the ‘‘spherical conﬁguration of small quantities of water such as raindrops’’ that form rainbows, Kant remarks: But that a celestial body in its liquid state should, entirely necessarily and as a result of such universal laws [of motion], strive to assume a spherical form— a form which subsequently harmonizes with the other purposes of the universe better than any other possible form, a spherical surface being capable, for example, of the most uniform dispersion of light—that is inherent in the essence of the thing itself. . . . But that each of these things should, in virtue of simple grounds, contain such an extensive adaptedness to harmony of many different kinds, and that a wonderful unity in the whole should, as a result, be able to be maintained—that is inherent in the very possibility of the things in question. And since the element of contingency, presupposed by any choice, here disappears, it follows that the ground of the natural unity can be sought in a wise being, [but] it cannot be sought in an arrangement due to the wisdom of that being. (WM 145–146; cf. II 102:18–23, 103:14–20; my emphasis.)24

Since the purposive organization lies in the things themselves, it is immanent to them, and it is caused by the very possibility of these things as such. Because the purposive organization of nature comes about through the possibility of things, the starting point of the physico-theological proof, purpose, converges with the starting point of the ontological proof, possibility. As an aside (which will become clearer in the next section), it must be noted that Kant’s ontological argument is not the standard conceptual proof of God’s existence by means of the assumption that existence is a property, together with the premise that the divine concept contains all properties. Kant rejects existence as a predicate (see II 70–74) and tries to derive the notion of a necessary existence from the analysis of possibility (in sections I.2.i–I.3.ii; II 77–84): something is possible only if it is thinkable; something is thinkable only if data is present to the mind; and data can be present to the mind only if the complete set of thinkable data already exists. Therefore, something is possible only if something exists. Because the negation of possibility is impossible, what is presupposed as existing must exist necessarily. Next (in sections I.3.iii–I.4.ii; II 84–89), he hopes to show that the complete set of thinkable data is the complete set of all positive properties that exists as a uniﬁed entity endowed with divine qualities. Kant grounds the physico-theological argument in the core concept of the ontological argument, possibility, by using the immanence of purpose (the crucial assumption of the immanent teleology that he developed in the Universal Natural History and reiterated in the Only Possible Argument) as the philosophical link connecting the two paths to God. The immanent teleology is the bridge between the scientiﬁc and the metaphysical viewpoints of the world. At the end of the ontological argument in part I, Kant asserts that God is the ground of all things and that God’s existence is derivable from the

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notion of possibility. Natural objects conform to God because he is their ground (II 91). God’s features, goodness and perfection, are derivable from possibility because God’s existence is derivable from it as well. As natural objects conform to God, their features correspond to His. Goodness and perfection of the creator are mirrored in the unity, harmony, and order of the creation.25 But as God’s features are derivable from possibility in general, the corresponding natural features of unity, harmony, and order—the very features that allow an argument from design at all—are derivable from the inner possibility of things (II 91–92). This explains the relationship of title and content. The standard English translation of the title, The Only Possible Argument in Support of a Demonstration of the Existence of God, certainly does not help because it makes it appear as if the one possible argument of the title is at odds with the two possible arguments of the text. But if one rendered the title of Kant’s book literally into English, it would read, rather awkwardly, ‘‘The Only Possible ‘Proof-Ground’ to a Demonstration of God’s Existence.’’26 A ‘‘proof-ground’’ (Beweisgrund) turns out to be different from an argument (Beweis). As Kant conceives of it, a ‘‘proof-ground’’ is the foundation of an argument. In the Only Possible Argument, he accordingly develops two arguments or Beweise, while, at the same time, he reconciles the two distinct arguments on a common basis or Beweisgrund. This basis is the only possible ‘‘proof-ground’’ or Beweisgrund that Kant speaks of in the title, and it consists of the inner possibility of things. The conceptual analysis of ‘‘possibility’’ leads to an a priori argument for God’s existence. The a posteriori argument from design rests on the notion of purpose that, in turn, pertains to the inner possibility of objects. Possibility, considered both a priori and a posteriori, constitutes the ultimate and unifying ground of both proofs because it is the starting point of the ontological demonstration and furnishes the features that make the physico-theological proof possible. Thus, the inner possibility of things is the common Beweisgrund of the two distinct Beweise. Furthermore, the architectonic of Kant’s work also explains the heading of part II, regarding the ‘‘usefulness’’ of the ontological proof. Because the argument from design is a mere probabilistic case for God’s existence, only the ontological demonstration will qualify as a genuine proof. And because the ground of the argument from design (purpose) is reducible to the ground of the ontological argument (possibility), the argument from design only seems to be an autonomous proof. As regards its conceptual roots, the argument from design appears as an ‘‘empirical version’’ of the ontological argument. Ultimately (in part III), Kant takes ‘‘proof ’’ to refer to a deductive demonstration aiming for certainty. In this technical and strict sense of ‘‘proof,’’ the argument from design is not a proof at all. Rather, it serves to illustrate the conceptual truths of the ontological argument on the level of natural science and observation. The argument from design is a distinct argument, but only to the extent that it is the empirical application of the basis of the ontological argument. Thus, Kant can choose with some plau-

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sibility, ‘‘On the Extensive Usefulness Peculiar to this [Ontological] Mode of Proof in Particular’’ as the heading of the section that deals with the argument from design. Accordingly, two arguments exist in the Only Possible Argument, the one as a proof, the other as a distinct commentary on the proof. Both converge in the same grounding of which the ontological proof is its metaphysical demonstration and the cosmological argument its scientiﬁc application.

8.3 The Ontological Demonstration With the investigation of God’s existence in the Only Possible Argument, Kant was trying to establish a bridge from philosophy of nature to rational theology. The precritical project involved the claim that reality is a uniﬁed whole in which rational and empirical aspects coexist and cohere. The structure of the Only Possible Argument illustrated this claim. Because reality depends on God and is a rational-empirical whole, reality’s dependence on God emerges in its rational as well as in its empirical aspects. Thus, Kant hoped, on the one hand, to infer God’s existence from the rational structure of reality by means of a conceptual proof that could disclose the logical relations of the ontological categories of the world. And he hoped, on the other hand, to infer God’s existence from the empirical sphere of reality by means of a physico-theological argument that would show the divine origin of the overall and systematic purposiveness of nature. Corresponding to the claimed uniﬁed coherence of reality, the rational, ontological proof and the empirical, physico-theological proof hang together. Their common ground, and thus the Beweisgrund of both arguments, is the inner possibility of objects existing in the world. A comparison of the two arguments reveals the ontological demonstration to be more powerful than the physico-theological proof. Only the ontological demonstration qualiﬁes as a genuine proof, that is, as a proof that entails its conclusion with deductive certainty. The ontological demonstration accordingly emerges as the centerpiece of the Only Possible Argument. The stability of Kant’s rational theology stands and falls with the validity of this demonstration because it is the only proof in the strict and deductive sense of the claims Kant hoped to advance. The Only Possible Argument was the ﬁnal result of a long series of reﬂections.27 The earliest visible trace of these reﬂections predated the Spin Cycle essay (1754) which had initiated Kant’s period of intense activity in the second precritical decade. An untidy pile of notes, assembled on the prize question of Alexander Pope’s ‘‘system’’ of optimism, contained the germ of the Only Possible Argument. The Prussian Royal Academy announced the question in 1753, and Kant probably jotted his thoughts down when he ﬁrst heard about it. Two years later, in 1755, when the actual competition took place, Kant was too busy with his M.A. thesis and his doctoral dissertation to participate, and so these notes never led to a submission. Nonetheless, the Reﬂexionen u¨ber Optimismus (1753?) were the basis of the Optimism essay written when the competition was over, and one of its phrases reveals a

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glimpse of what would later become the conceptual proof in the Only Possible Argument: Pope chooses a path that is the most elegant of all possible ones and that makes the beautiful proof of God’s existence intelligible to all people. This path constitutes the very perfection of Pope’s system; it consists in that all possibility is subjected to the dominion of a self-sufﬁcient original being. Under this being, the things can have no properties (not even those that one calls essentially necessary ones) except those that harmonize completely with the expression of God’s perfection. (XVII 233–234; my emphasis)28

Kant’s ontological proof in the Only Possible Argument rests on the claim that the possibility of things entails God’s necessary existence.29 The path from possibility to God was already visible in the Reﬂexionen, a path that Kant erroneously attributed to Alexander Pope. In the New Elucidation two years later, the germ of the ontological proof sprouted into its ﬁrst summary statement. Kant declared there as proposition 7: There is a Being, the existence of which is prior to the very possibility both of Itself and of all things. This Being is, therefore, said to exist absolutely necessarily. This Being is called God. (I 395:4–6; WM 15)

The subsequent two paragraphs in the New Elucidation contain a quick proof of this proposition: Possibility is only deﬁnable in terms of there not being a conﬂict between certain combined concepts; thus the concept of possibility is the product of a comparison. But in every comparison the things which are to be compared must be available for comparison, and where nothing at all is given there is no room for either comparison or, corresponding to it, for the concept of possibility. This being the case, it follows that nothing can be conceived of as possible unless whatever is real in every possible concept exists and indeed exists absolutely necessarily. . . . Furthermore, it is necessary that this entire reality should be united together in a single being. For suppose that these realities, which are, so to speak, the material of all possible concepts, were to be found distributed among a number of existent things; it would follow that each of these things would have its existence limited in a certain way. In other words, the existence of each of these things would be combined with certain deprivations. Absolute necessity is not compatible with deprivations as it is with realities. Deprivations, however, belong to the complete determination of a thing, and without this complete determination a thing could not exist. This being the case, it follows that the realities, which are limited in this way will exist contingently. It is, accordingly, a requirement for their absolute necessity that they should exist without any limitation, in other words, that they should constitute an Inﬁnite Being. Since the plurality of this being . . . would be a repetition . . . and hence a contingency opposed to absolute necessity, it must be concluded that only one such Being exists absolutely necessarily. (I 395:7–24; WM 15–16)

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This argument of the New Elucidation deserves to be quoted in its entirety because contrary to what commentators such as Schmucker (1963), Henrich (1960), and Reuscher (1977) claim, I think that it anticipated the demonstration contained in the Only Possible Argument.30 Both the outline of 1755 and the elaboration of 1762 amount to a conceptual argument that begins with an analysis of possibility and ends with the conclusion of God as the necessary being. Kant characterized the summary argument in the New Elucidation as ‘‘a proof based on essence’’ (I 395:26–27; WM 16). He characterized its beefed-up version in the Only Possible Argument as ‘‘the ontological proof ’’ (II 160; WM 199). The latter, he thought, is ‘‘capable of the rigor required of the demonstration’’ (II 161; WM 200).31 The rigor required by the demonstrative certainty of such a proof must be based on the ‘‘analysis of one’s concepts into . . . atoms’’ (II 75; WM 120).32 But the demonstration in the Only Possible Argument is not just another version in the long list of ontological arguments generated by theologians and metaphysicians since the eleventh century.33 Kant broke with the tradition and proceeded from an original insight. Once again, this break is already visible in the New Elucidation, where Kant remarked: I ﬁnd, indeed, the view repeatedly expressed in the teachings of modern philosophers that God has the ground of His existence posited in Himself. For my part, I ﬁnd myself unable to support this view. . . . Of course, I know that appeal [to a ground of God concealed within Himself] is made to the concept itself of God; and the claim is made that the existence of God is determined by that concept. It can, however, easily be seen that this happens ideally (idealiter), not really (non realiter). . . . The view we are discussing ought, therefore, rather to be formulated as follows: in framing the concept of a certain Being, which we call God, we have determined that concept in such a fashion that existence is included in it. If, then, the concept which we have conceived in advance is true, then it is also true that God exists. I have said these things, indeed, for the sake of those who support the Cartesian argument. (I 394:24– 395:3; WM 15)

The Cartesian proof of God’s existence arises from a concept of God that contains the determination of existence already as its property. As Kant put it, such a proof works in the imagination, but not in reality. We may frame a concept of God that includes existence only if we know that the concept is true—but this, of course, is at issue. Although Kant rejected existence as a property in the context of discussing the Cartesian proof, the claim that existence is a property was not solely a Cartesian claim but had been endorsed by Leibniz as well.34 Here, in the New Elucidation, we ﬁnd the ﬁrst of Kant’s assertions that existence is not an (analytic) predicate of a concept. Kant repeated the denunciation of existence-as-predicate with greater force in the Only Possible Argument (II 70–74). Any demonstration of God’s existence, he writes, will evidently involve the term ‘‘existence’’ (Dasein). This term needs to be clariﬁed because traditional ontological arguments have involved conceptual confusions (II 70). Kant thinks that we will ﬁnd, upon

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analysis, that existence is the ‘‘absolute position’’ of a thing (II 73–74), a status which things earn when God creates them. Furthermore, we will ﬁnd that existence is actually—and only—a relatum of predicates. Because an existing thing is related to its speciﬁc predicates (II 74), there is a relation of existence and predicates. But this is all. The conceptual dissection of ‘‘existence’’ does not reveal it as a predicate in its own right, and this is the reason for the failure of Descartes’s ontological argument. Descartes claimed to deduce God’s existence as a predicate from the concept of God, but beinga-predicate is not among the identiﬁable features of existence.35 Contrary to what Bauer (1964) claims, Kant’s objection to the classical ontological argument is actually almost as old as the ontological argument itself.36 However, Kant may have been the ﬁrst who made the point succinctly and clearly. Gaunilo, responding ‘‘On Behalf of the Fool’’ to Anselm’s Proslogion, voiced the ﬁrst doubt about existence as a feature of concepts.37 Centuries later, Pierre Gassendi objected to Descartes’s version in his reply to the Meditationes with the same doubt, arguing that it is all right to compare essence with essence, or existence with existence, or a property with a property, but it is inacceptable to compare existence with a property.38 In once again a different version, the charge against the ontological argument that was implicit in the New Elucidation and explicated in the Only Possible Argument (II 72–3), would rise to prominence in the Critique of Pure Reason.39 As Kant characterized the central charge against the ontological argument in the Critique of Pure Reason (A598/B626–A599/B627), the point of the objection is not that the predication of existence does not add anything to the knowledge of an entity or that the predication of existence fails to describe an entity. Rather, existence is not a predicate according to the critical Kant because the judgment ‘‘God exists’’ is synthetic and not analytic. In ‘‘God exists,’’ the predicate ‘‘exists’’ is not contained in the subject ‘‘God’’; rather, ‘‘exists’’ is added to ‘‘God.’’ Therefore, existence cannot designate a possible attribute of the notion of God, and it cannot be part of the series of properties that characterize the meaning of the notion ‘‘God.’’40 Because existence is the ‘‘absolute position’’ of an object and merely the relatum of its predicates instead of a predicate in its own right, as Kant argued in the Only Possible Argument (II 73–74), a different route needs to be taken in order to embark on an a priori demonstration of God’s existence. The new logical path, which Kant proposed, begins with the contingent existence of things in the world, then leads from there to the possibility of objects in general, and ends with the necessary existence of a divine being. Overall, his strategy in the Only Possible Argument was to show that an analysis of possibility discloses the existence of a necessary entity, and having established that, to infer from the necessary existence of such an entity its divine qualities which reveals the entity to be God. Kant’s demonstration is divided into a core segment, the argument for a necessary entity (sect. I.2.i– I.3.ii, II 77–84), followed by a concluding segment, the derivation of the entity’s divine qualities (sect. I.3.iii–I.4.ii, II 84–89). The concluding segment ﬂeshes out the necessary entity as the personal god of the Testaments. It

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involves inferences from the necessary being to its unity (II 84–5), immutability and eternity (II 85), supreme reality (II 85–7), spirit, reason, will (II 87–8), and ﬁnally its order, beauty, and perfection (II 88–9). These inferred features, Kant concluded, characterize the demonstrated entity as God (II 89). Of course, whether the concluding segment succeeds in establishing the conclusion that God exists will depend on the core segment that is supposed to establish the reality of an ens necessarium in the ﬁrst place. The core segment involves two main moves. First, Kant proved the claim that it is impossible that nothing exists (II 79). Next, he showed that something, namely, one being, exists necessarily (II 83–4). Because the substantiation of the latter claim presupposes the truth of the former claim, the ﬁrst move, which establishes that it is impossible that nothing exists, is the basis of the whole argument. The whole subsequent ediﬁce—in other words, everything—stands and falls with the ﬁrst move. The ﬁrst move thus deserves a closer look. Kant’s ﬁrst move contains four statements that serve as premises and four inferential steps, the fourth of which is the conclusion. These are the premises: (1). Anything that is self-contradictory is impossible. (II 77:10) (2). The negation of possibility is impossible. (II 79:3–4) (3). The Formal Condition of Possibility. What is possible must be internally consistent, i.e., it must conform to the principle of contradiction. (II 77:14–20, 31–33) (4). The Material Condition of Possibility. Anything that is possible must be thinkable, and for anything to be thinkable, the presence of material data to the mind is required. (II 78:10–14).41 On the basis of these premises, Kant drew four consecutive inferences. He began by commenting on the material condition: the presence of material data to the mind is a condition of possibility, but a condition of the presence of material data is the existence of things. Hence, (5). If nothing existed, then there could not be any material data present to the mind. (II 78:16–18)42 But given the material condition, anything possible requires the presence of such material data. Because they, in turn, depend on the existence of things, it follows that, (6). If nothing existed, nothing would be possible. (II 78:29–32)43 This is equivalent to saying that, (7). Something must exist if anything is possible (or: if something is possible, then something must exist). (II 78:22–26)44 With these steps, Kant thought that he had all that he needed for completing the ﬁrst move. He stated that the negation of possibility is impossible

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as the premise (2). He also inferred from the material condition the claim (6) that nothing would be possible if nothing existed. Given that, if nothing existed, possibility as such would be negated, and given that possibility cannot be negated, the conclusion of the ﬁrst move of the demonstration results: (8). Therefore, it is impossible that nothing exists. (II 79:2 and 79:14– 15)45 The importance of the interim conclusion (8) can be seen in that the construction of Kant’s overall demonstration now becomes transparent. The intended ultimate conclusion of the demonstration, that God exists, can already be made out in the shadows here. If it is indeed impossible that nothing exists, then not all existing things will be contingent things. For, if all things were contingent such that they might or might not exist, then it would be possible that nothing existed. This would run counter to the interim conclusion (8) just established. Thus, (8) implicitly suggests that something must exist no matter what. Such a thing, or group of things, would exist necessarily by deﬁnition, Kant believed.46 Hence, the interim conclusion that it is impossible that nothing exists prepares the way for the second move, that something—one being—exists necessarily. In essence, all that the remainder of the core segment of Kant’s demonstration of an ens necessarium needs is an argument for the unity of what exists necessarily: that there is one and only one uniﬁed necessary being distinguished from the contingently existing creation—that there is one God, not several. For, had Kant proved polytheism, he would have overshot his aim. That it is impossible that nothing exists presupposed for Kant the claim that nothing would be possible if nothing existed. In other words, in the structure of Kant’s argument, the interim conclusion that it is impossible that nothing exists presupposes the anterior claim that something is possible only under the condition that something exists. The presupposition hinges on premise (4), Kant’s material condition. The material condition (‘‘anything that is possible must be thinkable, and for anything to be thinkable, the presence of material data to the mind is required’’) is the tool that allowed Kant to make his ﬁrst move.47 At ﬁrst glance, the presupposition seems counterintuitive. We are used to think of possibility and existence in a different way. Common sense would tell us that something exists only if something is possible—not that something is possible only if something exists. We ordinarily accept the converse of Kant’s assertion as a modal principle, and we do so because existing things are possible by deﬁnition.48 According to Kant’s material condition (4), anything that is possible must be thinkable, and anything that is thinkable requires material data to be present to the mind. I think that Kant’s requirement for possibility should not be understood as the presence of such data to the mind (which would amount to an epistemic thesis), but as the presence of such data in general (which is an ontological claim instead). In the scholarly literature on the Only Possible Argument, the issue of how the material condition should be interpreted has been discussed in terms of the larger philosophical issue of

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whether the possibility that is the basis of Kant’s demonstration in general is a possibility of thought or a possibility of being.49 To take the material condition as an epistemic thesis, as Redmann (1962), Moreau (1969), and Laberge (1973) suggest, would raise odd questions. For one thing, the link between possible and thinkable would then become crucial, but there does not seem to be any consistent way of applying ‘‘thinkable’’ (which could be understood as ‘‘imaginable’’ or ‘‘intelligible’’) to the notion of possibility. If ‘‘thinkable’’ meant ‘‘imaginable,’’ then anything unimaginable, such as Descartes’s chiliogonum, would be impossible.50 But this is not true. Although a two-dimensional geometric ﬁgure with a thousand sides is unimaginable in its details (at least, for us with our limited cognitive powers), it is a consistent extrapolation of the polygonal series [triangle, square, pentagon, . . . , chiliogon, . . . ]. And if ‘‘thinkable’’ meant ‘‘intelligible,’’ then self-contradictory, impossible entities would have to be unintelligible. But I am not sure whether this can be defended either. Certainly, some impossible entities are unintelligible, such as a square circle—we can utter the words ‘‘square circle,’’ and although we understand ‘‘square’’ and ‘‘circle,’’ we fail to understand their union. But is this true in all cases? Are self-contradictory entities, terms, and propositions necessarily unintelligible? If we limit the multiple senses of ‘‘possible’’ to what has been called ‘‘absolute possibility,’’ which concerns descriptions that are formally consistent,51 then it seems difﬁcult to rule out the eventuality that there are descriptions (whether they be of entities, notions, or states of affairs) that are inconsistent and yet intelligible. If our cognitive structures indeed prohibited us from conceiving inconsistent notions, then we would commit less mistakes than we do. An additional problem is that an epistemic reading of the material condition would imply the reduction of the possible to the conceived, instead of (as we would expect) to the conceivable. Immediately after introducing the material condition, Kant remarks that without existence, nothing would be posited, no thinkable material would be given, and all possibility would disappear (II 78:16–18).52 Read epistemically, this would mean that if there was no sensory input, nothing could be conceived, and if nothing was conceived, nothing would be possible. To make possibility in general dependent on the epistemic activities of humans in particular seems absurd. Because the material condition concerns the inference from possibility to the existence of God, it is best understood as an ontological claim, as Campo (1953), Kopper (1955/56), and Lamacchia (1969) suggest. In this reading, Kant’s thesis amounts to the assertion that existence precedes possibility. ‘‘Existence’’ refers to the presence of the material that is the condition of possibility. Nothing would be possible if this material were not present. Objects are possible because their determining properties are already present somehow and somewhere. It is insufﬁcient for possibility, as a modal category of reality in general, that these properties are present as predicates to a human mind; they must be present in the sense of belonging to the ontological furniture of the world. That a unicorn is possible, regardless of the fact that it is not real, requires that its determining set of properties [horned,

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white, horselike, . . . ] exists. Moreover, such properties cannot solely subsist as elements of the things in the world, as elements of what exists contingently, because only if the properties existed necessarily could possibility be a modal category of reality. Contrary to what Gebler claims (1990), these properties must subsist independently, prior to all possible objects and prior to all existing things in the world.53 Kant does not speak of properties as such. He refers instead to that which gives meaning to the data presupposed by a possible concept. While considering a ‘‘ﬁery body’’ (II 80), he argues that such a body is possible if we are justiﬁed in assuming the data to its possibility, such as extension, impenetrability, and the other properties that determine the object ‘‘body.’’ The datum ‘‘extension’’ cannot be justiﬁed by appealing to experience because the object ‘‘body’’ would remain possible, even if it did not exist and were not empirically accessible. The justiﬁcation of the datum is possible only if the datum as such exists. This allows Kant to use the material condition for his ontological demonstration. For any concept to be meaningful, hence, for any object denoted by a concept to be possible, the object must be determined by properties, and the data of the concept must be present beforehand. Since this holds true of all possible objects and meaningful concepts, all conceivable properties have to be present beforehand. There accordingly exists a complete set of all conceivable positive properties, and this set must exist necessarily otherwise possibility would not always be possible, which is absurd. Thus, for Kant, the material condition establishes the necessary existence of the complete series of properties. Because something—the complete set of all conceivable positive properties—exists necessarily, it follows, Kant thought, that it is impossible that nothing exists. This is how Kant hoped to have established the desired interim conclusion that completes the ﬁrst move of his ontological demonstration. I argued earlier that the ontological proof in the Only Possible Argument is divided into two segments, an argument for a necessary entity, and an argument for the divine qualities of the entity according to the JudaeoChristian conception of God. The ﬁrst segment of the proof, which is intended to establish the existence of a necessary entity in general, and which is the core of Kant’s ontological proof, has two parts. The ﬁrst part is the ‘‘ﬁrst move’’ just described. There, Kant hoped to establish the claim that it is impossible that nothing exists. Having traced the structure of the ﬁrst move, it is now appropriate to ask whether this structure is sound. The ﬁrst move constitutes the foundation of the overall argumentative ediﬁce of the Only Possible Argument. Is this foundation solid? As we have seen, the persuasiveness of the ﬁrst move (and therefore, the persuasiveness of the ontological proof as such) hinges on the material condition. Kant had arrived at the a priori presence of all positive properties with the help of the material condition. But the stipulation and the employment of the material condition fails to meet Kant’s own methodological standard for a demonstration that is supposed to be a priori throughout. If one examined ‘‘possibility’’ analogous to his dissection of ‘‘existence,’’ two fea-

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tures of possibility would be evident: possibility is instantiated in possible concepts, and possible concepts are determined by predicates that characterize them. But it is not evident that such predicates have to exist prior to the possible concept itself. In other words, a conceptual analysis of ‘‘possibility’’ reveals the possibility of a conceptual whole and the possibility of its conceptual elements—it does not reveal the possibility of a conceptual whole and an independent and prior existence of its conceptual elements. This is a fatal ﬂaw. Precisely such an independent existence of the conceptual elements is what Kant would have needed for successfully inferring the interim conclusion. Without establishing the a priori existence of the series of such elements, he could not even think about going on to the second move and drawing conclusions about the uniﬁed totality of the series. The point of this negative verdict is this: Kant’s ontological proof would meet Kant’s own requirements only if all the building blocks of the proof were analytically derived from the dissection of the key terms. This is the methodological standard; there is no other because Kant’s proof is supposed to be a conceptual proof. The material condition is a key building block but not analytically derived from the term ‘‘possibility.’’ Instead, it emerges as a theoretical construct that surreptitiously slips into the proof. Therein lies the ﬂaw of Kant’s proof. Where does the material condition come from, then? It is an echo of Leibniz’s idea of the complete determination of possible concepts, the idea that a possible concept involves by its very nature the sum-total of positive predicates determining it. 54 The concept of a substance, according to Leibniz, is a priori complete such that all truly attributable predicates can be deduced from its concept. In #13 of the Discourse de la Me´taphysique, Leibniz had argued: . . . [T]he notion of an individual substance includes once and for all everything that can ever happen to it and that, by considering this notion, one can see there everything that can truly be said about it, just as we can see in the nature of a circle all the properties that can be deduced from it. (AG 44, G IV: 427–8)

The notion of a substance includes the complete series of all possible attributes. The complete series of the possible attributes, in turn, constitutes the essence of the substance. But, as Leibniz had noted in the Nouveaux Essais (bk. 3, ch. 3, #15): Essence is fundamentally nothing but the possibility of a thing under consideration.55

Thus, essence, being, and possibility are the same. For Leibniz, essence precedes existence. But essences do not ﬂoat in thin air. Rather, they subsist in the prior reality of the divine understanding. Before contingently existing objects instantiate them, the essences of beings and properties subsist as

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possible entities in the regio idearum, the ‘‘realm of ideas’’ as Leibniz had called it in The Ultimate Origination of Things: . . . [N]either those essences nor the so-called eternal truths pertaining to them are ﬁctitious. Rather, they exist in a certain realm of ideas, so to speak, namely in God himself, the very source of every essence and of the existence of the rest. The very existence of the actual series of things shows that we seem not to have spoken without grounds. For the reason for things must be sought in metaphysical necessities or in eternal truths, since (as I showed above) it cannot be found in the actual series of things. But existing things cannot derive from anything but existing things, as I already noted above. So it is necessary that eternal truths have their existence in a certain absolute or metaphysically necessary subject, that is, in God, through whom those things which would otherwise be imaginary are realized. (AG 151–2; G 7:305).

In other words, possibility (essence) precedes existence in that an essence subsists in God’s divine understanding as a possible before it becomes real. God brings the possible into existence by selecting it from its alternatives in the divine understanding.56 Leibniz’s idea of the complete determination of possible concepts involved the metaphysical view that God conceives the essences of things and properties in the divine understanding and selects those that he wants to become part of the world. Properties subsist ﬁrst as essences before they emerge within existing things. This is the link between Leibniz’s views and Kant’s material condition. As Watkins and Fisher (1997) correctly observe, Kant endorsed Leibniz’s theory of complete concepts while rejecting the Leibnizian description of existence as a predicate.57 That we, as parts of the real world, are capable of thinking of possible concepts in principle presupposes that the possible concepts have preexisted in God. In this sense, then, anything that is possible must be thinkable, and anything that is thinkable needs the presence of material data to the mind. The material data—Leibniz’s preexisting essences—makes possibility possible. Let us now turn to Kant’s second move. There, he needed to show that the complete series of existing properties is uniﬁed. Put differently, he needed to proceed from the completeness of the series to the totality of the series. This demonstration, he thought, would bring him closer to the goal of showing that there is one and only one necessary being, endowed with all positive properties—a being that is perfect and must therefore be God. Kant’s crucial argument, which represents the second move, occurs in the section ‘‘the necessary being is unique’’ and takes the form of a reductio: Suppose that A is one necessary being and that B is another. It follows from our deﬁnition that B is only possible in so far as it is given through another ground, A, as the consequence of A. But since, ex hypothesi, B is itself necessary, it follows that its possibility is in it as a predicate and not as a consequence of something else; and yet, according to what has been said, its possibility is in it only as a consequence, and that is self-contradictory. (II 84:3–8; WM 128)

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Prior to this reductio, Kant thought to have established that whatever exists necessarily constitutes the ground for any other being. Hence, any other being is the effect of what exists necessarily (II 83:31–33). The reductio begins with the supposition that two necessary beings exist, A and B. Since B is another thing, B’s possibility is the effect of something else. But whatever exists necessarily affects the possibility of anything else. Because A exists necessarily by supposition, and B(’s possibility is the effect of something else by the ﬁrst inference, A causes the possibility of B. But B is a necessary thing by supposition, and a necessary thing contains its own ground of possibility by prior argument, hence, B’s possibility ought to be B’s own predicate. Obviously, the possibility of a thing is either the effect of something else or it is the thing’s own predicate, but it cannot be both. Therefore, the supposition leads to a contradiction and must be false, implying that there is one necessary being. This completes the second move of Kant’s demonstration. A closer inspection shows that the second move fails just as the ﬁrst did. Kant fallaciously equivocates ‘‘ein jedes andere Ding’’ (‘‘every other thing’’) with ‘‘B [ist] ein anderes’’ (‘‘B is another’’). ‘‘Every other thing’’ belongs to the previously established claim that ‘‘every other thing can only occur as a consequence of that necessary being’’ (II 83:31–33, WM 128). ‘‘B is another’’ belongs to the supposition of the reductio that ‘‘A is one necessary being and B is another’’ (II 84:3). ‘‘Every other’’ in the earlier sentence means any thing other than a necessary being. ‘‘Another’’ in the later sentence means a second necessary being. Kant was able to reach his conclusion because he conﬂated the two meanings. In fact, the second move would have suffered from a problem, even if Kant had come up with an argument that avoided the fallacy of equivocation. By his own standards, any move in the overall a priori demonstration would work only if the conceptual analysis of ‘‘possibility’’ revealed the series of properties, as well as their combination, as the reiﬁed totality of the series. But this desired combination is not given; it accordingly remains spurious within a proof that wishes to be purely conceptual. Later Kant would realize that he was aiming for the impossible here, and he would write in the Critique of Pure Reason (A602/B630): ‘‘the connection of all real properties is a synthesis, the possibility of which we are unable to determine a priori.’’ Some commentators (Reich, 1937; Watkins and Fisher, 1997) suggest that the critical Kant would not think that the Only Possible Argument had aimed for the impossible—that the Critique of Pure Reason involved repudiations of the standard demonstrations of rational theology, but retained, at least implicitly, the conceptual proof of the Only Possible Argument. I ﬁnd this view implausible in light of what Kant was trying to accomplish in these works. In the Only Possible Argument, he intended to demonstrate God’s existence with the ontological proof. In the Critique of Pure Reason, he wanted to establish God as a regulative principle (A641/B669, A672/B700– A676/B704). In the Critique, Kant did not infer God as a constitutive principle, nor did he furnish a deductive proof of His existence. Instead, he

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emphasized that anything pertaining to the intelligible is unknowable. The critical Kant concluded in the ‘‘Transcendental Dialectic’’ that theoretical demonstrations of God’s existence are impossible. It would be odd if the critical Kant argued for this conclusion and retained, even implicitly, the precritical proof. If the precritical proof worked, then the critical Kant would have to except knowledge of God from the claimed theoretical inaccessibility of the intelligible. That the critical Kant did not do this indicates that he regarded the precritical proof as a failure. And if he regarded it as such, then the precritical proof would be without merit. It served a single purpose: to prove God’s existence. If it failed to achieve this, then there would be no point in retaining it.58 Judged by Kant’s own standards, the ﬁrst and the second move are both guilty of the same mistake. In the ﬁrst move, the material condition is not an analytically derived component of the concept of possibility but a metaphysical construct synthetically added to the conceptual analysis. And in the second move, the uniﬁed totality of the property-series embodied in one entity does not result from the conceptual analysis of the completeness of the property-series, but is secretly tacked on. Thus, both moves fail. Since they together constitute the foundation of the ontological demonstration, the whole ediﬁce of the Only Possible Argument crumbles, and what was intended as the completion of the precritical project instead planted the seed of the project’s destruction. Kant had avoided the great pitfall of the tradition, the identiﬁcation of existence with a predicate, only to be defeated by difﬁculties of his own.

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The Newtonian Program of the Prize Essay and Kant’s Crisis

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9.1 The Crumbling of the Precritical Project, Mendelssohn’s Prize Essay, and the Review of the Only Possible Argument The precritical project from 1755 to 1762 concerned the grand synthesis of the Newtonian model of nature with three assumptions of metaphysics: the purposive development of nature, the possibility of a morally relevant freedom, and the existence of God. Kant endeavored to unify the Newtonian model with the purposive development of nature in the Universal Natural History. In the New Elucidation, he tried to show that the possibility of a morally relevant freedom is compatible with the deterministic processes described by the Newtonian model of reality. He suggested a brief demonstration of God’s existence in the New Elucidation. Proceeding from this outline proof, Kant constructed the rational theology of the Only Possible Argument whose centerpiece was the ontological demonstration. In the Prize Essay (written 1762, published 1764), he moved to an altogether different topic, the task of constructing a methodology that would give certainty to the demonstrations of metaphysics.1 Very much in the spirit of the precritical project, he proposed that a viable philosophical methodology consists of a merger of Newtonian science and metaphysics. He contended that the reliability of speculative demonstrations of metaphysical assumptions require 209

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implementing the investigative strategies responsible for the success of Newtonian science. Despite the fact that the Prize Essay was about a different topic, the rational theology of the Only Possible Argument remained essential to the point that Kant wished to make in his methodological essay. He presented in the Prize Essay the ontological proof of the Only Possible Argument as a positive example of the new methodology. On the surface, everything seemed ﬁne in the development of Kant’s thought in the early 1760s. It certainly appeared as if the precritical project was racing full steam ahead. Science and metaphysics had been uniﬁed in terms of a comprehensive philosophy of nature in the 1750s; they had been uniﬁed in terms of the ontological and physicotheological arguments in the rational theology; and now, they were in the process of being uniﬁed in terms of their methodological program. Underneath this pleasant surface, however, trouble was brewing. The teleological cosmogony of the Universal Natural History resurfaced in the guise of an argument from design in the Only Possible Argument that Kant described as probabilistic at best. The resolution of the conﬂict between determinism and freedom in the New Elucidation had turned out to be spurious (and Kant knew this).2 The ontological demonstration of God’s existence in the Only Possible Argument was burdened with internal problems. As the examination of the Prize Essay will reveal, Kant began to realize that his grandiose project was in serious difﬁculties. In 1761, the Prussian Royal Academy announced a question for the competition of 1763. The prize question was on whether metaphysical principles, in particular, the principles of natural theology and morals, could be proven with the same clarity and precision as the truths of geometry.3 It was inevitable that eventually such a question would be asked in debates on the status of metaphysics and had haunted the academy since its resuscitation in 1744.4 Frederick II had invited philosophes and scientists such as Maupertuis, d’Alembert, La Mettrie, Voltaire, Lagrange, and Euler to Berlin, and these foreign resident members of the academy had little patience with the speculative leanings of the Germans. Although the School Philosophy remained entrenched for decades to come, the big systems suffered both from attrition within and from competition without. Leibniz was dead; Wolff had published his important works years earlier and kept repeating himself; and the Wolfﬁan disciples were not of the same intellectual caliber as the growing numbers of researchers who followed in Newton’s footsteps. Slowly, Leibniz’s and Wolff ’s stars were sinking. Newton’s star kept on rising. The earlier academy question on monads in 1745 was symptomatic of this situation. The Leibnizian monadology purported to explain the structure of bodies, but it was a matter of considerable controversy whether it had succeeded at substantiating its claims. Leonhard Euler (director of the mathematical class) rejected the monadology in the Gedanken von den Elementen der Ko¨rper (1746) because he thought that it conﬂicted with the structure of space as geometry describes it and as natural science presupposes it. At Maupertuis’s and Euler’s behest, a critique of metaphysical monads won the competition.5 In a

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plenary session in 1748, Euler addressed the academy with his paper Re´ﬂexions sur l’e´space et le temps, in which he argued that metaphysics cannot succeed as an independent investigation and must enlist the aid of the sciences as guides for its own research.6 In 1758, Pierre-Louis Moreau de Maupertuis, who had served as president until Euler succeeded him in 1756, fanned the ﬂames by publishing yet another challenge to the authority of metaphysics, the Examen philosophique de la preuve de l’e´xistence de Dieu employe´e dans l’Essai de Cosmologie. Maupertuis argued that only quantitative investigations possessed the capacity of achieving certainty in the substantiation of their claims. Metaphysical demonstrations, Maupertuis contended, were probabilistic at best and misguided at worst.7 The academicians in Berlin were split over what to make of these challenges. As some members attacked metaphysics, others, such as Johann Sulzer (director of the class of speculative philosophy) and Heinrich Samuel Formey (secretary of the academy), jumped to its defense. So the debates continued.8 Eventually, Sulzer suggested the prize question on the demonstrability of metaphysical principles, Euler approved it, and Formey announced it. In contrast to the outcome of the earlier contest on monads, metaphysics scored a victory in the competition on the demonstrability of its principles. The entry that garnered the prize was an outspoken apology of metaphysical demonstrations. In his winning treatise, the Abhandlung u¨ber die Evidenz in den Metaphysischen Wissenschaften (1764), Moses Mendelssohn granted that there is a practical difference in the persuasive force of mathematics and metaphysics—mathematics convinces everyone who understands it, but metaphysics does not. Although metaphysics does not possess the same capacity as mathematics to elicit unanimous responses among its students, this difference stems from a lack of intuitive intelligibility (Faßlichkeit) rather than a lack of intrinsic certainty in metaphysics (2:271–272).9 To the extent that there are difﬁculties within metaphysics, they are, in the last analysis, not structural deﬁciencies of the discipline. They are triggered by external circumstances instead. For example, a lot of the controversies surrounding metaphysics come about because it is an investigation of emotionally charged themes (2:295), and because its terms carry different meanings outside of the discipline (2:296). The controversies may be unavoidable, but they are not the fault of the metaphysicians. Metaphysics is just as certain as mathematics, but it is harder to grasp. Mendelssohn defended metaphysics by blaming its readers instead of its writers. Kant’s submission to the contest, the Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morals (the Prize Essay), turned out to be the runner-up at the award announcement. Stating his goal in the introductory paragraphs, Kant declared that he wishes to give metaphysics its highest possible certainty (II 275). In the ﬁrst chapter, he outlined the differences between mathematics and philosophy and argued that the latter should not follow the example of the former. In the second chapter, he identiﬁed and described ‘‘the only method for attaining the highest possible de-

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gree of certainty in metaphysics’’ (II 283). In the third chapter, he asserted that ‘‘metaphysics is capable of a certainty which is sufﬁcient to produce conviction’’ (II 292). He buttressed this claim with examples taken from his own works. Summarizing the contention of the Physical Monadology, Kant explained how simple elements constitute spatial bodies (II 286–287). Repeating the thesis of the New Elucidation, he argued that the ﬁrst principle of reason is a twin principle involving identity and contradiction (II 294– 295). And reiterating the steps of the Only Possible Argument, he outlined the conceptual proof for the existence of God in the fourth and last chapter of the tract (II 296–297).10 One can demonstrate God’s existence rigorously, he argued, and the so obtained theoretical knowledge of God reveals that metaphysical proofs are capable of achieving certainty. With the Only Possible Argument and the Prize Essay, Kant confronted in the ﬁnal months of the year 1762 both a ﬁrst-order and a second-order question—the problem of demonstrating God’s existence, and the problem of the reliability of metaphysical demonstrations. Answering the second-order question in the Prize Essay resulted in a new methodological proposal; answering the ﬁrst-order question in the Only Possible Argument led to the ontological proof. He hoped to achieve with the construction of the latter an illustration of the former. With its argument for and examples of the certainty of metaphysics, the Prize Essay certainly looked like just another apology of speculative philosophy. But this impression is misleading. That the Prize Essay was a proposal for a metaphysics of the future instead of a defense of the systems of the past revealed a fundamental difference between Kant’s runner-up and Mendelssohn’s winning entry. In important respects, Kant’s strategy was the opposite of Mendelssohn’s. Both recognized the murk of disputes that surrounded metaphysics. But Kant blamed the writers, not the readers. Whereas Mendelssohn believed that metaphysics (in its Leibnizian-Wolfﬁan form) was essentially complete, Kant had grave doubts about the present state of speculative philosophy in Germany. The doubts about metaphysics prompted him to propose a new methodology. He maintained that these new methods, if implemented, would elevate future proofs to the exactitude of the truths of geometry. The Prize Essay was an apology only to the extent that its author hoped to make a future philosophy capable of demonstrative certainty. The very fact that such a proposal seemed necessary implied that the established systems were ﬂawed. Unsurprisingly, the Prize Essay contains passing jibes against Leibniz (whose concept of a monad is ‘‘merely invented’’; II 277), against Wolff (whose analysis of mathematical similarity was misguided; II 277), and against Crusius (whose highest rule of certainty begs the question; II 295). While Mendelssohn’s Abhandlung u¨ber die Evidenz was a defense, Kant’s Prize Essay boiled down to a critique: metaphysics can be saved, but only at the price of rebuilding it from scratch. Is metaphysics capable of certainty? Mendelssohn’s reaction was a conﬁdent ‘‘yes’’; Kant’s answer was ‘‘not yet.’’ If his new method were adopted, Kant asserted, it would terminate the ‘‘endless instability of opinions and scholarly sects’’ (II 275; WM 247) that

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is symptomatic of the shortcomings of metaphysics. This denunciation of metaphysics was probably the root of the famous dictum in the Critique of Pure Reason that metaphysics is ‘‘the battleﬁeld of these endless controversies’’ (A viii). Discussing time as an example, Kant remarked in the Prize Essay, If we had as many correct deﬁnitions of time as there are deﬁnitions to be found in the books devoted to the subject, with what certainty could inferences be made and conclusions drawn. But experience teaches us the opposite. (II 284; WM 256–257)

The record of metaphysics, in Kant’s view, was anything but encouraging—a genuine deﬁnition of spirit was still lacking (II 277); nobody had ever intelligibly analyzed freedom (II 282); a good criterion of truth did not exist (II 295); and no proofs were available for the highest moral rules (II 299). Not only were a number of metaphysical terms still in want of basic clariﬁcations, but it was not even certain whether such clariﬁcations can be provided at all. Notions such as ‘‘representation,’’ ‘‘being next to each other,’’ and ‘‘being after each other’’ are ‘‘scarcely capable of analysis at all,’’ Kant remarked; ‘‘space,’’ ‘‘time,’’ or the terms denoting the many different feelings of the soul such as ‘‘the feeling of the sublime, the beautiful, the disgusting,’’ and so forth, are concepts that ‘‘can only be partially analyzed’’; ‘‘pleasure,’’ ‘‘displeasure,’’ ‘‘desire,’’ and ‘‘aversion’’ have not yet been adequately analyzed (II 280; WM 252–253). ‘‘Innumerable’’ metaphysical concepts are in want of suitable deﬁnitions, Kant noted. Metaphysical propositions are not faring any better. If one drew up a table of the indemonstrable propositions that lie at the foundation of philosophy, ‘‘such a table would constitute a scheme of immeasurable scope’’ (II 281; WM 253). He summarized: Metaphysics is without doubt the most difﬁcult of all the things into which man has insight. But so far no metaphysics has ever been written. (II 283; WM 255)11

Was he rebuking the work of others, or did he repudiate his own philosophical efforts as well? The precritical project was evidently metaphysics. None of the actual reconciliations of science and metaphysics—the teleological theory of the cosmos, the compatibilist theory of freedom, the dynamic theory of matter—amounted to a scientiﬁc theory in the meaning that Kant gave to the term. According to the Physical Monadology, natural science investigates the laws of nature, and metaphysics seeks to discover their underlying causes (I 475). According to the Prize Essay, mathematics concerns quantity, and metaphysics focuses on quality (II 282).12 In regard to either criterion, the precritical project was metaphysics, not science. It concerned causal explanations of the structures of reality in contradistinction to the natural sciences, and (as Mendelssohn believed as well) it involved qualitative procedures in contradistinction to the exact sciences.13 The ﬂip

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side of the methodological proposal of the Prize Essay was the case against the validity of metaphysics done so far. Where did this leave Kant’s own project? As we have seen, Kant’s precritical project concerned the reconciliation of the Newtonian model of nature with three assumptions of metaphysics— the purposive development of nature, the possibility of a morally relevant freedom, and the existence of God—and the combination of the scientiﬁc and metaphysical perspectives to a comprehensive and coherent philosophy of nature. In the Prize Essay, Kant presented the ontological proof as a positive example of the new method. He summarized the proof after boldy claiming that ‘‘the fundamental principles of natural theology are capable of the greatest philosophical certainty’’ (II 296; WM 270). He preserved one cornerstone of the precritical project with the continued defense of the ontological argument. But the two other cornerstones—purpose and freedom— were absent from the Prize Essay. The twin peaks of Kant’s philosophy in the 1750s had been the construction of an immanent teleology that justiﬁed purpose in nature and the analysis of causation that harmonized necessity with freedom. In the Prize Essay, he remained silent about the immanent teleology. It could not qualify as an instance of a deductively certain procedure of metaphysics because his earlier justiﬁcation of purpose in nature had been based on analogies and inductive reasoning and was thus merely probabilistic. With respect to the new methodological program, the immanent teleology ﬂunked. The ontology of freedom failed to make an appearance in the Prize Essay as well—although freedom, as the condition of the possibility of morals, belonged to the subject-matter of the essay, and although the ontology of freedom had been based on deductive reasoning. Not only did Kant not mention it, but he also maintained that nobody had ever succeeded in furnishing an explanation of the elements of freedom (II 282). But was not the New Elucidation in part this very explanation? It certainly had been the attempt at a metaphysics of freedom, but apparently it had not sufﬁced. With regard to the extant explanation of freedom and other subject-matters of philosophy, Kant declared in the Prize Essay, ‘‘so far no metaphysics has ever been written’’ (II 283; WM 255). Apparently, not even the causal analysis of freedom in the New Elucidation qualiﬁed as metaphysics. With the damning verdict that ‘‘so far no metaphysics has ever been written,’’ Kant did not spare his own efforts. The precritical project was falling apart. Of the envisioned metaphysics that combined Newtonian physics with a teleology of purpose, a deduction of freedom, and a demonstration of God, only the ontological proof remained. It was the last, solitary bulwark standing in the ruins of a once grand design. How solid was this last bulwark, in Kant’s assessment? The Prize Essay portrayed the ontological proof as the paradigm of certainty, but the Only Possible Argument, containing its detailed exposition, had presented it rather differently. In the preface of the Only Possible Argument, Kant had systematically downplayed the merits of the proof. Providence, he had written there

The Newtonian Program of the Prize Essay and Kant’s Crisis 215

(II 65; WM 111), had directly transmitted to our ‘‘natural common sense’’ the cognition that there is a God, thus, the endeavor of supplying a demonstration of this cognition is actually not that important. The insight that God exists does not depend on ‘‘the sophistry of subtle inferences’’ (ibid.). Certainly, such a demonstration might be able to illuminate much else in this object, but ‘‘to achieve this purpose, however, one must venture into the bottomless abyss of metaphysics’’ (II 65–66; WM 111). Kant had readily conceded in the preface of the Only Possible Argument that his ontological proof should not be mistaken for an actual demonstration (II 66). The desired proof has neither been discovered by others, nor has it been provided by the author in the text that follows. What he had intended to provide was less, he had written; he just hoped to provide the preliminary groundwork— ‘‘merely an argument in support of a demonstration’’ (II 66; WM 112). Even downgraded to a propaedeutic exercise, the ontological proof will not amount to much. Although the various analyses furnish correct information about the relevant objects, ‘‘they still await the ﬁnishing hand of the artist, and until they receive it they cannot be regarded as deﬁnitions’’ (ibid.). What the Only Possible Argument contains, Kant had revealed in the preface, is merely the ‘‘construction kit (Baugera¨th) for erecting a building,’’ a construction kit that has been ‘‘assembled with great difﬁculty’’ (II 66; my transl.).14 Perhaps the extraordinary modesty of the preface was a clever ruse to ensure the successful reception of the book. If so, then it surely worked. Mendelssohn reviewed the Only Possible Argument for the biweekly journal Briefe, die neueste Litteratur betreffend (‘‘Letters Concerning Current Literature’’) in four installments in April and May 1764. Although it is obvious that he was not quite convinced by Kant’s line of reasoning, his review was decidedly sympathetic. For Mendelssohn, the humble tone of the preface made all the difference. After all, a bombastic title such as The Only Possible Argument for a Demonstration of God’s Existence could have easily sounded offensive to the ear of an eighteenth-century metaphysician. Kant seemed to brag that only one proof is possible, namely, his own. And he did so at a time when philosophers and theologians, the intended readers, were championing a wide range of different proofs for God’s existence. The title might be construed as a challenge, or worse, as an insult. As Mendelssohn observed: After one had employed in the republic of scholars almost everything in the sciences and in nature as evidence for the existence of God—from algebraic formulas to the tiniest worm crawling in the dust—Mr. Kant dares to announce to the world, in a tract published in Ko¨nigsberg this year, the Only Possible Argument to a Demonstration of God’s Existence. Would he not set part of the whole republic against himself with this claim?15

But, Mendelssohn continued, the author ‘‘explains himself on this point in his preface with such an intelligent determination and at the same time with such modesty, that one needs to hear him out.’’ What saved Kant, in

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the reviewer’s opinion, is that he did not want to be understood as offering the ﬁnal and conclusive demonstration, but that he ‘‘merely wishes to provide the grounding of the proof (Beweisgrund), or the construction kit (Baugera¨the), and present it for examination.’’ Thus, the Only Possible Argument was intended as a foundational preparation of a future demonstration, as a Beweisgrund, and not as the actual delivery of a Beweis or demonstration as such. In the remainder of the review, Mendelssohn enumerated difﬁculties in Kant’s argumentation.16 Some pieces of Kant’s ‘‘construction kit’’ were problematic, but these problems struck Mendelssohn as questions requiring further answers or as claims needing greater elaboration, and not as quandaries dooming Kant’s endeavor.17 A clever ruse? Or tormented ambivalence? Whatever it was, Kant presented the ontological argument to the public through the ﬁlter of two contradictory characterizations. One and the same thing, the ontological proof, was, according to the Prize Essay, a demonstration achieving certainty in natural theology, and, according to the Only Possible Argument, a set of preliminary considerations supplying materials for an as yet unachieved demonstration. An awareness of the boldness of the title, combined with the urge to appease his audience, might have compelled Kant to downplay the proof in such a dramatic fashion. If the modesty of the preface was a gesture of respect to other metaphysicians, its purpose would have been to mollify the academic peers so as to persuade them of the merits of the book. But why had Kant’s qualiﬁcations been so much more intense than seemed necessary for achieving such a purpose? Why had the modesty escalated to selfdenigration? Since knowledge of God’s existence does not depend on one’s acquaintance with this particular demonstration, Kant had granted that the ‘‘only possible argument’’ was unnecessary. Because it was a ‘‘rough outline of a general draft’’ instead of a ‘‘precise painting in of all the lineaments in the individual parts’’ (II 66–67; WM 112), he had conceded that the proof was insufﬁcient. And as if this was not enough, he had admitted that this unnecessary and insufﬁcient argument was defective: In a reﬂection as difﬁcult as the present one, I can, I suppose, resign myself in advance to the fact that many of the things I shall say will be incorrect, that many of the elucidations I shall offer will be inadequate, and that many of the positions I shall develop will prove frail and defective. (II 68; WM 113–114)

Kant had confessed that his reasoning contains ‘‘defects’’ and ‘‘errors’’ that await ‘‘remedy’’ and ‘‘correction,’’ and he had voiced the hope that the reader will not rivet ‘‘his brooding attention on some detail or other’’ (II 67; WM 113). How can an author hope to be convincing if he grants that his argument is ﬂawed? There is reason to suspect that there was more involved in the humility of the preface than a strategic attempt at preempting critics. It is as if Kant suspected that the constructions of the Only Possible Argument did not meet the self-imposed standards of methodological rigor. If this is true, then none of the three cornerstones of the precritical project had suc-

The Newtonian Program of the Prize Essay and Kant’s Crisis 217

cessfully withstood the onslaught of Kant’s scrutiny. The immanent teleology was not worth mentioning because it was plausible but not certain; the reconciliation of natural necessity and moral freedom was problematic because a deduction of the concept of freedom was still missing; and the ontological argument failed as a paradigmatic example because it merely pointed in the right direction without constituting a conclusive demonstration. The precritical project as a whole was now in jeopardy.

9.2 Rebuilding Metaphysics from Scratch In the second edition of the Critique of Pure Reason, Kant would write that metaphysics ‘‘rests on concepts alone’’ (B xiv). Because it is supposed to yield new information and produce fresh insights, it ‘‘ought to contain a priori synthetic knowledge’’ (B18). But metaphysics has not yet succeeded at this task, and its procedure ‘‘has hitherto been a merely random groping’’ (B xv). In the Prize Essay—predating the second edition of the Critique by more than twenty years—Kant arrived at a similar assessment. Metaphysics operates with concepts, its signs are words whose abstract meanings need to be represented (II 278–9), and it ought to evolve into a synthetic endeavor analogous to mathematics (II 290). In both works, he regarded metaphysics as a promise rather than a practice and viewed mathematics as the yardstick of a successful investigation. As he remarked in the Critique, mathematics is ‘‘a shining example of how far, independently of experience, we can progress in a priori knowledge’’ (A4/B8). With the Prize Essay, Kant was heading toward the issue that would later acquire supreme importance, the problem of the possibility of metaphysics as a system of a priori synthetic judgments. With the Critique of Pure Reason, the problem would evolve to the fundamental question of whether such a metaphysics is possible. The concern of the Prize Essay was not so yet whether but how metaphysics can be possible. Asking ‘‘how’’ presupposes that metaphysics is possible in some manner, and that the issue is essentially a matter of determining the right form of metaphysics. The faith which this presupposition implies separated the Prize Essay from the Critique. In the later work, an older and disillusioned Kant would proceed to investigate the structure of cognition and identify the epistemic forms which organize and guide sensory impressions as the sought-after synthetic judgments a priori. In the earlier text, a younger and anxious Kant recognized that the synthetic thrust of metaphysics was problematic, but he did not yet perceive the full magnitude of the problem. Nor had he discovered that its resolution would require an epistemological instead of a methodological investigation. The methodological proposal of the Prize Essay amounted to a case for a conceptual analysis as the starting point of metaphysics. Synthetic philosophical reasoning is premature as long as the a priori notions that it involves are riddled with ambiguities. Eventually, metaphysics should turn into a synthetic discipline, but its current limitations prohibit this transformation at present:

218 The 1760s: Climax and Crisis Metaphysics has a long way to go yet before it can proceed synthetically. It will only be when analysis has helped us towards concepts which are understood distinctly and in detail that it will be possible for synthesis to subsume compound cognitions under the simplest cognition, as happens in mathematics. (II 290; WM 263)18

The reason for the mandatory analytic phase of metaphysics, Kant thought, lies in the peculiar difﬁculties that distinguish speculative philosophy from successfully synthetic disciplines such as the branches of mathematics (II 276).19 Geometry can make exact inferences about the properties of a circle by basing them on the concrete representation of a drawn circle; arithmetic generates exact results from calculations because the calculations involve speciﬁc signs that are posited as stand-ins for objects. Mathematics employs ﬁgures and symbols that are ‘‘concrete’’—that refer to speciﬁc, clearcut objects (II 278). Because mathematical objects are quantities (which are nonambiguous and can be sharply delineated), the utilization of such concrete signs is possible (II 282).20 Philosophy cannot proceed in concreto, Kant feared. It is forced to start with the concepts of common speech, that is to say, with ‘‘concepts which are given in a confused fashion’’ (II 278; WM 250). As he saw it, mathematics stipulates and deﬁnes its own concepts. Thus, mathematical concepts are precise. But metaphysics uses terms that already carry beforehand vague and ambiguous meanings (II 279). Like mathematics, philosophy pursues the discovery of general (necessary and universal) properties in its objects. But the only way this can be done, in the absence of concretely posited signs, is by abstraction. Metaphysics needs to identify the ‘‘core’’ senses of the words and distinguish them from coincidental connotations that words obtain through their usage in common speech: Hence . . . one has to focus one’s attention on the thing itself: one is constrained to represent the universal in abstracto without being able to avail oneself of that important device which facilitates thought and which consists in handling individual signs rather than the universal concepts of the things themselves. (II 279; WM 251)

Thus, philosophy must proceed in abstracto. This difference from mathematics is due to the different contents of the two disciplines. Echoing Crusius, Kant asserted that mathematics concerns quantities and metaphysics concerns qualities.21 But quantities are uniform, whereas qualities are inﬁnitely diverse. There are accordingly few primitive terms in mathematics, but an abundance of them in metaphysics (II 279–82). Because metaphysics has no choice but to operate with fuzzy terms denoting heterogeneous qualities, it is inevitable that metaphysicians often do not know what they are talking about, that their systems contain far more obscure concepts and questionable propositions than mathematics (II 280–1), and that their inferences are correspondingly more tenuous (II 282–3).22

The Newtonian Program of the Prize Essay and Kant’s Crisis 219

Since the concepts are the components on which all inferences depend, their analysis is necessary (II 280). If one skipped the analysis and started synthesizing right away, one would produce arbitrary, ‘‘grammatical deﬁnitions’’ instead of informative, philosophical deﬁnitions (II 276)—one would make words up instead of ﬁnding things out. The interminable controversies of metaphysics would then continue (II 278). The fundamental deﬁciency of current metaphysics is that their basic notions are neither clearly nor exhaustively known. Before we can hope to engage in fruitful synthetic constructions, we must ﬁrst provide an analytic foundation for such endeavors. However, the vocabulary of natural language can never be as precise as the symbols of the exact sciences. Even the most thorough dissection of terms would not furnish philosophy with a certitude that equaled the conviction of mathematics (II 290).23 But this does not matter, Kant thought, for the certainty of natural science falls short of the exact sciences too, while still sufﬁcing for the growth of knowledge. Speculative philosophy can be modeled after the natural sciences. If metaphysics wants to be as successful as physics, it must follow its example: The true method of metaphysics is basically the same as that introduced by Newton into natural science and which has been of such beneﬁt to it. Newton’s method maintains that one ought, on the basis of certain experience and, if need be, with the help of geometry, to seek out the rules in accordance with which certain phenomena of nature occur. (II 286; WM 259)

Kant applied here Newton’s proposal in query 31 in the Opticks, that analysis ought to precede synthesis in natural philosophy, and that analysis is guided by experience. Analysis, for Newton, had consisted of ‘‘making experiments and observations, and in drawing general conclusions from them by induction, and admitting of no objections against the conclusions but such as are taken from experiments, or other certain truths’’ (p. 404): By this way of Analysis we may proceed from Compounds to Ingredients, and from Motions to the Forces producing them; and in general, from Effects to their Causes, and from particular Causes to more general ones, till the Argument end in the most general. This is the Method of Analysis: And the Synthesis consists in assuming the Causes discover’d, and establish’d as Principles, and by them explaining the Phaenomena proceeding from them, and proving the Explanations. (Opticks, q. 31, 404–5)

Newton’s method meant for Kant that natural sciences must begin with well-conﬁrmed empirical data and proceed through quantiﬁcation and deduction to the identiﬁcation of the lawful structures of the phenomena. The features of this method are the absence of speculative approaches, the uncontested primacy of experience, and the employment of mathematics for the derivation of laws from quantiﬁed observations.24 Applied to metaphysics, these three aspects—an empirical focus, quantitative procedures,

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and speculative caution—enter into Kant’s rules for the correct method of metaphysics: The ﬁrst and the most important rule is this: one ought not to start with deﬁnitions, unless that is, one is merely seeking a nominal deﬁnition, such as, for example, the deﬁnition: that of which the opposite is necessary . . . One ought, rather, to begin by carefully searching out what is immediately certain in one’s object, even before one has its deﬁnition. (II 285; WM 258)

Deﬁnitions are never viable starting points for metaphysical investigations. In philosophy, ‘‘one can often come to know a great deal about an object with distinctness and certainty . . . prior to having a deﬁnition of that object, and even, indeed, when one had no intention of furnishing one’’ (II 284; WM 257). Proceeding from deﬁnitions would either involve a nominal deﬁnition (Namenerkla¨rung) that is ‘‘of little or no use to us, for even without the nominal deﬁnitions the world is understood well enough not to be misused’’ (II 284; WM 256), or a speculative deﬁnition that is arbitrary because it is not grounded in anything. Kant’s ‘‘ﬁrst and the most important’’ methodological rule reﬂects the speculative caution embodied in the ‘‘I feign no hypotheses’’ dictum that concludes the Principia. The legitimate startingpoint of metaphysics is the philosophical correlate of empirical experience. Just as physics begins with data gathered from the examination of phenomena, philosophy should begin with a certain, inner experience (sichere innere Erfahrung), with a procedure of ‘‘carefully searching out what is certain in one’s object’’ (II 286; WM 259): . . . by means of a certain inner experience, that is to say, by means of an immediate and self-evident inner consciousness (unmittelbares augenscheinliches Bewußtsein), seek out those characteristic marks which are certainly to be found in the concept of any general property. (ibid.)

Both for Newton and for Kant, speculative caution and primacy of experience went hand in hand. To deemphasize the former meant to emphasize the latter. Not unfettered speculation, but heuristic suppositions guided by observational data allowed the progress of the natural sciences. The point of the fourth regula philosophandi of the Principia (M 2:400, K 2:555) had been to establish the dependence of hypotheses on empirical evidence. Newton had not been hostile to speculation as such, but he had been impatient with objections based on speculative grounds to his empirical conclusions.

9.3 The Employment and Imitation of Mathematics Kant’s second rule for the correct method of metaphysics corresponds to the aspect of Newton’s method that concerns the systematicity of mathematical deductions:

The Newtonian Program of the Prize Essay and Kant’s Crisis 221 The second rule is this: one ought particularly to distinguish those judgments which have been immediately made about the object and relate to what one initially encountered in that object with certainty. Having established for certain that none of these judgments is contained in another, these judgments are to be placed at the beginning of one’s inquiry, as the foundation of all one’s inferences, like the axioms of geometry. (II 285; WM 258)

Earlier on, Kant had made it clear that metaphysics cannot employ mathematical procedures, in part because they are synthetic while metaphysics must start analytically, and in part because metaphysics is about the qualitative essences of things which preclude quantiﬁcation. The distinction drawn between mathematics and metaphysics entails that metaphysics cannot adopt the form of mathematics and begin with synthetic constructions. It further implies that metaphysics cannot directly implement and appropriate mathematical tools. But other aspects of mathematics should be followed. Kant’s second rule suggests that metaphysics ought to mirror mathematics in terms of its logical systematicity. Metaphysics involves deductive steps of reasoning, and they follow the same patterns of reasoning one ﬁnds in mathematics.25 The ﬁrst and second rule combined result in the following model: metaphysics should begin with a conceptual analysis, the resulting data should be organized as a list of axioms, and all subsequent reasoning should be based on these axioms alone. In addition to the logical systematicity of mathematics, metaphysics can follow mathematics in terms of its results. Although it remains unable of incorporating quantitative procedures into its own investigations, it should draw on the results of mathematics. The physical monadology illustrates that the resolution of the puzzle of the inﬁnite divisibility of substances must factor in the geometric conception of space (II 286–7). In this regard, metaphysics cannot argue against geometry, discounting its results as merely imaginary constructions. It should rather acknowledge and proceed from the results of geometry. In the Re´ﬂections sur l’e´space et le temps, Euler had argued that ‘‘the knowledge of these truths [of mechanics, geometry, and all the quantitative sciences] is capable of serving as a guide in these intricate searches [of metaphysics].’’ As several commentators rightly point out (Polonoff, 1971; Friedman, 1992b), the inﬂuence of Euler on Kant is evident.26 In the preface to the Negative Quantities, where Kant quoted from Euler’s Re´ﬂections, he stressed this point: Metaphysics seeks to discover the nature of space and establish the ultimate principles. . . . Now, nothing could be of more use in such an undertaking than the capacity to acquire reliably established data from some source or other, with a view to using them as the foundation of one’s reﬂections. Geometry furnishes a number of such data relating to the most universal properties of space. . . . (II 168; WM 207–8)

A third point of proximity between mathematics and metaphysics concerns the so-called geometric method.27 The geometric method suggests that

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philosophy adopts certain structural features of mathematics such as its precise orderliness, successive inferential steps, and explicit identiﬁcations of axioms, theorems, and corollaries. According to this method, philosophy is supposed to copy the deductive procedures characteristic of mathematics. Having established certain truths as axioms, philosophers ought to derive their claims deductively from them. Depending on their logical position in the argumentative context and their philosophical signiﬁcance in regard to the thrust of the treatise, the derived claims are then to be labeled ‘‘theorems,’’ ‘‘propositions,’’ ‘‘corollaries,’’ ‘‘lemmata,’’ and the like. The geometric method was primarily a stylistic matter, a nonmathematical duplication of mathematical style and reasoning. The origin of the method which had been popular with the Leibnizian-Wolfﬁan School Philosophers has been ascribed by several scholars (Wundt, 1924; Vleeschauwer, 1931; Paolinelli, 1974) to the natural philosopher Ehrenfried Walther von Tschirnhaus (1651–1701).28 Actually, the method was in use before Tschirnhaus published his work on philosophical methodology, the Medicina Mentis (1687; second and expanded edition 1695).29 Probably the best-known example of a work written more geometrico is Spinoza’s Ethica (1677). There were also signiﬁcant differences between Tschirnhaus’s assessment of the geometric method and its evaluation by the School Philosophers and the pietists. Both for Tschirnhaus and later philosophers such as Wolff or Crusius, rational, mathematical entities were immaterial and ﬁctitious, whereas physical entities were material and real (MM 74–76; H 104–5). But Tschirnhaus had found more similarities between rational and real entities than either Crusius or Wolff were willing to acknowledge. Both rational, mathematical objects and real, physical objects are known through conception, and both presuppose, in somewhat different form, extension (ibid.). Because they share the same cognitive access and the same ontological feature, they are sufﬁciently similar so that the investigation of one class of objects is relevant for the investigation of the other class. In Tschirnhaus’s methodology, these resemblances had turned into an argument for the use of mathematics in natural philosophy—both in terms of the actual employment of quantitative approaches (rejected by Wolff and Crusius), and in terms of the geometric method (adopted by Wolff; rejected by Crusius). In tune with his interests in a theory of research and the practice of experimentation, Tschirnhaus’s conception of ‘‘natural philosophy’’ bore more resemblances with Newton’s philosophia naturalis than with the natural philosophy advocated by the Wolfﬁans or the pietists.30 Kant rejected, like Crusius, the quantitative imitation of mathematics by philosophy. He had no problem with the imitation of mathematics in terms of the geometric method. To the extent that the geometric method concerned the logical structure of patterns of reasoning, Kant’s second rule for a new metaphysical method endorsed it. And to the extent that the geometric method amounted to a particular way of writing, to an idiosyncratic style, it was a matter of taste and methodologically irrelevant. Contrary to Friedman’s claim (1992b), the geometric method was not objectionable according to the Prize Essay.31 Kant was fond of the geometric method as a manner of organizing his exposition and used it in On Fire, the New Elucidation, the

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Physical Monadology, to a certain extent in the Inaugural Dissertation, and, in the critical period, in the Metaphysical Foundations of Natural Science (1786).

9.4 The Inner Experience of Conceptual Elements. Kant and Lambert According to Kant’s ﬁrst rule, the starting point of the proper procedure of metaphysics did not consist of the stipulation of a deﬁnition, but in the search of ‘‘what is immediately certain in one’s object’’ (II 285; WM 258). According to his second rule, the proper procedure involved the distinction of the ‘‘judgments which have been immediately made about the object and relate to what one initially encountered in that object with certainty’’ (ibid.). Kant likened the method of metaphysics to Newton’s method of natural science whose ‘‘basis’’ is ‘‘certain experience’’ (II 286; WM 259). One should then ‘‘seek out those characteristic marks’’ that are ‘‘certainly to be found in the concept of any general property,’’ and one should be guided during this search by ‘‘certain inner experience, that is to say, . . . an immediate and self-evident inner consciousness’’ (ibid.). The proper method of metaphysics is analysis. And analysis, as Kant conceived of it, revolves around the certitude of inner experience. In the Epistola ad Hardenberg de Summis Rationis Principiis (1752), Crusius had suggested a version of inner certitude that results from two of his three principles of metaphysics. The ﬁrst principle is the law of contradiction (Metaphysik, C 2:23, #13). The other two principles which ground inner certitude are the law of what cannot be separated (principium inseparabilium) and the law of what cannot be combined (principium inconiungibilium) (Epistola, C 4.1:351). The principium inseparabilium states that what cannot be thought in separation, is not separate; and the principium inconiungibilium states that what cannot be thought together, is not together. The three principles combined, Crusius had argued, constitute the structure of reasoning and express the criteria of truth (C 4.1: 352).32 God teaches us truth by means of them, and they force us to think in a particular way (C 4.1: 352–3). In other words, Crusius had been convinced that whatever we are forced to think of as true, is indeed factually true. Kant rejected this conception of inner certitude. The way we think, he reminded Crusius in the Prize Essay, does not necessarily indicate how things are. Therefore, a feeling of truth does not furnish a reliable criterion of truth (II 295). Although a feeling of truth is not a criterion of truth, Kant conceded to Crusius that it remains a part of such a criterion. In his view, it is undeniable that a feeling of certitude, in the sense of an immediate evident awareness, is a necessary condition of this criterion. Crusius’s mistake (to use contemporary terminology) had been to misidentify a necessary condition of truth as a sufﬁcient condition. As a necessary feature of truth, this immediate evident awareness gained universal relevance: Certainty in metaphysics is of exactly the same kind as that in any other philosophical cognition, for the latter can only be certain if it is in accordance

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with the universal principles furnished by the former. We know from experience that, even outside mathematics, there are many cases where, in virtue of rational principles, we can be completely certain, and certain to the degree of conviction. Metaphysics is nothing but philosophy applied to insights of reason which are more general, and it cannot possibly differ from philosophy in this respect. (II 292; WM 266)

Kant argued that his method of metaphysics is the same as Newton’s and that the investigations of metaphysics ought to follow rules which imitate the natural sciences. This has prompted Friedman (1992b) to equate Kant’s inner experience with Newton’s outer experience.33 Such an equation would blend the certitude of inner experience in metaphysics with the starting point of the sciences. Then, the starting point of metaphysics, as the positive ground of its investigations, would consist of the empirical data of the natural sciences as well as the axiomatic propositions of the exact sciences. But this reading is not quite right; it would at best underdetermine the supposedly evident ground of metaphysics. Kant concurred with Euler, particularly in the Negative Quantities, that metaphysical inquiries ought to incorporate the research results of mechanics and mathematics. For Kant, the materials provided by the sciences constitute part of the positive ground of metaphysics. But the scientiﬁc ground cannot be the metaphysical starting point as such. If the evident data and axiomatic propositions furnished by the sciences were the only positive ground of metaphysics, then metaphysics, as an analysis, would have to restrict itself to a conceptual dissection of the notions provided by the sciences. Not only would such a version of metaphysics degenerate to a largely superﬂuous qualitative commentary on what is better developed in a quantitative fashion, but it also could never do justice to the totality of the notions that Kant identiﬁed as the actual subject-matter of metaphysics in the Prize Essay. The notion of geometrical space, which is central to the ﬁrst example of a viable metaphysics (II 286–287), is a concept whose analysis contributes to the resolution of the problem of indivisible substances. But concepts of this sort alone do not sufﬁce as a foundation for metaphysics. Kant’s second example for a viable metaphysics, the ontological argument, makes this clear. Here, the starting point of the analysis is what is evident to inner experience about the notions of existence, necessity, and possibility. The ‘‘chief concept’’ of this analysis is the concept of the absolutely necessary existence of a being (II 296). The analysis of ‘‘necessary existence’’ leads to a second concept, ‘‘possibility’’ (II 297), and the analysis of both of these concepts brings one to other derivative notions, namely, ‘‘the concepts of [the divine] Being’s other determinations’’ such as ‘‘omnipresence’’ and ‘‘foreknowledge’’ (II 297), whose dissection would complete the proof. If metaphysics wishes to remain recognizable as a metaphysics, it will have to concern nonscientiﬁc concepts of the kind that the second example is about. Because the positive ground of metaphysics consists not only of the data and the axioms that are evident through the sciences, but also of

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the elementary components of genuinely metaphysical notions—elements that are open to an immediate evident awareness—the positive ground of metaphysics involves a version of certitude that is reminiscient of Crusius. Although Kant rejected the Crusian axioms, his own program prevented him from abandoning their underlying idea. For Kant, the ultimate criterion of metaphysical truth is the phenomenological certitude that arises when isolating the genuine elements of abstract concepts. If one assumes that these elements correspond to the structure and content of reality, and furthermore, that the ‘‘certainty to the degree of conviction’’ (which consists of the compelling belief that things must be just so and cannot be otherwise) guides the discovery of these elements, then one will revert to the Crusian position that whatever we are forced to think as true, must be true. But Kant’s ultimate criterion of metaphysical truth, the phenomenological certitude which indicates the correct analysis of abstract concepts into their elements, is problematic. This is obvious from Kant’s second example. A consideration of the concept of possibility—the starting point of the actual proof in the Only Possible Argument—reveals that the allegedly analytic derivation of ‘‘necessary existence’’ is not a sheer unpacking of ‘‘possibility,’’ but that it involves the tacit (and illicit) addition of philosophical constructs. In the example of the Prize Essay, Kant characterizes the concept of absolutely necessary existence as the starting point of the ontological argument. Arguably, nothing is added to this initial concept, but the concept itself, as a philosophical construct, is an addition. ‘‘Existence’’ is surely a given, but ‘‘absolutely necessary existence’’ is not. On one level, the Newtonian program of the Prize Essay is plausible. Because the problems of metaphysics can involve conceptual confusions, the concepts, their components, and their consequences must be clariﬁed. The clariﬁcation is an analytic procedure. One must be attentive that one chooses as the ground of any deduction only what is immediately evident, and that one does not import anything foreign to the deductions. But the source of the conceptual confusions that impede metaphysics is not only a sloppiness in logical form, but also a spuriousness in conceptual matter. Some fundamental concepts of metaphysics remain dubious regardless of how one tries to analyze them. Unfortunately, this includes concepts of both examples used by Kant—the absolutely necessary existence in the ontological proof, and the indivisible substance in the physical monadology. Kant realized that far more work would be required in order to clarify the difﬁculties surrounding metaphysical certainty. In a letter to Formey on 28 June 1763, in which he expressed his gratitude for the favorable assessment of the Prize Essay by the Prussian Royal Academy, he asked whether it might be possible to insert a supplement to the Prize Essay’s publication (X 41–2). On 5 August 1763, Formey responded reassuringly; if Kant sent the supplement to him, he would make sure that it would be printed in the volume of the prize essays (X 42). The supplement never materialized, and in May 1764, the Prize Essay was published without it. One and a half years later, on 13 November 1765, the

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Swiss-German mathematician and philosopher Johann Heinrich Lambert wrote Kant an extraordinary letter. Lambert had read the Only Possible Argument and the Prize Essay, and he introduced himself to Kant with a simple statement of allegiance. ‘‘I believe,’’ he wrote, ‘‘that the similarity of our ways of thinking will excuse this letter, its frankness, and the omission of customary circumlocutions’’ (X 51; Z 43–4).34 The similarity of thinking indeed covered a multitude of aspects. Lambert’s recently published Cosmologische Briefe u¨ber die Einrichtung des Weltbaues (‘‘Cosmological Letters on the Establishment of the Universe’’) contained a theory of the dynamic constitution of the solar system and the home galaxy that resembled Kant’s.35 Like the Universal Natural History, the Cosmologische Briefe was an application of Newtonian principles to astronomical phenomena, and unsurprisingly, both works converged in their results. Lambert explained to Kant that he had not been aware of the Universal Natural History when writing his book and only learned of its existence because Kant had mentioned it in the Only Possible Argument.36 Nor had he been aware, he continued, of Thomas Wright’s An Original Theory and New Hypothesis of the Universe (1750), the tract that was one of the sources of the Universal Natural History (X 53–4). In addition to the afﬁnity in matters of natural philosophy, Lambert shared with Kant crucial assumptions regarding the methodology of speculative philosophy. In the same year in which he had written the Cosmologische Briefe, he had prepared a tract on method that he titled Abhandlung von dem Criterium veritatis (‘‘Treatise on the Criterion of Truth’’).37 Prompted by the prize question on the demonstrability of metaphysical principles, Lam¨ ber die Methode, die Metaphysik, Theologie, bert had penned another essay, U und Moral richtiger zu beweisen (‘‘On the Method of Improving the Demon¨ ber die strations of Metaphysics, Theology, and Morals’’). He did not submit U Methode to the contest because he failed to meet the deadline.38 Lambert decided to incorporate material from both of these pieces in a comprehensive tome on the subject, the Neues Organon, oder Gedanken u¨ber die Erforschung und Bezeichnung des Wahren und dessen Unterscheidung vom Irrthum und Schein (‘‘New Organon, or Thoughts on the Discovery and Designation of Truth and its Differentiation from Error and Appearance’’).39 The Organon became Lambert’s main work. The remarkable feature of the Organon is that it was a large-scale execution of Kant’s methodological proposal. Kant had contended that metaphysics can only be saved if its basic concepts were analyzed, and Lambert endeavored to perform this very analysis in the Organon. Before Kant published the Prize Essay, Lambert had already arrived at the conclusion in the Criterium veritatis that ‘‘the certainty of the whole human cognition resolves in the question of the rectitude of concepts’’ (#46). Inspired by John Locke’s theory of the simple ideas (from the Essay Concerning Human Understanding of 1690), Lambert believed that the resolution of the question of concepts is tantamount to the analysis of complex concepts into their elements. The analysis terminates in ‘‘simple concepts’’ (einfache Begriffe). As he noted in the ‘‘Dianoiologie’’ (the ‘doctrine of the laws of thought’ and part I of the Organon), the simple concepts are the ultimate

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components of metaphysics and the foundation of the whole of knowledge (1:420, #653). In the ‘‘Alethiologie’’ (the ‘doctrine of truth’ and part II of the work), Lambert added that the distinguishing feature of simple concepts is their inevitable uniformity (1:457, #9). And once again, the epistemic indication of simple concepts, in addition to their structural feature of uniformity, is their immediate evidence (1:420, Dian. #653). The undeniable parallels prompted Lambert to write in his letter to Kant that ‘‘I found in [the Only Possible Argument] my own thoughts and even the phrases I would choose to express them, and I decided at once that if you were to see my Organon you too would ﬁnd your own likeness in most of my book’’ (X 51; Z 44). The letter concludes with an astonishing but perfectly logical proposal: Lambert wanted to collaborate with Kant. We are left to wonder how the history of ideas would had turned out if the philosophical collaboration had come to pass. Kant responded on 31 December 1765, obviously pleased, and returned the compliment by calling Lambert ‘‘the greatest genius in Germany’’ (X 54; Z 47). This was not just mere ﬂattery. Kant genuinely admired Lambert’s research and had already noticed ‘‘the fortunate agreement of our methods’’ (X 55; Z 48). Years later, while working on the Critique of Pure Reason, he wanted to dedicate the Critique to him and only changed his mind when he learned of Lambert’s death (1777).40 At any rate, in his reply in 1765, Kant expressed strong interest in working with Lambert (X 55). Lambert took Kant at his word. Lambert’s next letter (3 February 1766; X 62–7), obviously intended as a platform for discussions, concerns the relationship of form and matter and the comparison of philosophical and mathematical knowledge. But nothing came of it. Kant did not write back. Lambert would wait ﬁve long years before hearing from him again. When ﬁnally Kant wrote again, on 2 September 1770 (X 96–9), he apologized for the delay and described the new insights of the Inaugural Dissertation which he enclosed with the letter. By then, the opportunity for collaboration had passed. With the Dissertation, Kant was moving in a new direction. When Lambert read this last letter he would receive from Kant, he realized that their former common ground had crumbled away.41 Why did Kant not follow up on his pledge and begin the planned collaboration? The answer is simple: he was stuck. The proposal of the Prize Essay was going nowhere. Kant recognized that the Newtonian program was merely an outline and left important questions open—such as the issue of the certain, inner experience of the conceptual elements. In the Lecture Announcement (1765), he referred to the Prize Essay as ‘‘a short and hastily composed work’’ (II 308; WM 294). But he was unable to continue on the same route and ﬂesh the Newtonian program out. The supplement to the Prize Essay which he had promised to Formey was never written. The sequel, which his publisher Kanter had advertised in the catalog of the Leipzig book fair as the Proper Method for Metaphysics and that Lambert had inquired about in his ﬁrst letter, never materialized. Two other sequels to the Prize Essay, the Metaphysical Foundations of Natural Philosophy and the Metaphys-

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ical Foundations of Practical Philosophy, both of which Kant had announced to Lambert (X 56), never made it beyond the planning stage.42 When explaining the circumstances of the delay of the Proper Method for Metaphysics to Lambert in 1765, Kant revealed the difﬁculty that had slowed him down: Apropos, I must tell you, dear sir, that Mr. Kanter, in true bookseller’s fashion, did not hesitate to announce the title in the Leipzig catalog when he heard from me that I might have a work with that title ready for the next Easter fair. I have, however, departed so widely from my original plan that I now want to postpone this book a little while, for I regard it as the culmination of my whole project. My problem is this: I noticed in my work that, though I had plenty of examples of erroneous judgments to illustrate my theses concerning mistaken procedures, I did not have examples to show in concreto what the proper procedure should be. (X 56; Z 48–9)

As it turned out, this difﬁculty paralyzed Kant’s efforts for good. It made the hoped-for culmination of the precritical project impossible. Kant possessed an outline of a method for metaphysics, but he was at a loss as to how to implement it and turn investigative theory into philosophical practice. The conceptual confusions impeding metaphysics derived in part from the spuriousness of its concepts. Kant’s proposal of an analytic metaphysics involved the assumption that the material to be analyzed is sound in its essence and that only the synthetic constructions based on this material are in need of revisions. This assumption was unrealistically optimistic. Thus, the proposal of the Prize Essay did not point to a fruitful direction. True to Lambert’s and Kant’s assessment of their philosophical convergence, the same limitation is obvious in the Organon. The work was a meticulous analysis of the logic of concepts—but it did not lead anywhere. Like Kant’s proposal, Lambert’s philosophical analysis remained sterile; it neither grounded entrenched metaphysical tenets nor did it prepare a metaphysics of the future. Compared to the philosophy of nature in the 1750s and the critical philosophy of the 1780s, the Prize Essay was a genuine halfway house. The Newtonian program rests upon the realization that metaphysics involves a fundamental structural problem. In this regard, Kant had gone beyond the expectations and hopes of the previous decade. At the same time, the proposal for remedying the ﬂaws of metaphysics while preserving its essence did not yet lead to a fundamental epistemological examination of the conceptual material of metaphysics. In that respect, Kant’s thought had not yet attained the probing depth of the Critique. As it stood, the Newtonian program could not work. Kant would later acknowledge as much when remarking about metaphysics in the Prolegomena (1783) that ‘‘in this domain there is as yet no standard weight and measure to distinguish sound knowledge from shallow talk.’’43

T E N

The Reductio and Collapse of the Precritical Project

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10.1 The Crisis Deepens: Developments from 1763 to 1765 As Kant’s labors took a turn for the worse, his career took a turn for the better. In the years between the Prize Essay and the Dreams of a Spirit-Seer, the precritical project was on the decline, and what used to be the focus of Kant’s ambitions was rapidly becoming the target of self-doubt. At the same time, his star was on the rise. The middle-aged philosopher emerged from the obscurity of being a teacher toiling away in a backwater and stepped into the limelight as a researcher who started to get noticed in the capital. These two parallel developments, personal doubts and professional success, were not connected. On the contrary, he was getting known for the fruits of his project at the very time when he began to ﬁnd them unpalatable. While Kant felt paralyzed in his own work—neither willing to continue with philosophy of nature, nor capable of overcoming its methodological obstacles—Lambert acknowledged the cosmology of the Universal Natural History as a forerunner to the Cosmologische Briefe, Mendelssohn honored the rational theology of the Only Possible Argument with a review in four installments, and Formey edited the Prize Essay in a prestigious publication of the Prussian Royal Academy. In 1763, and in tune with his rising star, Kant completed a treatise that turned out to be his ﬁrst popular success: Observations on the Feeling of the 229

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Beautiful and the Sublime. The Observations was an eloquent and smoothly mixed cocktail of various inﬂuences. As numerous commentators point out, Rousseau’s attack on rigid rationality corresponded to the cognitive signiﬁcance that Kant assigned to feeling in the Observations (Gurvitch, 1971; Schrader, 1976; Ferrari, 1978; Cassirer, 1981; Reich, 1989; Piche´, 1990).1 Burke’s theory of aesthetic categories heavily inﬂuenced Kant’s conceptions of the beautiful and the sublime (Parret, 1992).2 The aesthetic application of Shaftesbury’s and Hutcheson’s moral sense theory furnished the philosophical underpinnings to this popular little work (Henrich, 1957/58; MacBeath, 1973; Sprute, 1980).3 Enamored with the moral sense theory, Kant claimed there that the foundation of true virtue does not consist in speculative rules, but in the ‘‘awareness of a feeling that lives in each human breast and that is more basic than the particular reasons for compassion and pleasantry’’ (II 217). Just as particular actions trigger a moral feeling, so the exposure to certain objects triggers aesthetic feelings. Both the ‘‘feeling of the beautiful’’ and the ‘‘feeling of the sublime’’ presuppose a certain pleasant excitability of the soul. The feeling of the beautiful can be affected by pretty, harmonious, or small things, and it manifests itself as a sensation of a delightful or charming attraction. The feeling of the sublime is prompted by the exposure to grandiose, simple, or enormous things and manifests itself as a moving sensation that can involve admiration as well as terror (II 208). In the Observations, Kant laid out a general theory of the sublime and the beautiful. He discussed these two notions with regard to humanity, gender differences, and national characters. The Observations went through three editions until 1771 and became his most widely read precritical work. He ﬁnished the 110-page essay in September 1763, submitted it to the university censor in October, and published it in the ﬁrst months of 1764.4 That for Kant the foundation of both ethics and aesthetics consisted at this point of feelings instead of reason indicated that his philosophical crisis continued to worsen. His disenchantment with speculative philosophy prepared the ground for his susceptibility to the inner sense theory. Sometime in 1764 or 1765, Kant annotated his Handexemplar of the Observations. There seemed to be no end to the annotations—he ﬁlled the margins of his personal copy of the Observations with comments, and when that space ran out, he added loose leaves until his Handexemplar was bulging at the seams and the size of the commentary far exceeded the size of the actual text.5 These handwritten additions to the Observations tell a fuller story. The ‘‘most important affair of humans,’’ Kant noted there, is to ﬁnd out ‘‘how humans can appropriately perform their function in the creation’’ (XX 41). The ‘‘most vital of all the sciences’’ pertains to the question of ‘‘what one must be in order to be a human being’’ (XX 45). The ‘‘ultimate aim’’ (der letzte Zweck) is the discovery of the ‘‘vocation of man’’ (XX 157). Taken in isolation, these remarks reveal Rousseau had inﬂuenced Kant, and not only as regards the moral and epistemic relevance of feeling, but also as regards the importance of ethical issues over anything else. More important, taken in context and compared to Kant’s efforts in the 1750s, they indicate Rousseau’s inﬂuence

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was accompanied by a larger change. In the previous decade, Kant had argued that ethics was grounded in metaphysics—the essential foundation of any type of philosophical inquiry. The culmination of philosophy had been speculative philosophy. But with the annotations, metaphysics had been cast out, and practical philosophy had usurped its throne. The downfall of metaphysics naturally threatened the precritical project. Because the precritical project consisted of a metaphysical-scientiﬁc synthesis, the demise of metaphysics marginalized the relevance of its envisioned synthesis with science. As if this was not enough, metaphysics acquired now a different role—a role that would prove crucial for the further development of Kant’s views: ‘‘One could say,’’ he wrote in the annotations of the Observations (XX 181), ‘‘that metaphysics is a science of the limits of human reason.’’ This note in the Handexemplar is remarkable. It is the ﬁrst appearance of the redeﬁnition of metaphysics which would later become so crucially important in the Critique of Pure Reason (Axix–xx, B18, B22–23). In 1766, he would announce the new conception of metaphysics in the Dreams of a Spirit-Seer.6 When the Observations appeared in print, Kant was busy with another treatise to be published in the spring of 1764. This was An Attempt to Introduce the Concept of Negative Quantities into Philosophy, a sequel to the critique on logical rationalism that had been initiated with The False Subtlety of the Four Syllogistic Figures (1762). Both tracts, the False Subtlety as well as the Negative Quantities, challenged the omnipotence of logic. In the False Subtlety, Kant had contended that many of the distinctions in syllogistic logic were arbitrary and contrived (II 55–57). Moreover, logical and physical difference (Unterscheidung) were not equivalent (II 59–60). According to Kant, a ‘‘logical difference’’ involved the negation that (A B); a ‘‘physical difference’’ referred to a perceptual distinction between different phenomena, prompting diverging actions. What he had in mind here was that only one kind of the mental act of Unterscheidung involved logical distinctions, whereas another kind involved cognitive discriminations which fail to match the structures asserted by logic. He sharpened the criticism in the Negative Quantities, challenging now the tenets of the School Philosophy with the idea of the nonequivalence of ‘‘logical difference’’ and ‘‘physical difference.’’ Perhaps the central assumption of the traditional logical rationalism was that logic mirrors the structure of nature—in other words, that logic was supposed to have its roots neither in social convention nor in psychological make-up, but in the ontological constitution of reality instead. This very assumption was the target of the critique of the Negative Quantities. Kant insisted the two types of opposition were fundamentally distinct. The one is the opposition of logic involving the principle of contradiction—the idea that A is not B. The other is the opposition of reality, as in the clash of opposing forces, describable by and involving Newton’s law of equality of action and reaction. The categorical distinction between these two oppositions is visible in their results: whereas logical opposition results in nothing, in negation, physical opposition results

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in something, namely, in rest (II 172). The Negative Quantities, a tract of seventy-six pages, was announced at the Easter book fair in 1764.7 From 1762 to 1764, Johann Gottfried Herder attended Kant’s classes on metaphysics. Herder took extensive notes which give us a look inside the classroom.8 The Metaphysik Herder, assembled during these years, illustrates the further erosion of the claims of speculative philosophy. Although Kant’s textbook, Baumgarten’s Metaphysica (ﬁrst edition 1739), was as conventional as it gets, Kant’s comments often were not. Kant proceeded from the juxtaposition of two distinct causal grounds, the Idealgrund and Realgrund in Crusius’s Logik (1745; #140), and radicalized this juxtaposition to a divorce of logical ground from real ground (cf. Metaphysik Herder, XXVIII 12). One result of their divorce was the distinction of logical and physical opposition that Kant elaborated in the Negative Quantities. Another result, visible in the Metaphysik Herder, was that the principles of speculative philosophy were diminishing in ontological importance. In the New Elucidation, Kant had maintained the ‘formal’ validity of the laws of identity and contradiction as principles of knowledge. There, he had also asserted their ‘material’ validity as principles of reality. According to the Metaphysik Herder, the laws of identity and contradiction are the forms of all afﬁrmative and negative judgments (XXVIII 8). The ontological relevance of these laws, in terms of their ‘material’ validity, was receding into the background. As the Metaphysik Herder indicates, Kant spoke in his courses about ‘‘material principles’’ (principii materiales). In the classroom he characterized them as principles of judgments that concern contingent things in nature. These material principles, however, are subordinate to the formal principles and serve as a go-between for the laws of identity and contradiction and the ontological structure of reality (XXVIII 9). Hence, the formal principles continued to apply to the ontological structures, but (in contrast to Kant’s earlier characterization in 1755) only indirectly, through the mediation of material principles. The ontological signiﬁcance of the principles of the New Elucidation would continue to diminish after the Metaphysik Herder. By 1770, Kant would characterize the law of contradiction as a merely subjective condition of judgment. In the Inaugural Dissertation of that year, he declared it is a fallacy (axioma subrepticium) to take the law of contradiction as an objective condition of reality. The statement ‘‘whatever is contradictory is impossible’’ is true for our cognitive structures. However, the statement understood ontologically would amount to an unproven assumption (II 415–16, #28). The law of identity, originally the summit of ontological principles in the New Elucidation, and later lumped together with the law of contradiction as one of two formal axioms in the Metaphysik Herder, was not even discussed in the Inaugural Dissertation. By 1783, Kant would conclude that the law of contradiction fully accounts for analytic judgments (cf. Prolegomena, IV 267, #2b). Identity, whose career had started so gloriously in the New Elucidation as the queen of the ontological laws, died the death of a formal truism that did not even deserve mention anymore.

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In the years between the Only Possible Argument (1763) and the Dreams of a Spirit-Seer (1766), Kant’s doubts on the validity of philosophical knowledge kept worsening. Had his reservations ﬁrst been limited to qualms about Leibnizian-Wolfﬁan assumptions in the False Subtlety, they next concerned the soundness of his own endeavors in the Only Possible Argument. In the Prize Essay, these doubts ballooned to reservations about metaphysics in general. The scepticism sharpened to hostility in a minor essay, the Essay on the Maladies of the Mind (1764), where Kant went as far as to denounce metaphysical speculation as a form of insanity (II 271). Eventually scepticism spilled over into other philosophical disciplines, moving from the speculative to the practical. Kant raised in the Prize Essay the ﬁrst probing questions about the reliability of moral philosophy (II 297), while still expressing the hope that ‘‘it must be possible to attain the highest degree of philosophical certainty in the fundamental principles of morality’’ (II 300, WM 274). Although he thought that ‘‘it has yet to be determined whether it is merely the faculty of cognition, or whether it is feeling . . . which decides [morality’s] ﬁrst principles’’ (ibid., WM 274–5), ethics appeared to him comparatively secure. He defended the moral sense theory in the Observations (II 217–18) and promoted practical philosophy to the apex of philosophical undertakings in the annotations to the book (XX 45, 157). But this would not last. By the time of the Announcement of the Organization of his Lecture in the Winter Semester 1765–66, Kant had come to believe ethics was suffering from the same uncertainty as metaphysics (II 311). The doubts which ﬁrst affected theoretical philosophy had begun to undermine practical philosophy too. Philosophy was in jeopardy on all fronts. In the years after 1762, when the storm clouds of a destructive scepticism darkened in Kant’s mind, the outward prospects of his life started looking increasingly sunny. His career ﬁnally began to move ahead. The Only Possible Argument as well as the Prize Essay (both completed at the end of 1762) had been a success. The Only Possible Argument was getting noticed, and reviews and responses appeared in print. A certain Daniel Weymann, a former student at the University of Ko¨nigsberg, who held a grudge against Kant because he had mistaken the earlier Optimism essay (1759) as a personal attack on his dissertation De mundo non optimo (1759), responded to the publication of the Only Possible Argument with a counterargument of his own, the Bedencklichkeiten u¨ber den einzig mo¨glichen Beweisgrund des Herrn M. Kants zu einer Demonstration des Daseyn Gottes (1763).9 This was followed by Gottfried Ploucquet’s more thoughtful appraisal, Observationes et commentatio in D. Cant de uno possibili fundamento demonstrationis existentiae Dei (1763), and by Moses Mendelssohn’s friendly and gentle review of the Only Possible Argument that we considered earlier in chapter 9, section 1. Weymann’s piece was insigniﬁcant, but Ploucquet’s and Mendelssohn’s publications had the effect of introducing Kant’s work to a wider audience.10 At the same time, the Prize Essay had been faring well in the competition of the Prussian Royal Academy. The jury chose Kant’s submission as the runner-up in July 1763,

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gave it an honorable mention in the award announcement, and permitted its publication together with Mendelssohn’s piece and two other essays in the prize question volume of the Prussian Royal Academy.11 Kant’s name was now known in Berlin. The Prussian government decided to offer the next professorship that would become available in Ko¨nigsberg to this talented privatdozent. Unfortunately, the ﬁrst vacancy, in July 1764, was for a post as a professor of poetry. The duties for this position involved, among other things, the composition of hymns, odes, and poems to be recited at ofﬁcial celebrations. Kant politely declined the offer. We can surmise that his refusal was no great loss for German lyrics. A year later, in 1765, something more appropriate turned up. The government offered him a position as an unterbibliothekar, as a sublibrarian, at the Royal Palace Library in Ko¨nigsberg. Kant happily accepted. Although his new employment seemed to be rather modest, it was actually a lucky break. It allowed him the freedom to continue teaching part time and to stay in touch with the university. At the same time, it was not as consuming as his previous teaching job, thus freeing up more time for his own research. Just as important, the position promised ﬁnancial security. The salary was small but steady. His former employment as a privatdozent had not been a reliable source of income because the pay ﬂuctuated with the number and size of classes. A privatdozent in Kant’s time was a visiting instructor, whose continued appointment was subject to periodic performance reviews, who did not receive a salary from the university, and whose pay was provided by the students registering for the announced classes. Kant was now forty-two years old.

10.2 The Outer Shell of the Dreams of a Spirit-Seer: The Attack against Swedenborg The Dreams of a Spirit-Seer, composed in late 1765 and published in early 1766, was a landmark in Kant’s development.12 For us, it is the last leg on our investigative journey. The Dreams of a Spirit-Seer was the terminus of the precritical project. With the Dreams, Kant drew the consequence from the doubts that had so painfully tormented him over the years. He bade farewell to all of his earlier hopes. But instead of bottoming out in depression and despair, he dissolved the precritical hopes in laughter and irony. By any measure, the Dreams is the most curious work which he ever completed. The outer shell of the Dreams is Kant’s polemic against the Swedish visionary and clairvoyant Emmanuel Swedenborg (1688–1772). This polemic is drastic. With its merciless mockery and no-holds-barred ridicule, it is utterly untypical for the ‘‘gallant magister’’ reputed for his grace and politeness. In terms of the art of invective, the Dreams ranks on equal footing with the great polemical works in the history of philosophy, such as Fichte’s unsparing offensive against Christian Erhard Schmid in Vergleichung des von Herrn Prof. Schmid aufgestellten Systems mit der Wissenschaftslehre (1795), Hegel’s notorious attack of Jakob Friedrich Fries and the romantics in the preface to the Grundlinien zur Philosophie des Rechts (1821), or Engel’s and Marx’s

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‘‘critique of the critical critique,’’ their bilious and obsessive assault on Bruno Bauer in the Heilige Familie (1845). What distinguished the polemics of the Dreams from these other works is that Kant did not assail a philosopher or theologian, but a mystic and assessor at the Swedish board of mines. His target was not an otherwise respectable theory, but a dreadful concoction of the fantastic and the occult. Kant must have had ambiguous feelings about the questionable subjectmatter because he published the Dreams anonymously. But he did not hide the fact of his authorship and sent copies of the work to Mendelssohn, Lambert, Formey, to the aesthetic philosopher Johann Georg Sulzer, to the physico-theologian Johann Peter Su¨ssmilch, as well as to several others. Mendelssohn, the only one of the recipients who replied, reacted to the Dreams with a letter (not extant) that, as Kant summed it up in his answer to Mendelssohn, articulated an ‘‘unfavorable impression’’ (X 69, Z 54). Mendelssohn was displeased by the tone of the Dreams which oscillated between ‘‘jest and earnest.’’ He reproached Kant for having demeaned himself by publishing on a theme so lacking in academic respectability.13 Mendelssohn, who had complimented the Only Possible Argument with a detailed review of thirty-three pages, deigned the Dreams with a frosty blurb consisting of a mere paragraph:14 The witty profundity that the little work is written with occasionally leaves the reader in doubt about whether Mr Kant wished to ridicule metaphysics or whether he intended to praise clairvoyance. Yet it contains important reﬂections, some innovative thoughts on the nature of the soul, as well as several objections to popular systems that would merit a more serious presentation.15

Mendelssohn’s review anticipated the difﬁculties modern interpreters have had with the ‘‘little work.’’ It is not easy to see what Kant was up to, whether he was attacking a Swedish spirit-seer, the German philosophical establishment, his own philosophy of nature, or maybe some kind of combination thereof. Mendelssohn was at a loss of what to make of the tract. What was Kant’s point? The irreverent tone of the book disturbed Mendelssohn because he had come down squarely on the side of metaphysics—as his Abhandlung u¨ber die Evidenz had amply illustrated. He was unsure whether and to what extent Kant’s sceptical ridicule was directed against him. Another point confusing Mendelssohn was that Kant had previously mounted the public stage with an apology of rational theology and with a constructive proposal for a metaphysical methodology. As Lambert and Formey expected Kant to write a follow-up to the Prize Essay, Mendelssohn was waiting for the sequel to the Only Possible Argument that he had encouraged Kant to write. All in all, Kant seemed to be on the verge of a professional breakthrough; his reputation had been growing—why now, a sarcastic essay lambasting a selfstyled magician? The origins of the Dreams dated back to the beginning of the decade. Several years earlier, a Danish ofﬁcer and philosophy student had told Kant

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about the extraordinary visionary successes of the seer in Stockholm. Swedenborg, rumor had it, was able to document his extrasensory talents through several unusual events attested by independent witnesses. At one occasion, the widow of the Dutch ambassador Harteville in Stockholm had received a quite considerable bill for a silver coffee service that her husband had acquired shortly before passing away. Widow Harteville assumed the bill had already been paid and asked Swedenborg for help. The spirit-seer proceeded to contact the ghost of the ambassador and learned from him that the bill had already been taken care of. The receipt, according to the ghost, could be found in a secret compartment in the left drawer of a cupboard standing upstairs. Upon receiving Swedenborg’s message, the widow searched according to Swedenborg’s instructions, and, lo and behold, found the receipt. On another occasion, Swedenborg was staying in Go¨teborg when a ﬁre broke out in distant Stockholm. Swedenborg became greatly agitated during dinner, informed his hosts that the house of a friend had burned down and his own house was in peril. Eventually, he calmed down and announced to his astonished company in Go¨teborg that the Stockholm ﬁre had been brought under control three doors down from his own residence. Messengers arriving on the next day from Stockholm conﬁrmed the visions. Charlotte von Knobloch, a correspondent of Kant’s, inquired about the veracity of these claims, and Kant replied 10 August 1763 with a long letter (X 43–48). In this letter, he related to Fra¨ulein Knobloch these events and the results of his own investigations. He confessed to her that he used to be a hardened sceptic about such tales (X 44). But the stories surrounding Swedenborg were a different matter because here, witnesses had come forward who, as in the case of the ambassador’s widow, were of high repute. He was not sure what to make of this ‘‘slippery affair’’ (X 48). He told Charlotte von Knobloch he had written Swedenborg directly, but the visionary had not replied. He had next asked an English acquaintance in Ko¨nigsberg, who planned to travel to Stockholm, to examine the rumors during his visit there. Upon arrival in Sweden, the Englishman conﬁrmed the events, including the fact that Swedenborg had once informed the Swedish Queen Louisa Ulrika of a personal message from her deceased brother, and that the queen, upon receiving the news, was fully convinced of the truth of Swedenborg’s vision. Kant’s acquaintance testiﬁed that the high society, as well as the royal court in Stockholm, considered Swedenborg to be credible, and that Swedenborg himself, whom he had paid a visit, turned out to be a polite and perfectly sensible gentleman (X 45). Swedenborg relayed through the Englishman that the answers to Kant’s questions could be found in his Arcana Coelestia (‘‘Secrets of Heaven,’’ 8 volumes, 1749–1756). Kant, intrigued, bought the work and read it. The Arcana Coelestia is the long-winded result of Swedenborg’s alleged conversations with the angels and the dead. Swedenborg claimed to have visited the realm of the angels and described the spiritual world en detail as a mirror-image of the real world. The spiritual world, as Kant summarized the accounts of the Arcana in the Dreams, contains gardens, sweeping land-

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scapes, residential areas, galleries, and arcades (II 364). Not only is the spiritual world just like ours, but, in addition, it strikes its angelic inhabitants as being so solidly real that they are often not aware they have passed on to the hereafter. Because they felt so convinced of their own reality, the angels would sometimes doubt Swedenborg’s assertions of the existence of a material world, and on one occasion, Swedenborg had to show a spirit his own funeral in order to convince him of the fact of his afterlife (Laywine, 1993).16 Of course, Kant hated the book. It did not help that he had been gullible enough to be intrigued by the stories surrounding the book and had been duped into paying the not inconsiderable sum of seven pounds sterling. The Dreams of a Spirit-Seer is a scathing review of the Arcana. Kant’s position is clear from the beginning to the end, from the ﬁrst sentence in the introduction (‘‘The realm of shades is the paradise of fantastical visionaries,’’ II 317, WM 305) to the concluding remark in the ﬁnal section: And to those who are eager of knowledge of such things and who attempt to inform themselves with such importunity about mysteries of this kind, one can give this simple but very natural advice: that it would probably be best if they had the good grace to wait with patience until they arrived there. But since our fate in that future world will probably very much depend on how we have comported ourselves at our posts in this world, I will conclude with the advice which Voltaire gave to his honest Candide after so many futile scholastic disputes: Let us attend to our happiness, and go into the garden and work! (II 373, WM 359)

Kant described Swedenborg (Germanized as ‘‘Schwedenberg’’ in the Dreams, and misspelled ‘‘Schredenberg’’ by Mendelssohn in his review of the Dreams) as the ‘‘arch-spirit-seer of all spirit-seers’’ (II 354, WM 341). The contents of Swedenborg’s work are ‘‘fantasies’’ (Phantasterei, II 364) and the ‘‘wild ﬁgments of the imagination (wilde Hirngespinste) of this worst of all enthusiasts’’ (II 366, WM 352). In short, ‘‘the great work of our author consists of eight quarto volumes stuffed full of nonsense’’ (II 360, WM 347). Alluding to Samuel Butler’s Hudibras (3 vols., 1663–1678), Kant solved the riddle of the Arcana with the words: If a hypochondriacal wind should rage in the guts, what matters is the direction it takes: if downwards, then the result is a f***; if upwards, an apparition or an heavenly inspiration. (II 348, WM 336)17

10.3 The Inner Core of the Dreams of a Spirit-Seer: The Reductio of the Precritical Project The anecdotes about Swedenborg’s clairvoyance and Kant’s polemics would be of limited interest if it were not for the fact that Swedenborg’s spirit-

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seeing was a stand-in for a larger philosophical issue. But what this issue might have been is far from clear if one proceeds from the various available interpretations of this work. As regards its tone, the assessments of the Dreams by its commentators range from the claim that it is the ‘‘most tortured of Kant’s writings’’ (Ward, 1972) to the assertion that it is ‘‘perhaps the wittiest piece that Kant ever wrote’’ which was ‘‘as close as Kant ever got to publishing a work of art’’ (Shell, 1996).18 Between these extremes, one ﬁnds the description of the Dreams as a ‘‘satyr play of the mind,’’ where ‘‘a reﬂective humor sports playfully with all [of metaphysics’s] concepts and divisions, with its deﬁnitions and distinctions, with its categories and its logical chains of conclusions’’ (Cassirer, 1981).19 The assessments of the contents of the Dreams are similarly divergent. They range from the claim that it merits ‘‘une place de premier rang parmi les classiques du rationalisme’’ (Courte`s, 1967, in Rozenberg, 1985) to its exact opposite, that the Dreams supposedly is the text in whose context ‘‘Kant stumbles across recent British epistemology, above all the sceptic and empiricist David Hume’’ (Ho¨ffe, 1994).20 For one commentator, the Dreams concerns ‘‘visionary speculation and rational scepticism’’ as ‘‘equally strong, if not competing, forces in Kant’s mind at this time’’ (Ward, 1972).21 For another interpreter, the Dreams ‘‘explodes Kant’s old approach to the problem of self-deﬁnition’’ and amounts to ‘‘Kant’s sketch of intelligible worldhood,’’ whereby it is ‘‘easy to see’’ that this sketch contains ‘‘the model for his later noumenal realm’’ (Shell, 1996).22 Obviously, these contradictory appraisals are of little help. The Dreams of a Spirit-Seer has two parts. In the preface, Kant confessed, ‘‘with a certain humiliation, to having been naive enough to investigate the truth of some of the stories of the kind mentioned,’’23 and admitted that ‘‘he found what one usually ﬁnds when one has no business searching at all, exactly nothing!’’ (II 318, WM 306). The ‘‘dogmatic’’ part I deals with the status of spirits in general. In the heading of section 1, Kant described this issue as ‘‘a tangled metaphysical knot, which can be either untied or cut as one pleases’’ (II 319, WM 307). In section 2, titled ‘‘a fragment of occult philosophy, the purpose of which is to reveal our community with the spirit-world’’ (II 329, WM 316), he wrestled, without much success, with the ‘‘pneumatic’’ laws of the spirit-world. Here he dealt with the questions of the relation of pneumatic laws to natural laws, their connection to moral motives, and the epistemic conditions of their perception. In section 3, titled ‘‘Anti-Cabbala: a fragment of ordinary philosophy, the purpose of which is to cancel community with the spirit-world’’ (II 342, WM 329), he drew a sceptical conclusion from the unsuccessful explorations of the issues in the preceding chapter. He compared the metaphysicians as the ‘‘dreamers of reason’’ to the spirit-seers as the ‘‘dreamers of sense’’ (II 342). He denounced the spirit-seers as lunatics. As he put it, their inspiration is explainable in that ‘‘the concepts of spirit-forms, inculcated into us by education, provide the sick mind with materials for its imaginings’’ (II 347, WM 335). In section 4, the ‘‘theoretical conclusion’’ of part I, Kant described the psychological appeal of apparitions with the ‘‘hope of the future’’ (II 349)—that is, the

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‘‘fond hope that one will oneself somehow survive death’’ (II 350, WM 337). He maintained that the Dreams ‘‘will bring the whole of our philosophical understanding of such [spiritual] beings to completion’’ (II 351, WM 338). He remarked: The theory can be completed, albeit in a negative sense of the term, by securely establishing the limits of our understanding and by convincing us that the various different appearances of life in nature, and the laws governing them, constitute the whole of that which it is granted us to know. (II 351, WM 339; Kant’s emphasis)

In the ‘‘historical’’ part II of the Dreams, Kant related Swedenborg’s putative exploits (section 1), explained the underlying assumptions of the Arcana (section 2), and drew a practical conclusion (section 3). The practical conclusion eliminates the dissatisfaction resulting from the theoretical conclusion (that is, that questions concerning spirits are unanswerable). Kant reminded the reader these questions concern ‘‘things of which I have no need’’ (II 369, WM 355). From the viewpoint of practical philosophy, the stipulation of a world of spirits is unnecessary. We do not derive from the spirit-world our moral prescriptions because we already possess them in our own heart, and we do not need to hope that another world will reward us for virtue in this world because good actions are their own reward (II 372). Thus, Kant concluded: Just as, on the one hand, a somewhat deeper enquiry serves to teach us that the convincing and philosophical insight in the case under discussion is impossible, so, on the other hand, one will have to admit, if one considers the matter quietly and impartially, that it is superﬂuous and unnecessary. (II 372, WM 358; Kant’s emphasis)

It is clear from this brief survey alone that more than just the Arcana was at stake in the Dreams. Kant was concerned with the immaterial world in general, the spirit-world governed by pneumatic laws. Entities populated this world that he variously called ‘‘spirits’’ (Geist, II 320), ‘‘immaterial beings’’ (321, 323), ‘‘spiritual natures’’ (323), ‘‘spiritual substances’’ (ibid.). These entities were philosophically interesting not so much as ghosts, but rather as ‘‘souls’’ (Seele, 322) and as ‘‘spontaneously active principles’’ (selbsttha¨tige Principien, 329). However, as he pointed out, it had not yet been demonstrated that the human soul is a spirit in the sense of an entity populating another, immaterial world (324). Nor is the appeal to these active, immaterial principles justiﬁable because it is ‘‘the resort of lazy philosophy,’’ and is thus ‘‘to be avoided at all costs’’ (II 331, WM 318). The notions of the spirit-world, active principles, immaterial substances, spirits, and souls were relevant not only for Swedenborg’s Arcana but also for the mainstream of the philosophical establishment. Swedenborg’s spiritseeing was a stand-in for dogmatic metaphysics. The larger issue represented

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by Swedenborg’s exploits was the legitimacy of philosophy so constructed. The full title of Wolff ’s magnum opus, the German Metaphysics, is ‘‘Sensible Thoughts on God, the World, the Human Soul, and All Other Things in General.’’ As its contents make amply clear, ‘‘human soul’’ is by no means meant metaphorically. Furthermore, Kant’s odd reference to ‘‘pneumatic laws,’’ an expression that sounds to our ears like a joke, was not necessarily intended as such, for the concept of pneumatic laws belonged to the traditional vernacular. For example, the ﬁnal book of Crusius’s Metaphysik was a Pneumatologie—that is, the metaphysical doctrine of the laws of spirits. Thus, the ‘‘occult philosophy’’ (as Kant called it in the Dreams I.2), which deals with spirits governed by pneumatic laws, concerns not an odd brainchild of occultism, but refers to the stipulations of academic philosophers of almost all shades. The postulate of the human soul as an immaterial, simple, and spontaneously active substance was a general tenet of the philosophical establishment (and those, such as Holbach, who did not subscribe to it, published their tracts under false names and in different countries).24 Because Kant denounced ‘‘occult philosophy’’ as lazy philosophy and concluded its subjectmatter to be inaccessible to human cognition, it is unsurprising that metaphysicians such as Mendelssohn reacted with unease and impatience. They felt attacked by the Dreams because they were attacked. Since a central theme of mainstream metaphysics was the investigation of aspects of the immaterial world, and Kant categorically denied any possibility of success in such investigations, the Dreams of a Spirit-Seer went a crucial step beyond the Prize Essay. In the earlier work, he had held out the hope that a metaphysics of the future would become viable. He had hoped that metaphysics would arrive at its conclusions eventually with conclusive certainty, provided it adopted the Newtonian program and subjected its own concepts to a systematic analysis. There, Kant’s reply to the Academy’s prize question of whether metaphysical principles can be proven with certainty had been a cautious ‘‘not yet.’’ With the Dreams, he abandoned the earlier hope and changed his reply to a categorical ‘‘never.’’ The denial of the viability of metaphysics in the Dreams went hand in hand with a redeﬁnition of metaphysics as a philosophical discipline. Whereas the Prize Essay had suggested a reform, in that metaphysics had to be an analytic inquiry ﬁrst before it could become synthetic, the Dreams suggested an outright revolution. In the Newtonian program of 1762, Kant had proposed to postpone such synthetic-speculative investigations. Now such investigations were to be renounced in principle. The theoretical conclusion of part I of the Dreams amounted to the overthrow of metaphysics understood as the inquiry concerning aspects of the immaterial world. Right before the practical conclusion of part II, Kant identiﬁed two advantages of metaphysics: The ﬁrst is this: it can solve the problems thrown up by the enquiring mind, when it uses reason to spy after the more hidden properties of things. But hope

The Reductio and Collapse of the Precritical Project

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is here all too often disappointed by the outcome. And, on this occasion, too, satisfaction has escaped our grasp. (II 367, WM 354)

In other words, the ﬁrst advantage of metaphysics is not an advantage at all for speculation fails to deliver what it promises. A quote from Virgil’s Aneid follows: ‘‘Thrice did the image escape my vain embrace, like to the light breezes and a ﬂeeting dream’’ (ibid., tr. WM 456; cf. Aneid II: 793–4 and VI: 701–2). Kant continued: The second advantage of metaphysics is more consonant with the nature of the human understanding. It consists both in knowing whether the task has been determined by reference to what one can know, and in knowing what relation thie question has to the empirical concepts, upon which all our judgments must at all times be based. To that extent metaphysics is a science of the limits of human reason. (II 367–368, WM 354; Kant’s emphasis)

With the overthrow of traditional metaphysics as a synthetic and speculative enterprise, and with the redeﬁnition of metaphysics as the science of the limits of human reason, Kant had now planted the seeds that would eventually hatch the enterprise of the three Critiques. As one commentator (Beiser, 1992) rightly put it, the Dreams is the ‘‘crowning work of the 1760s,’’ which ‘‘represents the height of Kant’s growing disaffection with metaphysics’’; ‘‘all the critical forces that had been mounting in the earlier writings of the 1760s now reach their climax in a complete scepticism toward metaphysics.’’25 But the scepticism toward the metaphysical establishment is only one part of the inner core of the Dreams of a Spirit-Seer. The other (and more intriguing) part of this inner core concerns the fact that Swedenborg’s world of angels is the ultimate and absurd consequence of Kant’s own precritical project. At ﬁrst sight, such a claim seems odd. After all, the precritical project was about the construction of a philosophy of nature. Swedenborg’s visions were about the depiction of the realm of angels. What could be more different than these two ventures? Furthermore, Kant’s precritical project and Swedenborg’s angelology proceed from different ontological presuppositions. Swedenborg had adopted the Leibnizian assumptions of substance and cause; he had characterized the angels somewhat like monads and had described the causal schema of the spirit-world in terms of the preestablished harmony.26 Kant, on the other hand, rejected in the 1750s the preestablished harmony as an ontology of causality, in line with his commitment to the veracity of the Newtonian model of physical reality, and postulated a system of physical inﬂux between interacting substances instead. Contrary to what Laywine (1993) suggests, the causal system of the model of nature constructed by Kant did not entail the causal system of the world of angels envisioned by Swedenborg.27 But although Swedenborg’s and Kant’s speciﬁc assumptions fail to match, and Swedenborg had described the laws of the spirit-world in a way that

242

The 1760s: Climax and Crisis

differed from Kant’s account of the laws of the physical world, there remained an intimate and curious connection between the precritical philosopher and the spirit-seer. Kant’s letter to Mendelssohn on 8 April 1766 on the Dreams is revealing. First, Kant explained the tone that Mendelssohn took issue with: It was in fact difﬁcult for me to devise the right style (Methode) with which to clothe my thoughts, so as not to expose myself to derision. It seemed to me wisest to forestall other people’s mockery by ﬁrst of all mocking myself; and this procedure was actually quite honest, since my mind is really in a state of conﬂict on this matter. (X 69–70, Z 55; my emphasis)

After admitting that the Dreams had been intended as a self-critique and not just as a critique of Swedenborg, he conceded that the critique had also been directed against metaphysics in general: As to my expressed opinion of the value of metaphysics in general, perhaps here and again my words were not sufﬁciently careful and qualiﬁed. But I cannot conceal my repugnance, and even a certain hatred, toward the inﬂated arrogance of whole volumes full of what are passed off nowadays as insights; for I am fully convinced that the path that has been selected is completely wrong, that the methods now in vogue must inﬁnitely increase the amount of folly and error in the world, and that even the total extermination of all these chimerical insights would be less harmful than the dreamed-up science itself (die ertra¨umte Wissenschaft) with its cursed (verwu¨nschten) contagion. (X 70, cf. Z 55; I modiﬁed Zweig’s translation somewhat)

But what about this self-critique? Where is the connection to Swedenborg? In the following, Kant came to the point: In my opinion, everything depends on our seeking out the data of the problem, how is the soul present in the world, both in material and in non-material things. . . . My analogy between a spiritual substance’s actual moral inﬂux and the force of universal gravitation is not intended seriously; but it is an example of how far one can go in philosophical fabrications, completely unhindered, when there are no data, and it illustrates how important it is, in such exercises, ﬁrst to decide what is required for a solution of the problem and whether the necessary data for a solution may be lacking. (X 71–2, Z 56–7; Kant’s emphasis)

It seems that the problem was the relationship of material and immaterial things, and the presence of the soul in both. The problem, which Kant readily concedes, is that ‘‘one can go . . . completely unhindered’’ from a model of physical nature resting on universal gravitation, such as his own, to a Swedenborgian model of the spirit-world resting on ‘‘moral inﬂux’’ (cf. also II 334–5). Let us recall the essential features of the precritical project. In 1754, Kant had identiﬁed universal gravitation as nature’s universal engine (I 186) and

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assessed Newton’s theory of universal gravitation as reason’s most successful attempt at understanding nature (I 468). Through the Newtonian conversion, he had found the key to making progress with the vision that the explanation of the world must combine physical and metaphysical vantage points—a vision which had been vague and ambiguous in the Living Forces. In the 1750s, the physical vantage point had become Newtonian mechanics. The metaphysical vantage point consisted in the assumptions of the purposiveness of reality, the freedom of human action, the immortality of the human soul, and the existence of God. The works that followed had been exercises in reconciling the two perspectives. In the Universal Natural History, Kant had tried to integrate the notion of purpose in the Newtonian description of the cosmos through his theory of immanent teleology. In the New Elucidation, he had tried to integrate the free, spontaneous causation involved in human activity in a schema of interaction that accounted for the deterministic, efﬁcient causation of Newton’s physical processes. In the Physical Monadology, had had employed the notion of a simple substance, although he did not go as far as characterizing the immortality of the soul through its substantial simplicity. In this work, he had explained the volume and inertia of spatial bodies through the spatially extended force-grid generated by nonspatial pointal entities. In the Only Possible Argument, he had tried to show how two parallel lines of reasoning, the one involving metaphysics, the other based on Newtonian nature, lead to the existence of God, and how these lines were braided together on their conceptual basis. The fundamental assumption of all of these works had been that reality, conceived in its widest sense, is coherent and uniﬁed. Metaphysics and science equally apply to the elucidation of reality because reality incorporates an intelligible, qualitative component and a sensible, quantitative component. Nature is one and the same, and its metaphysical and empirical sides are intimately connected. The logical consequence of the uniﬁed model of reality produced by the precritical project is an ontological monism. The empirical and metaphysical sides of reality cohere because they are ultimately only aspects of the same uniﬁed structure of reality. Hence, souls belong to the world, they interact with each other and with bodies, and they are real only under the condition that they partake in the empiricalmetaphysical uniformity of nature as a whole. Thus, Kant wrote in the Prize Essay: I admit that the proof we have in our possession for establishing that the soul is not matter is a good one. But take care that you do not infer from this that the soul is not of a material nature. For this latter claim is universally taken to mean not merely that the soul is not matter, but also that it is not a simple substance of the kind which could be an element of matter. But this requires a separate proof—the proof, namely, that this thinking being does not exist in space in the way in which a corporeal element exists in space, that is to say, in virtue of impenetrability; it also requires proof that this thinking being could not, when combined with other thinking beings, constitute something extended, a conglomerate. But no proof has actually been given yet of these

244 The 1760s: Climax and Crisis things. Such a proof, were it to be discovered, would indicate the incomprehensibility of the way in which a spirit is present in space. (II 293, WM 266–7)

Kant acknowleded that the soul is not matter, but he refuses to acknowledge that the soul is not of material nature. As Ameriks correctly found out, this balancing act highlights Kant’s early and crucial difﬁculty in drawing a line between material and immaterial things.28 Nevertheless, Kant needed to draw such a line while insisting that the soul is somehow material. In the context of the precritical project, a soul that is not of material nature is a soul that does not belong to the world, cannot be embodied, and cannot causally interact there. The price of the uniﬁed world of the precritical project is that souls, ultimately, must be of the same kind as the elementary wellsprings of force that constitute the spatial bodies of the Physical Monadology; their force must be of a similar kind as the forces described in the Universal Natural History; and they are, together with physical processes, subject to the same fundamental patterns of reality deduced in the New Elucidation. This must be the case, otherwise, the model of nature that incorporates both intelligible and empirical components would fall apart, and the envisioned synthesis of science and metaphysics that is the essence of the precritical project would fail.29 Thus, the inevitable consequence of the precritical project was that bodies and souls, or material and immaterial substances, are subject to the same laws. At the same time, the precritical project must not rule out the possibility of an afterlife—that is, the possibility that material substances remove themselves from their physical embodiment and interact purely among themselves. If Kant had wanted to rule this out, he would have had to embrace atheism or materialism. Doing so would have been inconsistent with the synthesis of nature and God that occurred in various guises in the Universal Natural History, the New Elucidation, and the Only Possible Argument. Therefore, Kant was committed to the claim that souls continue to exist after they left their mortal bodies behind. What would such an immaterial community of souls look like? Because souls are substances that obey the same fundamental laws as bodies, the immaterial community of the souls must contain the same structure as the physical world. The reductio ad absurdum of the precritical project is Swedenborg’s spirit-world—a world whose ghostly inhabitants are not even aware of their postmortal state because it looks and feels just like their old home. It is therefore correct to say (Laywine, 1993) that Kant found in the Arcana coelestia a caricature of his own metaphysics.30 Something horrible had happened to Kant, and the Dreams is the reﬂection of this traumatic event. Just when his career as a philosopher was making progress, just when he harvested the ﬁrst modest fruits of success, his whole system, the work of more than ten years, had come crashing down. It was as if Kant could never escape misfortune. His ﬁrst book had been ridiculed. His second book had been impounded and burnt to ashes. His third book was misguided. And now, the precritical project in its entirety had turned into a bad joke. How else could he react if not with the odd mixture of laughter and bitterness that make up the odd tone of the Dreams?

Conclusion

-0

WITH THE DREAMS of a Spirit-Seer, the story of the precritical project comes to an end. What I have tried to show here is that the philosophy of the young Kant reveals a greater unity and a more interesting coherence than has previously assumed. Although the precritical project collapsed, its relevance remains. Kant’s vision, of harmonizing a rigorous description of physical reality with substantial answers to the perennial questions of our existence, is the vision of philosophy in general. In this regard, the precritical project has not lost anything of its topical signiﬁcance. In the aftermath of the precritical project, Kant began to regard metaphysics as a synthetic and a priori speculative business. Metaphysical truths are ‘‘unearthed from within ourselves,’’ as Leibniz put it in the Nouveaux Essais (G 5:46, AG 294) that were published just when the precritical project collapsed. In 1764 or 1765, Kant realized that the problems surrounding the mining of the mind for a priori truths called for examining the viability of such mining in general—metaphysics must become a science of the limits of human reason. In the Reﬂexionen of 1769 and 1770, he argued that this science of the limits of reason concerned the ﬁrst principles of reason, and that these principles were the conditions of how things are thought (R 3946, XVII 359; R 3978, XVII 373–374). Metaphysics ought to become an ontology of the concepts determining these conditions, but as such an ontology, it will concern structures of only subjective validity. 245

246 The 1760s: Climax and Crisis

In the preface to the Nouveaux Essais, Leibniz had suggested to distinguish between between physical and metaphysical ‘‘genera’’ or ‘‘matters’’ (G 5:56, 59–60; AG 302–303). Their confusion, he had written there, gives rise to a false conclusion. This had been the conundrum of the precritical project in a nutshell. It was the very coherence of Kant’s model of reality that had made it so vulnerable to a reductio to the Swedenborgian vision—if the physical, material world and the metaphysical, immaterial world hang together such that they share the same ontological structure, then the immaterial world will correspond to the material world, and the metaphysical realm of the angels will be indistinguishable from the physical realm of our quotidian affairs. The nub of the problem had been the convergence (or, as Leibniz would put it, confusion) of the two worlds. The marriage of metaphysics and science had not worked out, and their divorce was in order. In the Inaugural Dissertation of 1770, Kant drew the consequence, slashed through the gordian knot of the precritical project, and sliced its model of reality into two halves: the mundus intelligibilis of metaphysics and the mundus sensibilis of science. The bifurcation of reality into a phenomenal and a noumenal world amounted to the antithesis of the precritical project and was a ﬁrst, tentative step toward the critical philosophy. Kant’s reaction to the collapse of the precritical project is a testimony to his greatness as a philosopher and to his strength as a man. He had the courage to confront long-held convictions, to examine their faults, and to draw the consequences. The features of the new system—the examination of the limits of human reason, the separation of noumenon and phenomenon, and the practical rather than theoretical access to the noumenon— still had to be put together. This turned out to be an intensely laborious task that would consume more than a decade of Kant’s life, until the Critique of Pure Reason was ready for publication in 1781. In terms of boldness, the new critical project was a retreat from the magniﬁcent metaphysical dream of the precritical project. But Kant never abandoned the hope that he could eventually go ahead again. He wanted to proceed from the preliminary epistemological investigation in the transcendental critique once again to nature, to build a philosophical transition to physics, and to reconcile the vantage point of science with a newly understood metaphysical perspective. But when he ﬁnally made this leap forward with the Opus Postumum, the attempt foundered on the reefs of old age.

Notes

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INTRODUCTION

1. For Kant’s negative publicity about his early efforts, see Dilthey (1902), v, and Henrich (1965), 252. Kant’s request of excluding the early writings from a collection of his works fell on deaf ears; the editor J. H. Tieftrunk, his former student, included several in Immanuel Kant’s vermischte Schriften. A¨chte und vollsta¨ndige Ausgabe (Halle: Reger, 1799). For Kant’s review of Herder’s Ideen, cf. Kant’s Recensionen . . . (1785), VIII 43–66; for the background of the Herder review, cf. Beiser (1987), 141–53. For the ‘‘great light’’ remark, jotted down in the margins of Baumgarten’s textbook on metaphysics (Reﬂexion R 5037, XVIII 69), see Tonelli (1963), 369–75, and Schmucker (1976), 393–434. For the ‘‘philosophical revolution,’’ see Kant’s preface to the second edition of the Critique of Pure Reason; cf. B xxii. See also the passage in B xvi that inspired the popular phrase ‘‘Kant’s Copernican revolution,’’ where Kant argues that we should imitate the procedure of Copernicus’s revolution in the sciences. 2. See Beck (1969b), 429. The ‘‘U¨berweg’’ is an authoritative, old-fashioned, multivolume history of philosophy in Germany, akin to ‘‘Copleston’’ in Anglo-American academia; cf. Friedrich U¨berweg, Grundriß der Geschichte der Philosophie, 5 vols., Berlin, 1923–28. The charge of Kant’s lack of coherence is from Cassirer (1981), 92–4. The charge of the lack of originality can be found in Beck, ibid., 426–30, and in popular histories of philosophy; for instance, in Friedlein (1980), 219, Sto¨rig (1980), 2:55–7, or in Hirschberger (1981), 2:271. The charge of the lack of continuity, or the clean break between the eclectic early Kant and the ingenious late Kant is considered selfevident and thus rarely explicated. For such an explication, cf. Schultz (1965), 70. As

247

248 Notes to pages 6–17 a result of the alleged lack of relevance, monographs of Kant tend to skip over the precritical period. For instance, S. Ko¨rner, in Kant (Harmondsworth, England: Penguin, 1990), takes ‘‘Kant’’ to be exclusively synonymous with the old Kant, beginning his account of Kant’s philosophy with the ﬁrst Critique. O. Ho¨ffe, in Immanuel Kant, tr. M. Farrier (Albany: SUNY, 1994), a book 290 pages long, devotes ﬁve and a half pages on the precritical philosophy; Kant’s ﬁrst book, the Living Forces, merits only two paragraphs. 3. The Kant-Studien published 868 articles from 1937 (vol. 42) to 1996 (vol. 87). Of these, 513 articles are about Kant, and of these, 493 papers are on the critical Kant, 20 on the precritical Kant. Recent international bibliographies, such as the one compiled for 1994⁄95 by M. Kuhn for the North American Kant Society, reﬂect the same disparity; cf. North American Kant Society Newsletter 11⁄12 (1995–96): inserts. 4. Adickes’s comprehensive investigation of Kant’s philosophy of nature (Adickes, 1924a) should probably be added to Henrich’s list of outstanding pioneers of the precritical philosophy, because this work was not only the ﬁrst systematic exposition of Kant’s contributions to natural science, but also the ﬁrst detailed assessment of the contents of Kant’s early works. 5. Polonoff suggests that the dominant themes that ran through Kant’s early philosophy were the loosely connected investigations of forces, simple substances, and the cosmos. See Polonoff (1971), passim; esp. 1–2, 201–5. 6. Unless otherwise indicated, quotations from the A- and B-editions follow Pluhar’s translation of the Critique (1996). 7. See Lambert’s letter to Kant on 13 November 1765, and Kant’s reply to Lambert on 31 December 1765; in X 51, 54. The translation follows Zweig (1967), 43–4, 48.

CHAPTER ONE

1. The critical period petered out over a period of years. In 1796, Kant started a new work which was to become his Opus Postumum. In 1798, Kant’s strength began to wane (cf. letter to Lichtenberg, XII 247). In 1800, Kant’s ﬁnal publications appeared (a preface to R. B. Jachmann’s Pru¨fung der Kantischen Religionsphilosophie, and a postscript to a German-Lithuanian dictionary, each only a single page in length; cf. VIII 441 and VIII 445). In 1801, according to the testimony of E. A. C. Wasianski and other friends, Kant’s intellectual powers began to ﬂag and he stopped working for good; see Goulyga (1985), 282–84. Kant’s ﬁnal notebook dates from 1803, but concerns only affairs of quotidian life. He died 12 February 1804. For the end of Kant’s philosophical activities, see also Mecklenburg (1970), 93–6, and Fo¨rster (1995), xvi. 2. During the silent decade, Kant worked mainly on the manuscript of what would become the ﬁrst edition of the Critique of Pure Reason. The publication of the work in May 1781 marked the beginning of the critical period. 3. For the mistaken identiﬁcation of the Living Forces with Kant’s doctoral dissertation, see Vleeschauwer (1962), 16; and Beiser, 30, in Guyer (1992). Beck, in (1969b) 430, labels the Living Force more correctly as ‘‘a’’ dissertation. The ﬁles of the Ko¨nigsberg philosophy department (Acta fac. Phil.) merely mention the Living Forces as having been submitted for the departmental censorship approval prior to its publication; cf. I 522. Kant’s M.A. thesis was the treatise On Fire (1755); the Acta fac. Phil. contain the entry, ‘‘Honores Magistri Philosophiae, specimine physico de Igne exhibito, sibi expetiit Candidatus Emanuel Kant, quos etiam post examen rigorosum . . .

Notes to pages 17–23 249 obtinuit’’; cf. I 562. Kant’s doctoral dissertation was the New Elucidation (also 1755); the Ko¨nigsberg Acta fac. Phil. list it among the ‘‘Dissertationes hoc semestri habitae’’; cf. I 565. 4. Descartes thought about rectilinear inertia but did not understand the importance of internal resistances to changes of motion; see, for example, the ﬁrst and third laws of motion in Le Monde, AT 11:38, 43–4, and the ﬁrst and second laws of motion in the Principia Philosophiae (1644), AT 8:62–3. 5. Aristotelian metaphysics dominated natural philosophy until the 17th century. It was taught as the ofﬁcial doctrine in some universities until the early 18th century. For Aristotle’s conception of motion, see Physics, V.1, 241b34 and 242a47–9. For the complexities of Galileo’s critical relation toward Aristotelian metaphysics, see Clavelin (1976), 261–76. For Galileo’s ﬁrst formulation of his law of inertia, see the Istoria e dimostrazioni intorno alle macchie solari (1613), i.e., the ‘‘Letters on Sunspots,’’ in Galileo (1957), 113. For Descartes’s critique on Galileo’s inertia, compare Le Monde, AT 11: 43–4. 6. There are some evident similarities between the Galilean and Cartesian methodology, such as the emphasis on quantiﬁcation and the relevance of experiments. However, Descartes had some reservations about Galileo’s methods. In a letter to Mersenne (1638), Descartes praised Galileo for his independence from Aristotle and for his mathematical treatment of physical questions, but criticized him for his disorganized investigations and for focusing on speciﬁc effects at the expense of studying general causes, cf. AT 2:380. For Leibniz’s critique of Galileo’s methodology, see Leibniz’s letter to Foucher (1675), G 1:371. 7. Translated as ‘‘The Assayer’’ in Galileo (1957), 237–8. See the quote at the beginning of this chapter. Early commentators such as Koyre´ read Galileo as an ontological Platonist according to whom things are reducible to numbers; see, for instance, Koyre´ (1966), passim; Koyre´ (1943a), 333–48; Koyre´ (1943b), 400–28; ‘‘Galileo’s Treatise De Motu Gravium: The Use and Abuse of Imaginary Experiment,’’ in Koyre´ (1968), 44–88, orig. pub. in Revue d’Histoire des Sciences 13 (1960): 197–245. For a similar Platonist reading of Galileo’s methodology, see Clavelin (1976), 267–8. Other, more recent commentators do not equate Galileo’s anti-Aristotelianism with Platonism, in part on grounds of Galileo’s methodological remarks in the Maccie solari: ‘‘to penetrate the true and internal essence of natural substances . . . I hold to be as impossible an undertaking with regard to the closest elemental substances as with more remote celestial things,’’ cf. Galileo (1957), 123. For more recent commentators who question Koyre´’s Platonist reading of Galileo, see Girill (1970), 501–20; and Hatﬁeld, ‘‘Metaphysics and the New Science,’’ in Lindberg and Westman (1990), 93–166, esp. 118–28. 8. See Galileo (1957), 123–4. 9. Mathematics was important for Descartes as the key to unlock nature and as the model for all sciences. Although this is a well-known motive of Cartesian thought, Descartes’s actual positions on mathematics were uneasy and complex. For Descartes’s praise of mathematics, see, for instance, his Regulae ad directionem ingenii (wr. 1628/9), rule 4, AT 10:377–8. For an example of the standard interpretation of Descartes as the unfettered rationalist, cf. Burtt (1970), 106–15. For Descartes’s reservations about mathematics, see his Discours de la Me´thode (1637), I.10, II.6, II.11, AT 6:7, 18–9. For challenges to the standard interpretation, cf. Frankfurt (1977), 36– 57; and the papers by Frankfurt and Garber in Hooker (1978). 10. The Cartesian conception of a wholly inert matter rests squarely on the basis of Galilean mechanics. See Galileo, Discorsi e dimostrazioni matematiche, intorno a` due

250 Notes to pages 23–25 nuove scienze (Leiden, 1638); tr. by H. Crew and A. de Salvio as Dialogues Concerning Two New Sciences (New York: Dover, 1954), 181. Descartes’s inert matter and Newton’s inertia are different: the Newtonian inertia of a mass allows (correctly) for resistance to changes in motion or rest; the Cartesian inert matter is indifferent to motion and rest and, consequently (and erroneously), does not allow for resistance. It follows from Descartes’s notion of inert matter that the amount of matter does not affect a body’s behavior in cases of impact. In La Statique (1673), Ignace Pardis drew the absurd conclusion (but consistent with the Cartesian premises!) that equal forces can move unequal masses; see also Westfall (1971), 195–8. 11. For Descartes’s equation of force and action, compare his letters to Mersenne 13 July and 15 Nov 1638, AT 2:232, 432–3; for Descartes’s equating of action and motion, see his letter to Morin 13 July 1638, AT 2:204. 12. The relevant passage is Principia Philosophiae II.36; AT 8:61–2. Descartes differentiated between motion and quantity of motion and declared that God preserved the latter. Descartes’s principle of the conservation of motion is a principle of the conservation of the quantity of motion. The principle of the conservation of the quantity of motion appears ﬁrst in Le Monde, ch. IV; AT 11:43. 13. In the Princ. Philos. II.36; AT 8:62, Descartes refers to the second body being ‘‘duplo major,’’ twice as large as the other, thus referring to size. 14. The situation is different when the motions involved are not constrained and become real motions, as in the case of freely falling or rising bodies. The interchangeability of velocity and displacement is correct as long as one deals with virtual motions (that is, motions constrained by a simple machine). The term ‘‘virtual motion’’ was not part of the vocabulary of Descartes and Leibniz; Jean Bernoulli coined it in 1717. 15. Garber, in Cottingham (1992), 303, remarks on the Cartesian importance of motion: ‘‘. . . all there is in body is extension, and the only way that bodies can be individuated from one another for Descartes is through motion. In this way, it is motion that determines the size and shape of individual bodies, and thus, motion is the central explanatory principle in Descartes’s physics.’’ 16. See the ﬁrst sentence of Leibniz’s Principes de la Nature et de la Grace, fonde´s en raison (1714); G 6:598. Substance, characterized by a dynamic essence, is the ultimate building block of reality; in the Entretien de Philarete et d’Ariste, suite du premier entretien d’Ariste et de Theodore (1712), Leibniz also deﬁnes it as whatever can be conceived of as existing independently of other things; G 6:581. In the earlier, unpublished Pars secunda of the Specimen dynamicum (1695), Leibniz argues that force (vim) is something absolutely real in created substances, while motion is more like a being of reason and a mere relation among phenomena: ‘‘. . . motum habere aliquid de Ente rationis; . . . motum quoad phaenomena in mero respectu consistere’’; cf. Leibniz, Specimen dynamicum, ed. and tr. H.-G. Dosch et al. (Hamburg: Meiner, 1982), 40, 42. 17. Antibarbarus Physicus (1710–16?), G 7:343–4; translated in AG 319. 18. See Leibniz’s Animadversiones in partem generalem Principiorum Cartesianorum (1702); G 4:370, in which he comments on Principia philosophiae II.36. Leibniz’s Brevis demonstratio was published ﬁrst in the March 1686 issue of the Acta Eruditorum; cf. also GM 6:117–9. For detailed discussions of Leibniz’s arguments in the ‘‘Brevis demonstratio’’ and the ensuing debate, see Campo (1939), 1:209–15; Costabel (1966), 264–87; Iltis (1971), 21–35; Fichant (1974), 195–214; and Garber (1995), 270–352, esp. 309–21.

Notes to pages 25–26 251 19. See Iltis (1971), 22. For a bibliography of the relevant primary sources, cf. ibid., p. 22 note 4. 20. See Iltis, (1971), 25. She adds, ‘‘there is no evidence that Descartes himself made this error, although his followers certainly did.’’ 21. For a translation of Leibniz’s ﬁrst argument against the Cartesian measurement in the Brevis demonstratio, see Loemker (1956), 2:456–7; for a good exposition of the argument, see Polonoff (1971), 7. 22. For variations of the same basic argument, see Leibniz’s Discours de me´taphysique (1686), #17, G 4:442–4; Animadversiones, G 4:370–1. My description is based on the expanded and as I take it, clearest version of the argument stated in the Animadversiones; G 4:371–2. Galileo’s times-squared law of falling bodies established that the average velocity of a body (beginning at rest and falling freely) is proportional not to the simple distance, but to the square root of the distance the body falls; v 冪h, or v2 h; cf. Galileo, Discorsi, 174 (day 3, nat. acc. mot.: theorem 2). Modern formulations of this law are v 冪2as , or s 1⁄2at2, where v is velocity, s is distance, t is time, and a is the gravitational acceleration (a 32 ft/sec2, or 9.8m/sec2. For Kant’s discussion of the argument, see chapter 2 below. 23. One could render Leibniz’s steps of reasoning in the following way: (1): A (weight 4 and velocity 1) moves horizontally. A collides with B (weight 1, velocity 0). A transfers its full force F to B and sets B into motion. (2): According to Galileo, height velocity2 (a body’s height stands in inverse proportion to a body’s weight). (3): F could raise A to height 1; by (2). (4L): According to Leibniz, F gives B velocity 2. (5L): If F gives B velocity 2, then F could raise B to height 4; by (2). (4D): According to Descartes, F gives B velocity 4. (5D): If F gives B velocity 4, then F could raise B to height 16; by (2). (6): However, F raising A to height 1 can raise B only to height 4; by (1), (2), (3). /.: Therefore, (4L) & (5L) are true, and (4D) & (5D) are false. 24. See Iltis (1971), 25; compare also Costabel (1973), 126. The 1691 text is in GM 2:215–31. The 1692 text, which contains an elegant and systematic exposition of Leibniz’s main argument against the quantity of motion and in support of living force, was discovered by Costabel, cf. ibid., 108–31. For the Specimen Dynamicum, see GM 6:234–54 for the Latin text, and Dosch (1982) for a Latin-German edition. For English translations, see Loemker (1956), 2:711–38, and AG 117–38. 25. See Christiaan Huygens, ‘‘Regles du mouvement dans la recontre des corps,’’ Journal de sc¸avans (1669): 19–24, rule 6. Translation by Iltis, (1971), 22. Before this public announcement, Huygens had already demonstrated the formula in De motu corporum ex percussione (1656), in: Oeuvres comple`tes 22 vols. ed. Socie´te´ Hollandaise des Sciences (La Haye: M. Nijhoff, 1888–1950), 16:73. However, Huygens was not a defender of vis viva as Leibniz understood it. Huygens did not think one could inﬂate F mv2 to a fundamental metaphysical principle. He suggested the formula as a principle of the conservation of force in his main work, Horologium oscillatorum (1673) but did not intend it to be a principle of the conservation of vis viva; cf. Oeuvres, 18:125. For Huygen’s critique on Leibniz, see Oeuvres, 19:164–5. On Huygens’s role in the debate, see Campo (1939), 1:211; Westfall (1971), 149, 156–8; and Polonoff (1971), 5. 26. It should be mentioned that in addition to the mechanical proofs for vis viva, Leibniz proposed also an a priori argument for mv2 in the Dynamica (1689– 90), GM 6:291–2 and 6:345–67, that he summarizes in a letter to Bayle (no date), G 3:60: ‘‘Dans les mouvemens uniformes d’un meˆme corps (1) l’action de parcourir

252 Notes to pages 26–27 deux lieues en deux heures est double de l’action de parcourir une lieue en une heure . . . ; (2) l’action de parcourir une lieue en une heure est double de l’action de parcourir une lieue en deux heures (ou bien les actions qui font un meˆme effect sont comme leur vistesses). (Donc 3) l’action de parcourir deux lieues en deux heures est quadruple de l’action de parcourir une lieue en deux heures. Cette demonstration fait voir qu’un mobile recevant une vistesse double ou triple, a` ﬁn de pouvoir faire un double ou triple effect dans un meˆme temps, rec¸oit une action quadruple ou noncuple. Ainsie les actions sont come les quarre´es des vistesses’’ (my emphasis). Note that Leibniz equates here, like Descartes before him, action with force. On this terminological quirk, as well as on the a priori arguments, see Garber (1995), 313–4 and 349n112. 27. For Catelan’s ﬁrst critique of Leibniz, see Abbe´ de Catelan, ‘‘Courte remarque de M. l’Abbe´ de Catelan ou` l’on montre a` M. G. W. Leibniz le paralogism contenu dans l’objection pre´ce´dente,’’ Nouv. d. l. Re´p. d. Lettres (September 1686): 999–1003; also in G 3:40–2. Leibniz’s defense begins with a letter to Pierre Bayle (the editor of the Nouv. d. l. Re´p. d. Lettres), G 3:42–9, and continues with a letter to Arnauld (8 Dec 1686), G 2:80; Discourse de me´taphysique (1686, p. posthum.); Dynamica de potentia et legibus naturae corporae (1687, p. posthum.); Re´plique de M. Leibniz a` M. l’Abbe´ de Catelan . . . (p. in Nouv. d. l. Re´p. d. Lettres, February 1687). Catelan’s second critique of Leibniz was ‘‘Remarque de M. l’Abbe´ de Catelan sur la re´plique de M. Leibniz touchant le principe mecanique de M. Descartes . . . ,’’ Nouv. d. l. Re´p. d. Lettres (June, 1687): 577–89. Leibniz’s second defense begins, once again, with a tract addressed to Bayle, the ‘‘Re´ponse de M. L. a` la Remarque de M. l’Abbe´ D. C. contenue dans l’Article 1. des ces Nouvelles, mois de Juin 1687, ou` il pre´tend soutenir une Loi de la Nature avance´e par M. Descartes,’’ G 3:49–51. The second defense continues in the following texts; ‘‘Extrait d’une lettre de M. Leibniz sur un principe ge´ne´ral utile a` l’explication des loix de la nature par la conside´ration de la sagesse divine, pour servir de re´plique a` la re´ponse du R. P. Malebranche,’’ Nouv. d. l. Re´p. d. Lettres (1687—at this point, Malebranche had joined the fray by publishing objections to Catelan’s critique of Leibniz), see also G 3:51–5; ‘‘De causa gravitatis et defensio sententio suae de veris naturae legibus contra Cartesianos,’’ Acta Erud. (1690); ‘‘De prima philosophiae emendatione et de notione substantiae,’’ Acta Erud. (1694); Specimen dynamicum (part I p. 1695; part II p. posthum.); letter to Burcher de Volder (April 1699). For Malebranche’s involvement, see Costabel (1973), 41–3. 28. This argument is in Papin’s second paper against Leibniz, ‘‘Mechanicorum de viribus motricibus sententia,’’ Acta Eruditorum (January 1691): 6–13. For a detailed description of the Leibniz-Papin exchange and the relevant bibliography, compare Iltis (1971), 30–32, notes 29–31. 29. See G 7:352: ‘‘Selon eux [Newton and his followers], Dieu a besoin de remonter de temps en temps sa Montre.’’ Leibniz’s critique on Newton to Caroline constitutes the ﬁrst letter of the Leibniz-Clarke correspondence, but this letter was not the ﬁrst time that Leibniz expressed his disagreement with the Newtonian philosophy. He had questioned Newton’s law of universal gravitation, in particular its implied rejection of the vortex theory and the celestial ether, in a letter to Huygens as early as 1690; cf. GM 6:189–193; AG 309–12. In subsequent letters to Huygens, in 1694, he criticized the hypothesis of absolute motion that Newton had framed on the basis of his bucket experiment; cf. GM 2:184–5, 199; AG 308–9. Before the disagreement with Newton’s views led to the quarrel with Clarke, Leibniz repeated and expanded his criticisms on Newton in various other correspondences, in the The´odice´e (1710), esp. in section 19, and in the Antibarbarus Physicus.

Notes to pages 27–31 253 30. Polonoff, in his admirably detailed study of the vis viva debate (1971), 5–38, differentiates the controversy more ﬁnely than I do, in various stages and sub-stages; cf. ibid., 6. Although the attention to subtle intricacies may be historically preferable, a quicker sketch is sufﬁcient for the present purposes. 31. This summary partly follows Weatherford (1982), 22–23. Weatherford’s helpful account contains some minor errors. Jacques Bernoulli was born in 1655, not 1654. Weatherford, ibid., 23, states that the elder Nicholas Bernoulli ﬂed the Belgian persecution. In fact, the family left Antwerp in 1570 and became Swiss citizens in 1622; the elder Nicholas was born the year after. 32. Some relevant Leibnizian publications during this stage of the controversy were J. Hermann, Phoronomia, sive de viribus et motibus corporum solidarum et ﬂuidarum (Amsterdam, 1716); M. G. Poleni, De castellis, per quae derivantur ﬂuviarum aquae (Padua, 1718); J. Hermann, ‘‘Loix de la nature touchant les forces des corps et leur vrai mesure’’ (1719); W. J. s’Gravesande, Physicae elementa mathematica experimentiis conﬁrmata (Leyden, 1720); W. J. s’Gravesande, Philosophiae Newtoniane institutionies in usus academica (Leyden, 1723; a revised and shortened version of the earlier Physicae elementa); J. Bernoulli, Discours sur les loix de la communication du mouvement contenant la solution de la premie`re question propose´e par Messieurs de l’Acade´mie Royale des Sciences pour l’anne´e 1724 (Paris, 1729). 33. H. Pemberton, ‘‘An account of some experiments to prove the force of bodies in motion,’’ Philosophical Transactions of the Royal Society (London, 1720), 32/371: 57ff.; C. Maclaurin, De´monstration des loix du choc des corps (Paris, 1724); various notes and papers by G. Eames appeared in the Phil. Trans. Royal Soc. in 1726–7, 34/396: 184; 34/396:188ff.; 35/400:343ff.; S. Clarke, ‘‘Of the propagation of velocity and forces in bodies in motion,’’ Phil. Trans. Royal Soc.(1728), 35/401:382; J. Jurin, Dissertationes Physico-Mathematica (London, 1732). 34. J. J. D’O. de Mairan, ‘‘Dissertation sur l’estimation et la me´sure des forces motrices des corps,’’ Me´moires de l’Acade´mie Royale des Sciences (Paris, 1728), 1– 49. 35. Mme de Chaˆtelet, Institutions de Physique (Paris, 1740); J. J. D’O. de Mairan, Lettre a` Mme de Chaˆtelet sur la question des forces vives (Paris, 1741); Mme de Chaˆtelet, Re´ponse sur la question des forces vives (Brussels, 1741); J. J. D’O. de Mairan, Dissertation sur les forces motrices des corps (Paris, 1741; essentially a reprint of Mairan’s Dissertation of 1728). 36. See Westfall (1971), 208. Compare also Gunther (1923–45), 8:184. 37. See Garber (1995), 313. 38. Polonoff mistakenly states (1971), 9, that Leibniz conceded to the Abbe´ within this exchange that the mv calculation can sometimes be correct. Actually, it was the other way around; the abbot conceded to Leibniz that the mv2 calculation can sometimes be correct. See Catelan, ‘‘Courte Remarque,’’ G 3:41–2; and Leibniz, reply to Catelan sent as the second letter to Bayle (no title, no date), G 3:43. 39. Cf. Leibniz, Specimen Dynamicum, ed. Dosch et al. (1982), 12. Leibniz’s distinction between dead and living force will play a crucial role in Kant’s attempt at a resolution; see below chapter 2 for a more detailed discussion. 40. For such misleading representations, see Vleeschauwer (1962), 19; Schultz (1965), 70; and Ho¨ffe (1994), 11. For a somewhat better account of d’Alembert’s role, compare Adickes (1924a), 1:75–7. However, Adickes mistakenly believed that d’Alembert wrote his introductory essay already in 1743. For useful descriptions of d’Alembert’s role, see Jammer (1962), chapter 11; Hankins (1965), 285–6; Hankins (1968), xxii; and Iltis (1970), 115–24.

254 Notes to pages 31–35 41. Shell, in (1996), 10, alleges a connection between d’Alembert and Euler. She maintains that Kant’s Living Force was obsolete, ‘‘compared with Euler’s Mechanica sive motus scientia (1736) or d’Alembert’s Essai [sic] de dynamique (1743).’’ Shell’s association of d’Alembert and Euler is misleading. Euler’s Mechanica was not a precursor to the solution of the problem of living forces, because his mechanical theory in the 1730s involved the rejection of the Cartesian formula. More interesting and better informed is Iltis’s suspicion of a connection between Boscovich and d’Alembert; see Iltis (1970), 115–24. Iltis argues that Boscovich realized, like d’Alembert, that vis viva and mv are equally valid. This is true, but Boscovich hid this correct solution under an emphatically Cartesian stance. Boscovich rejected vis viva both in his dissertation De viribus vivis (1745) and in his main work, Theoria philosophiae naturalis (1758); tr. as A Theory of Natural Philosophy (1966), part 2, #293, p. 113. See also chapter 2 below. 42. The ﬁrst French reviews of the Principia (ﬁrst edition 1687) appeared in the Bibliothe`que Universelle (March 1688) and in the Journal des Sc¸avans (August 1688). The reviewer of the Bibliothe`que Universelle, who might have been John Locke, did not understand what the Principia was about. The anonymous review in the Journal des Sc¸avans was critical and derisive. The situation started to change after the publication of the second edition of the Principia (1713). Once again, the book was reviewed in the Journal des Sc¸avans (March 1715), but this time, the review was descriptive, precise, and full of admiration. In 1732, the ﬁrst of the French philosophes, Maupertuis, openly rejected the national dogma of Cartesianism in favor of Newtonian physics, followed soon thereafter by Voltaire and others. For further details about the reviews of the Principia, cf. Cohen (1971), 145–61, 252–4. De Gandt, in (1995), 14, adds that Newton tried to help Locke to understand what the Principia was about. Newton composed for Locke in four pages a demonstration that the planets by their gravity move in ellipses. For this text, entitled ‘‘On Motion in Ellipses,’’ see Newton (1962b), 293–301. 43. All references are to Jean Le Rond d’Alembert’s Traite´ de Dynamique (Paris, 17582). 44. In terms of the calculus, a (instantaneous acceleration) is deﬁned as lim (∆t→0) ∆v/∆t (t stands for time, v for velocity), which is the same as dv/dt. So, F could also be expressed as mdv/dt. 45. If one looks at the space integral of Newtonian force, one gets work or kinetic energy: ∫Fds 1⁄2mv2 (the 12⁄ ; is just a constant and cashes out in units—in this sense, d’Alembert’s formula is merely a modiﬁcation of Leibniz’s formula). The time integral of Newtonian force, on the other hand, equals momentum: ∫Fdt mv. 46. Letters to Serena (London, 1704; repr. Stuttgart/Bad Cannstatt: FrommannHolzboog, 1964), ﬁfth letter, #15, 17, 19–22, esp. #13, p. 183, and #20, p.201–2. For Toland’s conception of active matter, see Casini (1967), 39–50, esp. 41–2; for the background of Toland’s interpretation of Newton, see Metzger (1938), 40, 108–9, 204; Giuntini (1979), 225; and Stewart (1981), 54. 47. The Principles of the Philosophy of Expansive and Contractive Forces (Cambridge, 1727), 286; Disquisitions relating to Matter and Spirit (London, 1777), 5–6. For the shift of the deﬁnition of matter from a passive to an active construct, see Yolton (1983), chapters 5–6. 48. See chapters 5 and 7 below.

Notes to pages 36–40 255 CHAPTER TWO

1. ‘‘Kant unternimmt ein schwer Gescha¨fte, / Der Welt zum Unterricht. / Er scha¨tzet die lebend’gen Kra¨fte; / Nur die seine scha¨tzt er nicht.’’ Gotthold Ephraim Lessing’s jingle appeared in the satirical magazine, Neuestes aus dem Reich des Witzes (July 1751): 32. 2. Erdmann (1876), 7–8, defends the shortcomings of the Living Forces with this explanation, quoting Gottsched, Ludovici, Borowski, and other contemporaries of Kant who complained about the insufﬁciencies of the Ko¨nigsberg book trade. 3. Cf. Roger Boscovich, De viribus vivis. Dissertatio habita in Collegio romano S.J. (Rome, 1745). In the revised and enlarged second edition of Boscovich’s Theoria philosophiae naturalis redacta ad unicam legem virium in natura existentium (Venice, 1763), the relevant arguments are restated in a digression on the composition of forces, #277–95, bracketed in #276 by the acknowledgment of Huygens’s formula and the rejection of vis viva in #293. See also Boscovich’s Theory of Natural Philosophy, tr. J. M. Child (Cambridge, Mass.: MIT Press, 1966), 107–115. 4. For Kant’s erroneous interpretation of the ‘‘square of velocity’’ in Leibniz’s formula, see Living Forces, #92–101, I 101–112. For his implicit rejection of Galileo, see also # 31, I 44; #37, I 48–9. For his rejection of mv2 as a quantity with physical relevance, cf. #98, I 107; #101, I 112; #114, I 139–40; #125, I 149. The only reference to Huygens is in #40, I 50. (Kant mentions him in one breath with Wren and Wallis and states he does not want to cite their mechanical discoveries.) For Kant’s assessment of Newton in the Living Forces, see chapter 3 below. I disagree with Wundt (1924), 99, who claimed that Kant’s ﬁrst book reveals a sound familiarity with the relevant literature. As Polonoff (1971), 39, persuasively argued, and as is also suggested by the frequency patterns of authors cited in the Living Forces, Kant’s sources for writing the Living Forces were conﬁned to the issues of the Acta Eruditorum, the Commentarii Petropolitanae, the Institutions de Physique by Mme du Chaˆtelet, and the Elementa physicae by Peter van Musschenbroek. Instead of a sound familiarity with the literature, it appears that Kant mostly read some Leibnizian papers, general textbooks, and the Mairan-Chaˆtelet exchange in the ﬁnal ‘‘literati’’-period of the debate. 5. Christian Wolff, whom Kant credits in #16, I 28, distinguishes between vis mortua and vis viva in his metaphysical main work, the Cosmologia generalis (Frankfurt/Leipzig, 1731), W II:4, #356–7. Wolff ’s paper ‘‘Principia Dynamica’’ contains the ﬁrst account of his theory of dynamics based on the vis motrix. It was published in the Commentarii academicae scientiarum imperialis Petropolitanae, volume I (St. Petersburg, 1728). For an extensive account of Wolff ’s contribution (or lack thereof) to the vis viva question, see Campo (1939), 1:215–54. Wolff ’s deﬁnitions of the relevant terms are largely a repetition of Leibniz’s description in the Specimen dynamicum. Jean Bernoulli differentiates between a force morte and a force vive in a similar fashion in his Discours sur les loix de la communication du mouvement (Paris, 1727), chapt. 5, #2–3. Kant praises Bernoulli for his ‘‘insight’’ in #128, I 150–1. Christian August Crusius should be mentioned as a non-Leibnizian who subscribed to the same distinction between living and dead force, cf. Crusius’s Entwurf der nothwendigen Vernunftwahrheiten (Leipzig, 1745), C 2:764–82, #396–408. 6. In #6, Kant mentions a ‘‘certain astute author’’ who would have perfected the triumph of physical inﬂux over preestablished harmony had it not been for a certain conceptual confusion regarding the ‘‘place’’ of the soul. Watkins (1995a), 286, n.16, argues that it is likely that Kant refers here to Martin Knutzen, who was Kant’s teacher and a proponent of physical inﬂux. Knutzen proposed a synthesis of Leib-

256 Notes to pages 40–48 nizian principles and physical inﬂux in Systema causarum efﬁcientium (1735), in particular in # 21, 29, 33–5. For details on Knutzen’s inﬂuxionist view of causation, see Erdmann (1876), 52, 84–94, and Watkins (1995b), 307–28. 7. Compare also Heimsoeth (1971), 85–8. 8. The full titles of Bilﬁnger’s works are De harmonia animi et corporis humani, maxime praestabilita, ex mente illustris Leibnitii, commentatio hypothetica and Dilucidationes philosophicae de Deo, anima humana, mundo et generalibus rerum affectionibus. 9. See Knutzen, Systema causarum efﬁcientium, p. 192, #55. 10. See, for instance, the Specimen dynamicum, GM 6:241 (Dosch, 1982, 24), the Animadversiones, G 4:395, and the ﬁrst draft of the Systeme nouveau pour expliquer la nature des substances et leur communication entre elles (c. 1694), G 4:473. 11. In his Elementa physices (1741), #35–44, G. E. Hamberger argued that an inner force (vis insita) constitutes resistance and impenetrability, which are genuine actions of bodies and indicate that bodies are in a state of perpetual activity. The vis insita constitutes a continuous, uniform striving toward motion. It is possible to contain such an incessant striving and be at rest; in that case, the body’s tendency to move is omnidirectional and results in an equilibrium. 12. See Shell (1996), 16. 13. See ibid., 21. This anticipation can be found in the Inaugural Dissertation but not in the Living Forces. In section 3 of the Inaugural Dissertation (1770), Kant describes time as an apriori (purus) intuition (II 399) that is not derived from the sensible world or empirical reality (II 398). Instead, time is a formal principle that the sensible world presupposes (II 398, 402). Kant’s description of space is analogous, cf. II 402– 405. 14. See Friedman (1992b), 5. 15. See Tonelli (1966), 460. 16. Of course, the gravitational grip is strictly speaking mutual. The attractive forces of the orbiting bodies affect the central body as well, although the greater mass of the central body forces the motions of the other bodies into orbits and not vice versa. 17. Cf. Leibniz, untitled tract against the Cartesians (May 1702), G 4:394; see also Leibniz’s ﬁfth letter to Clarke, #29, G 7:395–6. 18. Tonelli (1959b), 10–11, rightly concludes from Kant’s ﬁrst general proof of vis viva in #17 that an absolutely empty space does not exist for Kant. According to Adickes (1924a), 1:91, Kant’s proof fails because it presupposes an ether and does not work for a Newtonian void. Adickes’s objection seems misguided given that Kant rejected the void out of hand. 19. I shall limit myself to a summary of Kant’s main ideas here. For a step-bystep analysis of section II, see Adickes (1924a), 1:118–44. 20. Cf. #29, I 42: ‘‘Allein es war ein unrecht angewandter Grundsatz des Cartes, der [Leibniz] zu einem Irrthum fu¨hrte, . . . [Leibniz] setzte na¨mlich folgenden Satz fest: Es ist einerlei Kraft no¨tig, einen vier Pfund schweren Ko¨rper einen Schuh hoch zu heben, als einen einpfu¨ndigen vier Schuhe.’’ Kant’s confusion of Galileo and Leibniz is implicit in his consideration of falling bodies in #31–37 and #113a.II. There Kant argues that Leibniz errs in stipulating a proportionality between the effect of gravity (Schwere) and the traversed spaces; rather, the Cartesian proportionality between the effect of gravity and the time duration applies (I 44). The force of falling bodies cannot be measured by the square of velocities and thus does not reveal the Leibnizian formula; instead, the Cartesian formula applies (I 48–9). Kant changes his tune in section III #139, maintaining now in bold contradiction to his earlier statements that the force by means of which a body overcomes the resistance of gravity

Notes to pages 48–57 257 is like the square of the body’s velocity, and that the phenomenon of gravity neither proves nor disproves the living forces (I 162). 21. Cf. #93, I 103: ‘‘Denn es ist deswegen noch nicht die Wirkung gro¨ßer als ihre Ursache, und die immerwa¨hrende Bewegung selber ist in diesem Falle keine Ungereimtheit, weil die hervorgebrachte Bewegung nicht die wahre Wirkung der Kraft ist, welche dieselbe eigentlich nur veranlaßt hat, folglich auch immerhin gro¨ßer sein kann als diese, ohne daß man gegen das Grundgesetz der Mechanik ansto¨ßt.’’ 22. In section I, Kant also acknowledged the existence of a dead pressure or vis mortua measurable as mv. But this Cartesian concession is in tune with a straightforward Leibnizian stance. Leibniz, Jean Bernoulli, Wolff, and others had granted a distinction between living and dead force, permitting a restricted relevance to the Cartesian formula. For example, Leibniz distinguishes in the Specimen dynamicum between various types of primitive and derivative forces. Primitive active force is either living force, connected to actual motion, or dead force, vis mortua, connected to acceleration; see GM 4:238; Dosch (1982) 12–14. 23. According to Kant’s argument in section II of the Living Forces, F mv is the only adequate formula, as he repeats time and again; there is only one quantity of force, which is the Cartesian quantity of motion; and a quantitative mechanics must follow Descartes’s approach. Compare #28, I 40–1; #37, I 48–9; #65, I 74; #98, I 107; #101, I 112. 24. See Watkins (1995a), 289, and Adickes (1924a), 1:142. 25. Tonelli (1959b), 24, accuses Kant of having plagiarized the concept of viviﬁcation from Christian August Crusius, speciﬁcally from #450 of Crusius’s Entwurf der nothwendigen Vernunftwahrheiten (Leipzig, 1745; Crusius’s Metaphysik). The paragraph mentioned by Tonelli concerns free will, not viviﬁcation; cf. C 2:877–80. Motion and force are discussed in # 390–443, chapter 2 of the book on Cosmology in Crusius’s Metaphysik. In #405, Crusius remarks that bodies might possess intrinsic forces that are triggered rather than caused by external impacts; cf. C 2:778–80. This involves a general idea of viviﬁcation, the idea of an external trigger of an internal force. But Tonelli’s charge of plagiarism is exaggerated because viviﬁcation is a fullﬂedged theory in Kant and only an idea in Crusius, and because Kant derives viviﬁcation from Leibniz’s principle of continuity alone rather than from anything else. See also the discussion of continuity in chapter 3 below. 26. Christian Wolff rejected the mere possibility of an experimental demonstration of living force; see Wolff ’s Cosmologia generalis, #377, W II.4, 273: ‘‘quod mensuras virium per experimenta ad examen revocaturi nobis caveamus, ne eadem in motibus instituamus, ubi vires vivae locum non habent.’’

CHAPTER THREE

1. 1749 was the year in which the Living Forces ﬁnally appeared in print. It is likely that Kant’s letter from 23 August 1749 addressed Albrecht von Haller, but the identity of the recipient has not been conclusively established. At that time, Kant was still prepared to defend the claims he advanced, but the ﬁrst doubts had already crept into his self-assessment. He wrote in the letter that he intended to wake up the German academics with his work, and that he was in the process of preparing a sequel that would lend further support to his claims; see X 1–2. 2. The Hypothesis physica nova appeared in two parts, Theoria motus concreti and the Theoria motus abstracti. Leibniz declared his support of Cartesianism in #57, see A VI:ii:248. Garber (1995), 275, observes that the spirit behind the Hypothesis physica

258 Notes to pages 57–61 nova is thoroughly mechanistic. For the Cartesian inﬂuence on the early Leibniz, see also Costabel (1973), 11–16. 3. See also G 4:444. Garber (1995), 283–4, concludes that there are two levels in Leibniz’s natural philosophy, a mechanical philosophy at the surface and a metaphysics that is the proper physics. 4. See GM 6:241; Dosch (1982), 22–4. 5. See the Oeuvres philosophiques latines et franc¸oises de feu M. Leibnitz, ed. R. E. Raspe (Amsterdam/Leipzig: 1765), 7 vols. 6. Thomasius was temporarily allied with the pietist cause and became the target for the pietist theologian Joachim Lange. Lange reproached Thomasius in the Notwendige Gewissensru¨ge (Halle, 1702; the title of Lange’s tract means, ‘‘Necessary Reprimand’’) for an unacceptable freedom of thought. On Thomasius’s philosophical independence, see Gawlick (1989), 256–73. 7. See Budde’s Elementa philosophiae theoreticae (Halle, 1703), p. IV, c.1. For his relationship to other pietist thinkers, see Wundt (1945), 63–75. 8. Tonelli (1969), xxii, describes Crusius’s philosophical independence. Tonelli’s useful summary needs to be qualiﬁed because Crusius remained concerned about avoiding any conﬂict with theology. Crusius still acknowledged the essential superiority of the biblical doctrine. Accordingly, rational proofs must not violate biblical tenets, as he emphasizes in the Anleitung u¨ber natu¨rliche Begebenheiten ordentlich und vorsichtig nachzudenken (1749), C 4.1:460. 9. Kant’s position of independence has been described by Tonelli in (1959b), viii, as ‘‘un eclettico indipendente antiwolfﬁano.’’ Tonelli’s characterization of Kant’s independence as an independence from Wolff is not correct for the 1740s. Kant’s attitude toward Wolff changed from a sympathetic stance in the Living Forces to an increased critical assessment in the 1750s and ’60s. 10. J. C. Unzer (‘‘Unzerin,’’ b. Ziegler, ‘‘Zieglerin’’) was not only the single female member of the ‘‘textbook authors,’’ but indeed the only female philosopher in Germany, similar to Chaˆtelet in France. Her main work was Grundriß einer Weltweisheit fu¨r das Frauenzimmer, which went through two editions, in 1751 and 1767. 11. For the Cartesian analysis of being in terms of essence, see Sala (1988), 24–5. For the rejection of this approach by their Wolfﬁan contemporaries, see E´cole (1989), 207. 12. See Bilﬁnger, Dilucidationes, W III.18:5, #6. For details on Bilﬁnger’s thought, see Liebing (1961) and Kintrup (1974). 13. See Wolff, Philosophia prima sive Ontologia, W II.3:143, #174. 14. See Baumgarten, Metaphysica (1739), #55–56, p.15–16. 15. Kant also praises another method (#88–91, I 93–99) as the ‘‘main source of this treatise’’ (p. 94): when analyzing a proof, one should examine the validity of its individual steps, and one should examine the tacit assumptions, the path of demonstration, and the actual result. ‘‘If people had always made an effort to reason thus, they could have avoided much error in philosophy,’’ Kant afﬁrms (#89, I 95). Adickes (1924a), 1:136, rightly points out that this method is trivial and did not save Kant from error. 16. For Schultz, the postreformatory concept of antithesis, and the antithetic method, see Hinske (1972), 48–59. On Kant’s relation to Schultz, see also Erdmann (1876), 140. 17. See Cassirer (1981), 13. 18. See Goulyga (1985), 19. 19. See Schultz (1965), 12–13; Cassirer (1981), 15–17.

Notes to pages 61–68 259 20. See Gerhardt and Kaulbach (1979), 69. 21. Kant’s declaration in the Living Forces # 19, I 30, that metaphysics must be supplemented by mathematics, does not turn into investigative practice; Kant comments on mathematical demonstrations without hardly ever construing his own. 22. The full title of Crusius’s Physics is Anleitung u¨ber natu¨rliche Begebenheiten ordentlich und vorsichtig nachzudenken (Leipzig, 1749); ‘‘Guide to an Orderly and careful Reﬂection on Natural Events.’’ 23. For all practical purposes, metaphysics and philosophy are the same for Crusius, who often uses the two terms interchangeably. 24. The pietist philosopher Ru¨diger wrote on logic and mathematics, cf. his De sensu veri et falsi, 1709, and part 1.1., Logica, of his main work Philosophia synthetica, 1706/7 (reissued later under several different titles), and had no qualms about the use of mathematics as an auxiliary science for philosophy; see Schepers (1959), 82–4, 117. Crusius’s demarcation between mathematics and philosophy echoes Ru¨diger’s views as well. Ru¨diger distinguished between mathematics as the science of the possible and philosophy as the science of the real in De sensu veri et falsi (Leipzig, 1722; new edition), II.iv.3. n.c. Accordingly, Crusius takes the objects of philosophy as real entities that are either necessary or contingent, see his preface to the Natu¨rliche Begebenheiten; C 4.1:460. Despite superﬁcial resemblances, similar parallels between Crusius and Wolff are coincidental. In contrast to Crusius, Wolff held various and conﬂicting views on the subject. In the Aerometriae elementa (1709), W II.37:ii, Wolff conceived of both mathematics and philosophy as sciences of the possible. This ontological afﬁnity between mathematics and philosophy legitimized for Wolff the employment of the ‘‘geometric method’’ in philosophy—a method rejected by the pietists because of the fundamental difference they perceived between mathematics and philosophy. In the later and better known Philosophia prima sive Ontologia (1730), W II.4:114, #133, Wolff changed his mind and distinguished between real-philosophical and imaginary-mathematical objects. This is the view that Kant adopted in the 1740s. 25. For the principle of continuity in Leibniz, see Specimen dynamicum II: ‘‘Ex nostris quoque corporis viriumque notionibus id nascitur, ut quod in substantia ﬁt, sponte et ordinate ﬁeri intelligi possit. Cui connexum ut nulla mutatio ﬁat saltum’’ (Dosch, 1982, 44). For Leibniz’s identiﬁcation of this notion with the law of continuity, see ibid., 48. 26. See Leibniz to Des Bosses, 29 May 1716, G 2:515. Continuity, for Leibniz, applies to a series whenever it is such that there is a point between any two given points. Compare Kant, Liv. Force, #28, I 40, ln.13–17. 27. Friedman (1992b), 17 n., reads Kant’s principle of continuity exclusively as a mathematical principle. I suspect that continuity has a mathematical and a metaphysical meaning for Kant. The German term for mathematical continuity is Stetigkeit, a term Kant does not use. Nonetheless, Kant fails to distinguish sufﬁciently between these two senses, and the confusions in Kant’s laborious account may explain the difﬁculty of interpretation. 28. The conspicuous absence of Newton in the Living Forces was noticed by Wundt (1945), 100. Polonoff (1971), 39, argues that Kant was not familiar with the Philosophical Transactions of the Royal Society, the main platform for Newtonian publications. To all appearances, Kant read a paper that James Jurin published in the Commentarii academicae scientiarum imperialis Petropolitanae, volume II (St. Petersburg, 1739), and the Dissertationes physico-mathematicae (ﬁrst published in London, 1732), which were reprinted in the Acta Eruditorum (Leipzig, 1735). Jurin is the only New-

260 Notes to pages 68–69 tonian philosopher Kant discusses in the Living Forces; see note below. As regards Martin Knutzen and Newton, see Erdmann (1876), 124, 130. Knutzen’s treatise on comets, Vernu¨nftige Gedanken von den Kometen (1744), echoed Newton’s views. Kant’s ﬁrst exposure to Newton was through Knutzen who loaned Kant Newton’s works. 29. Kant mentioned Newton in the preface, I 7, and in #48, I 58, cited Newton’s law of inertia in #132, I 155, and referred to ‘‘Newton’s disciples’’ in #143, I 164. He discussed Jurin in #45, I 56; #110, I 122–3; and #136, I 158. 30. See Isaac Newton, Opticks, or A Treatise of the Reﬂections, Refractions, Inﬂections & Colours of Light (4th edition 1730), ed. by A. Einstein, E. Whittaker, I. Bernard Cohen, D. H. D. Roller (New York: Dover, 1979), 400. All future references to the Opticks will refer to this edition, unless speciﬁcally noted. 31. For Newton’s conception of inertia, see deﬁnition 3 and law 1 of the Principia; M 1:2,13; K 1:40–41, 54. Kant’s Latin citation of Newton’s principle of inertia is not verbatim but betrays that he does not have any ﬁrst-hand knowledge of Newton, having gleaned what he knows about Newtonian physics from a general textbook, or, possibly, from Wolff ’s Cosmologia generalis which contains a paraphrase of Newton’s ﬁrst law similar to Kant’s in #309, W II.4, 232. Kant quotes ‘‘Newtons Regel’’ as ‘‘Corpus quodvis pergit in statu suo, vel quiescendi, vel movendi, uniformiter, in directum, nisi a causa externa statum mutare cogatur’’ (I 155). By comparison, Newton’s own formulations of the principle are ‘‘Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis cogitur statum illum mutare’’ (in the 1687 and 1713 editions of the Principia), and ‘‘Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus illud a viribus impressis cogitur statum suum mutare’’ (in the deﬁnitive 1726 edition of the Principia; K 1:54). 32. Newton did not discuss vis viva in the Principia, but his rejection of living forces is obvious enough. First, mv, not mv2 found entrance into the preliminary def. 2 (quantity of motion); see M 1:1, K 1:40. Furthermore, a convergence of gravity and living force is ruled out already on grounds of Newton’s denial that gravity is the essence of bodies—if there is anything like an essence, then it would be inertia, Newton mentions in rule 3; see M 2:398–400, K 2:552–5. Finally, Newton’s own conception of force implicit in the law of acceleration amounts to F ma; see M 1:13; K 1:54–5. Interestingly, the conclusion of proposition 9 in book I is equivalent to ∫ Fds ∆(1⁄2mv2); see M 1:125–7, K 1:211–15; there, Newton implicitly derived the work-energy equation, but, as Westfall (1971), 488–9, argues, without grasping the importance of what he had found. 33. Newton demonstrates universal gravitation in the ﬁrst 14 propositions of book III and states the law of universal gravitation in prop. 7 of bk. III. Before the Principia, Newton speculated that gravity is due to a descending etherial shower in the Questiones quaedam philosophiae (1644). In De Gravitatione et aequipondio ﬂuidorum (wr. after 1668), Newton rejected ether and spatial plenum and argued for a spatial void. This latter view found entrance in the Principia; see explanation to prop. 10, bk. III; M 2: 419, K 2:586. The declared absence of a propagating spatial medium implies action at a distance. Kant, however, does not yet subscribe to a spatial void in the 1740s, and action at a distance still remains an action propagated through an ether. I concur here with Tonelli’s interpretation of this issue, who concluded in (1959b), 11, that for Kant, the possibility of action at a distance still presupposes a rareﬁed spatial matter. For further details on this matter, see chapter 4 below. 34. The problematic standard assessment of Kant as a Newtonian ab initio originated with Adickes (1924a), 1:80, who argued that Kant proceeded from a Newto-

Notes to pages 69–75 261 nian premises in his consideration of living forces. More recently, Marty (1980), 26, revived this reading and claimed that the Living Forces is a testimony to the relevance of Newton for Kant. Other defenders of this view are Friedman, who asserts in (1992b), 5, that the Living Forces initiated Kant’s attempt to revise Leibniz-Wolfﬁan monadology in light of Newtonian physics, and Laywine, who argues in (1993), 34–6, that Newton’s law of inertia underlies the Kantian criticisms of moving force and that Kant’s concept of force seems to be very much in the spirit of Newton’s. 35. For instance, the work of James Jurin, the only Newtonian he was somewhat familiar with, was relevant for Kant only in terms of the Cartesian objections to the mv2-formula. See #110, I 122: ‘‘Die Cartesianer haben den Vertheidigern des neuen Kra¨ftemaßes niemals mit mehr Zuversicht Trotz bieten ko¨nnen, als nachdem Herr Jurin den Fall gefunden hat, dadurch man auf eine einfache Art und mit sonnenklarer Deutlichkeit einsieht: daß die Verdoppelung der Geschwindigkeit jederzeit nur die Verdoppelung der Kraft setze.’’

CHAPTER FOUR

1. The two essays are Untersuchung der Frage, ob die Erde in ihrer Umdrehung um die Achse Vera¨nderungen erlitten habe, ‘‘Investigation of the question of whether the Earth has suffered changes in its axial rotation,’’ in I 183–192 (the Spin Cycle essay), and Die Frage, ob die Erde veralte, physikalisch erwogen, ‘‘The question of the aging of the Earth, considered physically,’’ in I 193–214 (the Aging Earth essay). The Spin Cycle essay appeared 8 and 15 June 1754; the Aging Earth essay appeared in a series of installments from 10 August to 14 September 1754 in the Wo¨chentliche Ko¨nigsbergischen Frag-und Anzeigungsnachrichten. 2. According to J. Rahts, the editor of the Universal Natural History in the Academy edition, most copies of the book were locked up and stored; see ‘‘Einleitung,’’ I 35. Adickes (1924a), 2:205–6, repeating Rahts’s account, notes that the book received one, favorable review in 1755, and six copies existed in German university libraries by the 1920s (how many of these copies survived the Second World War is another question). Krafft, in the postscript to his edition of the Universal Natural History, adds that the impounded copies of the bankrupt publisher were destroyed in a warehouse ﬁre; see Krafft (1971), 193. 3. There is considerable confusion about the academic status of Kant’s early texts; see also chapter 1, note 3. On Fire has been misidentiﬁed as Kant’s doctoral dissertation by Ho¨ffe (1994), 12, and Cassirer (1981), 36. The Acta Fac. Phil. of the University of Ko¨nigsberg indicate that On Fire was Kant’s master’s thesis; see I 562. 4. The New Elucidation has been mistaken for Kant’s professorial thesis or habilitationsschrift by Ho¨ffe, ibid., 12, and Schmucker, (1980), 160. According to the Acta Facult. Phil. of Ko¨nigsberg, Kant’s doctoral thesis or doktorarbeit was the New Elucidation; see I 565. Kant wrote his habilitation a year later; it was the Physical Monadology (1756). 5. For further historical and scientiﬁc information about the Lisbon quake, see Bolt (1993), 7–8, 209. 6. The three earthquake papers are Von den Ursachen der Erderschu¨tterungen bei Gelegenheit des Unglu¨cks, welches die westlichen La¨nder von Europa gegen das Ende des vorigen Jahres betroffen hat, ‘‘Of the causes of the seismic tremors at the occasion of the misfortune that struck the western European countries end of last year’’ (I 417– 428); Geschichte und Naturbeschreibung der merkwu¨rdigsten Vorfa¨lle des Erdbebens,

262 Notes to pages 75–82 welches an dem Ende des 1755sten Jahres einen großen Theil der Erde erschu¨ttert hat, ‘‘History and natural description of the most curious events connected to the earthquake that shook a large part of the earth at the end of 1755’’ (I 429–462); Fortgesetzte Betrachtung der seit einiger Zeit wahrgenommenen Erderschu¨tterungen, ‘‘Consideration of the seismic tremors that have been perceived for some time (Sequel)’’ (I 463– 472). 7. Cf. Protogaea, in Leibniz (1949), 1:16–17. Leibniz repeated the salient points of his theory of terrestrial formation in the Theodice´ (1710); see G 6:262–3. The precritical Kant did not adopt the Leibnizian thesis that the earth was originally molten and hot; his theory of matter formation in the Universal Natural History was a ‘‘cold’’ theory; see also chapter 5 below. Only later, in the Volcano essay (1785), would he realize that the accretion of matter involves heat and causes originally molten planetary bodies; see VIII 74–5. 8. The lecture announcement for the Summer Semester 1756 is Neue Anmerkungen zur Erla¨uterung der Theorie der Winde (I 489–504). The lecture announcement for the Summer Semester 1757 is Entwurf und Anku¨ndigung eines Collegii der physischen Geographie nebst dem Anhange einer kurzen Betrachtung u¨ber die Frage: Ob die Westwinde in unseren Gegenden darum feucht seien, weil sie u¨ber ein großes Meer streichen (II 1–12). 9. For the discovery of the trade wind mechanism, see George Hadley, ‘‘Concerning the Cause of the General Trade-Winds,’’ Philosophical Transactions 39 (1735): 58– 62. For the discovery of the coastal wind mechanism, see J. A. Segner, Einleitung in die Naturlehre (1754), 531–532. For a systematic and detailed exposition of the strengths and ﬂaws in Kant’s meteorological theories, see Adickes (1924a), 2:328– 353. 10. The course announcements for 1758 and 1759 were Neuer Lehrbegriff der Bewegung und Ruhe und der damit verknu¨pften Folgerungen in den ersten Gru¨nden der Naturwissenschaft (II 13–26), and Versuch einiger Betrachtungen u¨ber den Optimismus (II 27–36). The next cluster of writings, in the 1760s, consisted of the short tract On the False Subtlety of the Four Syllogistic Figures (1762); Kant’s third book, Only Possible Argument of a Demonstration of God’s Existence (1763); the important Prize Essay, ‘‘Investigations of the Clarity of Principles of Natural Theology and Ethics’’ (1764); and his ﬁrst popular success, the treatise Observations on the Feeling of the Beautiful and the Sublime (1764). 11. See I 186:29, 186:36, I 191:07. In unpublished notes to the Spin Cycle essay, Kant also mentioned Huygens. In the notes, he examined Huygens’s hypothesis that gravitational attraction is homogenously distributed throughout the interior of the earth. Kant rejected this idea, and following Newton, argued that gravity is smaller in the earth’s interior than on the surface, and that gravitational attraction increases in proportion to the distance from the center of the earth; see XXIII 5–7. 12. Before the actual publication, Kant replaced the technical term ‘‘cosmogony’’ with the ‘‘universal natural history’’ (Allgemeine Naturgeschichte), a title he might have borrowed from Buffon’s Histoire naturelle that was translated into German as the Allgemeine Historie der Natur (vol. 1 pub. Hamburg/Leipzig, 1750), as Shea (1986), 115, speculates. 13. A numerical comparison of the references in these early writings dramatically mirrors Kant’s philosophical shift from the 1740s to the 1750s. In the Living Forces, Kant refers to Leibniz 123 times, to Descartes 71 times, and to Newton 4 times. In the geophysical essays and the Universal Natural History, Kant does not refer to Leibniz at all, mentions Descartes once (critically), and names Newton 39 times. For the speciﬁc locations of the references in the texts, see Martin (1967–9), vol. 20.

Notes to pages 81–85 263 14. Chandrasekhar (1995), 399, notes that Newton’s theory of the tides, developed in 1686, went against the scientiﬁc common-sense of the time. Galileo scoffed at the possibility of explaining tides, and Huygens did not believe Newton’s subsequent theory. Chandrasekhar exaggerates somewhat. Galileo did develop a theory of the tides in 1595 that involved a mechanical explanation of the tides through the two circular motions of the earth assumed by Copernicus; see Drake (1980), 29. He then composed a paper on the subject in 1616 that he tried to publish in 1618; see Drake (1957), 221. Nonetheless, the theory of the tides was fully Newton’s discovery; Galileo did not so much explain the tides but used them as a piece of evidence for the motion of the earth. 15. The summary of Newton’s theory of oceanic tides in this paragraph follows Chandrasekhar’s excellent exposition (1995), 399–400. 16. Adickes (1924a), 2:318, corrected Kant’s date of 2 million years to 200 million years. Although Adickes’s suggestion is better than Kant’s, he was nonetheless mistaken by one order of magnitude. 17. Shea (1986), 120, remarks that Kant’s theory of tides was worked out by George H. Darwin in his book The Tides (1898). This is correct, but Darwin’s work appeared half a century after Robert von Mayer’s study. 18. The Prussian Royal Academy in Berlin announced the prize question in 1752, to be answered in 1754, and later postponed the deadline to 1756. The question (actually, a group of questions) was, ‘‘Si le mouvement diurne de la Terre a e´te´ de tout temps de la meˆme rapidite´, ou non? Par quels moyens on peut s’en assurer? Et en cas qu’il y ait quelque ine´galite´, quelle en est la cause?’’ See Kgl. Preuss. Akademie, Nouvelles me´moires de l’acade´mie royale (Berlin, 1770); also compare I 539. 19. It is possible that Kant courted the cosmic ether once more in the 1760s, in order to account for the eventual loss of celestial motions. In the Universal Natural History (I 317–320), Kant argues that nature can revive itself to renewed selforganization after having decayed into disorganization and entropy (the so-called phoenix-motive, see chapter 5 below). In the Only Possible Argument (II 110), Kant drops the phoenix, now allowing that a disorganized part of nature may be balanced out by nature’s greater fertility somewhere else. Eventually, the solar system will grind to an entropic halt (II 110). The reason for this change, according to Adickes, may be the renewed signiﬁcance of a cosmic ether. Herder recorded that Kant lectured on the solar system, stating that the cosmic ether impedes the motion of planets until it turns into rest as the ﬁnal state of the solar system; see Adickes (1911b), 76–8, and the same (1924a), 2:225. 20. In the Metaphysical Foundations, Kant argues that the rejection of the ether involves hypotheses that are in their last consequence implausible, such as the claim of impenetrable atoms, and the claim of an utterly empty space; see IV 515, 534, 563–4. As an aside, it should be noted that the standard English translation of the Metaphysische Anfangsgru¨nde der Naturwissenschaften as Metaphysical Foundations of Natural Science is misleading. Anfangsgru¨nde are ‘‘preliminary grounds,’’ which are quite different from ‘‘foundations.’’ 21. Kant’s discussions of the ether in the Opus Postumum revived the earlier theory of On Fire. In XXI 378, Kant deﬁnes the ether as an expansive aerial matter. Heat is a derivative expansibility depending on this matter (Kant calls this also caloric, a term he uses frequently synonymously with the ether in the Op. Post.). Kant adds (ibid.): ‘‘To assume such a matter ﬁlling cosmic space is an inevitably necessary hypothesis, for, without it, no cohesion, which is necessary for the formation of a physical body, can be thought.’’ Characteristic of the sketchy nature of the work, Kant

264 Notes to pages 85–89 wavers between different assessments of the ether. On a later fascicle of the Op. Post., in XXII 125, Kant weakens the signiﬁcance of ether by assessing the ether as a ‘‘merely hypothetical thing . . . assumed only in order to explain certain phenomena.’’ At other occasions in the Op. Post., Kant’s thought goes completely in the opposite direction; he resurrects ether as the ‘‘material in cosmic space,’’ rules out the possibility of empty space, and develops a proof of the ether’s existence based on the unity of experience, making the ether an a priori condition of the system of experience; compare XXII 129 and, in particular, XI 226. Quoted translations by Eckhart Fo¨rster and Michael Rosen in Kant (1995), 12 and 206. For a concise summary of Kant’s ether theory in the Op. Post., see Ellington (1985a), xx–xxi, and the same (1985b), 218. 22. See David Hume, An Enquiry Concerning Human Understanding (1748), edited by L. A. Selby-Brigge (Oxford: Clarendon, 1983), section 7.1, 73n. It is interesting that Hume’s reading of Newton having ‘‘recourse to an etherial active ﬂuid to explain his universal attraction’’ is located in the chapter famous for Hume’s sceptical examination of causation. For more details on this matter, see Rosenberg (1993), 68–9. 23. See Newton (1953), 54. 24. Compare Westfall (1971), 364. My account of Newton’s changing positions toward the ether is a simpliﬁcation of Westfall’s analysis. For greater details in this matter, see ibid., chapter 7, ‘‘Newton and the Concept of Force,’’ 323–423, an enlightening examination of the evolution of Newton’s views. Because the ether ﬁlls both molecular space and permeates cosmic space, the early Newton did not ﬁnd it necessary to distinguish, in contrast to Kant, between a molecular and a cosmic ether. 25. For the Questiones quaedam philosophiae, see University Library Cambridge, Add. MS 3996. For the Hypothesis Explaining the Properties of Light, see Correspondence 1: 364. For De aere et aether, see Newton (1962), 214–28. For comments on these texts, see Westfall (1971), 328–335, 364–5, 373–5. Another important text in this context is Newton’s letter on ether to Robert Boyle (28 February 1678/9) in Newton (1953), 113–16. 26. Westfall (1971), 391–9, proposes a resolution of the puzzle of the ether in Newton that is well worth summarizing: the ether of the Opticks did not compromise Newton’s natural philosophy because the ether embodied the very problem of action at a distance which it pretended to explain. Westfall argues that one can distinguish three phases in Newton’s position toward the ether: ﬁrst, the support of the material ether in Newton’s youth; then, the rejection of the material ether and the acceptance of forces in the ﬁrst editions of the main works; ﬁnally, the acceptance of an immaterial ether in the later editions of the main works. This immaterial ether is God, who by His inﬁnity constitutes absolute space, and by His omnipotence is actively present throughout it. God’s dominion over the world consists of the fact that every movement in the world is, ultimately, the immediate effect of His power. The advantage of the immaterial ether consists in it making possible the precise mathematical formulation of force. The demand for causal mechanisms (inviting a material ether) in traditional mechanical philosophies constantly thwarted the drive to express mathematical regularities in nature. Newton’s immaterial ether, God, was free of this shortcoming. Now, matter could move according to mathematical laws. 27. See Adickes (1924b), passim, especially 72–80, and compare Adickes (1924a), 1:1–64, for a more in-depth discussion. In contrast to the natural philosophers who loom large on Kant’s horizon, Descartes, Leibniz, and Newton, Kant neither made any original contributions to mathematics, nor methodically performed any experi-

Notes to pages 89–93 265 ments. We know of some experiments that he performed, but they were very infrequent and always amateurish. 28. See Krafft (1971), 180–1. He further suggests that Kant might have been inﬂuenced by Leibniz’s employment of analogies, as Leibniz uses them in a late geological natural history, the Protogaea. Krafft’s latter suggestion might well be true, considering that the Protogaea was published in the years prior to the Universal Natural History, in 1749, and inﬂuenced other authors Kant read, such as Buffon. For Leibniz’s employment of analogies, see Sticker (1967), 244–59; and the same, (1969), 2:176–96. 29. Kant’s pursuit of a different class of causes is quite evident from the organization of the Universal Natural History. For instance, section II.1 of the work bears the title, ‘‘On the Origin of the Planetary System and the Causes of Planetary Motion’’; II.4, ‘‘On the Origin of the Moons and the Motions of Planets around their Axes’’; II.5, ‘‘On the Origin of the Ring of Saturn . . .’’; II.7, ‘‘On Creation in its Complete Inﬁnite Scope, both in Terms of Space, as in Terms of Time.’’ 30. Adickes convincingly explains in (1924b), 74, that the enthusiasm with which Kant embraces the approach of physical science remains the enthusiasm of an outsider. In incorporating the methodological principles of physical science into his own philosophy of nature, Kant acknowledges them as the foundation and standard for his own inquiries but not as actual tools for his investigation. 31. Actually, this statement at I 235 is somewhat misleading. The ground for any analogy must be something that one is certain of—the plausibility of an analogy depends not only on the closeness of relevant similarities between original and object of the analogy, but also on the certainty of knowledge one has of the original that is to serve as the basis of the analogy. Astronomical knowledge, the knowledge in question, must be observational. Strictly speaking, then, the cosmological system is grounded in observation and proceeds according to analogy. 32. See also Tonelli (1959b), 80–1. 33. Compare also query 31 in the Opticks, esp. 376 and 397. 34. The scientiﬁc perspective of nature assumes this regular constitution of nature, and a metaphysical perspective supplementing natural science ought to agree with it. Metaphysical theories of nature involving divine interferences pose the exception, either in the form of the possibility of outright miracles, as the Pietists and Wolff suggested, or in the form of the ‘‘hand of God’’ that subtly readjusts the physical regularity of nature. Predictably, Kant feels challenged by these theories and endeavors to minimize God’s external inﬂuence on nature by showing that divine interferences are not necessary for explaining the workings of physical nature. 35. Kant was perfectly aware of the elliptic form of planetary orbits. The characterization of orbits as circles rather than as ellipses is not meant to contradict Kepler, who had calculated in 1609 the elliptic orbit of Mars and in 1618 the elliptic orbits of the other then known planets; cf. Kant’s discussion of Kepler in I 244. Nor is it the case that Kant regarded the orbital circle simplistically as having a metaphysically privileged status, as Shea suggests in (1986), 104. Rather, Kant’s reference to orbital circles is a stylistic quirk indebted to Newton. Newton used ‘‘circles’’ and ‘‘orbital ellipses’’ interchangeably; cf. Principia, book III, phenomenon 1; K 2:556, M 2:401; ibid., Schol. Gen.; K 2:759, M 2:543–4. Kant does the same in I 245:29–37 (my emphasis): ‘‘Der Unterschied zwischen den Laufkreisen der Kometen und Planeten besteht also in der Abwiegung der Seitenbewegung gegen den Druck, der sie zum Fallen treibt; welche zwei Kra¨fte je mehr sie der Gleichheit nahe kommen, desto a¨hnlicher wird der Kreis der Cirkelﬁgur, und je ungleicher sie sind, je schwa¨cher die

266 Notes to pages 93–99 schießende Kraft . . . ist, desto la¨nglicher ist der Kreis, oder . . . desto excentrischer ist er, weil der Himmelsko¨rper in einem Theile seiner Bahn sich der Sonne weit mehr na¨hert, als im andern.’’ 36. The resemblance of planetary orbits to true circles is close. The actual eccentricity of Venus is a mere .007, of Earth .017, and of Mars .093. At its aphelion, earth is less than two-tenths of a percent closer to the sun than at its perihelion. 37. According to Kepler’s harmonic law, the ratio between the square of the orbital period of a planet and the cube of the planet’s distance from the sun is constant. According to Newton’s inverse square law, the gravitational force decreases in proportion to the square of the distance between the mass objects. The derivation extends over prop. 1–14 in Principia bk III. The inverse-square relation emerges ﬁrst in prop. 5, cor. 2; universal gravitation is introduced in prop. 7. 38. Shea (1986), 98, claims, ‘‘Under the guiding thread of analogy, [Kant] assumed that the mechanical laws that led to the formation of a system of heavenly bodies would eventually cause their destruction.’’ This is not quite correct because Kant’s arguments concerning the eventual destruction and subsequent resurrection of parts of the cosmos are teleologically motivated. The function of analogies, as I hope to have shown, is to explain the expansion of the Newtonian model to a cosmology, not to the destruction of the cosmos.

CHAPTER FIVE

1. Ameriks, in (1982), 11–17, divides Kant’s philosophy in four stages: an initial empiricist phase (1746–1755), a subsequent rationalist phase (1756–1763), a sceptical phase (1764–1768), and a fourth and critical phase (1768–1804). For his characterization of the empiricist period, see ibid., 13. 2. See Ameriks (1982), 13. 3. See Beck (1969b), 431; and Shea (1986), 115. 4. In I 229 and I 230, Kant does not mention Voltaire. But his dictum, ‘‘Gebet mir Materie, ich will eine Welt daraus bauen!’’ (I 230) echoes Voltaire’s declaration, ‘‘Donnez-moi du mouvement et de la matie`re, et je vais faire un monde’’ in his Ele´ments de la philosophie de Newton (1738); cf. Oeuvres comple`tes, 22:404. In a similar fashion, Maupertuis borrowed Voltaire’s expression for his own exposition of Newtonian physics, the Essai de cosmologie (1750); cf. Oeuvres, 2:23. 5. See Tonelli (1959b), 43–6; Shea (1986), 100–101; and Schneider (1966), 172. 6. See Joachim Lange, Caussa Dei et religionis naturalis adversis atheismum (Halle, 1727), W III.17:24. 7. Christian Thomasius, for example, who was keenly aware of the tension between theology and science, poured out his ridicule over the sciences in the Versuch vom Wesen des Geistes (1699), a tract he wrote during his pietist phase that inﬂuenced eighteenth-century pietism; compare also Schmidt (1863), 488. 8. See Franz Buddeus, Isagoge Historico-Theologica ad theologiam universam singulasque eius partes (Leipzig, 1727), I.4.#29, p. 252. For Buddeus, the purpose of physics was to explicate the natural phenomena mentioned in the Bible. 9. See Andreas Ru¨diger, Physica divina, recta via, eademque inter superstitionem et atheismum media at ultramque hominis felicitatem, naturalem, atque moralem ducens (Frankfurt, 1716), I.i.1.#51. Ciafardone (1986), 295, observes that Ru¨diger excluded the quantitative approach from physical investigations because mathematics was only capable of providing static explanations and thus unsuitable for the dynamically caused phenomena present in nature.

Notes to pages 99–102 267 10. This argument illustrates the depth of Kant’s newfound Newtonian conviction. Kant thought that Newton’s account of physical nature was simply right. The Principia increasingly dominated natural philosophy on the continent in the ﬁrst half of the eighteenth century. Alexander Pope’s intended epitaph for Newton (1730) reﬂects the enthusiastic reaction of growing numbers of philosophers: ‘‘Nature, and Nature’s Laws lay hid in Night. / God said, Let Newton be! And all was Light.’’ See Pope (1963), 808. 11. Buddeus and Thomasius rejected Wolff ’s conception of philosophy as a Weltweisheit (‘‘world wisdom’’) because it reminded them too much of the sapentia saecularis condemned by Tertullian; see Arndt (1989), 280–3. 12. Compare Christian Wolff, Deutsche Teleologie (1723), W I.7:2, #2, and I.7:6, #8. See also Wolff ’s essay Von der Erkenntnis der go¨ttlichen Eigenschaften aus der Natur (1736), W I.21.1:508. 13. Compare Dt. Metaph., W I.2:389–90 #639; Cosm. Gen., W II.4:416–7 #533. Wolff acknowledged the fundamental ontological problem with miracles in that he conceives of them as being supernatural in the literal sense of the word, that is, as conﬂicting with the structure of nature. According to E´cole (1990), W III.12.1:251, the Wolfﬁan distinction between nature and miracles consists in the fact that the ‘‘natural’’ contains reason and cause in the essence and nature of a being, whereas the ‘‘supernatural’’ is deﬁned as that which does not internally contain its own reason. Thus, there is a diametrical, ontological opposition between natural and supernatural. 14. How close Wolff ’s teleology teeters at the brink of comedy is illustrated by these selections from #47 of the Deutsche Teleologie, W I.7:74–5 (my translation): The Sun creates day through its light. . . . Daylight, however, is very useful. Because of it, we can comfortably do our chores. But in the evening, we either cannot do them at all, or not as easily, requiring additional efforts, such as the one involved in the art of making light. The beasts can ﬁnd their fodder during the day. But during the night, they would probably not ﬁnd it. Moreover, we have to thank the light of the Sun that we are able to see everything that is on the ground, not just what is near, but also and especially what is far away. Thus we can recognize the things truly when they are close and also when they are far away. This, in turn, creates multifarious uses. It is useful not only in human life, to do our necessary errands and to travel, but it is useful also and especially in the knowledge of nature, which rests in its largest part on observations that we perform by means of sight and that we could not do without the light of the Sun. Whoever does not want to comprehend this advantage created through sunlight ought to imagine how he would feel if he had to perform all his tasks for a month without daylight and in night. Thus he will sufﬁciently be persuaded by his own experience of the use of sunlight, in particular if he had to do many things on the street or in the ﬁelds.’’ 15. Compare Voltaire’s entry, ‘‘Fin, Causes Finales,’’ in his Dictionnaire philosophique (1764; Paris: Garnier-Flammarion, 1964), 192: ‘‘. . . il faut avoir un e´trange amour des causes ﬁnales pour assurer que la pierre a e´te´ forme´e pour baˆtir des maisons, et que les vers a` soie sont ne´s a` la Chine aﬁn que nous ayons du satin en Europe.’’ In the Only Possible Argument (II 131) Kant sides with Voltaire’s reservations about the arbitrary equations of uses and purposes. 16. For Kant’s critique of Wolff in the Only Possible Argument, see Schmucker (1963), 455; Heimsoeth (1971), 1–92, esp. 26–9. E´cole (1991), 261–73, argues that Kant’s criticisms of Wolff are frequently unfair and based on misinterpretations. Al-

268 Notes to pages 102–104 though E´cole’s charges raise interesting possibilities, they are not plausible as regards Kant’s speciﬁc and well-directed criticisms of Wolff ’s teleology. 17. One can identify the physico-theologians as a third group of metaphysicians next to the pietists and the Wolfﬁans, but to a certain extent, such compartmentalizations are misleading. The physico-theologians were distinguished through their uniquely focused literature on aspects of the divine design in nature. Relevant philosophical differences between them and the pietists and the Wolfﬁans did not exist. The Pietismusstreit between Wolff and the pietists of Halle University did not affect the physico-theologians since this conﬂict was settled during the ﬁrst third of the eighteenth century, and the majority of the physico-theological literature emerged later. Afﬁnities more than differences deﬁned the relationship of the physicotheologians to the other two metaphysical camps. Both the physico-theologians and the pietists proceeded from lutheran theology; their common teleological-lutheran heritage may derive from works such as Philip Melanchthon’s Initia doctrina physicae (1541). Both the physico-theologians and Wolff held the earlier teleological treatises by Derham and Nieuwentyt in high esteem. Christian Wolff dedicated his Deutsche Teleologie to Derham, wrote a preface for the German edition of Nieuwentyt’s treatise, and authored introductions to several works by the German physico-theologians (see also notes below). 18. For Hume’s discussion of an argument from an overall design of the world machine, see part II of the Dialogues; compare Hume (1980), 15–20; for a discussion of an argument from the speciﬁc design of the eye, see part III; cf. ibid., 25. 19. The German translation of Derham’s work appeared as Physikotheologie oder Natur-Leitung zu Gott, durch aufmerksame Betrachtung der Erdkugel und der darauf beﬁndlichen Creaturen. Zum augenscheinlichen Beweiß, daß ein Gott, und derselbige ein Allergu¨tigstes, Allweises, Allma¨chtiges Wesen sey(Hamburg, 1730). Nieuwentyt’s opus, whose full title is Het regt gebruik der Werelt beschowingen, ter overtuiginge von Ongodisten en ongelovigen, aangetoont door B. N. Med. Doct. (Amsterdam, 1715), was published in German with a preface by Christian Wolff as Die Erkenntnis der Weisheit, Macht, und Gu¨te des go¨ttlichen Wesens aus dem rechten Gebrauch der Betrachtungen aller ¨ berzeugung der Atheisten und Ungla¨ubigen (Frankfurt, irdischen Dinge dieser Welt, zur U 1732). 20. The enumerated works are only a small fraction of the actually published literature on this subject in Kant’s time. For instance, in addition to Peter Ahlwardt’s Brontotheologie (Greifswaldt, 1746), similar derivations of God from thunder were authored by Andreas Claudius Rhyzel, Johann Heinrich von Seelen, and Johann Heinrich Zopf. For a survey and detailed bibliography of the physico-theological literature, see Philipp (1957), 21–32, and 186–218. Gebler (1990), 62 and 169, discusses some of these works, but Gebler’s bibliographical data are not always reliable. 21. In the Only Possible Argument, Kant discusses several physico-theologians by name. Derham’s and Nieuwentyt’s efforts honored human reason in the recognition of God in nature, ‘‘although occasionally much vanity entered [these efforts] by trying to make all kinds of physical insights and pipe dreams (Hirngespinste) respectable under the banner of religious zeal’’ (II 160). Furthermore, Kant refers to [Johann Peter] Su¨ßmilch (cf. II 122), the author of Die go¨ttliche Ordnung in den Vera¨nderungen des menschlichen Geschlechts aus der Geburt, dem Tode und der Fortpﬂanzung desselben erwiesen (Berlin, 1741, w. a preface by Christian Wolff), and to [Thomas] Burnet (cf. II 127), an earlier author of a physico-theology of earth, rocks, and mountains, the Theoria sacra Telluris (1682, tr. into German 1698). 22. Note, though, that Newton’s impression about collisions is not correct. Neither motion nor energy is lost in the collision of bodies. The lost bodily motion

Notes to pages 104–107 269 reappears as the increased molecular motion within the bodies, and the apparently lost energy is transformed to heat. As Burtt (1970), 267, points out, this solution was postulated by Leibniz but disregarded by Newton. 23. In the long ﬁnal query 31 of the Opticks, Newton remarks, ‘‘Motion is much more apt to be lost than got, and is always upon the Decay’’ (p. 56). In a letter to Richard Bentley on 25 February 1693, Newton argues that ‘‘this frame of things could not aways subsist without a divine power to conserve it’’; compare Newton (1953), 56. 24. Compare Opticks, query 31 (1979), 399–400. The irregularites in nature ‘‘will be apt to increase till this System wants a Reformation’’ (402). God must periodically interfere to counteract these increasing irregularities and to reform the system. 25. For more extensive discussions of Newton’s teleology, see Strong (1952), 147– 67; Herrmann (1975), 205–14; Heimann (1978), 271–83; and Buchegger (1990), 35– 48. 26. One could argue that this incommensurability was absent from Newton’s private views on this matter. Although Newton publicly stated that he left the identiﬁcation of the cause of gravity ‘‘to the consideration of my readers,’’ he identiﬁed it later in life as the immaterial ether that is tantamount to God’s active omnipresence in space (see chapter 4 above). It follows that all processes are ultimately caused by God, that physical forces are just shorthand expressions for divine activities, and that there is no categorical division between opposing intrinsic and extrinsic process-types. The esoteric views contained in Newton’s early and unpublished papers lead up to the same result, through a different set of considerations. In De Gravitatione et Aequipondio Fluidorum (MS Add. 4003; wr. between 1664 and 1668), Newton speculated that God contained both space and extension in his own being; compare Newton (1962b), 90–121. Hence, physical nature of space and extended bodies are divine emanations. The motions of bodies in space are accordingly generated by God’s own activity. As in Newton’s later views, his early considerations suggest that there is only one fundamental category of process in the ontology of nature, namely, God’s action, and that the distinction between processes intrinsic and extrinsic to nature dissolves into a merely phenomenal difference. Newton’s early speculations on the spatiality of God were indebted to the Cambridge Platonists such as Henry More and Isaac Barrow (Newton’s teacher and predecessor on the Lucasian chair). For Barrow’s speculations on absolute space as the omnipresence of God, and on the convergence of existing space with an existing God, see Isaac Barrow, The Mathematical Works, ed. W. Whewell (Cambridge, England: Cambridge University Press, 1860), 1:149–54. 27. I shall here discuss Kant’s remarks on cosmogony, cosmology, and teleology in the Universal Natural History, the Optimism essay, and the Only Possible Argument as one systematic whole. Discrepancies between the accounts of 1755, 1759, and 1763 will be indicated in subsequent notes. 28. As commentators largely agree, there were no clear winners in the priority dispute over the invention of the calculus. There is insufﬁcient evidence to substantiate Newton’s charges that Leibniz stole the calculus from him, and it is likely that Newton and Leibniz developed their own versions of the calculus independently and in ignorance of each other. For detailed accounts of the dispute, see Aiton (1985),59– 67, 337–40; and Westfall (1993), 273–96. For a brief summary of the essential events in the dispute, see Ariew (1995), 35–6. For an older, but still valuable appraisal of the circumstantial evidence against Leibniz, see also W. W. Rouse Ball, A Short Account of the History of Mathematics (New York: Dover, 1980; reprint of 4th edition 1908), chapters 16 and 17. Ball’s relevant pages on the priority dispute have been transcribed by D. R. Wilkins of the School of Mathematics at Trinity College, Dublin, for the

270 Notes to pages 107–111 world wide web at http://www.maths.tcd.ie/pub/HistMath/People/Leibniz/RouseBall/ RB㛮Leibnitz.html. 29. See, for instance, Monadologie, #3, #17–18, G 6:607, 609. Compare also Leibniz’s remark in the Antibarbarus physicus, G 7:343–4: ‘‘Omnia quidem in natura ﬁeri mechanice, sed Metaphysica esse principia mechanismi.’’ 30. Hence, to portray Kant generally as an anthropocentrist, as Hoff (1983), 63– 70, does, may be justiﬁed with respect to his critical views, but is false as regards Kant’s precritical thought. 31. That the world is perfect is a continuing theme in the precritical philosophy in the 1740s and ’50s; Kant argues for it as early as the Living Forces (compare I 25) and as late as the Optimism essay; see II 31. 32. Compare Baumgarten, Metaphysica (1739; 7th ed. 1779), part II, chapt. 3, sect. 1 (#436ff.). Baumgarten discusses the features of the best of all possible worlds in this section, which he labels mundus optimus or mundus perfectissimus. 33. See Augustine, The Nature of the Good: Against the Manichees, in the same (1953), 326–48, esp. 326–30 and 337. 34. Paragraph and page numbers follow the seventh edition of the Metaphysica (1779). 35. In a footnote of the Optimism essay (II 30–31), Kant distinguished between relative and absolute perfection. Absolute perfection, ‘‘Vollkommenheit im absoluten Verstande,’’ contains the ground of reality within itself. Relative perfection, ‘‘Vollkommenheit im respektiven Verstande,’’ is the harmony of the diverse according to a rule. The degree of reality determines the degree of relative perfection, and since God is the highest reality, something is perfect in so far as it agrees with the divine properties. Kant’s distinction agrees with Leibniz’s views on the matter; compare Monadologie #41, 42, and 48, G 6:613, 615; AG 218–19. 36. Guyer (1998), 227, points out that Baumgarten’s association of beauty and phenomenal or sensory perfection stems originally from Wolff, and that Baumgarten actually employed two distinct meanings of beauty. Having deﬁned beauty in terms of the sensory perception of perfection in the Metaphysica, he replaced this deﬁnition in the Aesthetica: ‘‘Baumgarten subtly but crucially redeﬁned beauty as ‘the perfection of cognition by means of the senses as such,’ or as the perfectly realized potential of sensory representation. . . . The subtlety of Baumgarten’s revision escaped many readers of the time, including his own disciple Georg Friedrich Meier and perhaps Kant as well, who may have relied on Meier’s German popularizations rather than Baumgarten’s own intricate and lengthy Latin magnum opus’’ (Guyer, ibid.). 37. Kant used this formula both generally, as regards nature as such (I 365), and in speciﬁc contexts such as the systematic interconnection of galaxies (I 308). In the Only Possible Argument, Kant employs the ‘‘chain of being’’ in its general sense, as a union of all parts of creation, including even possible things (II 132). The term was made popular by Alexander Pope, who explicated the metaphor in the ﬁrst forty-ﬁve lines of An Essay of Man (1733); compare Butt (1963), 504–506. For a history of the term, see Lovejoy (1936), chapters 2–6. 38. Compare Hume, An Enquiry Concerning Human Understanding, #90, p. 114–5. 39. The earliest evidence of Kant’s acquaintance with Hume is a letter by Johann Georg Hamann to Kant, dated 27 July 1959 (X 15—it is ironic that it was Hamann, a romantic metaphysician and speculative spirit, who directed Kant’s attention to Hume, the Scotsman who awoke Kant from his ‘‘dogmatic slumber’’). Hamann’s letter and the role it played in Kant’s life is discussed in some detail in Beiser (1987), 23– 4.

Notes to pages 111–114 271 40. In the Universal Natural History, Kant still takes the possibility of miracles seriously enough to test his conviction that everything in physical nature occurs mechanically. This conviction prompts him to ﬁnd mechanical explanations of miraculous events. If earth once resembled Saturn, wearing a ring of ice, Kant speculates, and if this ring somehow became unstable, collapsing back to earth, the ensuing gigantic rains could have caused the biblical Deluge (I 303–4). In the Only Possible Argument, true to his growing scepticism, Kant rejects this explanation of the Deluge, because it makes God resort to mechanical gizmos to intervene in nature (II 134). This would make God appear boastful with useless art, Kant remarks; an omnipotent God could have created the world from the start on so that things follow naturally (II 135). In the same way that the ‘‘least philosophical’’ method is the appeal to miracles, the ‘‘best and truest’’ method of physico-theology is to search for reasons for the perfection of nature in nature’s own necessary general laws (II 136). 41. In the course of his philosophical development, Kant possibly changed his view on the activity of matter twice. He argued for an active matter throughout the precritical philosophy, cf. Living Forces #1 I 17; Universal Natural History I 264; Only Possible Argument II 148. In the critical period, Kant rejects active matter, cf. Critique of Pure Reason A 413/B 440; Metaphysical Foundations of Natural Science IV 544; the essay On Volcanoes on the Moon (1785) VIII 75–6. In the Opus Postumum, Kant once again reverts to an active conception of matter; cf. XX 190–1, 200–1. 42. With the transformation of matter into an active concept, Kant was in the company of other Newtonian interpreters of the eighteenth century, such as John Toland, Roger Boscovich, Joseph Priestley, and James Hutton. See also chapter 7, section 2, below. 43. See Werkmeister (1980), 6–7; and Shea (1986), 115–6. 44. Shea (1986), 115–6, argues that Kant erred in ascribing a force of repulsion to Newton because such a notion cannot be found anywhere in the Principia; Kant’s likely sources of inspiration in that regard were Buffon’s Histoire naturelle and Lucretius’s De rerum natura. Although Shea’s assessment is correct as regards the Principia, it is incorrect as regards Newton’s Opticks, thus Kant’s identiﬁcation of a Newtonian force of repulsion cannot be simply dismissed as a simple error (see also the text below). The difﬁculties with repulsion pertain not so much to its Newtonian origin but rather to its conception. It is not entirely clear what the repulsive force actually is. Adickes (1924a), 2:247, asserts that Kant identiﬁed repulsion with elasticity. However, Kant only enumerates elasticity among the various effects and phenomena of repulsion, hence, there is an asymmetry in the Universal Natural History between the straightforward equation of attractive force with gravity and the equation of repulsive force with elasticity. A further difﬁculty lies in the fact that Kant stated in I 234 and elsewhere that gravitation is paired with repulsion, only to pair gravitation in I 242 with a ‘‘shooting force’’ (schießende Kraft). ‘‘Shooting force’’ is Kant’s label for inertial force, which suggests an identity of inertia and repulsion, but for obvious reasons, this cannot be the case. 45. For De aere et aether, see Newton (1962), 214–28; for Newton’s ontological addition of a force of repulsion, see Westfall (1971), 377. 46. University Library Cambridge, Add. MS. 3970.3, 338. 47. Adickes, who wrote his (1924a) twenty years before the astrophysical conﬁrmation of the nebular hypothesis, believed Kant’s cosmogony was false; compare ibid., 2:250–52. 48. For Laplace’s cosmogonical theory, see his Exposition du syste`me du monde (Paris, 1796), ‘‘Note VII et Dernie`re,’’ 301–8.

272 Notes to pages 115–120 49. For a discussion of some of these differences between Kant and Laplace, compare Adickes (1924a), 2:297–300; and Paneth (1955–56), 342. For Kant’s and Laplace’s commitments to determinism, see chapter 6, section 4 below. 50. The last decade of the eighteenth century saw a ﬂurry of reprints of the Universal Natural History. In 1791, a short excerpt was appended to a German edition of William Herschel’s cosmological papers. In 1797, the Universal Natural History appeared in its entirety three times: as a reprint of the ill-fated 1755 edition, in the ﬁrst volume of the so-called Voigt’sche Sammlung, and in the second volume of an anthology of Kant’s early writings. In 1798, the Universal Natural History was released as a separate publication once more, and in 1799, Tieftrunk included the work in his collection of Kant’s writings. For bibliographical details see II 547. 51. Schopenhauer refers to ‘‘Kants und Laplaces Hypothese’’ in book 2 #27 of the ﬁrst volume (1818) of Die Welt als Wille und Vorstellung; compare Schopenhauer (1977), 1:200. 52. See Hoskin (1970), 44–52; and Hetterington (1973), 461–2. 53. Considering Kant’s remarks in I 247–58, Shea (1986), 97, misunderstands the relationship between solar system and Milky Way when he writes that the Milky Way belongs to the solar system as its extension. 54. Quoted after the 1st edition of the Original Theory or New Hypothesis of the Universe, London, 1750. 55. Kant read a review of Wright’s book in a 1751 issue of the Freie Urtheile und Nachrichten zum Aufnehmen der Wissenschaften und Historie u¨berhaupt, a journal published in Hamburg; compare Krafft (1971), 179. Details about Wright’s (limited) inﬂuence on Kant may be found in Adickes (1924a), 2:227–35; Paneth (1955–56), 337– 49; Whitrow, (1967), 48–56; and Jones (1971), 29–34. 56. The road to Hubble’s conﬁrmation of the Wright-Kant-Curtis claim that cloudy stars were extragalactic nebulae is a long and complicated story. In 1761, Johann Heinrich Lambert advanced in his Cosmologische Briefe a view similar to Kant’s. In the 1780s, Charles Messier prepared an astronomic catalogue listing 103 nebulae. In 1802, William Herschel published a catalogue listing 2,500 nebulae; in the 1830s, his son, John Herschel, supplemented this list with 1,300 more nebulae. William Herschel advanced different theories on the nature of nebulae, arguing, at different times, that they were single stars, glowing clouds, or clusters of stars. John Herschel did not advance a speciﬁc theory but was convinced that nebulae did not possess true nebulosity but were resolvable into more speciﬁc structures. In 1864, William Huggins discovered by means of spectrographic analysis that nebulae fundamentally differ from single stars and speculated that they consisted of a luminous ‘‘ﬂuid.’’ Most astronomers at the close of the nineteenth century assumed that nebulae were protostars inside the Milky Way; until Hubble’s conﬁrmation, Curtis’s resurrection of Kant’s idea remained a minority view. 57. See 3ieme soir, in Oeuvres comple`tes, ed. Alain Niderst (Paris: Fayard, 1990–93), 2:70. 58. See Ameriks (1982), 85–6. 59. See Principia, bk. III, prop. 6 and prop. 6 cor. 2; M 2:411, 413, K 2:572, 574. 60. In the System of the World, sect. 17, Newton appealed to God who ‘‘placed different bodies at different distances from the sun, so that the denser bodies always possess the nearer places, and each body enjoys a degree of heat suitable to its condition, and proper to its constitution’’; cf. M 2:566. Kant rejects Newton’s explanation because it involves false teleologizing (the inner planets are denser because

Notes to pages 120–126 273 God wishes them to endure more heat); see Univ. Nat. Hist., I 271. In contrast to Newton, Kant deduces the particular arrangement of matter in the solar system from mere physical causes. 61. Kant knew of Fontenelle and referred to him in I 195–6 and I 353. To illustrate Fontenelle’s idea of the increase of intelligence in proportion to solar distance, Kant quotes in I 360 from ‘‘Epistle II’’ of Pope’s An Essay on Man (see below section 6 of this chapter). Fontenelle’s Entretiens was a great success in Germany. Johann Christoph Gottsched translated the book in 1726 and edited in 1751 a multivolume collection of Fontenelle’s writings. The German Entretiens went through ﬁve successive printings between 1727 and 1760. For the history of Gottsched’s translation, see Saine (1987), 21. 62. Compare Shell (1996), 67; for similarly problematic readings, see ibid., 67, 70–3. 63. Johann Gottfried Herder incorporated Kant’s thesis of the human mediocrity on the cosmic scale in his Ideen zur Philosophie der Geschichte der Menschheit (1784– 91); see Kant’s Recension von Herders Ideen (1785), VIII 46. 64. An Essay on Man, Epistle II, lines 31–34; see Pope (1963), 517. 65. The Khoi-Khoin lived originally in the southernmost regions of the African continent but were pushed to the North and East by invading European settlers. The Nama of Namibia are the only group of the Khoi-Khoin people that survived their racial identity in colonial Africa. 66. Eze (1997), 7, comments on the Observations: ‘‘It is therefore not unfair to point to Kant’s statement: ‘‘This man was black from head to toe, a clear proof that what he said was stupid’’ as clear proof that Kant ascribed to skin color (white or black) the evidence of rational (and therefore human) capacity—or the lack of it. For the critical Kant’s conceptions of anthropology and race, racist tendencies, and interpretation of Rousseau regarding human nature, see Eze, ibid., 103–40. 67. Dating of the text according to Adickes (1911a), 9–32, esp. 279. 68. See Firla (1994): 60–94. Firla blames Kant for his racism, arguing that Kolb, in his Caput Bonae Spei Hodiernum (Nu¨rnberg, 1719), strove for a balanced narrative, praising African customs he liked and criticizing those he disliked, whereas Kant selected for his lecture only the negative passages of Kolb’s portrayal of African people, compare Firla, ibid., 69–77; Firla-Forkl (1994), 432–42. 69. For the hierarchy of human races, see Buffon’s Allgemeine Historie der Natur (Leipzig, 1752), 211. 70. Compare Firla (1994), 61. The image of the stupid Hottentot was common to eighteenth-century philosophy; compare also Fontenelle’s Entretiens; in Oeuvres 2:78. 71. See Beiser (1987), 141–5. 72. See V 161. Translation by L. W. Beck; compare Kant (1956), 166. 73. See also Adickes (1924a), 2:312–13. 74. Compare Rosenberg (1993), 73. Rosenberg points out that the modernization of science in this respect was due to Hume’s theory of causation. 75. For a sampling of modern philosophers who have argued for the rehabilitation of teleology against its reductivist critics, either generally in the philosophy of science or speciﬁcally in the philosophy of biology, see Ayala (1970), 1–15; Mayr (1982), passim; M. Ruse (1986), 43–50; Bedau (1992), 33–51; Kitcher (1993), 379–97; Dawkins (1995), 80–85. 76. Several modern environmental ethicists have developed theories of intrinsic value of nature that derive the notion of value from the notion of a purposive de-

274 Notes to pages 126–131 velopment in organic nature, thereby unwittingly resurrecting Kant’s immanent teleology; compare Attﬁeld (1981), 33–54; the same (1983), passim; the same (1995), 7– 15; Rodman (1983), 88–92; Taylor (1994), 71–83. 77. The crititical Kant thought that the class of nonrational moral patients was empty; see, for instance, the Moralphilosophie Collins (1785), XXVII.1 458–63, or the Metaphysics of Morals (1797), V 241. In the Critique of Pure Reason (1781), B830, B835, Kant located value in an extranoumenal realm, and in the Foundations of the Metaphysics of Morals (1785), IV 385, he limited the relevance of ethics, in theory, to the territory of freedom and rationality, and in practice, to the will of man. The often-heard reproach by current environmental philosophers that Kant was a staunch anthropocentrist is, as regards the critical Kant, justiﬁed. 78. Johann Gottfried Herder developed a philosophical anthropology based on the Universal Natural History in the Ideen zur Philosophie der Geschichte der Menschheit (1784–91). For the precritical Kant’s inﬂuence on Herder, and for the critical Kant’s reaction to this inﬂuence, see Beiser (1987), 149–58. Ernst Haeckel acknowledged the inﬂuence exerted by the Universal Natural History on his views of organic evolution in his Weltra¨thsel (1899); see Haeckel (1992), 258–61.

CHAPTER SIX

1. The ﬁrst edition of the Universal Natural History consisted of a preface of 56 pages, an outline of Newtonian concepts in 6 pages, and three parts comprising 204 pages. Whereas Kant’s fame in old age led to several republications of the Universal Natural History between 1791 and 1799, the ﬁrst edition of the New Elucidation remained the only edition during Kant’s lifetime. 2. See Cassirer (1981), 92–4, and compare the introduction above. 3. Although Kant’s exposition was clear, his Latin was not free of grammatical mistakes; it lacked the eloquence of Descartes’s and the erudition of Crusius’s. For a list of errors, see Lasswitz, ‘‘Lesarten,’’ I 567. 4. According to Lasswitz’s annotations to the New Elucidation in the Akademie Ausgabe (I 565), nothing further is known of Borchart, nor of Johann Gottfried Mo¨ller and Johann Reinhold Grube, the two law students. Their participation in Kant’s rigorosum seemed to have been their only claim to fame. 5. As Erdmann relates in (1876), chapter 2, Aristotelianism dominated the intellectual climate in Ko¨nigsberg in the early 1700s. Pietism superseded it in the 1720s, only to be challenged by the Leibnizian-Wolfﬁan School Philosophy in the 1740s. By 1755, the time of Kant’s dissertation, the School Philosophers dominated the scene in Ko¨nigsberg. Compared to accounts of early eighteenth-century German philosophy, such as Beck (1969b) or Wundt (1945), one notices that the events in Ko¨nigsberg mirrored nationwide developments, but with a delay of ﬁfteen to twenty years. This was the conservative hinterland; changes in the intellectual climate occurred here later than elsewhere. 6. The eventual knowledge that Kant was the author of the book had no negative repercussions. His cover was not blown until after having won all his degrees; in 1756, the Universal Natural History was listed in a bookseller’s catalogue with Kant’s name next to it. 7. See note 5 above. 8. In the Deutsche Metaphysik, Wolff introduces the Grund des Widerspruchs or principle of contradiction in #10, p. 6, the Satz des zureichenden Grundes or principle

Notes to pages 131–132 275 of sufﬁcient reason in #30, p.16–17, and the Satz des nicht zu Unterscheidenden or principle of the identity of indiscernibles in #589, p. 364. 9. See Georg Bernhard Bilﬁnger, Dilucidationes philosophicae de Deo, anima humana, mundo, et generalibus rerum affectionibus (1725), I.3, #67–80, p. 64–75, for his discussion of the principles of contradiction and sufﬁcient reason. For the principium identitas indiscernibilium or principle of the identity of indiscernibles, see ibid., I.4, #94, p. 87. Bilﬁnger calls the principle of identity the principium Aristotelicum and discusses it in the context of the principium Cartesii (Bilﬁnger’s label for the cogito ergo sum) in ibid., III.3, #239, p. 232. 10. See Wolff, Ontologia sive prima philosophia (1730), I.1.i, #27–55, p.15ff., for the principium contradictionis (principle of contradiction), and I.1.ii, #56–78, p. 39ff., for the principium rationis sufﬁcientis (principle of sufﬁcient reason). 11. In the Ontologia, Wolff speaks of a number of additional principles, such as the principii individuationis (#228–9), essendi (#874), ﬁendi (ibid.), cognoscendi (#876), externum (#880), and internum (#882). Despite their labels, none of them is an ontological axiom in the strict sense, and none of them is very interesting. The principle of individuation or principium individuationis concerns the causal determination of a being into a concrete object and is a derivative of the principle of sufﬁcient reason; see ibid., p.189. Further derivatives of the principle of sufﬁcient reason are the principii essendi and ﬁendi, the principles of being and becoming. The former concerns the reason for the possibility of a thing, and the latter the reason for the actuality of a thing; see ibid., p. 648. The principium cognoscendi or principle of knowing is not a principle, but a label for a premise in an argument. It refers to ‘‘any proposition by means of which the truth of another proposition is intelligible’’ (#876, p.649). The principii internum and externum, or internal and external principles, are additional terms that describe derivative aspects of the principle of sufﬁcient reason. Wolff deﬁnes an internal principle as ‘‘what exists in the object grounded by the principle (principiato)’’ and an external principle as ‘‘what exists outside the grounded object’’ (#880, p. 652). In the subsequent comment, Wolff explains: the principium essendi of a house is its matter; the principium ﬁendi is its architect. Because matter is constitutive of the house and is part of it, matter is the principiium internum of the house. The architect, another causal factor responsible for the house, is not part of the house and thus represents the principiium externum of the house. 12. In the Philosophia deﬁnitiva, Baumeister lists the principles of contradiction (#345, p. 67) and sufﬁcient reason (#351, p. 68) as the main principles of ontology, and repeats the list of the derivative principles of being, becoming, knowing (#545–7, p. 106), as well as the internal and external principles (#548, p. 106–7). The indicated page numbers refer to the 1775 edition of Baumeister’s work. 13. See Baumeister, Institutiones metaphysicae. Ontologiam, cosmologiam, psychologiam, theologiam denique naturalem complexae, #23, p. 21–2, #30, p. 28, # 169, p. 127– 30, #158, p. 121, and #340, p. 231. 14. See Baumgarten, Metaphysica, I.1.ii and iii, #7–24, p. 3–9, for a list of the principles. The principle of the excluded middle, or principium exclusi tertii, is a derivative of the principle of contradiction and asserts that ‘‘everything possible is either A or non-A’’ (#8, p. 3). The principle of effect, or principium rationati, states that ‘‘everything possible is a cause, or, nothing is without effect’’ (#22, p. 8). The principle of reciprocity, or principium utrinque connexorum, claims that ‘‘everything possible is cause and effect’’ (#24, p. 9). 15. See Reusch, Systema metaphysicum antiquiorum atque recentiorum item propria dogmata et hypotheses exhibens, Ont., ch.1, #8, p. 4–5, and Ont., ch. 1, #16, p. 30. In

276 Notes to pages 132–134 Reusch’s terminology, the principium contradictionis is the principium essentiarum, and the principium exclusi tertii is the principium exclusi medii. 16. See Canz, Philosophia fundamentalis suis disciplinis comprehensa variisque difﬁcilioribus quaestionibus enodandis, #32–34, p. 5, for the principle of contradiction, and #89, p. 13, for the principle of sufﬁcient reason. Canz speaks also of a principium complexum (#810), a principium incomplexum (#811), the already familiar principii cognoscendi, essendi, ﬁendi (#807–9), as well as the principii individuationis (#281) and indiscernibilium (#308–11). He adds a principium creationis, which is a derivative of the principle of sufﬁcient reason (#1442), talks about the principii heuristica in logic (#3823), coins the principium rationis formalia (#2244) and the principium rationis materialia (#2245), throws in a list of principii mechanica (#1733), and speaks in general terms of the principii physica (#1734). 17. The passages relevant for ontological principles in Bo¨hm’s Metaphysica in usum auditorii sui ordine scientiﬁco conscripta are #24–27, 42, 147, 302–3, and 530. See Coing’s Institutiones philosophicae. De Deo, anima humana, mundo, et primis cognitionis humanae principiis, #12, p.15, for the principle of contradiction. For the principle of sufﬁcient reason, cf. #44–45, p. 53–55; for the principle of the excluded middle, cf. #12, p.15–16; for the principle of indiscernibles, cf. #216–19, p. 200–3; and for the principles of existence, essence, being, possibility, and knowing, cf. #48, p. 59–60 (in Canz’s rendering, the principium cognitionis is a compound axiom consisting of a principium complexum of knowledge a priori and a principiumm incomplexum of knowledge a posteriori). 18. For Wolff ’s elevation of the principle of contradiction, see also Heimsoeth (1971), 9, and Schro¨der (1988), 45–6. For a divergent interpretation, compare Richter (1992), 123. Richter sees Wolff as presupposing the principle of identity for the principle of contradiction. Richter’s reading, however, is an interpretation challenged by Wolff ’s own (repeated and emphatic) assertations of the logical and ontological primacy of contradiction; cf. Dt. Metaphysik, #10, p. 6, and Ontologia, #27–8, p. 15–16. 19. Because the Latin text of the New Elucidation is printed in an unusually small and single-spaced font in the Academy Edition, compressing a lot of material to each page, I indicate lines as well as pages when citing from it. 20. Kant’s treatment of identity and contradiction is reminiscent of Leibniz, but he could not have known the Nouveaux Essais at the time of writing the New Elucidation because they were not published until 1765. Leibniz had identiﬁed in the Nouveaux Essais (wr. 1703–5) the principles of identity and contradiction as the rules governing the consistency of nature; see G 5:14. Leibniz advanced various views on the subject. In the second letter to Clarke, he suggested that identity or contradiction is the foundation of mathematics (G 7:355). In the Monadologie, he stated that his reasoning is based on the principles of contradiction and sufﬁcient reason (G 6:612). Leibniz’s shifting views spawned a chaos of interpretations. Russell (1992), 166, identiﬁes the principle of contradiction, not the principle of identity, as the ﬁrst truth of reason; Tymieniecka (1963), 387, identiﬁes the principle of identity, not the principle of contradiction, as Leibniz’s ﬁrst truth of reason; Rescher (1967), 47–9, doubts that Leibniz had an explicit principle of identity, but believes it is implicitly given in the identity of indiscernibles and in the substitution principle, tantamount to ‘‘Leibniz’s Law’’—(x)(y)(x y ⇔ [Fx][Fx ⇔ Fy]). Rescher’s reading led to a controversy in its own right; cf., for instance, Feldman (1970), 510–22; Curley (1971), 497–501. 21. Translation from I. Kant, Theoretical Philosophy, 1755—1770, edited and translated by D. Walford and R. Meerbote (Cambridge, England: Cambridge University

Notes to pages 134–136 277 Press, 1992). References to this translation are indicated by WM, followed by the page number. 22. See Discourse de la Me´taphysique #8, G 4:433. Leibniz’s containment theory of truth anticipated the modern coherence theory, according to which a true statement is one that coheres with a system of other statements. Leibniz’s view was not without problems; it entailed that all truths are analytic and necessary, as Arnauld had been quick to point out. For more details, see Castan˜eda (1990), 255–72; Chinn (1988), 29–45; and Fried (1978), 575–84. For a discussion of analytic truth in Leibniz, see O’Briant (1979), 159–222, esp. 199. For a brief but instructive survey of problems with Leibniz’s account, see Mercer and Sleigh (1995), 107–11. 23. See Moses Mendelssohn, Abhandlung u¨ber die Evidenz der metaphysischen Wissenschaften (Mendelssohn’s Prize Essay, 1764), in Gesammelte Schriften, 2:273. For the system of Mendelssohn’s epistemology, see the introductory ‘‘Vorerkenntnis’’ of his later Morgenstunden (1785), in Ges. Schr., 3.2:10–67. 24. The point that ‘‘the intelligible element in every idea or notion must have an independent and absolute existence’’ was made by Reuscher (1977), 18–32, esp. 20. Reuscher continues (21–2): ‘‘And if in a comparison of notions the contents or realia did not exist, one would have nothing to compare. In other words, the existence of the realia is the necessary ground of the possibility of possibility of notions not being mutually incompatible.’’ 25. Later, in the Critique of Pure Reason, Kant deﬁned truth along the lines of the correspondence view, as the agreement of knowledge (concepts) with its object; compare A58/B82, A191/B236, A643/B670. But now he realized that this was merely a nominal deﬁnition of truth and could not be more than that. The transcendental turn made the correspondence view inacceptable as a metaphysical deﬁnition. A justiﬁcation of true judgments about objects would require the prior assumption of the existence of such objects in order to allow the examination the correspondence of judgments with these objects. He pointed out this circularity in the Logik (IX 50) and in the Logik Blomberg (XXIV.1 81): the correspondence between the structure of the object and the content of the proposition is both the assumption and the proof of the assumption. 26. Reuscher (1977), 20–21. The passage relevant for Reuscher’s interpretation is I 389:13–15, ‘‘Quandocunque identitas subiecti inter ac praedicati notiones reperitur, propositio est vera; quod terminis generalissimus, ut principium primum decet, expressum ita audit: quidquid est, est.’’ 27. Compare #524: ‘‘Veritatis criterium est determinabilitas praedicati per notionem subjecti’’; #505: ‘‘Est itaque veritas consensus judicii nostri cum objecto, seu re repraesentata.’’ 28. See Wolff ’s Ontologia, W II.3:360–82, #472–94; esp. p. 383, #495: ‘‘Veritas adeo, quae transcendentalis appellatur & rebus ipsis inesse intelligitur, est ordo in varietate eorum, quae simul sunt ac se invicem consequuntur, aut, si mavis, ordo eorum, quae enti conveniunt.’’ Compare also Wolff ’s earlier Ratio praelectionum in Mathesin et Philosophiam (1718), sec. II, c. 2, #18–19. 29. ‘‘Certitudo obiectiva est apperceptibilitas veritatis in ente’’; Baumgarten, Metaphysica, 7th ed. 1779, #93, p. 26. 30. See Heimsoeth (1971), 7–8; Sala (1988), 31–2. Both commentators observed that Wolff and Baumgarten interpreted the question of being as a question of knowledge of being. Thus, Kant’s characterization of ontological axioms as principles of metaphysical cognition followed the tradition.

278 Notes to pages 136–139 31. Compare query 31 in the Opticks, 376. Consistency is related to simplicity because any exception to a law would involve a complication of nature’s structure; cf. ibid., 397, and Principia, bk. III, rule 1, K 2:550, M 2:398. 32. See Leibniz’s Annotatiunculae subitanae ad librum de Christianismo mysteriis carente, in ‘‘An Appendix containing some Pieces found among Mr. Toland’s Papers,’’ John Toland, The Miscellaneous Works (London, 1747), 2 vols., 2:69. 33. See E´cole (1990), 228. Wolff proceeded from Leibniz’s doctrine of the best of all possible worlds and considered the world to be perfect. A perfect world, however, requires a well-ordered organization, compare Cosmologia Generalis, W II.4:433, #554. Since there is order in the world, its processes are subject to laws. These laws hold true in principle and without exception. Contradictions are not possible, the world is internally consistent; ‘‘nullis contradictoriis in mundo locus est’’ (ibid., 71, #78). 34. See Buddeus, Isagoge Historico-Theologica ad theologiam universam singulasque eius partes (Leibzig, 1727), I.4, p. 261, #29. 35. Crusius’s main work, commonly referred to as his Metaphysik, has the title Entwurf der notwendigen Vernunft-Wahrheiten, wiefern sie den zufa¨lligen entgegengesetzt werden (‘‘Essay of the necessary truths of reason in so far as they differ from the contingent truths’’), and consists of four parts, ‘‘Ontologie,’’ ‘‘Natu¨rliche Theologie,’’ ‘‘Kosmologie,’’ and ‘‘Pneumatologie’’ (doctrine of soul and mind). 36. Laywine (1993), 35, identiﬁed another and important similarity between Kant’s and Newton’s laws: the three elements of Kant’s principle of succession correspond to the contents of Newton’s three laws of motion. For further details on this matter, see section 6.3 below. 37. See Leibniz’s ‘‘On Freedom and Possibility’’ (an essay written in Latin between 1680 and 1682; editor’s title), AG 19; ‘‘Primary Truths’’ (Latin, wr. probably 1686; editor’s title), AG 31; ‘‘On Freedom’ ’’’(Latin, 1689; editor’s title), AG 96; Principes de la nature et de la grace (1714) #7–9, G 6:598–9. 38. What the principle means beyond this simpliﬁcation is a matter of debate. For Russell (1992), 30 and 34–5, it involves two principles, a principle of possible contingents stating that all possible causes are desires or appetites, and a principle of actual contingents stating that all actual causation is determined by the desire for the good. For Rescher (1967), 25, it involves one principle, the principle that every true proposition is analytic. Similarly, Rutherford (1992), 40, takes the ‘predicate-insubject principle’ to be a more precise version of the principle of sufﬁcient reason. Then again, Brody (1977), 4 and 55, views it as a generic metaphysical principle of causation that has nothing to do with a logical ‘predicate-in-subject’ principle of analytic truth. A very useful interpretation is Frankel’s conception of Leibniz’s sufﬁcient reason as a compound consisting of several subordinate principles; compare Frankel (1986), 324 and 328. According to Frankel, sufﬁcient reason consists of a principle of grounds (‘‘every true proposition has a proof a priori’’), a principle of reason (‘‘God does nothing without a sufﬁcient reason’’), and a principle of causation (‘‘every event has a cause’’). 39. As regards Leibniz’s derivation of the principle of sufﬁcient reason, Frankel (1986), 321, argues that Leibniz suceeded in such a derivation only for the logical aspect of the principle of sufﬁcient reason, ‘‘every true proposition has a proof a priori,’’ while the metaphysical aspects of the principle of sufﬁcient reason, ‘‘every event has a cause,’’ and ‘‘God does nothing without a sufﬁcient reason,’’ remained independent. Kant did not furnish an explicit derivation of the principle of determining reason in the New Elucidation. He linked the ontological ratio cur vel ﬁendi to the principle of

Notes to pages 139–143 279 identity through an ‘‘identical ground’’ as a version of the ontological ground; cf. I 392 note; and he linked the cognitive ratio quod vel cognoscendi to the principle of contradiction in Proposition 5, I 393, in which he declared that ‘‘every true proposition is determinate in respect of a predicate,’’ which means that ‘‘the predicate is posited to the exclusion of its opposite’’ (WM, 13). Reuscher (1977), 21–3, characterizes their relationship such that the principle of contradiction makes the principle of determining reason possible. As I take it, this does not mean that the latter is logically entailed in the former, but rather, that the former is a necessary condition for the formulation of the latter. 40. Compare Burdick (1991), 4: ‘‘[Leibniz] is merely saying that the states [of monads] follow each other causally (in his strict metaphysical sense) independent of every other entity except God.’’ 41. See Mercer and Sleigh (1995), 100. Mercer and Sleigh argue (ibid.) that Leibniz articulated the key features of the preestablished harmony in several drafts and essays that concerned the connection of substances to the universal harmony of things, such as ‘‘On the Secrets of the Sublime’’ (February 1676) and ‘‘On Truth, the Mind, God, and the Universe’’ (March/April 1676). The relevant passages are A VI.iii 400, 508–12, 588. 42. See also Monadologie, #2. The fact that Leibniz often wrote as if causal interactions existed led to divergent readings. Russell (1992), 89, and Miller (1988), 248–9 and 252–3, for instance, took Leibniz’s statements about the existence of interaction at face-value and accordingly viewed it to be inconsistent with the preestablished harmony. Considering that Leibniz viewed interacting bodies as phenomena, not as substances like the noninteracting monads, I ﬁnd Brown’s reading in (1992), 67–9, more plausible: Leibniz spoke sometimes with metaphysical rigor and sometimes as a natural philosopher. Since natural philosophy is concerned with the explanation of phenomena such as bodily collisions, talk of causation is a permissible shorthand manner of speaking, for mechanical explanations would only be impeded by occult metaphysical concepts. Leibniz switched gears between the metaphysical analysis of substances and the mechanistic investigations of phenomena. 43. This is not to say that Kant opposed Leibniz’s account of causality. Aware of the strength of the preestablished harmony for the justiﬁcation of freedom, Kant kept a Leibnizian backdoor open. The pre-established harmony returned to the New Elucidation in the guise of the divine schema of interaction, expressed by the principle of coexistence (cf. I 412–16). For further details, see section 6.3 below. 44. Compare the chapter ‘‘De Legibus motus’’ in Wolff ’s Cosmologia generalis (1731). For the inﬂuence of Newton’s ﬁrst law on Wolff, cf. # 309, W II.4: 232; for the inﬂuence of Newton’s third law, cf. # 318, 346, 348, W II.4: 237–8, 252–3, 255– 6. 45. See Cosmologia generalis, W II.4: 240, #323. 46. Frederick William I, Prussian king until 1740 and father of Frederick the Great, forced Wolff into exile. Frederick William I, an uncouth fellow who only read the Bible and military manuals, had been convinced by Wolff ’s enemies that Wolff, in examining issues of causality and questioning the possibility of free will, was implicitly pardoning the desertion of the king’s soldiers. He gave Wolff forty-eight hours time to leave the state or be executed at the gallows. For further details, see Goulyga (1985), 11. 47. Regarding this derivation, see Beck (1969b), 25–26, and Heimsoeth (1971), 15. 48. See Wolff ’s Deutsche Logik (1714), W I.1: 116, #4; Deutsche Metaphysik , W I.2: 18, #31; Prima philosophia sive Ontologia, W II.3: 47, #70. In the Ontologia #56,

280 Notes to pages 143–146 p. 39, Wolff deﬁned the axiom: ‘‘per rationem sufﬁcientem intelligimus it, unde intelligitur, cur aliquid sit,’’ the sufﬁcient reason makes intelligible why anything is. Compare also ibid. #70, p. 47: ‘‘Nihil est sine ratione sufﬁciente, cur potius sit, quam non sit,’’ nothing is without a sufﬁcient reason explaining why something exists rather than not. 49. See Deutsche Physik (1723), W I.6: 62, #34. The Deutsche Physik is Wolff ’s Vernu¨nftige Gedanken von den Wirkungen in der Natur. Beck (1969b), 258, refers to it as the ‘‘German Cosmology.’’ 50. See Leibniz’s Epistola ad Fardellam prior (1690), in L. A. Foucher de Careil, ed., Leibniz. Nouvelles lettres et opuscules ine´dits (Paris, 1857; repr. Hildesheim, Olms, 1971), 317. 51. After the publication of the Deutsche Metaphysik, Wolff considered the term ‘‘geometric necessity’’ as an unfortunate choice of words and drops it in the Anmerkungen. There, he issued a programmatic statement: things are either necessary or they are contingent. Only God is necessary, and everything in the world is contingent, cf. W I.3: 15, #7. E´cole (1990), 241, remarked that the nexus elementorum constituted by the continuous mutual affectation of the simple things corresponds to the nexus rerum of composite things, but this reading is correct only as regards Wolff ’s later views. 52. See Cottingham (1992), 240 and 254 note 9. 53. Descartes, The Passions of the Soul, translated by S. Voss (Indianapolis/Cambridge: Hackett, 1989), article 30, p. 35. Compare AT 11:351. 54. Compare Ameriks (1982), 32 and 77. For the relevant loci of Kant’s discussion of the simplicity of the soul in his later lectures, see Metaphysik L1 (1770s), XXVIII 226 and 266; Metaphysik L2 (1790–1), XXVIII 590; Metaphysik Dohna (1792–3), XXVIII 682; Metaphysik Ko¨nigsberg2 (1793–4), XXVIII 754 and 759; and Metaphysik Ko¨nigsberg3 (1794–5), XVIII 830. 55. A further problem with this dogma of rational psychology, which Kant does not mention but which remains signiﬁcant nonetheless, is the difﬁculty of accounting for aspects of one’s inner life that do appear as discrete parts of one’s mind, such as thoughts or memories. 56. In the New Elucidation, Kant criticized Wolff on various counts. Wolff ’s conception of God as having His own immanent cause (Dt. Meta. #930) was for Kant in contradiction with the sequential nature of causal processes. For Kant, God is the ﬁrst cause, but cannot be self-caused; the causal chain simply stops with God (I 394). Kant also rejected Leibniz’s principle of the identity of indiscernibles (and Wolff ’s adoption of it; Dt. Meta. #586), arguing that things can possess the same properties and yet be distinct if they occupy different locations in space (I 409). Finally, Kant took issue with Wolff ’s two types of necessity (I 398–400). This criticism is quite complicated: it is directed against Baumgarten (who advocated his own version of Wolff ’s distinction) and Crusius (who had rejected Wolff ’s distinction). Kant hoped to save the distinction against Crusius, not in Wolff ’s or Baumgarten’s form, but in his own. For further details, see section 6.4. below. 57. Translated, the full title of Crusius’s De Usu means ‘‘Philosophical Dissertation on the Use and Limits of the Principle of Determining Reason, Commonly Called the Principle of Sufﬁcient Reason.’’ For Crusius’s differentiation between the grounds of being and knowing, see De Usu, C IV.1:191–2, #15, and 218–22, #40. 58. Finster (1986), 75–7, observed that Crusius derived the distinction between the two aspects of sufﬁcient reason from his theory of simple substances. The Leibnizian-Wolfﬁan deﬁnition of the simple as the absence of parts is insufﬁcient,

Notes to pages 146–151 281 Crusius argued in his Metaphysik (C II:173–97, #107–19), because it cannot account for the difference between ideal and real simplicity. That it is possible to dissect an entity, in a thought-experiment, into ideal parts does not entail that we can actually do so and divide it into real parts. It may be added to Finster’s account that Crusius’s argument involves the thesis that an ideal, mental distinction is a posteriori and does therefore not entail a real distinction. This thesis inﬂuenced Kant’s characterization of the ratio cognoscendi as a ‘‘consequent’’ reason. 59. In the Epistola ad Hardenberg, Crusius criticized the Leibnizian-Wolfﬁan account of causality as being ambiguous and false (C IV.1:335), because it misrepresented the principle of sufﬁcient reason as a principle of determining reason (336), and thus excluded the possibility of freedom (358). 60. See Metaphysik, C II:49, #31; 52, #33; 148, #84; Physik, C IV.1:541, #23; Logik, C III:262, #143. 61. Benden (1973), 16, argues that Crusius’s principle of determining reason is valid for all being, all thought, and all human action. In light of Crusius’s distinction between determining and sufﬁcient reason, this claim is erroneous. 62. Morally relevant activity stands accordingly under the principle of sufﬁcient reason; see De Usu, C IV.1:259, #45, and Metaphysik, C II:149, #84. Crusius mapped out a whole tree of subordinate principles in De Usu, 248, #40, labeling the subform relevant for moral activity as the principium rationis sufﬁcientis moralis (243, #32). 63. There is, of course, a problem with characterizing the principium successionis as Kant’s fourth axiom, as there is with characterizing the principium coexsistentiae as the ﬁfth axiom of Kant’s ontology. Succession and coexistence are, strictly speaking, theorems, not axioms, because Kant described them as corollaries to the principle of determining reason. But there is a certain arbitrariness to Kant’s descriptions. Identity, contradiction, and determining reason are principles for Kant, and yet, determining reason presupposes contradiction, and contradiction presupposes identity. Similarly, coexistence presupposes succession, and succession presupposes determining reason. Kant is never quite clear on the actual logical relationships holding among these ﬁve principles. None of them except identity is a genuine, axiomatic principle, because each of them, except identity, are partially based on earlier principles. But considering that these ﬁve principles are the cornerstones of Kant’s ontology, I prefer calling all of them ‘‘axioms’’ for the sake of simplicity. 64. See Laywine (1993), 35–6. 65. The principle of coexistence states that ‘‘ﬁnite substances do not, in virtue of their existence alone, stand in a relationship with each other, nor are they linked together by any interaction at all, except in so far as the common principle of their existence, namely the divine understanding, maintains them in a state of harmony in their reciprocal relations’’ (I 412:37–38–413:1–2; WM 40). Kant enumerates several implications of this principle under the heading Usus (I 414), the ﬁrst of which is that coexistence grounds space, since ‘‘place, position, and space are relations of substances, in virtue of which substances, by means of their reciprocal determinations, relate to other substances . . . and are in this way connected together in an external connection . . .’’ (I 414:10–12; WM 42). 66. Interesting in this context is Guillamaud’s investigation of the notion of negation in Kant’s thought; cf. Guillamaud (1990), 173–85. Lack of causal determination is a form of negation (175), and although negation as such is for Kant a reality, it merely remains a ‘‘superﬁcial’’ reality, not an ontological reality (177). 67. The subsequent page numbers refer to Pierre Bayle, Historical and Critical Dictionary, transl. by R. Popkin (Indianapolis/New York: Bobbs-Merrill, 1965). For a

282 Notes to pages 151–154 sketch of the introduction of the trichotomy into eighteenth-century philosophy, see Ameriks (1992), 261–3 and 275–6. 68. The roots of occasionalism can be traced back to Al-Ghazali (Algazel), author of Logica et Philosophia (11th century), and to Gabriel Biel (16th century). Occasionalism emerged as a view of the Cartesians, such as Johannes Clauberg, Louis de la Forge, and Ge´rauld de Cordemoy. Arnold Geulincx, the ﬁrst main proponent of the view, argued in the Disputationes Ethicae (1665) that God had adjusted mind and body like two clocks such that their actions are synchronized. But their interaction is just an illusion; ‘‘we are only the spectator of the machine of the body,’’ Geulincx remarked. Occasionalism was made famous through Nicholas Malebranche, with Traite´ de la nature et de la graˆce (1680) and the Meditations chre´tiennes (1683), and through Antoine Arnauld, with Des Vraies et des Fausses Ide´es contre ce qu’enseigne l’auteur de la recherche de la ve´rite´ (1683; a critical response to Malebranche). 69. Leibniz objected in the Monadologie (G 6:622, #80) to Descartes’s sympathies for physical inﬂux. Physical inﬂux violates the law of conservation of the direction in matter. If the soul could interact with the body, then this could inﬂuence the body to change direction. The quantity of motion depends on the direction of motion, and if the direction of motion could be changed, the motion-vector would be different, altering the overall quantity of motion. This could not be, because the law of the conservation of motion, as Leibniz interpreted it, prohibited this. Kant did not accept Leibniz’s interpretation of conservation as a conservation of vector-sensitive motion and accepted only a law of the conservation of reality in the New Elucidation: the quantity of absolute reality in nature does not change; it neither increases nor decreases (I 407). Motions are merely phenomena and not realities (I 408), which implies that the direction of motion is irrelevant to the conservation of absolute reality. 70. While Wolff argued for a nexus rerum in nature, he doubted in the Psychologia Rationalis whether physical inﬂux can explain the apparent interaction between mind and body (#573–4). If substances directly interacted, then according to physical inﬂux, a transfer of power from one substance to the other would take place. But such a transfer of power would amount to a transfer of being. How could being conceivably ﬂow from one substance to another? Wolff found physical inﬂux implausible because he did not know how to make sense of it (W I.6:495, #574). 71. According to Beck (1969b), 279, and Laywine (1993), 26, Gottsched favored physical inﬂux. Against them, Watkins (1994), 98–100, showed that Gottsched remained neutral on this issue, entertaining arguments in favor of physical inﬂux without subscribing to the view. In (1995b), 306–7, Watkins notes, ‘‘For although [Gottsched] does not take an ofﬁcial stand on the issue [of physical inﬂux], he is unequivocal about the possibility of Physical Inﬂux, since he responds to a number of important objections raised against that theory.’’ Gottsched stated in his main work, the Erste Gru¨nde der gesammten Weltweisheit, that the inﬂuence of one substance on another should not be taken literally as a ﬂux of being, but as a ﬁgurative expression; cf. Erste Gru¨nde der gesammten Weltweisheit, #630, vol. 2, p. 350. 72. By interpreting Newtonian mechanics in this characteristically determinist fashion, Kant did not so much modify Newton’s assumptions but explicate what they already implicitly contained. Nagel (1987), 278–9, explains the deterministic structure of Newtonian mechanics: the laws of motion become equations in their mathematical form. They spell out that the time-rate of change in the momentum of each mass-point in the system is dependent on a deﬁnite set of factors. These equations

Notes to pages 154–162 283 of motion contain an unspeciﬁed function, the force-function. If applied to a physical phenomenon such as a moving body or a mass-point, the equations will contain the speciﬁcation of two constants, the position of the mass-point, and its momentum at an indicated initial time. Position and momentum constitute the mechanical state of the mass-point and are determined by three coordinates each, on grounds of the three-dimensionality of space. We can chart out the course of this mass-point through space if the corresponding coordinates for all other mass-points in this space are given, and in this sense, Newton’s mechanics emerges as a genuinely deterministic system of nature. 73. See Laplace, Oeuvres comple`tes, ed. Academie des sciences (Paris: GauthierVillars, 1886), 8:vi-vii. In 1814, Laplace published the introduction separately as the Essai philosophique sur les probabilite´s. In his Exposition du syste`me du monde (1798), Laplace arrived at conclusions similar to Kant’s in the Universal Natural History; see chapter 5, section 4 above. 74. See Julien Offray de La Mettrie, L’homme machine, ed. P.-L. Assoun (Paris: Denoe¨l/Gouthier, 1981). References follow the pagination of this edition. 75. See Baron Paul Henri Thiry d’Holbach, Systeˆme de la Nature, ou Des Loix de Monde Physique & du Monde Moral (London, 1770), 2 vols. The indicated page numbers refer to the ﬁrst volume. 76. The same speciﬁcations apply to the ﬁnal causation of the immanent teleology developed in the Universal Natural History. In all types of causation, effects cannot be larger than their causes. Considering that human life has an end—virtuous rationality leading to happiness—it follows that the end is a perfection mirroring the perfection of nature. The continuous realization of this end in human life increases the amount of perfection. But this increase does not involve an ontological accumulation of perfection. It does not, because the overt increase of perfection is nothing but the ﬁnal unfolding of perfection contained in the material entelechies. Thus, Kant argues in the New Elucidation that the continuous progression to further perfections of the intellect conforms to the law of conservation of reality (I 407:5–6). The ‘‘increase’’ of rationality, as a component of the ﬁnal development of humans, is an unfolding as well. This requires Kant to assume that the inﬁnite notion of the universe is contained in the soul (I 408:7–8).

CHAPTER SEVEN

1. Kant’s respondens or commentator was Lucas David Vogel; his critics were Ludwig Ernst Borowski, Georg Ludwig Mu¨hlenkampf, and Ludwig Johann Krusemarck. All of them were students in the theology department. Borowski (1740–1831) joined the faculty in Ko¨nigsberg soon after Kant. He later became known as Prussia’s only Protestant archbishop and as Kant’s ﬁrst biographer with Darstellung des Lebens und Charakters Immanuel Kants (Ko¨nigsberg, 1804). 2. The Seven Years War (1756–1763) had far-reaching implications. Allied with Great Britain, Prussia fought Austria and its partners France and Russia. The war eventually pulled Spain in as well and spread to the overseas possessions. In the beginning, Russia led successful military campaigns against Prussia and occupied East Prussia, including Ko¨nigsberg, from 1758 on. The tide of war turned when the Russian tsarina Elisabeth died in 1762. After the subsequent Prussian-Russian peace accord, Prussia defeated Austria and France. The Seven Years War transformed vic-

284 Notes to pages 162–163 torious Prussia from a provincial kingdom to a leading European power and enabled Great Britain to greatly expand its empire. The English crown aquired Cuba and the Philippines from Spain and Canada and Lousiana from France. 3. For the publication history of the Monadologie, see Rescher (1991), 5, 9, 13– 16; Wilson (1995), 442–74. 4. For Descartes’s corpuscular theory of elements, see Le Monde, ch. 6, AT 11:31– 6; Principia philosophiae, book 3, #46–125, AT 8:100–174. For Newton’s corpuscular theory of light, see Opticks (4th ed./1730), query 29, p. 370–4. 5. For Descartes’s rejection of atomism, see Principia philosophiae, 3 #20, AT 8: 51–2. For Maupertuis’s endorsement of atomism and objections to the monadology, see Syste`me de la nature, #63, in Oeuvres 2:182; Lettre sur la nature des corps, ibid., 2: 266; Lettre sur les monades, ibid., 2:264. Maupertuis shared the hypothesis of the correspondence of component and composite properties with Crusius; see Metaphysik, C 2:195, #119. The atomism endorsed by Maupertuis was not the same that Descartes’s rejected; Maupertuis and Descartes were less in disagreement than it might seem. For the change of meaning of the term ‘‘atomism,’’ see this section below. 6. In Leibniz’s characterization, unextended and perceiving monads were supposed to constitute extended and nonperceiving bodies. For the lack of monadic extension, see Monadologie, #1–3, G 6:607; for the property of monadic perception, see #17–24, G 6:609–11. Note that Maupertuis’s hypothesis of the correspondence of component and composite properties fails as an argument against the monadology; it falls prey to the fallacy of composition. Properties of parts are not necessarily like the properties of the whole. 7. The prize question was: ‘‘Savants of all countries, you are invited by the members of the academy to work on the following question: begin with a short and precise exposition of the doctrine of monads and subject the doctrine to examination. Determine whether it may be vigorously refuted and destroyed by unassailable arguments or whether it may be proved. In the latter case, attempt to deduce from these principles an intelligible explanation of the phenomena of the world and in particular the origin and motion of bodies’’ (Transl. Polonoff). For further details, see Beck (1969b), 314–17; Polonoff (1971), 77–89. 8. See Bayle, Historical and Critical Dictionary, tr. R. H. Popkin (Indianapolis/New York: Bobbs-Merrill, 1965), 359. Note that there are two Zeno emtries in Bayle’s dictionary, one on ‘‘Zeno of Elea,’’ the other on ‘‘Zeno the Epicurean.’’ The relevant discussions of motion, extension, continua, and divisibility are in Bayle’s entry on ‘‘Zeno of Elea.’’ 9. See Gassendi, Syntagma Philosophicum (1658, posthum.), in Opera Omnia 1:308. 10. See Garber (1992), 300–301. 11. See Descartes, Principles of Philosophy, II:20, AT 8:51–52/Cott 1:231–323. See also note 12 below. 12. Strictly speaking, Descartes argued not for the divisibility of atoms, but for the impossibility of atoms (Princ. Phil., part II, art. 20). Descartes operated with the classical meaning of ‘‘atom’’ because its modern meaning (as a divisible corporeal particle), adopted by Maupertuis and Euler, was the result of the Cartesian critique. 13. See Tonelli (1959b), 184–5; Polonoff (1971), 84. Compare also Euler’s Gedanken von den Elementen der Ko¨rper, #72, p. 412, and Maupertuis’s Lettre sur les monades, in Oeuvres 2:264. 14. The fallacy of division indicates that knowledge of the properties of the whole does not permit any deductive inference on the properties of the parts. That there are no formal grounds to conclude anything about the latter on the basis of the

Notes to pages 163–166 285 former can be seen in the fallacious argument, ‘‘water is a compound that does not burn. Therefore, its components, hydrogen and oxygen, do not burn either.’’ 15. Absolute space conﬂicts with the principle of sufﬁcient reason, for if space were absolute then there would be no reason for the particular order in which things ﬁll space; see third letter to Clarke, #5, G 7:364. The empty space possible through absolute space conﬂicts with the principle of plenitude, according to which nature’s inﬁnite richness does not allow empty gaps in its structure. ‘‘Tout est plein dans la nature,’’ Leibniz remarked in the Principes de la nature et de la Grace, G 6:598. Empty space also contradicts the principle of the identity of indiscernibles because empty space is supposed to consist, by deﬁnition, of distinct and yet indistinguishable parts; see Primary Truths (editor’s title), in Leibniz (1990), 91. An anonymous reviewer of my manuscript added the following useful observation: If empty space existed, then God could have created the entire universe two feet over to the left. This alternative possible universe would have to differ from the actual world because all its content would be located in a different ‘‘place,’’ even though this world would be absolutely indiscernible from the actual world. Because this consequence is evidently absurd, Leibniz feels compelled to reject empty space. 16. See Leibniz, On Copernicanism and the Relativity of Motion (1689; editor’s title), AG 91. 17. See Leibniz, ﬁfth letter to Clarke, #33, G 7:396. 18. As Leibniz put it in the Specimen Dynamicum (sect. 2), space ‘‘has something’’ of the being of reason: ‘‘at spatium, tempus et motum habere aliquid de Ente rationis; nec per sed quatenus Divina attributa, immensitatem, aeternitatem, operationem aut substantiarum creatarum vim involvunt, vera et realia esse’’ (ed. Dosch et al., 40). 19. M. Radner and D. Radner (1987), 401, argue that Leibnizian space is ideal only if abstracted from bodies, but as the sum-total of their relations, the ideality of space has a ﬁrm ontological basis. Since Leibniz’s assessment of the reality of space involves both ambiguities and inconsistencies, his position is not altogether clear. Other commentators discounted the reality of relations on which the reality of space depends and argued for a thoroughgoing ideality of Leibnizian space; compare Freudenthal (1969), 150–65, esp. 161; Russell (1992), 119–22. 20. It must be noted, though, that the absolute space of Directions in Space is not exactly the same as the absolute space of the Principia. What Kant actually rehabilitated was an ontologically reiﬁed version of an inertial reference frame, hence, a blend of substantial and absolute space; see II 382–383. 21. I am grateful to an anonymous referee of the manuscript for reminding me of Kant’s defense of absolute motion without absolute space in the 1780s. 22. Because in the Academy Edition, the Latin text of the Physical Monadology is printed in the same small font as the New Elucidation and accordingly contains a lot of material per page, I indicate line numbers as well as page numbers when citing from it. 23. In the terminology of the Physical Monadology, a monad is the same as a simple substance, an element, a simple thing, a simple part, or an original component of a body; see Kant’s footnote at I 475. 24. Vuillemin (1955), 122–23, reads Kant’s conception of space as a straightforward adaptation of the Leibnizian schema, in that Kant juxtaposed the appearance of space with the reality of metaphysical forces and substances. My impression is that the textual evidence does not bear out Vuillemin’s interpretation. As I hope to make clear in what follows, I ﬁnd Adickes’s assessment of Kant’s space as adopting

286 Notes to pages 166–169 the Leibnizian relational character while rejecting its ideality more plausible; see Adickes (1924a), 2:153 and 2:166–7. 25. As a result, Kant could accept the possibility of an empty space. Since the void conﬂicts with the Leibnizian identity of indiscernibles (see note 15 above), Kant rejected Leibniz’s law in the New Elucidation, I 409–10. 26. The second and third contradiction between metaphysics and geometry are couched in an ambiguous wording which has led to conﬂicting interpretations. Kant writes: ‘‘The one (haec) contends that empty space is necessary for free motion, the other (illa) rejects it. The one (haec) shows proﬁciently that attraction or universal gravitation can hardly be explained from mechanical causes but rather from the innate forces of bodies that are active at rest and at a distance, the other (illa) reckons this explanation among the empty games of the imagination’’ (I 475:26–476:2). In the sentence immediately preceding the quotation, haec refers to geometry (endorsing inﬁnite divisibility of space) and illa to metaphysics (rejecting it). If it is the case that Kant remained consistent with his reference of ‘‘the one’’ and ‘‘the other,’’ then the sentences quoted would mean that geometry defends empty space and innate forces acting at a distance and that metaphysics rejects these claims. This is the reading of Weischedel in Kant (1960), 1:519note, and Friedman (1992b), 4 and 9note. But since it is certainly odd to assume that innate forces are assumptions of geometry, other commentators argue that Kant switched the references here. In this alternate reading, the sentences quoted would mean that metaphysics defends empty space and innate forces acting at a distance and that geometry rejects these claims. For this interpretation, see Adickes (1924a), 2:147, and Vuillemin (1955), 121–122. The puzzle can be resolved by considering what geometry actually meant for Kant. Adickes and Vuillemin would have been right only if Kant had literally intended geometry when writing ‘‘geometry’’ because innate forces were not a claim of geometry but a claim of metaphysics. But one must remember that Kant tried to reconcile the mathematical science of Newton with the qualitative approach of metaphysics. In the Physical Monadology, ‘‘geometry’’ signiﬁed the quantitative perspective of Newtonian physics, and ‘‘metaphysics’’ the monadology of Leibniz (see also section 7.3 below). Thus, Weischedel’s and Friedman’s reading applies because innate forces such as universal gravitation are a claim of Newtonian physics and not a claim of Leibnizian metaphysics. It is in line with Kant’s overall argumentation to take ‘‘geometry’’ as a pars pro toto, as a stand-in for something larger here. Newton’s mathematical approach to nature indeed required the assumption of innate gravitational forces acting from bodies at rest over a distance through empty space. A historical example is John Keill’s Epistola . . . in qua Leges Attractionis aliaque Physiques Principia traduntur, in the Philosophical Transactions of the Royal Society 26 (1708): 97, where these Newtonian ( geometric) assumptions had been identiﬁed and elaborated. Kant knew of Keill and referred to him in the Physical Monadology; compare I 484, 486. This reading is reenforced by considering that Leibniz, Kant’s representative of the metaphysical perspective, rejected empty space, action at a distance, and universal gravitation; see Leibniz, Principes de la nature et de la Grace, G 6:598; ﬁfth letter to Clarke, #35, G 7:418 and #118–120, G 7:397. In this idiosyncratic sense, empty space, the innate force of gravity, and action at a distance, were for Kant the claims of geometry and not the claims of metaphysics. 27. The propositions in the Physical Monadology are labeled ‘‘deﬁnitio,’’ ‘‘theorema,’’ ‘‘problema,’’ and so forth. These are Kant’s own identiﬁcations, in contrast to the New Elucidation, whose analogous identiﬁcations were added by Weischedel in Kant (1960).

Notes to pages 169–174 287 28. See Euler, Gedanken von den Elementen der Ko¨rper (Berlin, 1746), #72, p. 415. 29. Compare Kant’s own words: ‘‘[I]t is plain that all composition of a body can be abolished, though all the parts which were formerly combined together nonetheless continue to exist. When all composition is abolished, moreover, the parts which are left are not compound at all; and thus they are completely free from plurality of substances, and, consequently, they are simple’’ (WM 53; I 477:12–15). 30. Polonoff (1971), 148–149, suggests that Kant did not accept the principle ‘‘composite beings are composed of simple beings,’’ which Euler rejected, and to this extent, he believes that Kant successfully evaded Euler’s criticism. But as the analysis of the argument shows, Polonoff ’s charitable reading is not tenable. Kant implicitly endorsed and utilized the principle, and by falling prey to an illicit equivocation of ‘‘composition,’’ he could not avoid Euler’s objection. 31. The ﬁrst version of the proof, involving the dissection of parallel lines, is in I 478:4–34. This proof is a standard deduction of the inﬁnite divisibility of space. Jacques Rohault employed this proof in a textbook of Cartesian mechanics, Traite´ de Physique (Paris, 1671), chapt. 9, #4. Walford and Meerbote emphasize in WM 422, note 6, that Rohault used this proof to demonstrate the inﬁnite divisibility of matter. The second version of the proof, involving the dissection of the hypotenuse of a triangle (I 479:1–13), is derived from John Keill’s Introductio ad veram physicam (1701; 5th ed. London, 1741), 28–9. 32. The natural divisibility that Gassendi emphasized over the supernatural divisibility of the simple elements is necessarily not a division that can be practically or technically achieved; natural divisibility means that it is logically possible to divide the simple element further. 33. I am grateful to an anonymous reviewer of this chapter for explaining this precritical problem of divisibility to me, and for informing me about the divergent account of the Metaphysical Foundations. 34. Kant rejects physical monads and their activity-spheres in the Metaphysical Foundations and accordingly reinterprets the dynamic balance of attraction and repulsion: ‘‘When it is said, then, that the repulsive forces of the directly mutually driving parts of matter stand in inverse proportion to the cube of their distances, this means only that they stand in inverse proportion to the corporeal spaces which one thinks of between parts that nevertheless immediately touch each other, and whose distance must just for this reason be termed inﬁnitely small in order that such distance may be distinguished from all actual distance’’ (Ellington, p. 74–75; IV 522). 35. Like Kant, Newton’s disciples tended to assume that matter is a dynamic and active entity; see Schoﬁeld (1970), 125. The issue between these so-called mechanists and the materialists subscribing to a passive concept of matter was one of viewing force as either inherent in matter or not; see Heimann and McGuire, (1971), 235– 236. Yolton (1983), 92–94, describes how Newton wavered regarding the inherence and reality of force. Although Newton often emphatically rejected the inherence of force in matter, he used the concept of force as if force were inherent in matter. It was therefore hard for his disciples to resist taking ‘‘force’’ as just a label without ontological meaning. For further details, compare also McMullin (1978), passim. 36. Adickes (1924a), 2:159, argues that the characterization of inertia as a force in the Physical Monadology should not be taken literally because Kant only meant by it the mass factor in mv. This does not really let Kant off the hook because at the same time, Adickes concedes that for Kant, the attractive, repulsive, and inertial forces are all equally original dynamic manifestations of the monad, see ibid. 2:160.

288 Notes to pages 174–185 37. Kant continued to adhere to this revised position throughout the critical period; compare the Metaphysical Foundations of Natural Science, IV 550–1. 38. See Newton, Principia, book 3, Scholium Generale, K 2:764. With this phrase, Newton stated his unwillingness to feign hypotheses regarding the cause of gravity. Friedman (1992b), 2, rightly remarks about the preface of the Physical Monadology, ‘‘Newton is clearly paradigmatic of the non-metaphysical investigators of nature referred to in the ﬁrst paragraph.’’ 39. ‘‘In experimental philosophy we are to look upon propositions inferred by general induction from phenomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions.’’ Principia, book 3, rules of reasoning in philosophy, M 2:400. 40. However, ‘‘geometry’’ should not be understood literally. Although the physical monadology presupposes the geometric deﬁnitions of point and line, as well as the geometric conception of space, Newton’s quantitative approach to natural phenomena involved other mathematical tools besides geometry, most important his theory of ﬂuxions, the Newtonian calculus. 41. See Newton, An Account of the Book Entituled Commercium Epistolicum, in Hall, Philosophers at War. The Quarrel between Newton and Leibniz, 314 and 312. First publication in the Philosophical Transactions of the Royal Society 29 (1714–16), compare there p. 224 and 222. The historical context of this text was the unfortunate priority dispute over the invention of the calculus. Subsequently indicated page numbers refer to Hall’s edition and to the Transactions. For a detailed account of the priority dispute, the Commercium Epistolicum, and Newton’s review, see Westfall (1980), 698–781, esp. 769–71. 42. The reason of the curious self-reference in the third person is as follows. In 1711–12, a committee appointed by the Royal Society (with Newton presiding) investigated the priority dispute and found in Newton’s favor. In 1713, a volume with the evidence that led to the committee’s decision appeared, the Commercium epistolicum D. Johannis Collins, et aliorum de analysi promota (‘‘The Correspondence of the Learned John Collins and Others Relating to the Progress of Analysis’’), to which Leibniz responded with an anonymous sheet that he had circulated on the continent. In 1714, the enraged Newton tried to further his own cause by writing An Account of the Book Entituled Commercium Epistolicum, in which he pretended to be an anonymous reviewer of the previously published volume. See Westfall (1980), 273–296.

CHAPTER EIGHT

1. The Only Possible Argument (1763) and the Prize Essay (1764) established Kant’s reputation. In 1769, the University of Erlangen offered him a position as a professor in its philosophy department, and in 1770, the University of Jena followed suit. Kant declined both invitations because he preferred to stay in Ko¨nigsberg and suspected that something would turn up in his hometown sooner or later. The University of Ko¨nigsberg made him the desired offer in spring 1770. 2. Letter from 14 December 1758; see X 5–6. 3. The West Winds essay was a sequel to the Theory of Winds treatise (1756) that contains Kant’s theory of monsoon rains; see chapter 4 above. For preparatory drafts to Kant’s wind theory, see Reﬂexionen 90–92; XIV 555–63.

Notes to pages 186–189 289 4. This is implicit in Kant’s realization in this treatise that the axial rotation (a circular motion) of the earth would go on forever if space was a void and earth was perfectly solid; compare I 185–187. 5. Only considerably later would Kant concern himself with the relationship of inertial motions and absolute space. In the Directions in Space, the puzzle raised in Motion and Rest that inertial motions are rectilinear and uniform to something still remained open. Kant eventually tackles it in the Metaphysical Foundations of Natural Science, where he tried to show that motion and rest can be referred to absolute space (IV 558–560). 6. The derivation of absolute space in the Directions in Space does not quite result in the Newtonian concept of space. Although Kant excludes Leibniz’s relative space, he does not endorse a Newtonian opposite that allows absolute motion. This is also evident in Kant’s rejection of Euler’s ‘‘a posteriori’’ proof that derives absolute space and absolute motion from the laws of dynamics (II 378); see Leonard Euler, ‘‘Re´ﬂexions sur l’espace et le temps,’’ Me´moires de l’Acade´mie des Sciences de Berlin (1748), in Euler, Opera Omnia, III.2:376–383. What this absolute space might be for Kant, remains open. It is therefore incorrect to read the Directions in Space as a sign of Euler’s inﬂuence on Kant, as Garnett (1965), 109–112, does. For an earlier, but more informative presentation of Kant’s relationship to Euler, see Timerding (1919), 18–64. For further details on Kant’s Directions in Space essay, compare Radner and Radner (1987), 385–402; Friedman (1992b), 28–30, 41–44. 7. Although the inference of the best of all possible worlds based on the standard conception of God sounds odd, Kant is actually right. The Christian conception of God as an omnipotent, omniscient, and benevolent being entails that if such a being decided to create, it would create only the best. Because God is benevolent, God would choose the best; because God is omniscient, God would know how to identify the best; and because God is omnipotent, God would be able to create the best. Since, as Kant remarked, the creation of the best world follows from the ‘‘natural’’ conception of God; the existence of evil is a problem. 8. In the Essay of Man (1734), Pope had written: ‘‘All Nature is but Art, unknown to thee; / All Chance, Direction, which thou canst not see; / All Discord, Harmony, not understood; / All partial Evil, universal Good: / And, spite of Pride, in erring Reason’s spite, / One truth is clear, ‘Whatever is, is right.’ ’’ (ln. 289–295). In 1753, the Berlin Academy posed the question, for the competition of 1755, ‘‘On demande l’examen du syste`me de Pope, contenu dans la proposition: Tout est bien.’’ The selected prize essay was by A. F. Reinhard, Vergleichung des Lehrgeba¨udes des Herrn Pope von der Vollkommenheit der Welt, mit dem System des Herrn von Leibnitz (1757), who argued that Pope’s and Leibniz’s optimism are basically the same and equally implausible. In the ensuing controversy, Kant’s Optimism was an attempt at coming to Leibniz’s rescue. The critical Kant felt embarrassed about this little piece and tried to remove extant copies from circulation; see Walford and Meerbote, WM liv–lvii. 9. For further details on the ‘‘Kinderphysik ﬁasko,’’ see Beiser (1987), 20–24, 32– 33. 10. The reason for the sudden turnabout of the Russian position in the war was probably more personal than anything else. Peter III, of German descent and married to a German princess, admired Prussia and pursued a relentless pro-German policy. Unsurprisingly, other members of the Russian court found Peter’s policies intolerable and ousted him after a few months. A new tsarina, Catharina II, mounted the throne and annulled Peter III’s last decrees, terminating the military alliance with Prussia.

290 Notes to page 189 For a period of weeks, Ko¨nigsberg came once more under Russian jurisdiction. Eventually, Prussian diplomats were able to negotiate a compromise with the tsarina. The two nations agreed to respect each other as equals, and Russia returned all occupied territories to Prussia in August 1762. In return, Frederick the Great thanked Catharina II by electing her as the ﬁrst female member to the Academy of Arts and Sciences in Berlin. 11. The three lecture announcements—West Winds, Motion and Rest, and Optimism—as well as the eulogy on Funk were published as small brochures numbering eight pages each by Driest in Ko¨nigsberg. 12. The volume of early writings that has already been published in the ongoing Cambridge edition of Kant’s works contains the Only Possible Argument. This volume, translated and edited by D. Walford in collaboration with R. Meerbote, does not contain the Living Forces, the Universal Natural History, or any other of the more scienceoriented texts of the precritical period. Quotations from the Only Possible Argument that utilize the Walford-Meerbote translation are indicated by WM throughout this chapter. 13. For the ﬁrst occurrence of Hume’s name in Kant’s works and correspondence, see Hamann’s letter from 27 July 1959, X 15. For the ﬁrst occurrence of Rousseau’s name, see the supplement to Hamann’s letter dated end of December 1759, X 30. 14. See Vleeschauwer (1962), 13, and Werkmeister (1980), 15. 15. Biographical facts highlight the remarkable impression that Rousseau left on Kant. After Kant was once forced to sell off his complete library in order to make ends meet, he resolved never to buy books again. But among the few books that he did end up acquiring were Emile, La Nouvelle Heloise, and the Lettre a` d’Alembert by Rousseau. The only picture in Kant’s study (in fact, the only picture in Kant’s house) was an intaglio portrait of Rousseau by Watelet. Rousseau had been the sole philosopher who succeeded in disturbing the order in Kant’s life. Kant, who was a creature of habits, enjoyed a daily afternoon walk through town of such regularity that it was said that the citizens of Ko¨nigsberg could set their watches according to his unshakeable routine. As the story goes, this ritual of the daily Spaziergang was interrupted only once, namely, when Kant, reading Emile, was so absorbed in the book that he forgot to leave the house that day. See Schultz (1965), 28, 67; Ferrari (1971), 479. 16. Apart from the doubts about the validity of scientiﬁc knowledge, Rousseau’s main inﬂuence was on Kant’s ethics, see Reich (1989), 80–96. The extent and nature of this ethical inﬂuence, however, is a matter of debate. Schilpp (1938), 161, argues that Rousseau’s ethical inﬂuence on Kant was in terms of questions not answers. Rousseau raised questions such as the issue of the extent of moral responsibility, but he did not impress his answers on Kant, and Kant never became an actual adherent of Rousseau’s ethics. Schmucker (1961), 257–259, credits Rousseau with greater inﬂuence on Kant. Schmucker distinguishes two phases of phases of development in Kant’s ethics, the second of which reveals Rousseau’s signiﬁcance. In a ﬁrst phase (1755–1762), Kant emancipated himself from Wolff ’s moral philosophy because of the impact that Crusius and Hutcheson had on his thought; in the second phase (1765–1775), Kant began to construct his own ethics on the basis of Rousseau. Reich, ibid., 82, adds that Rousseau’s inﬂuence in 1764–1766 led to Kant’s disenchantment with Shaftesbury and Hutcheson. Beck (1984), 17–30, esp. 22, thinks that Rousseau’s ethical inﬂuence on Kant can hardly be overestimated. According to Beck, Kant made a Rousseauistic revolution in ethics analogous to his Copernican revolution in epistemology. Kant adopts Rousseau’s idea that freedom is the obedience to a law which

Notes to pages 190–193 291 man gives to himself (cf. Contract Social I #8). Be this as it may, Rousseau had in any case a powerful inﬂuence on Kant (who actually compared him to Newton). However, it is not correct, as Beck characterizes it, that philosophy before Kant grounded the moral law in the will of God. Kant himself made the moral law dependent on God’s will (Kant’s ‘‘material principle of ethics’’); compare the Prize Essay, II 300. 17. ‘‘Considering metaphysical truths in general and in particular the ﬁrst principles of natural theology and morals, are these principles capable of proofs as distinct as are the truths of geometry? If they are not, what is the real nature of their certainty? To what degree can the required certainty be raised, and is this degree sufﬁcient to carry conviction?’’ Announced in the Berlinischen Nachrichten von Staatsund gelehrten Sachen 75 (23 June 1761). Translation by Polonoff (1971), 178. For the German original and further details, see Lasswitz’s annotations to Kant’s Prize Essay in II 493. 18. See Beiser (1992), 39. Compare also note 20 below. 19. Schmucker (1980), 107–108, investigates the relationship between the ontological and the physico-theological proofs, noting that most interpretations have avoided tackling this issue. He observes that the title of part II does not match its contents but does not explain why. As regards the relation of the two proofs, Schmucker, ibid., 127, suggests that they mutually supplement each other such that the physico-theological argument adds persuasive force and psychological plausibility to the ontological argument—a point echoed by Gebler in (1990), 120. Schmucker, ibid., 129, correctly acknowledges that both proofs derive from the same basis, the ‘‘Realgrund aller Mo¨glichkeiten,’’ the real ground of all possibilities. But ultimately, Schmucker remains unable to explain why Kant constructs two arguments in a work called Only Possible Argument. His best guess, in the conclusion of the relevant section of the Ontotheologie des vorkritischen Kant, is that the physico-theological argument is a ‘‘sekunda¨re Weiterentwicklung,’’ a ‘secondary and further development’ of the ontological argument (p.135). 20. This assessment has been misinterpreted in that Kant, supposedly, objected to the physico-theological proof because it can only assert God as a demiourgos, not as a creator, and that it shows God to be wise, powerful, and beneﬁcient, and not omnipotent, omniscient, and inﬁnite; see Beiser, (1992), 39. In fact, however, Kant directed this objection only to the physico-theological arguments based on contingency: ‘‘The order of nature, in so far as it is regarded as contingent and arising from the power of choice of an intelligent being, is in no way proof that the things of nature, which are widely connected in such an order, also owe their existence to this Author’’ (II 124, WM 165; my emphasis). As regards the physico-theological argument based on necessity (Kant’s own version of the proof), Kant granted that it ‘‘establish[es] . . . the existence of some incomprehensible great Author of the totality which presents itself to our senses,’’ and that the argument leads to the conclusion ‘‘[t]hat there is only one ﬁrst Author’’ (II 160, WM 199). Kant’s objection to the physico-theological argument in general, and even in its best version, was a different one: the physicotheological argument based on necessity is weakened by the general limitation of all probabilistic arguments based on experience. Kant admitted that ‘‘this mode of proof will never be capable of mathematical certainty or precision’’ (ibid.). 21. Heimsoeth (1970), 86, characterizes section II.7 of the Only Possible Argument as a ‘‘brief summary’’ of the cosmogony of the Universal Natural History. This is generally true, but there are a few minor differences that Adickes (1924a), 2:273– 275, points out: the Universal Natural History contains two explanations for the zodiacal light of the sun (compare I 304–306), but the Only Possible Argument mentions

292 Notes to pages 193–198 only one (II 147). The summary of the cosmogony in the O.P.A. does not mention the intermediate stages of the formation of the universe that consists of the orbital motions of material particles around the sun (II 146–147); compare Adickes, ibid., 2:250. Apart from this, Adickes also sees a change as regards the so-called phoenix motive of the U.N.H., believing that Kant changed its meaning in the O.P.A. The ‘‘phoenix motive’’ is the idea Kant elaborates in the U.N.H. that the universe is cyclical (I 318; see also chapter 5 above). Adickes interprets it in the U.N.H. as an actual resurrection, but sees in its rewording in the O.P.A. (II 110) only the suggestion of a replacement instead; see ibid., 2:225. I do not see a difference between the two characterizations of the phenix motive; it seems to me that Kant never intended it to amount to a mystical teaching about an actual and literal resurrection a` la Nietzsche’s doctrine of the eternal return. 22. The same goes for the Universal Natural History. Gebler (1990), 92, remarks to the cosmogonies of both works: ‘‘Obwohl Kants Himmelsmechanik in der Folge zu einere Profanisierung des Himmelsgeba¨udes . . . fu¨hrt, steht sein Entwurf einer rein mechanischen Kosmogonie unter der Pra¨misse der Sakralisierung aller Vorga¨nge durch die go¨ttlich eingepﬂanzten Naturgesetze.’’ 23. See note 19 above. 24. I retranslated the ﬁnal clause of the last sentence. Compare the original (II 103:18–20): ‘‘und da hier das Zufa¨llige, was bei jeder Wahl voraus gesetzt werden muss, verschwindet, so kann der Grund dieser Einheit zwar in einem weisen Wesen, aber nicht vermittelst seiner Weisheit gesucht werden.’’ 25. This is a further development of the reﬂection in the Optimism essay (1759) according to which nature exists on the penultimate level of perfection (the ultimate level is God). Nature reﬂects the features of ultimate perfection on its penultimate level; see I 33. Kant had already identiﬁed in the Universal Natural History the main features of the perfection visible in nature as unity, harmony, and order; see I 226, 306, 314–317. Gebler (1990), 98, rightly states that according to Kant’s conception, the world never reaches perfection as such. 26. The title of the Only Possible Argument is: ‘‘Der einzig mo¨gliche Beweisgrund zu einer Demonstration des Daseins Gottes.’’ Despite the conventional English title of Kant’s work, Beweisgrund is not ‘‘argument’’; rather, Beweisgrund is the Grund, ‘‘ground,’’ of the Beweis(e), ‘‘proof(s).’’ A Beweisgrund is not an argument because it is the grounding or foundation of an argument. Thus, the title of the book, properly translated, actually means: The Only Possible ‘‘Proof-Ground’’ of a Demonstration of God’s Existence. 27. Henrich (1960), 154, sees the function of the Only Possible Argument in the development of a new rational theology because Kant was dissatisﬁed with the available theories in rational theology which strikes me as quite plausible. 28. ‘‘Pope wa¨hlete einen weg, der, um den scho¨nen Beweis von Gott allen menschen vernehmlich zu machen, der allergeschikteste unter allen mo¨glichen ist und der, welches eben die vollkommenheit seines Systems ausmacht, alle moglichkeit der Herrschaft eines allgnugsamen Uhrwesens unterwirft, unter welchem die Dinge keine andern Eigenschaften, auch so gar nicht solche, die man wesentlich notwendige nennt, haben konnen, die nicht vollkommen zu ausdru¨ckung seiner Vollkommenheit zusammen stimmen.’’ (I did not correct the orthographical and grammatical idiosyncrasies of Kant’s style.) 29. Henrich (1960), 156, puts it differently: according to the Only Possible Argument, all possibility is dependent on God. My reading, that possibility entails God, concerns a different level: ontologically, possibility depends on God; logically, and on

Notes to page 198 293 grounds of the ontological dependence, the concept of possibility entails the concept of God. For the dependency of possibility on God, see the connection of Kant’s argument to Leibniz’s doctrine of the regio idearum at the end of this section. For further details on Kant’s ‘‘essentialist’’ ontological commitment which prepares the connection between the possibility of a thing and the necessary existence of God, see Sala (1988), 18–53, esp. 24 and 34. 30. The relationship of the two proofs is controversial. The scholars mentioned above argue that there is little connection between the two arguments and that the earlier proof still involves a conception of existence as a predicate. Schmucker (1963), 446, and Henrich (1960), 181–182, argue that Kant grants to Descartes that the concept of an omnitudo realitatis contains existence as a necessary and analytically derivable property, and that he rejects the conclusion asserting God’s real existence because the premise of the Cartesian proof contains only the thought, or imagined existence. Schmucker continues (ibid.) that Crusius was the actual author of this objection and that Kant merely repeats Crusius’s argument. It must be noted, however, that Crusius accepted existence-as-a-predicate; see C 2:73, #45 (see also the following note). Reuscher (1977), 20, claims that Kant regards existence as a predicate in the New Elucidation. Laberge (1973), 89–102, sees another difference: whereas the proof of the Only Possible Argument suggests a theistic conception of God, the argument of the New Elucidation leads up to a Spinozistic God whose inner attribute is extension. 31. It is therefore quite wrong to assume, as Hildebrandt (1954), 19, does, that Kant rejected the ontological argument for God’s existence in the Only Possible Argument. 32. Marion, in (1992), 201–218, esp. 203, nicely points out that this is merely one dimension of what Kant means by an ‘‘ontological proof.’’ The statement above reﬂects the later deﬁnitions in the ﬁrst Critique that ‘‘an ontological argument infers the exitence of a supreme cause absolutely a priori from mere concepts’’ (A590/B619), or that it establishes ‘‘the existence of a supreme being from concepts’’ (A602/B630). The other dimension of the ontological argument, as Kant understands the term, is that it is ontological because it leads to the existence of a supreme being by relying not merely on concepts, but also on the concept of the essence of the being—thus, ‘‘ ‘Ontological’ does not indicate the simple attainment of being as existence, but rather the quite extraordinary fact that this being attains existence solely by means of its pure essence.’’ For further details of Kant’s thoughts on existence and essence, see Sala (1988), 18–53. 33. The ontological argument was ﬁrst fully developed by Anselm of Canterbury (1033–1109) in chapters 2–4 of the Proslogion (1078). Thomas Aquinas (1225–1274) did not accept it, neither in the Summa Theologica (cf. I, 2, i) nor in the Summa contra gentiles (cf. I.ch.10–11). Instead, he preferred the demonstration of God’s existence from effects rather than from the concept (all of Thomas’s ‘‘Five Ways’’ start from empirical knowledge of the physical world; see Sum. Theol. I, 2, iii, c.). Descartes offered two arguments for God’s existence in the Meditationes de prima philosophia (1641), a ‘causal’ or ‘cosmological’ argument in Meditation III, and a ‘conceptual’ or ‘ontological’ argument (as Kant refers to it in the ﬁrst Critique A592/B620–A595/ B623) in Meditation V. The argument in Meditation V is a reformulation of Anselm’s proof. Descartes elaborated the argument further in his replies to objections by Caterus, Gassendi, and a ‘‘group of philosophers and theologians.’’ Spinoza offered another version of the proof in the Ethica (1677, posth.) in the remarks following proposition 11 of part I. Modern defenders of the ontological argument are Ch.

294

Notes to pages 198–200

Hartshorne and N. Malcolm; a recent proponent of an ontological argument for the nonexistence of God is J. N. Findley. See Platinga (1965), 111–159, for a collection of their relevant papers. A modern (and curious) attempt at rescuing the traditional ontological proof against Kant’s critique can be found in Bauer (1964), 161–74. 34. See, for instance, Leibniz’s discussion of the ontological proof in his Letter to Countess Elizabeth, on God and Formal Logic, G IV 290–9 and AG 235–40. ‘‘As for me,’’ Leibniz wrote, ‘‘I genuinely believe that anyone who has recognized this idea of God, and who sees that existence is a perfection, must admit that existence belongs to a God’’ (AG 237). 35. Historically, the most inﬂuential version of the ontological argument was constructed by Anselm of Canterbury (1033–1109) in his Proslogion (1078), see Opera Omnia, 1:45–124. Kant does not refer to Anselm when criticizing the traditional ontological proof. His targets were Descartes’s versions in the Meditationes de prima philosophia (1641); see II 156–7. In Meditation III, # 22–38, Descartes suggests a causal proof based on the consideration that we are ﬁnite minds. Since the representation of God is inﬁnite by deﬁnition, we could not have made it up. The representation must therefore come from an external cause: ‘‘ab aliqua substantia quae revera esset inﬁnita procederet’’ (AT 7:45). In Meditation V, # 7–11, Descartes advances a conceptual proof. He argues there that the concept of God comprises a certain immutable set of perfections, and since existence is a perfection, God must exist. Descartes identiﬁes existence as a predicate of God: ‘‘. . . ﬁt manifestum non magis posse existentiam ab essentia Dei separari quam ab essentia trianguli magnitudinem trium eius angulorum aequalium duobus rectis’’ (AT 7:66). Kant’s contemporaries, such as Christian August Crusius in his Metaphysik, endorsed the existence-as-a-predicate view (C 2: 73, #45). Crusius’s reservation (see note 33 above) to Descartes does not quite go to the heart of the issue. 36. Bauer (1964), 161–162, argues that Kant’s objection against existence as a predicate is original. Against such a reading, Hildebrandt (1954), 19, points out that Kant inherited this objection from Leibniz. It might be added to Hildebrandt’s observation that Leibniz, in turn, inherited the objection to Anselm’s version from Gaunilo, and the objection to Descartes’s version from Gassendi. See also the following two notes. 37. ‘‘The fool might make this reply: This being is said to be in my understanding already, only because I understand what is said. Now could it not with equal justice be said that I have in my understanding all manner of unreal objects, having absolutely no existence in themselves, because I understand these things if one speaks of them, whatever they might be?’’ Quoted from Anselm (1962), 304. See also Gaunilo’s Pro Insipiente; in Anselm, Opera Omnia, 1:125–129. 38. See AT 7:322–3. Compare also Pierre Gassendi, ‘‘On the Fifth Meditation,’’ Cott 2:224. 39. Kant rejects existence as a predicate in the Critique of Pure Reason, A598/ B626–A599/B627. That Kant’s objection is already fully developed in the Only Possible Argument prompts Schmucker to argue repeatedly that Kant formulated his deﬁnitive position about the ontological argument already in the Only Possible Argument, and that the only difference to the ﬁrst Critique was Kant’s conviction in the Argument that a different version of the proof could still get off the ground. Compare Schmucker (1963), 451; (1975), 1:271. For a succinct analysis of the critical version of Kant’s charge against the classic ontological proof, see Harris (1977), 90–92. 40. See Ho¨ffe (1994), 125–6, and Wood (1992), 399–400. Wood points out that despite the fame of Kant’s claim, Kant has remarkably little to say in its defense:

Notes to pages 200–201 295 ‘‘The uncontroversial claim is that to say ‘X exists’ is to say that there is some object to which the concept of X corresponds. The point that really needs to be established, however, is that ‘is’ or ‘exists’ is not also a reality or perfection, which might belong to the nature of something or be contained in its concept’’ (Wood, 400). Ho¨ffe (ibid., 125) refers to the objection to Kant in Hintikka (1969), 45–54, that ‘‘existence,’’ in a sense, is indeed a predicate, although this predicate has the peculiarity of being redundant for all descriptive purposes. 41. (1) ‘‘Alles, was in sich selbst widersprechend ist, ist innerlich unmo¨glich.’’ (II 77:10; ‘‘Anything which is self-contradictory is internally impossible.’’ WM 122) (2) ‘‘Wodurch alle Mo¨glichkeit u¨berhaupt aufgehoben wird, das ist schlechterdings unmo¨glich.’’ (II 79:3–4; ‘‘That, by means of which all possibility whatever is cancelled, is absolutely impossible, . . .’’ WM 124) (3) ‘‘Selbst nach dem Herren Crusius, . . . ist im Unmo¨glichen allemal eine Verknu¨pfung mit Etwas, was gesetzt, und Etwas, wodurch es zugleich aufgehoben wird. Diese Repugnanz nenne ich das Formale der Undenklichkeit oder Unmo¨glichkeit’’ (II 77:14–20; ‘‘But even according to [Crusius], the impossible always contains the combination of something posited with something which also cancels it. I call this repugnancy the formal element in inconceivability or impossibility.’’ WM 123) ‘‘. . . [D]ie U¨bereinstimmung aber des einen mit dem anderen nach dem Satze des Widerspruchs sind das Formale der Mo¨glichkeit.’’ (II 77:31–33; ‘‘The agreement, however, of the one with the other, in accordance with the law of contradiction, is the formal element in possibility.’’ WM 123) (4) ‘‘Es ist . . . zu ersehen, daß die Mo¨glichkeit wegfalle . . . auch wenn kein Materiale, kein Datum zu denken da ist. Denn alsdann ist nichts Denkliches gegeben, alles Mo¨gliche aber ist etwas, was gedacht werden kann . . .’’ (II 78:10–14; ‘‘It is clear . . . that possibility disappears . . . also when there exists no material element, no datum, to be thought. For then nothing is given which can be thought. But everything possible is something which can be thought, . . .’’ WM 123) 42. (5) ‘‘Wenn nun alles Dasein aufgehoben wird, so ist nichts schlechthin gesetzt, es ist u¨berhaupt gar nichts gegeben, kein Materiale zu irgend etwas Denklichem, und alle Mo¨glichkeit fa¨llt ga¨nzlich weg.’’ (II 78:16–18; ‘‘Now, if all existence is cancelled, then nothing is posited absolutely, nothing at all is given, there is no material element for anything which can be thought; all possibility completely disappears.’’ WM 123) Note that inference (6) is already visible in the last subordinate clause. 43. (6) ﬁnds its full statement at the end of section I.2.ii: ‘‘Demnach zu sagen: es existirt nichts, heißt eben so viel, als: es ist ganz und gar nichts; und es widerspricht sich offenbar, dessen ungeachted hinzuzufu¨gen, es sei etwas unmo¨glich.’’ (II 78:29– 32; ‘‘Accordingly, the assertion ‘Nothing exists’ means the same as the assertion ‘There is nothing whatever.’ And it is obviously self-contradictory to add, in spite of this, ‘Something is possible.’ WM 124) Step (6) is formally derivable from the material condition (4) and the ﬁrst inference (5) by contraposition and hypothetical syllogism. 44. (7) ‘‘Allein daß irgend eine Mo¨glichkeit sei und doch gar nichts Wirkliches, das widerspricht sich, weil, wenn nichts existirt, auch nichts gegeben ist, das da denklich wa¨re, und man sich selbst widerstreitet, wenn man gleichwohl will, daß etwas mo¨glich sei.’’ (II 78:22–26; ‘‘On the other hand, to say that there is a possibility and yet nothing real at all is self-contradictory. For if nothing exists, then nothing which could be thought is given either, and we contradict ourselves if we still wish to say that something is possible.’’ WM 123–4) Formally, step (7) follows from (6) by contraposition.

296 Notes to pages 202–206 45. (8) ‘‘Mithin ist es schlechterdings unmo¨glich, dass gar nichts existire.’’(II 79: 14–15; ‘‘As a consequence, it is absolutely impossible that nothing at all should exist.’’ WM 124). This statement is both the concluding sentence of I.2.iii and its heading (II 79:2). The conclusion follows from (2) and (6) by modus tollens. 46. Of course, this presupposes the tacit assumption that the ‘something’ which exists no matter what is a ‘something’ that exists continuously as a concrete object or as a group of objects. Without such an assumption, the condition ‘‘something must always exist’’ could equally well be satisﬁed by an ontological structure of the universe such that whenever one object winks out, another must pop up. In that case, the overall universe, as the mere collection of things, would exhibit a necessary existence, while all of its objects remain limited to contingent existence. In other words, Kant’s overall demonstration requires not merely the successful establishment of the three mentioned moves, but it needs the additional justiﬁcation of the tacit assumption that allows him to make his second move on the basis of the ﬁrst. Kant did not seem aware of making this assumption and thus did not supply the needed justiﬁcation. 47. Schmucker (1980), 77, takes (2) and (4) as the two basic principles involved in the ontological demonstration, i.e., the (trivial) idea that the negation of possibility is impossible, and the material condition, that the possibility of the material of possibles is thinkable only on the basis that something exists. 48. For instance, in standard introductory texts in modal logic, one ﬁnds exercises (whereby A is a sentence and 〫 is the possibility sign) in which the reader is supposed to prove that the schema A → 〫A is valid and that the schema 〫A → A is invalid; see, for instance, Chellas (1980), 10–11. 49. The question of whether the material condition should be taken as an epistemic or as an ontological condition is reﬂected in the literature on the Only Possible Argument in the larger issue of whether the possibility that is the basis of Kant’s demonstration is a possibility of thought or a possibility of being. The former option is tempting if one proceeds from the transcendental viewpoint of the critical Kant, but seems questionable considering the objectives of the precritical Kant. For defenses of the former option, see Redmann (1962), Moreau (1969), and Laberge (1973). For defenses of the latter option, see Campo (1953), Kopper (1955/56), and Lamacchia (1969). 50. In Meditatio VI, Descartes argues that a chiliogonum is possible and perfectly consistent, although it is evident that a thousand-sided ﬁgure cannot be imagined in its entirety; see AT 7:72–3. 51. See Aune (1972), 422–423. 52. ‘‘Wenn nun alles Dasein aufgehoben wird, so ist nichts schlechthin gesetzt, es ist u¨berhaupt gar nichts gegeben, kein Materiale zu irgend etwas Denklichem, und alle Mo¨glichkeit fa¨llt ga¨nzlich weg.’’ 53. Because it is not a matter of what is empirically given, but of what is given before being instantiated in the empirical objects, it is problematic when Gebler (1990), 130–131, notes that the intelligibility of the concept of possibility depends on what is empirically given. 54. See also Leibniz’s letter to Arnauld (May 1686), G 2:37. See also Rescher (1979), 72; Wong (1980), 247; Adams (1982), 247; and Chinn (1988), 39. 55. Translation from Leibniz (1981), 293. Compare G 5:272. 56. Compare Leibniz’s Theodice´e, part I, #52: Since . . . God’s decree consists solely in the resolution he forms, after having compared all possible worlds, to choose that one which is the best, and bring

Notes to pages 206–209 297 it into existence together with all that this world contains, by means of the all-powerful word Fiat, it is plain to see that this decree changes nothing in the constitution of things: God leaves them just as they were in the state of mere possibility, that is, changing nothing either in their essence or nature or even in their accidents, which are represented perfectly already in the idea of this possible world. Translation from Leibniz (1985). See also G 6:131. A valuable and clear explication of Leibniz’s involved views of essence, the realm of ideas, and the preexistence of possibility can be found in Rutherford (1995), 74–5, 91. 57. Watkins and Fisher (1997), 6–7, write: Kant is pointing to an inconsistency here between Leibniz’s theory of complete concepts and his views on existence. Leibniz holds that existence is a perfection, or a positive simple predicate, and that since God contains all perfection he must likewise contain existence. Kant recognizes that this conception of existence is inconsistent with the Leibnizian position that God is in possession of complete concepts of possible things. If the concept of a possible thing is indeed complete, then whatever it is that is effected by God’s choice to actualize that thing, it cannot be the case that any new predicates are added to this concept, since it is already complete. Thus, to say that a thing, x, exists cannot be, as Leibniz seems to indicate, to say that the predicate of existence is included in the concept of x. Watkins and Fisher conclude (ibid., p.9) that ‘‘Kant is able to maintain the Leibnizian theory of complete concepts while removing the inconsistency which arises from treating existence as a predicate.’’ 58. Reich’s interpretation in (1937), 5–8, concerns the alleged puzzle that Kant skirted the whole issue of the ontological demonstration in the Transcendental Dialectic of the ﬁrst Critique, ruling out all the other proofs of God’s existence except his own precritical construction. Watkins and Fisher (1997), 16, follow Reich and maintain that this puzzle exists in that the critical Kant endorses his precritical argument while rejecting its conclusion—such that the precritical argument, in the Critique, would establish God as a regulative principle. In my view, the puzzle seen by Reich and resurrected by Watkins and Fisher does not exist. The central ﬂaw of the precritical proof consists of the assumption that a synthesis of properties is a priori possible. The critical Kant discards this assumption in A602/B630. As Henrich (1960), 140–141, argues, the critical Kant rejects his precritical proof in B385–B392.

CHAPTER NINE

1. The Prize Essay concerns metaphysics as well as ethics, as its full title indicates: ‘‘Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morals.’’ I shall limit my discussion of the text to metaphysics. The focus of my monograph is Kant’s philosophy of nature which was his primary concern from 1746 to 1770, and not Kant’s practical philosophy. Furthermore, even in the Prize Essay, the relevance of ethics remained secondary as compared to metaphysics. The divisions of the text illustrate this, which are labeled, ‘‘I. General comparison of the manner in which certainty is attained in mathematical cognition with the manner in which certainty is attained in philosophical cognition’’; ‘‘II. The only method for attaining the highest possible degree of certainty in metaphysics’’; ‘‘III. On the nature of metaphysical certainty’’; ‘‘IV. Concerning the distinctness and certainty of which the fun-

298 Notes to pages 209–211 damental principles of natural theology and morality are capable’’ (Translations follow WM). Ethics is discussed only in the three pages of section IV.2. It can even be argued that ethics, in Kant’s precritical conception of philosophy, is reducible to metaphysics. See Fo¨rster (1982), 285–290, as well as note 12 below. 2. At the latest by 1762, the time of the composition of the Prize Essay, Kant must have become disenchanted with his analysis of freedom in the New Elucidation because he remarked in the Prize Essay, ‘‘The relation of a trillion to unity is understood with complete distinctness, whereas even today the philosophers have not yet succeeded in explaining the concept of freedom in terms of its elements, that is to say, in terms of the simple and familiar concepts of which it is composed’’ (II 282; WM 255). If Kant thought a successful explanation of the concept existed because he had furnished it, this would have been the place to mention it. 3. The announcement was the following: ‘‘Considering metaphysical truths in general and in particular the ﬁrst principles of natural theology and morals, are these principles capable of proofs as distinct as are the truths of geometry? If they are not, what is the real nature of their certainty? To what degree can the required certainty be raised, and is this degree sufﬁcient to carry conviction?’’ See also above chapter 8, section 1. 4. In 1696, Frederick I (1657–1712) created the precursor of the academy, the Akademie der scho¨nen Ku¨nste (academy of arts), and in 1700, he founded the Prussian Royal Academy as such, as the Sozieta¨t der Wissenschaften (academy of sciences), with Leibniz as president. Under the successor Frederick William I (reign from 1712–1740), who was a soldier and for all practical purposes a moron, the Prussian Royal Academy was left with little funds. It diminished in importance, and its meetings degenerated to social gatherings. The intellectual center relocated to the east; many German scholars joined the Russian Academy of Sciences in St. Petersburg, founded in 1724. Upon the accession of Frederick II in 1740 (who was rightly known as Frederick the Great, 1712–1786), things in Berlin took a turn for the better. He reconstituted Frederick I’s Sozieta¨t der Wissenschaften as the Acade´mie des Sciences et Belles-Lettres in 1744, appointed Maupertuis as its president, and attracted leading international scholars as resident members to Berlin. Euler became the director of the mathematical class of the academy. This was the second and real beginning of the academy. 5. For further details, see chapter 7, sections 1–2, above. 6. See Me´moires de l’Acade´mie Royale des Sciences et Belles-Lettres (Berlin, 1750). The relevant passages are pp. 314–325 and 376–377. Euler’s paper has been translated as Reﬂections on Space and Time in Koslow (1967). 7. This tract is not identical with Maupertuis’s earlier treatise, the Essai de Cosmologie (Paris, 1750). The Examen philosophique was a reexamination of the cosmological proof that Maupertuis had constructed as a probabilistic argument in the Essai. It appeared ﬁrst in a volume of the Me´moires de l’Acade´mie Royale des Sciences et Belles-Lettres (Berlin, 1758). Polonoff (1971), 165, notes that this paper was the ﬁrst important work appearing in Germany which took note of David Hume’s arguments on causality. 8. Johann Sulzer (1720–1779) was inﬂuenced by Wolfﬁanism but rejected Wolff ’s ‘‘one faculty’’-theory of cognition (according to which reason and will are two aspects of the same faculty of representation), arguing for a cognitive faculty of aesthetic taste instead. His writings were primarily in aesthetics; his main work was the Allgemeine Theorie der scho¨nen Ku¨nste (1774). Heinrich Samuel Formey (1711–1797) was a quite orthodox Leibnizian-Wolfﬁan School Philosopher and the author of La Belle Wolfﬁenne (6 vols.; 1741–1753). In the Re´cherches sur les e´le´ments de la matie`re, he

Notes to pages 211–213 299 criticized the Cartesians for their treatment of force that allegedly involved misusing mathematics by confounding imaginary, mathematical notions with real, metaphysical notions; see his Me´langes philosophiques (Leyden, 1754), 1:258. Max Dessoir immortalized Formey with the following words in his Geschichte der neuren deutschen Psychologie (Berlin: Dunker, 1901): ‘‘The man actually produced nearly 600 books besides a frightful number of reviews . . . in part because he felt happy only in his work, and in part ‘pour donner un peu d’aisance a` ses enfants.’ Besides that, he had the largest correspondence known in Germany since Leibniz’. And toward the end of his life he accomplished a stroke of genius: incapable of creative work but likewise incapable of doing nothing, he himself published his oeuvres posthumes’’ (p. 192). Translated by Beck (1969b), 315. 9. Page numbers refer to Mendelssohn, Gesammelte Schriften (22ff. vols.), ed. by F. Bamberger et al. Reprint of the edition Berlin, 1931 (Stuttgart/Bad Cannstatt: Frommann-Holzboog, 1971ff.), vol. 2. 10. There are accordingly three locations of the ontological proof in Kant’s precritical oeuvre—in the New Elucidation I 395–396, in the Only Possible Argument II 78– 92, and in the Prize Essay II 296–297. Kant outlined the proof in the Prize Essay as follows: In order to arrive at [the concept of the absolutely necessary existence of a being], the metaphysician could ﬁrst of all ask the question: is it possible that absolutely nothing at all should exist? Now, if he realizes that, were absolutely nothing at all to exist, then no existence would be given and there would be nothing to think and there would be no possibility—once that is realized, all that needs to be investigated is the concept of the existence of that which must constitute the ground of all possibility. He will develop this idea and establish the determinate concept of the absolutely necessary being. . . . [A]s soon as the existence of the unique, most perfect and necessary Being is established, then the concepts of that Being’s other determinations will be established with much greater precision, for these determinations will always be the greatest and most perfect of their kind; they will also be established with much greater certainty, for the only determinations which will be admitted will be those which are necessary. (WM 270–271) 11. Once again, this reminds one of Kant’s later remarks of the Critique of Pure Reason (Aviii–Aix, tr. Kemp Smith): ‘‘Time was when metaphysics was entitled the Queen of all the sciences; and if the will be taken for the deed, the pre-eminent importance of her accepted tasks gives her every right to this title of honour. Now, however, the changed fashion of the time brings her only scorn; a matron outcast and forsaken, she mourns like Hecuba: Modo maxima rerum, tot generis natisque potens—nunc trahor exul, inops.’’ (‘‘First I was the greatest of all things, powerful through so many children and sons-in-law—but now, I am led away, outcast, helpless.’’) 12. In II 282, Kant speaks of ‘‘philosophy,’’ not ‘‘metaphysics,’’ but he often uses these terms interchangeably. In the precritical works, Philosophie is always used synonymously with Weltweisheit (‘‘world-wisdom’’), and Philosophie is frequently used synonymously with Metaphysik. The latter identiﬁcation is possible to the extent that Metaphysik is the paradigmatic core of Philosophie. Kant’s precritical employment of the terms mirrors common usage. The prize question (‘‘Considering metaphysical truths in general and in particular the ﬁrst principles of natural theology and morals, are these principles capable of proofs as distinct as are the truths of geometry?’’) implies the same interchangeability of metaphysics and philosophy in that ‘‘natural

300 Notes to pages 213–218 theology’’ and ‘‘morals’’ are taken as aspects of metaphysics. When discussing Kant’s precritical notion of philosophy, Fo¨rster (1982) uses ‘‘metaphysics’’ and ‘‘philosophy’’ as if they were synonyms; see ibid., 285–304, esp. 285–289. As Fo¨rster suggests (289– 290), the interchangeability of the two notions in Kant’s vocabulary ends when the third precritical decade drew to a close. At that point in time, Kant recognized that the very possibility of metaphysics must be established, and he realized that a preliminary, critical investigation is needed. Since this critical investigation was fundamental to philosophy but different from metaphysics, Philosophie, at the latest from 1770 on, was not synonymous with Metaphysik anymore. 13. Mendelssohn, in his Abhandlung u¨ber die Evidenz, maintains the same distinction: ‘‘Die Mathematik ist eine Wissenschaft der Gro¨ssen (Quantitatum), und die Weltweisheit u¨berhaupt eine Wissenschaft der Beschaffenheiten (Qualitatum) der Dinge’’; see section II, Ges. Schr. 2:286. 14. Compare the original, ‘‘Was ich hier liefere, ist auch nur der Beweisgrund zu einer Demonstration, ein mu¨hsam gesammeltes Baugera¨th, welches der Pru¨fung des Kenners vor Augen gelegt ist, um aus dessen brauchbaren Stu¨cken nach den Regeln der Dauerhaftigkeit und der Wohlgereimtheit das Geba¨ude zu vollfu¨hren.’’ Walford and Meerbote render Baugera¨th as ‘‘materials’’ in WM 112. This is not quite right because ‘‘materials’’ in this context would be Baumaterial. 15. My translation. See Mendelssohn, Zwey hundert und achtzigster Brief (26 April 1764), in Ges. Schr. 5.1: 602. The citations in the subsequent paragraph are from the same passage on p. 602. 16. Mendelssohn took issue with what we termed Kant’s ‘‘material condition’’ in chapter 8 above. This is interesting because our negative appraisal of Kant’s proof on grounds of the material condition converges with Mendelssohn’s misgivings. As Mendelssohn explains, if read as an epistemic condition, then the material condition (not Mendelssohn’s term) would mean that our possibility of thinking representations presupposes real things. But this would not show, what Kant hoped to show, that possibility itself would vanish if there were no real things and we consequently could not think them; see Zwey hundert und achtzigster Brief in Ges. Schr. 5.1: 604–606, esp. 606. If read as an ontological condition, as it were, then the material condition would mean that the material data of all that is thinkable existed eternally in God. But this would merely amount to the existence of concepts, and not, as Kant hoped to establish, to the actual existence of entities; see ibid., 5.1: 607. 17. Mendelssohn concludes his review with the following remark: ‘‘The glimmer of truth shining forth from several of [Kant’s] propositions will stimulate the wish among the specialists that the author collected the construction materials personally, in order to erect a building that could be incessantly permanent through its solidity and regularity, and that would fully satisfy the scrutinizing eye of reason.’’ My translation. See Mendelssohn, Beschluss des zwey hundert und ein und achtzigsten Briefes (10 May 1764), in Ges. Schr. 5.1: 616. 18. According to Fo¨rster (1982), 286–287, the precritical conception of metaphysics must therefore follow an analytic procedure. Although this is correct, it must be remembered that the analytic procedure is only what makes metaphysics possible. The analytic procedure is the propaedeutic of metaphysics, not the conception of metaphysics as such. 19. Kant pretty much ignored the multifarious interpretations of ‘‘analysis’’ and ‘‘synthesis’’ by Wolff and other School Philosophers and sticks to their classical meanings: analysis is the dissection of concepts; synthesis is the combination of concepts. Tonelli (1976b), 178–213, formulates helpful deﬁnitions of the classical meanings of

Notes to pages 218–219 301 the terms: ‘‘. . . [A]nalysis or resolutio (Auﬂo¨sung) is that cognitive procedure which, beginning from sensible and/or complex representations, aims at establishing their constituent parts . . . until some ‘simple’ or ‘irresoluble’ elements, or the ‘causes’ of the ‘effects’ are reached, which are the ‘elementary notions’ or the ‘ﬁrst principles.’ The synthesis or compositio (Zusammensetzung), on the contrary, begins with those elementary notions and ﬁrst principles, and, combining them and deducing from them, elaborates more complex notions and propositions, viz. derives the ‘effects’ from the ‘causes,’ until it reaches, if it can complete its procedure, at least a part of those representations not offered by experience’’ (ibid., p. 179). 20. Kant’s synthetic conception of mathematics has a certain ring of plausibility, but it must be noted that even Euclid subjected his propositions to analysis before the propositions could be stated as deﬁnitions and axioms. Accordingly, Newton regarded analysis as a genuine mathematical method and noted in q. 31 of the Opticks (p. 404) that mathematics begins with a method of analysis that ‘‘ought ever to precede the Method of Composition.’’ See also Polonoff (1971), 190–191. 21. See Christian August Crusius, Anleitung u¨ber natu¨rliche Begebenheiten ordentlich und vorsichtig nachzudenken (Leipzig, 1749); C 4.1: 508. 22. While both Kant and the pietist philosophers agree in that there are signiﬁcant differences between philosophy (metaphysics) and mathematics, this agreement is coincidental and involves different reasons. Unlike Kant, the pietists infer the distinction between philosophy and mathematics from ontological considerations similar to Wolfﬁan views—mathematics is about the possible, philosophy is about the real. Kant, as we have seen (chapter 3 above), disagrees. For him, both philosophy and mathematics are about the real. For further details on the relation of philosophy and mathematics according to the pietists and the Wolfﬁans, see Ciafardone (1986), 289– 305, esp. 292. 23. As Kant saw it, the ability to use symbolism is the decisive advantage of mathematics over philosophy. For the connection of this conception to Kant’s critical notion of intuitive geometry, as well as the problems of this theory of mathematics, see Kitcher (1975), 36–41. 24. With the exception of Rule IV, the four Regulae Philosophandi of book III of the Principia mainly concern the assumption of nature’s uniformity and have comparatively little to do with what Kant considered relevant in Newton’s methodology. Newton’s rules are as follows (M 2:398–400): Rule I. We are to admit no more causes of natural things than such as are both true and sufﬁcient to explain their appearance. Rule II. Therefore to the same natural effects we must, as far as possible, assign the same causes. Rule III. The qualities of bodies, which admit neither intensiﬁcation nor remission of degrees, and which are found to belong to all bodies within the reach of our experiments, are to be esteemed the universal qualities of all bodies whatsoever. Rule IV. In experimental philosophy we are to look upon propositions inferred by general induction from phenomena as accurately or very nearly true, notwithstanding any contrary hypothesis that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions. Newton suggested that natural processes are parsimonious (rule I), that their causal structure is uniform (rule II), and that the features of bodies are homogeneous and

302 Notes to pages 219–222 allow of generalization (rule III). Rule IV explicates the primacy of experience over speculation. Kant’s ﬁrst rule of reasoning in metaphysics (see text below) is modeled on Newton’s fourth rule. Aside from this, Rule IV pertains to the assumed uniformity of nature just as the previous rules: on grounds of nature’s uniformity, it is legitimate to rely on generalizations that are inductively inferred from the phenomena and to take such claims as descriptions of nature, unless or until new examinations require us to qualify the generalizations. 25. Kant seems to referring here to the hierarchical organization of claims that one ﬁnds, for example, in Euclid’s Elements, whose 10 axioms entail 467 theorems. 26. Quoted after Koslow’s translation in Koslow (1967), 116. Compare Friedman (1992b), 16, 19–20, and Polonoff (1971), 195–197. The signiﬁcance of Euler’s inﬂuence prompts Friedman to call the methodological proposal of the Prize Essay Kant’s ‘‘Newtonian-Eulerian method.’’ 27. In the Latin vernacular of eighteenth-century philosophy, standard labels for the geometric method are mos geometricus, methodus geometrica, and methodus geometrarum. This paragraph summarizes points made in greater detail in Scho¨nfeld (1998), 69–73. 28. See Wundt (1924), 32; Vleeschauwer (1931), 651–677; Paolinelli (1974), 8. 29. The full title of Tschirnhaus’s work, in the deﬁnitive second edition, was Medicina Mentis, sive Artis inveniendi Praecepta generalia (Leipzig, 1695). In subsequent citations, I will use MM to refer to this edition and H to refer to its German translation by Haussleiter in Tschirnhaus (1963). 30. Crusius assigned rational and real objects to different modal and ontological categories, believing them to be mutually exclusive. He thought that the objects of mathematics and philosophy do not share any relevant features. He argued in his Metaphysik (1745) that mathematical and philosophical descriptions remain incommensurable, even when they seem to concern the same material (such as the determination of simples and compounds). To integrate the two different descriptions would accordingly involve some kind of category mistake (cf. #116–119, C 2:182– 197). In the Natu¨rliche Begebenheiten (1749), he characterized mathematics as a discipline about quantities whose objects are imaginary and abstract entities, and philosophy as a discipline about qualities whose objects are real and concrete things (C 4.1: 481–2, 508). Because the rules for investigating an object depend partly on its features, the investigations of rational and real objects must be different and mathematics and philosophy cannot learn from one another. Crusius roundly rejected the adoption of mathematical tools as well as the geometric method. Wolff, on the other hand, drew in the Philosophia prima sive ontologia (1730) a distinction between rational and real objects on the basis of his theory of universals. In his view, rational objects were universals, and real objects were individual things (singularia) (cf. #110, W II.2: 90–1). Because of this categorical difference between the two classes of objects, the investigation of one class of objects should not merge with the investigation of the other class. Accordingly, Wolff ruled out the actual philosophical employment of mathematics. But despite the categorical distinction, universals evidently have something to do with individual objects: singularia instantiate universals (realistically speaking), or they contain universals as their essences (nominalistically speaking and following Wolff). For Wolff ’s conception of the relationship between universals and singularia, cf. Ontologia #143, 227–230, 235, 239, 248; W II.3: 120–1, 188–190, 193– 4, 205. Since rational objects as imaginary universals constitute the essences of concrete individual things, the two types of objects share some features. The universals,

Notes to pages 222–228 303 studied by mathematics, are the general forms of the concrete, individual things, studied by philosophy, and this makes mathematics relevant for philosophy. Although philosophy cannot integrate its material characteristics, the actual mathematical procedures, it can integrate its formal characteristics, the overall structure of reasoning, and accordingly adopt the geometric method. See also Corr (1972), 323–324. 31. See Friedman (1992b), 21. 32. See also chapter 6, section 1 above. 33. See Friedman (1992b), 22–24. 34. I quote from Kant, Philosophical Correspondence 1759–99, ed. and transl. by A. Zweig (Chicago: University of Chicago Press, 1967), referred to as Z. 35. J. H. Lambert, Cosmologische Briefe u¨ber die Einrichtung des Weltbaues (Augsburg, 1761). 36. Kant had no qualms about believing Lambert and never suspected the Cosmologische Briefe of plagiarism, since he knew only too well that only very few copies of the Universal Natural History ever reached the public on grounds of the bankruptcy of the publisher. 37. J. H. Lambert, Abhandlung von dem Criterium veritatis (1761). The Abhandlung was not printed during Lambert’s lifetime. See Bopp (1915). ¨ ber die Methode, die Metaphysik, Theologie, und Moral richtiger 38. J. H. Lambert, U zu beweisen (1762; unpublished). See Bopp (1918). 39. J. H. Lambert, Neues Organon, oder Gedanken u¨ber die Erforschung und Bezeichnung des Wahren und dessen Unterscheidung vom Irrthum und Schein, two volumes (Leipzig: Wendler, 1764). Reprinted in J. H. Lambert, Philosophische Schriften, ed. H. W. Arndt, 7 vols. (Hildesheim: Olms, 1965ff.), vols. 1 and 2. 40. See Pierce (1931–35), vol. 2, #345, and Beck (1969b), 402. 41. See Lambert’s letter to Kant on 13 October 1770; X 103–110. Lambert reacted to Kant’s split between the intelligible and sensible world in the Inaugural Dissertation with the following words: ‘‘Till now I have not been able to deny all reality to time and space, or to consider them mere images and appearance. I think that every change would then have to be mere appearance too. And this would contradict one of my main principles (No. 54, Phaenomenology [part IV of the Organon])’’ (X 110; Z 66). 42. Zweig takes the announcement of the Metaphysical Foundations of Natural Philosophy in 1765 as the ﬁrst indication of Kant’s later Metaphysical Foundations of Natural Science (1786); see Kant (1967a), 49 note. It is certainly possible to suspect a connection between the early plan and the later work, but the Metaphysical Foundations of Natural Philosophy, had they been written, would have hardly resembled the Metaphysical Foundations of Natural Science. The later book, composed between the ﬁrst and second edition of the Critique of Pure Reason, is a supplement to the ﬁrst Critique in that it applies the table of categories to the principles of Newtonian physics. As the Critique concerns general metaphysics and an analysis of nature in general, the Metaphysical Foundations of Natural Science concerns special metaphysics and an analysis of corporeal nature in space. The contents of the Metaphysical Foundations of Natural Science are an instantiation or realization of the contents of the Critique of Pure Reason, just as the contents of Newton’s Principia are conceived by Kant as an instantiation or realization of the contents of the Metaphysical Foundations of Natural Science (together with empirical regularities, such as the ones described by Kepler’s laws). The Metaphysical Foundations of Natural Science rests on Kant’s Copernican turn and presupposes the critical conception of metaphysics as the transcen-

304 Notes to pages 228–230 dental system of synthetic judgments a priori. This is fundamentally different from the precritical conception of metaphysics as a transcendent system of speculative philosophy presupposed in the Prize Essay. 43. See IV 256. Translation by Carus in Kant (1902), 2.

CHAPTER TEN

1. For a survey of Rousseau’s signiﬁcance for Kant, see Ferrari (1978), 348–356. For Rousseau’s inﬂuence on the Observations, see Gurvitch (1971), 385–405; Cassirer (1981), 86–90; Reich (1989), 80–96; and Piche´ (1990), 625–35. For the inﬂuence of the theory of feeling on the Observations and the continuities between this work and the critical period, see Schrader (1976), 143–164, esp. 157–159. 2. Several years before Kant’s Observations, Edmund Burke (1729–1797) published his own work on the topic, A Philosophical Enquiry into the Origin of Our Ideas of the Sublime and Beautiful (1757). For Burke’s conceptions of the beautiful and the sublime and their inﬂuence on Kant’s, see Parret (1992), 317–343, esp. 326–327. 3. The moral sense theory is a view held by several seventeenth- and eighteenthcentury British philosophers. Its basic claim is that our capacity of distinguishing between right and wrong rests on a general faculty, the moral sense, that is part of the human constitution, and that manifests itself in sentiments and feelings. The main defenders of this view were Anthony Ashley Cooper, Earl of Shaftesbury (1621– 1683) and Francis Hutcheson (1694–1747). Shaftesbury presented his views in An Inquiry Concerning Virtue or Merit (1699), which became volume II of his later Characteristics of Men, Morals, Opinions, Times, 3 vols. (London, 1711). Hutcheson further elaborated the moral sense theory, expanding its applicability to aesthetics, in An Inquiry into the Original of our Ideas of Beauty and Virtue (London, 1725) and An Essay on the Nature and Conduct of the Passions and Affections (London, 1728). For further details, see Norton (1977), 181–197. The young David Hume was inﬂuenced by Hutcheson and temporarily argued for the same view; see especially his Treatise of Human Nature (London, 1740), book III.i.1–2. For further details on the relationship of the moral sense theory and Kant’s early ethics, see Henrich (1957–8), 49–69; MacBeath (1973), 283–314; and Sprute (1980), 221–237. 4. The Observations was the only early text that was reprinted twice during the precritical period. The second edition appeared with Kanter in Ko¨nigsberg in 1766, the third with Hartknoch in Riga in 1771. 5. The annotations are indeed of considerable quantity. Whereas the Observations numbers 51 pages in the Academy Edition (II 205–56), the annotations are four times as long, numbering 189 pages in the same edition (XX 3–192). For the story of the annotations, see Lehmann, ‘‘Einleitung,’’ in the Anhang of XX, 471–5. As regards their dating, Lehmann tells that F. W. Schubert, who edited part of Kant’s Nachlass in his Immanuel Kant’s Briefe, Erkla¨rungen, Fragmente aus seinem Nachlasse (1842), assumed that Kant compiled these notes between 1765 and 1775 when using the Observations in his anthropology course. Lehmann disproves Schubert’s thesis and points out that Kant used the ‘‘Psychologia empirica’’ of Baumgarten’s Metaphysica Editio III (1753), and not the Observations, as his textbook for the course taught in these years. Because the Observations had nothing to do with the anthropology lectures, there is no reason to assume the annotations to the Observations came into existence when Kant taught that course. Based on an analysis of their content, the editors of the Akademieausgabe ﬁrst supposed the annotations were written sometime

Notes to pages 230–232 305 between 1763 and 1769 and eventually concluded they were written in 1764 and 1765. 6. See Dreams II 368: ‘‘In so fern ist die Metaphysik eine Wissenschaft von den Grenzen der menschlichen Vernunft’’ (Kant’s emphasis). Based on this fundamental recasting of metaphysics, L. E. Borowski remarked in the part of his biography authorized by Kant that the Dreams contains the seed of the Critique of Pure Reason; see his Darstellung des Lebens und Charakters Immanuel Kants (Ko¨nigsberg: Nicolovius, 1804), 59. Werkmeister (1980), 45, follows Borowski and argues that the Dreams anticipated the ﬁrst Critique because of its attacks on metaphysical speculation and its questions regarding God, freedom, and immortality—questions that pointed to the Transcendental Dialectic of the Critique. 7. Kant’s critique was directed against the philosophical establishment in general and not only against the Leibnizian-Wolfﬁans. For the objections to Crusius in the Negative Quantities, see Puech (1990), 187–204, esp. 192–196. For the ‘negative quantities’ in the Negative Quantities as well as their fate in Kant’s later assessment of this work, see Guillamaud (1990), 173–185. It is curious that Kant rejected in the Negative Quantities the notion of the inﬁnitely small (which undermines his earlier assumptions in the Physical Monadology); see Ro¨d (1990), 497–505, esp. 498–499. The critique of rationalism that marks the Negative Quantities to the extent that Kant sets himself in opposition to the views of the New Elucidation culminates in the ﬁnal objection (cf. II 201–4): he challenges the metaphysicians to explain according to the law of identity how one thing can produce another. Beiser (1992), 42, comments: ‘‘Hence the relationship of cause and effect, the fundamental constituent of our knowledge of matter of fact, cannot be reduced to the principle of identity. Here Kant had anticipated, though without possessing the terminology, the central question of the ﬁrst Critique: How are synthetic a priori judgments possible?’’ 8. For the signiﬁcance of the Metaphysik Herder, see Puech (1990), 187–204. The contents of the Metaphysik Herder conform, to an extent, to the positions in Kant’s publications of these years. For instance, as in the Prize Essay, Kant emphasizes in the classroom that the method of metaphysics must not orient on mathematics and should be analytic instead of synthetic; see XXVIII 157. But one must be careful not to overestimate the signiﬁcance of the Metaphysik Herder. One reason for caution is that the lectures are twice removed from Kant’s thought: they are the transcripts of a student, and they are transcripts of lectures that Kant gave not on his own philosophy, but on Baumgarten’s textbook. Furthermore, the notes must be taken in context; isolated from their context, their meaning can change quite signiﬁcantly. For instance, following a passage on XXVII 60, Puech, ibid., 199, believes that Kant ‘‘accepte l’ide´e de l’origine sensible de tous les concepts.’’ Puech’s interpretation suggests a resolution of the puzzle of the Prize Essay regarding the starting point of metaphysics: metaphysics begins with the analysis of concepts, and the elementary components of concepts are, according to the Metaphysik Herder, empirical data. Because Kant (Herder) writes on XXVII 60, ‘‘Die Data zu den Begriffen sind die Empﬁndungen,’’ it would then follow that Friedman’s reading is correct, that the empirical data of the natural sciences are the starting point of the conceptual analysis of metaphysics (see chapter 9, section 4, above). However, the full passage in the Metaphysik Herder runs: Nihil est in intellectu: Aristoteles Locke. Die Data zu den Begriffen sind die Empﬁndungen [missing] nur 2 Sinne genommen, so weit [missing] Andere Philosophen haben anerschaffene Begriffe geglaubt. Plato anima est tabula

306 Notes to pages 232–237 idearum aber sie sind doch dunkel und mu¨ssen blos durch Empﬁndugn klar werden. Kinder saugen durch angebohrne Begriffe Kein Philosoph wird [missing] mit anderen Sa¨tzen die Mo¨glichkeit des Saugens sich vorstellen ko¨nnen. Taken in its context, the sentence, on which Puech’s interpretation of Kant’s empiricism rests, turns out to be merely part of an innocuous historical survey that begins with the empiricism of Aristotle and Locke and ends with the idealism of Plato. 9. On Weymann’s tracts, see Walford and Meerbote, ‘‘Introductions to the Translations,’’ WM lvi and lx. Kant, it seems, did not take this polemics too seriously. For his reaction to the initial misunderstanding, compare Kant’s letter on 28 October 1759 to Johann Gotthelf Lindner (X 22–23). 10. Gottfried Ploucquet (1716–1790) taught a version of Wolfﬁan philosophy in Tu¨bingen since 1750. He was a nonresident member of the Prussian Royal Academy, and he was known at the time for his idealistic interpretation of the Wolfﬁan theory of space in the Principia de substantiis et phaenomenis (1764) and for his efforts at constructing a viable alternative to Wolff ’s logic by resurrecting Leibniz’s plan of an ars combinatoria. 11. Together with Kant’s Prize Essay and two other runner-ups, Mendelssohn’s Abhandlung u¨ber die Evidenz in den metaphysischen Wissenschaften was published by the Berlin academy as the Dissertation qui a remporte´ le prix propose´ par l’Acade´demie royale des sciences et belles lettres de Prusse, sur la nature, les espe`ces, et les degre´s de l’e´vidence avec les pie`ces qui ont concouru (Berlin: Haude & Spener, 1764). For the Abhandlung u¨ber die Evidenz, see Mendelssohn, Gesammelte Schriften, 2:267–330. See also chapter 9, section 1, above. 12. We have a relatively good idea of the time of the inception of the Dreams. Instead of bringing the completed manuscript to his publisher Kanter, Kant forwarded it almost page by page, giving them to Kanter as he wrote them. Kant remarked that the Dreams were written in a hurry. The imprimatur of the ﬁrst edition is 1766, and the academic censor, whom Kanter bypassed (leading to a ﬁne of 10 reichsthaler that the bookseller had to pay), received the printed tract on 31 January 1766; compare Menzer’s annotations in II 500–507, and Kant’s letter to Mendelssohn on 8 April 1766 in X 69. Considering that Kant rushed through the composition of the tract, the Dreams were probably not begun until relatively late in 1765, and, given the censorship date, Kant must have ﬁnished it, at the latest, sometime in January 1766. 13. See Zweig (1967), 54 note; Walford and Meerbote, ‘‘Introductions to the Translations,’’ WM, lxviii. 14. For Mendelssohn’s review of the Only Possible Argument, see chapter 9, section 1, above. The review of the Only Possible Argument, numbering 33 pages in its original edition, appeared in two ‘letters,’ of two installments each, in Briefe, die neueste Literatur betreffend 18 (1764): 69–80, 81–87, 87–96, 97–102 ; see Gesammelte Schriften, 5.1: 602–16. 15. Mendelssohn’s review of the Dreams of a Spirit-Seer appeared in the Allgemeine deutsche Bibliothek 4.2 (1767): 281; see Gesammelte Schriften, 5.2: 73. The passage translated above is the second half of the review. For a translation of the review in its entirety, compare part III title page above. 16. See Emmanuel Swedenborg, Arcana coelestia quae in Scriptura Sacra seu Verbo Domini sunt detecta (London: John Lewis, 1749–56), 8 vols. in 4 tomes, p. 4622. For a condensed English edition, see Arcana Coelestia, tr. John Faulkner Potts (New York: Swedenborg Foundation, 1949). Laywine (1993), chpts. 4 and 5, esp. 64–71, gives a detailed and valuable account of the factual and philosophical contents of Sweden-

Notes to pages 237–241 307 borg’s work and its relation to the Dreams of a Spirit-Seer. For the anecdote of Swedenborg having to take ‘‘one deluded soul’’ to its own funeral service, see Laywine, ibid., 70. 17. Compare the original passage in Butler’s Hudibras (vol. 2, book 3, lines 773– 776): ‘‘As wind i’th’ Hypocondres pent, / Is but a Blast if downward sent; / But if it upward chance to ﬂy, / Becomes new Light and Prophecy.’’ 18. As regards the former, see Ward (1972), 34. For the latter quote, see Shell (1996), 6, 131. 19. See Cassirer (1980), 78–79. 20. See Rozenberg (1985), 15. Rozenberg approvingly cites this phrase from F. Courte`s, ‘‘Introduction,’’ in Kant, Reˆves d’un visionnaire (Paris: Vrin, 1967), 7. For the latter quote, see Ho¨ffe (1994), 19. 21. See Ward (1972), 35. 22. See Shell (1996), 6, 111. 23. The stories ‘‘of the kind mentioned’’ refer to the ‘‘magical apparitions’’ (Geistererscheinungen) Kant discussed in the ﬁrst paragraph of the preface, see II 317. 24. In order to evade the censor, the French materialist Paul Henri Thiry d’Holbach (1723–1789) published his main work, Syste`me de la nature, ou, des loix du monde physique et du monde moral (1770) in London and under an assumed name (Jean Baptiste de Mirabaud). 25. See Beiser (1992), 45. 26. Relevant for the Leibniz-Swedenborg connection is Swedenborg’s De coelo et eius mirabilis, et de inferno, tr. by J. A. Ayer as Heaven and its Wonders, and Hell (New York: Swedenborg Foundation, 1932), 47, 155–158. Laywine (1993), 63–67, summarizes the salient points of this connection: Every angel has certain inner states that continually succeed one another. The inner state of an angel consists in the love of God, faith, wisdom and intelligence. . . . Swedenborg informs us that, by virtue of their—changing—inner states, all angels have particular differences, but some of them resemble one another, as members of the same family often have similar features and mannerisms. . . . The bond that ties all the members of an angelic society together issues directly from their inner states. . . . Elsewhere in Heaven and its Wonders, and Hell, Swedenborg tells us that harmony in creation depends on the inner states of the angels . . . [i]t depends, moreover, on change of these inner states. . . . Though Swedenborg likes to stress the dependence of all creatures on God, he is perfectly happy to grant that creatures have the power to act under their own steam. This is as true of the angels as of any other spiritual creature. . . . Swedenborg apparently thinks that the angels require God’s assistance to make their power take effect. Just for that reason, divine inﬂux—God’s universal concourse—is the ultimate cause of all order in heaven and on earth. . . . [T]he thing to point out now is that Swedenborg shares this idea of God’s universal concourse with Leibniz. Leibniz’s system of pre-established harmony rests as squarely on the idea that God must assist creatures as it does on the idea that creatures can act under their own steam. 27. Laywine (1993), 56, 77–78, 100, suggests to establish the speciﬁc connection of Kant and Swedenborg in terms of a coherence of their causal theories. For the reasons stated, I ﬁnd this suggestion implausible. But Laywine is entirely correct as regards her general contention ‘‘that Kant was moved on the occasion of reading the

308 Notes to pages 241–246 Arcana coelestia to write Dreams of a Spirit-Seer as a diagnosis of the problems in his own metaphysics . . .’’; ibid., 57. 28. See Ameriks (1982), 29–30. 29. Considering Kant’s preoccupation with Swedenborg’s fantastic stories in the Dreams, Friedman, following Ameriks (1982), 29–30, points out in (1992b), 28, that the crucial problem is ‘‘that Kant’s own metaphysics has itself placed the material and the immaterial worlds in uncomfortably close proximity.’’ As Friedman explains (ibid., 27–28): Kant is convinced . . . that material substances and immaterial substances do really interact and therefore that they are present to one another in a single world. But copresence and the possibility of real interaction are grounded, in the ﬁrst instance, precisely by the fundamental laws of physical dynamics. It is these laws, and these laws alone, which ﬁrst constitute both the copresence of all simple substances and space. Hence, both material and immaterial substances are in space, and both, moreover, are subject to the very same fundamental laws of physical dynamics. There is thus a very real danger of collapsing the distinction between material and immaterial substances completely. 30. See Laywine (1993), 71.

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LITERATURE ON KANT

Adickes, Erich. Untersuchungen zu Kants physischer Geographie. Tu¨bingen: Mohr/Siebeck, 1911a. ———. Kants Ansichten u¨ber Geschichte und Bau der Erde. Tu¨bingen: Mohr/Siebeck, 1911b. ———. Kant als Naturforscher. 2 vols. Berlin: DeGruyter, 1924a. ———. ‘‘Kant als Naturwissenschaftler.’’ Kant-Studien 29 (1924b): 70–97. Allison, Henry. ‘‘The Concept of Freedom in Kant’s ‘Semi-Critical’ Ethics.’’ Archiv fu¨r Geschichte der Philosophie 68 (1986): 97–115. ———. ‘‘Kant’s Refutation of Materialism.’’ The Monist 72 (1989): 190–208. Ameriks, Karl. Kant’s Theory of Mind. Oxford: Clarendon Press, 1982. ———. ‘‘The Critique of Metaphysics: Kant and Traditional Ontology.’’ 249–279 in Guyer 1992. Auxter, Thomas. ‘‘The Teleology of Kant’s Ectypical World.’’ 487–93 in Laberge et al. [1976]. Axinn, Sidney. ‘‘Ambivalence: Kant’s View of Human Nature.’’ Kant-Studien 72 (1981): 161–170. Bauer, Johannes. ‘‘Zum einzig mo¨glichen Gottesbeweis.’’ Salzburger Jahrbuch fu¨r Philosophie 8 (1964): 161–174. Beck, Lewis White, ed. Kant Studies Today. La Salle, Ill.: Open Court, 1969a. ———. Early German Philosophy. Kant and His Predecessors. Cambridge, Mass.: Harvard University Press, 1969b.

Bibliography 315 ———, ed. Proceedings of the Third International Kant Congress. Dordrecht: Reidel, 1972. ———. ‘‘What Have We Learned from Kant?’’ 17–30 in Wood [1984]. Beiser, Frederick C. The Fate of Reason. German Philosophy from Kant to Fichte. Cambridge, Mass.: Harvard University Press, 1987. ———. ‘‘Kant’s Intellectual Development: 1746–1781.’’ 26–61 in Guyer [1992]. Bennett, Jonathan. Kant’s Analytic. Cambridge, England: Cambridge University Press, 1981. ———. Kant’s Dialectic. Cambridge, England: Cambridge University Press, 1981. Bird, Graham. Kant’s Theory of Knowledge. New York: Humanities Press, 1973. Bonsiepen, Wolfgang. ‘‘Die Ausbildung einer dynamischen Atomistik bei Leibniz, Kant und Schelling, und ihre aktuelle Bedeutung.’’ Allgemeine Zeitschrift fu¨r Philosophie 13 (1988): 1–20. Borowski, Ludwig Ernst. Darstellung des Lebens und Charakters Immanuel Kants. Ko¨nigsberg, 1804. In Groß [1993]. Brittan, Gordon J. Kant’s Theory of Science. Princeton: Princeton University Press, 1978. Broadie, Alexander, and Pybus, Elisabeth M. ‘‘Kant’s Treatment of Animals.’’ Philosophy 49 (1974): 345–386. Bro¨cker, Walter. Kant u¨ber Metaphysik und Erfahrung. Frankfurt a. M.: Klostermann, 1970. Buchdahl, Gerd. ‘‘Der Begriff der Gesetzma¨ssigkeit in Kants Philosophie der Naturwissenschaft.’’ 90–121 in Heintel and Nagl [1981]. Butts, Robert E., ed. Kant’s Philosophy of Physical Science. Dordrecht: Reidel, 1986. Campo, Mariano. La genesi del criticismo Kantiano. Varese: Magenta, 1953. Carrier, Martin. ‘‘Kant’s Relational Theory of Absolute Space.’’ Kant-Studien 83 (1992): 399–416. Cassirer, Ernst. ‘‘Kant und das Problem der Metaphysik. Bemerkungen zu Martin Heideggers Kantinterpretation.’’ Kant-Studien 36 (1931): 1–26. ———. Kant’s Life and Thought. First published in Germany in 1918. Translated by J. Haden. New Haven: Yale University Press, 1981. Ciafardone, Raffaele. ‘‘Von der Kritik an Wolff zum vorkritischen Kant. Wolff-Kritik bei Ru¨diger und Crusius.’’ 289–305 in Christian Wolff. 1679–1754. Edited by Werner Schneider. Studien zum achtzehnten Jahrhundert 4. Hamburg: Meiner, 1986. Courte`s, F. ‘‘Introduction a` la traduction franc¸aise des Reˆves d’un visionnaire,’’ 1–27 in Kant 1967b]. Cross, F. L. ‘‘Kant’s so-called Copernican Revolution.’’ Mind 46 (1937): 214–7. Cousin, D. R. ‘‘Kant on the Self.’’ Kant-Studien 49 (1957–58): 25–35. Dahlstrom, Daniel O. ‘‘Kant’s Metaphysics of Nature.’’ 271–290 in Dahlstrom, ed. Nature and Scientiﬁc Method. Washington, D.C.: Catholic University of America Press, 1991. De Jong, Willem R. ‘‘How is Metaphysics as a Science Possible? Kant on the Distinction between Philosophical and Mathematical Method.’’ Review of Metaphysics 49 (1995): 235–274. ———. ‘‘Kant’s Analytic Judgments and the Traditional Theory of Concepts.’’ Journal of the History of Philosophy 33 (1995): 613–641. Deleuze, Gilles. La philosophie critique de Kant. Paris: Presses Universitaires de France, 1971. Dilthey, Wilhelm. ‘‘Vorwort.’’ In Kant, Akademy Edition, vol. I (1902): v–nxv. Dryer, D. P. ‘‘Kant’s Argument for the Principle of Causality.’’ 214–221 in Laberge et al. [1976].

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a priori forms of intuition, 6 abstraction, 64, 67 Acade´mie Royale des Sciences. See Paris Academy acceleration, 22 Acta Eruditorum, 57 action at a distance, 43, 69, 85–7, 142, 168–9 (see also causation) Adickes, Erich, 49, 69, 89, 114 aesthetics, 230 Africa, 122–3 Ahlwardt, Peter, 102 Brontotheologie, 102 air, 77, 86 (see also atmosphere) Albertina, 18, 73–4, 131, 185 Alembert, Jean Le Rond d’, 18, 31–5, 62, 210 Discours pre´liminaire, 19, 31–4, 37 on force, 18–19, 31–35, 62 on mass, 33 Traite´ de dynamique, 18, 31–7, 62

algebra, 92 (see also mathematics) America, 122 Ameriks, Karl, 9–10, 96, 119, 244 analogy, 91–5, 118 as a method, 91–5 of moral inﬂux and gravity, 242 in nature, 136 of nature and humans, 155 in ontology, 118 of organic and inorganic nature, 155 analysis, 223–6 angels, 236–9 animal emanations, 76 Anselm of Canterbury, 200 Proslogion, 200 anthropocentrism, 76, 101, 108 (see also teleology) and the utility of nature, 98–103 Kant’s rejection of, 118, 121 antinomies, 61 antithesis, 60–1 (see also methodology)

333

334 Index apes, 71 aquifers, 76 argument from design, 191–7 Aristotle, 22, 144 and Aristotelianism, 151 De anima, 144 on metaphysics, 22–3 on the soul, 144 Arouet, Franc¸ois Marie. See Voltaire Asia, 78 astrology, 75–6 astronomy, 92 atheism, 99, 145 atmosphere, 75–7, 185–6 (see also air) atomism, 162–3 attraction, 66–7, 86–7 (see also force) Augustine, 108–9 De natura boni, 108–9 Austria, 162, 185, 189 Azores, 74 Barenius, 78 Bauer, Bruno, 235 Bauer, Johannes, 200 Baumgarten, Alexander Gottlieb, 59, 109–10, 132–5, 142, 232 Aesthetica, 110 on being and the good, 109 Metaphysica, 60, 109, 132, 151, 177, 232 on metaphysics, 177 on perfection, 110 on truth, 135 Baumeister, Friedrich Christian, 59, 131– 2 Institutiones metaphysica, 132 Philosophia deﬁnitiva, 131–2 Bayle, Pierre, 151, 163 Dictionnaire historique et critique, 151, 163 Beck, Lewis White, 6, 97 Being, 60, 108–10, 146, 201, 205–8 (see also metaphysics, ontology) chain of, 116–121 (see also nexus) Beiser, Frederick, 9–10, 192 Benden, Margarete, 147 Berlin Academy, 28, 84, 162–3, 188– 90, 197, 210, 225, 229, 233–4 Bernoulli, Daniel 27–8 Hydrodynamica, 28

Bernoulli, Jacques, 27–8, 92 Ars coniectandi, 27–8, 92 Bernoulli, Jean, 27–8, 40 Bernoulli, Nicholas, 27–8 Bernoulli, Nicholas (the elder), 27 Bernoulli, Nicholas (the younger), 28 best of all possible worlds, 41–2, 107–9, 141, 188 Bible, 59, 99, 144 big bang, 116 Bilﬁnger, Georg Bernhard, 27, 40, 56– 62, 131 and Bilﬁnger’s rule, 60–4 Commentatio hypothetica de harmonia animi et corporis, 59 De harmonia praestabilita, 40, 151 Dilucidationes philosophicae, 40, 59, 60, 131 body, 21, 41–6, 51–2, 63–8, 79–89, 92, 161–179 (see also mass) elastic, 33, 47, 68–9, 85 Boerhaave, Herrmann, 35 Bo¨hm, Andreas, 59, 132 Metaphysica, 132 book trade, 37 Borchart, Christoph Abraham, 131 Boscovich, Roger, 31, 37 De viribus viris, 37 Brahe, Tycho, 59 British empiricists, 11–13 brothels, 75 Budde, Franz, 59, 98–9, 137 bushmen. See San people Buffon, George L. L., 123 Histoire naturelle, 123 Burke, Edmund, 230 Butler, Samuel, 237 Hudibras, 237 calculus, 28, 92 (see also mathematics) Camus, Abbe´, 28 Canz, Gottlob, 59, 132 Philosophia fundamentalis, 132 Cardan, Jerome, 92 liber de ludo alea, 92 Caroline of Wales, 27 Cartesians, 19, 21, 23, 39 (see also Descartes) Cassirer, Ernst, 8–9, 74, 129, 238

Index 335 Catelan, Abbe´ de, 26, 30, 47 (see also Leibniz) caterpillars, 97, 103 catholicism, 75 causal explanation, 92 causality. See causation causation, 7, 53, 68, 90–2, 99–101, 128– 48 and compatibilism, 129, 137–8, 148, 155 efﬁcient, 91, 154–60 ﬁnal. See teleology inﬂuxionist, 129–30 (see also physical inﬂux) intersubstantial, 129–30 intrasubstantial, 129, 140–7 (see also pre-established harmony) occasionalist, 7, 140–1 of physical processes, 156 pre-established, 7, 38–41, 129–30, 140–7 and the principle of sufﬁcient reason, 4, 138–48 (see also principle) spontaneous, 99–100, 130, 141–44, 148, 150–6 (see also freedom) cause of cave formation, 76 of earthquakes, 75–7, 90 of existence, 139–44 of force, 66–7 of gravity, 43–67,177 caves, 75–6 celestial coronae, 78 celestial mechanics, 4, 12, 79–80, 89– 94, 98, 104, 126 celestial objects, 67, 97 change of momentum, 22 Chaˆtelet, Marquise de, 29, 47 Clarke, Samuel, 27–8 (see also Leibniz) circles, 93 cloudy stars. See galaxy cognition, 131–6 cohesion, 84–6 elementary, 113 Coing, Johann Franz, 132, 135 Institutiones philosophicae, 132, 135 Collegium Fridericanuim, 61 collision, 47, 57, 104, 113 Copernicus, Nicolaus, 59 combustion, 75–6, 84–8

comets, 13, 71, 86, 114 Commentarii Petropolitanae, 28, 59 community, 153 problem of, 10 compatibilism, 7, 129, 137–8, 148 (see also causation, freedom) problems of, 155–60 condensation, 115 conservation of force, 26–7, 173 conservation of energy, 83 conservation of motion, 23–4, 49, 104 contact, 171–2 continental drift, 76 corpuscle, 87, 162, 170 (see also particle) cosmic medium, 84, 87–8, 152 (see also ether) cosmogony, 7, 80, 90–1, 93, 97, 108, 117, 124–7, 191 cold, 115 hot, 114–15 mechanical, 116–17 and racism, 122–4 cosmology, 90–2, 97–98, 117, 126 cosmos, 71, 80, 89–93, 101–3, 112, 117, 121–7 Crusius, 5, 12, 58–67, 99, 137, 142, 156–9, 212, 218, 222–3 on causation, 139, 146–8 De usu, 146–8 Epistola ad Hardenberg, 137, 223 Ethik, 147 Logic, 232 on mathematics, 12 Metaphysik, 137, 223, 240 on natural science, 5, 12 Natu¨rliche Begebenheiten (Physik), 5, 12, 63–4, 67, 137 Curtis, Heber, 116

dead force. See force dead pressure. See force deﬂection, 113 (see also rotation) as lateral motion, 113 deism, 34 density, 89, 112, 123–5 of planets, 123 Denso, J. D., 102 Chortotheologie, 102

336 Index Descartes, 5, 20–8, 30–4, 39, 47–9, 56– 70, 62–4, 68–9, 80–2, 88–9, 140, 144, 162–3 on bodies, 163 on force, 20–23, 29, 46–55 (see also quantity of motion) on God, 199–200 on kinematics, 5, 19–33, 38, 43, 46– 55, 58–9, 89, 96, 162 Le monde, 21 Letter to Huygens (5 Oct. 1637), 21, 23 on mechanics, 19–33, 46–55, 162 Meditationes, 140 Principia philosophiae, 23–4 on the soul, 144 on vortices, 5, 43, 80–2, 84 (see also ether) Derham, William, 102, 116 Physicotheology, 102 Desaguilliers, J. T., 29 determinism, 79, 95, 100, 130, 137–8, 142, 150, 154–160 and the nexus rerum, 156 and philosophy of nature, 154–5 dispersion, 112 divisibility, 163, 168–75 dust, 114 dynamics, 29, 36, 39, 43, 58, 66–8, 85– 6 (see also Leibniz) Eames, G., 28 earth, 43, 56, 71–7, 80–4, 94 aging of, 7 and continental drift, 76 equator of, 77 and moon, 80–4 and plate tectonics, 76 rotation of, 56 rotational deceleration of, 83–4 and soil, 76–7 earthquake, 74–7, 90 cause of, 75–7, 90 and cave gases, 75–6 purpose of, 76 and tsunami, 75 ecliptic plane, 105 Einstein, Albert, 22 on mass, 22 elasticity, 85, 112, 174 (see also body) elastic strain, 76

electricity, 87 electromagnetism, 35 ellipses, 93 energetics, 31 energy, 22, 24, 34–5, 76, 162 as Cartesian force, 24 conservation of, 83 kinetic, 22, 33–4, 48, 78 (see also living force) as mass, 22 mechanical, 24 as work, 22 Engels, Friedrich, 234–5 enlightenment, 123 entelechy, 19, 22, 23, 41, 45, 111, 125, 130, 164 (see also teleology) entropy, 105–6, 124 (see also nature, motion) environmental philosophy, 126 Epicurus, 163 epistemology, 133–5, 139, 146 equilibrium, 33 essence, 23, 48, 60, 64, 67, 205–6 essential striving, 111 (see also teleology) ether, 43, 44, 69, 80–1, 84, 152, 175 (see also cosmic medium, molecular medium) ethics, 230–1 Euler, Leonard, 12, 28, 31, 34, 151–4, 160, 163, 169, 210–11, 221 Gedanken von den Elementen der Ko¨rper, 152, 163, 169, 210 Letter on the Systems of the Monads, 12 Lettres a` une Princesse d’Allemagne, 12 Re´ﬂexions sur l’e´space et le temps, 211, 221 eurocentrism, 123 evil, 108, 157, 188 evolution of nature, 127 existence, 7, 134, 201–8 absolute, 134 cause of, 139, 143–44 contingent, 134, 139–40 necessary, 224–5 as a predicate, 199, 201, 208 experience, 50, 90 inner, 220, 223–8

Index 337 experiment, 177–8 Kant’s gun shot, 44, 53 Newton’s pendulum, 86 extension, 41, 57, 164, 166, 171 as a property, 7, 134, 199, 201, 208 extraterrestrials, 117, 120–1, 124 (see also Mercury, Saturn) eye, 78 Fabricius, J. A., 102 Pyrotheologie, 102 Hydrotheologie, 102 Faraday, Michael, 35 Fermat, Pierre de, 92 Fichte, Johann Gottlieb, 234 Firla-Forkl, Monika, 123 Fisher, Mark, 206–7 ﬂuids, 84 ﬂuid dynamics, 28 foggy stars. See galaxy Fontenelle, Bernard L. B. de, 118–21, 123 Entretiens, 118, 120–1 force, 18–26, 30–32, 44, 57–8, 66, 81– 97, 161–79 accelerative, 66 attractive, 85–6, 110–13, 167–175 cause of, 66–7 centrifugal, 112, 114–15 conservation of, 26–7, 173 dead, 19, 21, 30, 39, 44–5, 52–3, 65, 69 (see also momentum) as energy, 22 as entelechy, 22 (see also teleology) erosive, 76 essential, 41–2, 97 as force vive. See living force gravitational, 34–42-3, 67–9, 80–8, 103, 105, 112–13, 114, 120 (see also gravitation) impelling, 44 of impenetrability, 169 inertial, 32, 45, 169, 173–4 (see also inertia) living. See living force magnetic, 87 measurement of, 20, 24, 34 modern conception of, 22, 34–5 monadic, 170–1 motive, 66

parallelogram of, 47, 137 as quality, 20 as quantity, 20 repulsive, 85–6, 110–111, 113, 168, 170–175 substantive, 69, 85 tectonic, 76 types of, 44 as vis motrix, 39 as vis viva. See living force Formey, Heinrich Samuel, 59, 162, 211, 225, 227, 229, 235 forms of intuition, 42 France, 185, 189 Francke, August Hermann, 98 Frederick the Great, 29, 161–2, 185, 210 freedom, 17, 79–80, 95–6, 99–100, 129, 136–8, 141–4, 150, 154–60, 213– 14, 217 (see also causation) and autonomy, 141–2 and compatibilism, 129, 137–138, 148, 154–160 and inclinations of the will, 157–160 and intellectual motives, 156 and physics, 128, 138 of the turnspit, 142 free fall, 25, 30, 54 freethinkers, 13, 97, 99 (see also deists) French philosophes, 11–12, 162–3 friction, 45 Friedman, Michael, 9–10, 42, 65, 69, 221–4 Fries, Jakob Friedrich, 234 Frisi, Padre S. J., 84 galaxy, 7, 91, 113–19, 125 (see also Milky Way) Andromeda, 116 extragalactic nebulae, 116 rotation of, 115–17 Galileo, Galilei, 15, 22, 23, 29, 58, 47 and the book of nature, 23 on free fall, 25, 30 Il saggiatore, 15, 23 on inertia, 22 Macchie solari, 23 on mechanics, 22–30, 45 on philosophy, 15 on weight, 22

338 Index gas, 114 Gassendi, Pierre, 57, 163, 200 Gaunilo, 200 On Behalf of the Fool, 200 Gebler, Fred, 194, 204 geophysics, 73–4 geology, 73–4 geometric method, 221–2 geometry, 90, 167–79, 218 (see also mathematics) Gerhardt, Volker, 61 God, 17, 23–4, 41, 68, 76, 79, 91–92, 96–112, 130–7, 151–4, 157, 167, 183, 190–208 benevolence of, 102, 105 as cause of existence, 139–40, 143–5 existence of, 17, 190–208 hand of, 101, 103, 106, 111, 114, 193 and interaction, 190 intervention of, 98–101, 105–107, 111, 140, 154 magniﬁcence of, 99–101, 108 minimalistic conception of, 154 as necessary being, 191–208 omnipotence of, 102, 105, 163 omniscience of, 102, 105 and perfection, 198 revelation of, 99–101, 137 as summum bonum, 196 and teleology, 190 (see also miracles, miraculum restitutionis, rational theology, teleology) Gottsched, Johann Christoph, 12, 59, 132, 151 on cosmology, 12 Erste Gru¨nde der gesamten Weltweisheit, 12, 132, 142 on metaphysics, 12 on natural science, 12 on physics, 12 Graunt, John, 92 Bills of Mortality, 92 Gravesande, W. J. s’, 27–8 gravitation, 5, 42–3, 71, 80, 85, 89, 105, 113–17, 142, 152 and attractive force, 85–6 cause of, 43, 67 center of, 113

force of, 34, 42–3, 67–9, 80–8, 103, 105 and perturbations, 93–94 as the single universal rule, 71, 89, 113–117 and the three body problem, 94 and tides, 79–84 Greene, Robert, 34 Expansive and Contractive Forces, 34 Greenlander. See Inuit gunshot experiment. See experiment Hadley, George, 78 Cause of the General Trade Winds, 78 Haeckel, Ernst, 127 Haller, Albrecht von, 35, 56 Halley, Edmond, 21, 116 Hamann, Johann Georg, 178–9, 189–9 Socratic Memorabilia, 178 harmonic law, 93 Hartung, Johann Heinrich, 18, 75, 128, 161 Hegel, Georg Wilhelm Friedrich, 8, 234 height, 24–5, 47 orbital, 120 Heimsoeth, Heinz, 8 Heinsius, B.H., 102 Chionotheologie, 102 Helve´tius, Claude Adrien, 123 Henrich, Dieter, 8, 199 Herder, Johann Gottfried, 6, 35, 121, 123, 127, 232 Auch eine Philosophie der Geschichte der Menschheit, 123 Ideen zur Philosophie der Geschichte der Menschheit, 6 Vom Erkennen und Empﬁnden, 35 Hermann, Jacob, 27 Herschel, William, 115 Herzog-Albrecht Universita¨t. See Albertina Hinske, Norbert, 60–1 Ho¨ffe, Otfried, 74, 238 Hoffmann, A., 98 Holbach, Paul Henry Thiry d’, 155–9 Systeˆme de la nature, 155–6 Hooke, Robert, 29 hottentots. See khoi-khoin Hubble, Edwin, 116

Index 339 humans, 71, 118–24, 155 cosmic mediocrity of, 119–21 evolution of, 127 as material entities, 118–9, 155 Hume, David, 13, 61, 102, 111, 123, 179, 189, 238 Dialogues concerning Natural Religion, 102 Enquiry concerning Human Understanding, 13, 111 Huygens, Christiaan, 21–24-6, 31, 37–8, 92, 165 De rationciniis in ludo aleae, 92 hydrogen, 77 impenetrability, 171–2 impulse, 34, 44, 66–7 and causation, 156–60 incongruent counterparts, 165, 188 Indians, 122 inertia, 21–3, 32, 68, 186–7 curvilinear, 22 inertial frames, 112, 165–66 measured by mass, 186 intension, 51–3, 186 interaction, 40, 138–54 of substances, 151–3 Inuit, 104, 122 inverse-square law, 42, 69, 172 iron, 75 Journal des Savants, 58 Jupiter, 125 Jurin, James, 28, 47, 68, 78 Justi, Johann Heinrich, 163 Kant, Immanuel Aging Earth essay, 73 on causation, 128–30, 138–9, 148– 60 and comets, 125 on cosmogony, 110–121 Cosmogony, 80 correspondence with Knobloch, 236 correspondence with Lambert, 227–8 correspondence with Mendelssohn, 242 and critical philosophy, 6–7, 17, 84– 5, 160 Critique of Practical Reason, 125, 142

Critique of Pure Reason, 3, 4, 10–11, 19, 61, 79, 97, 126, 145, 160, 184, 200, 207–8, 217, 227–8, 231 Directions in Space, 165, 184, 187 doctoral dissertation, 18, 73–4, 131, 161 Dreams of a Spirit Seer, 14, 136, 181– 7, 234–45 Earthquake essays, 75–6, 80, 90 Eulogy on Funk, 185 False Subtlety, 136, 145, 189, 231 father (Johann Georg Kant), 18, 73 Foundations of the Metaphysics of Morals, 141 on freedom, 142, 154–60 habilitationsschrift. See Kant, professorial dissertation Handexemplar Observations, 230–31 Herder Review, 6 and Hume, 111, 179, 189 Inaugural Dissertation, 14, 184, 187, 223, 227, 232 on independence, 58–9 and intellectual honesty, 19, 246 Kinderphysik, 188 Lecture Announcement, 227, 233 Lectures on Physical Geography, 122–4 Living Forces, 3–5, 15–31, 36–70, 74, 79–81, 91, 96, 110–11, 130, 173, 183, 186 Living Forces II (planned sequel), 56 magisterarbeit. See Kant, master’s thesis Maladies of the Mind, 233 master’s thesis, 73–4, 84, 161 Metaphysical Foundations of Natural Philosophy, 227 Metaphysical Foundations of Natural Science, 79, 85, 126, 150, 166, 171, 223 Metaphysical Foundations of Practical Philosophy, 227–8 on metaphysics, 15, 17, 219–28 Metaphysik Herder, 232 Metaphysik L1, 50, 145 on method, 17–18, 47, 56–62, 66–8, 213–338 and the model of nature, 17–18, 789– 80, 89, 93–8, 104, 126

340 Index Kant, Immanuel (continued ) Motion and Rest, 66, 78–9, 165, 174, 185–88 mother (Anna Regina Kant, b. Reuter), 61 Negative Quantities, 221, 224, 231–2 New Elucidation, 19, 38, 55, 74, 96, 98, 128–61, 167, 187, 198–200, 210, 212, 222, 232 and Newtonian conversion, 17–18, 69–70, 73, 79–84, 96, 173, 186 and Newtonianism, 10, 17, 62–70, 73– 95, 97 Observations on the Beautiful and Sublime, 122, 124, 229–30 On Fire, 46, 74, 84–89, 95, 152, 161, 169, 174, 222 Only Possible Argument, 98, 101–3, 107, 111, 114, 124, 136, 179, 184– 216, 224–32 Optimism essay, 79, 106–10, 185, 188 Optimism reﬂections, 197–198 Opus postumum, 8, 246 and philosophical development, 4, 6, 9–10, 17, 20, 94, 107, 129, 165– 66, 171, 183, 214–28 Physical Monadology, 19, 35, 38, 46, 74, 79, 85, 90, 161–79, 186–7, 213, 221–3 and precritical period, 4, 9–10, 17 and precritical philosophy, 6–9, 17–18 and precritical project. See precritical project on pre-established harmony, 150 professorial dissertation, 73–4, 161 Prolegomena, 228, 232 Proper Method for Metaphysics, 227–8 Prize Essay, 14, 51, 118, 189–90, 209– 29, 240, 243 and racism, 121–4 on reconciliation of metaphysics with natural science, 4, 9–10, 13–14 and rejection of dualism, 118–19, 137–8 and scepticism, 17–18, 233 and silent decade, 17 Spin Cycle essay, 37, 56, 73, 79–84, 88, 90, 95, 98, 126, 152, 186, 197 and teaching, 78–9, 106–7, 131, 161, 185, 232–4

and teleology, 106–13 Theory of Winds essay, 77–8, 90, 185 and transcendental turn, 85 on truth, 135 Universal Natural History, 13–14, 19, 34–38, 46, 54, 69, 71, 74, 77– 80, 88–126, 128, 154, 159–60, 167–8, 173–75, 191, 193, 226, 229 Volcanoes on the Moon essay, 115 West Wind essay, 77–8, 185–6 Kant-Laplacian hypothesis, 114–15 Kant’s version of, 113–17 Laplace’s version of, 114–15 Kant-Studien, 6 Kanter, Johann Jacob, 189, 228 Kaulbach, Friedrich, 61 Kepler, Johannes, 93 khoi-khon, 122 kinematics, 43, 86 (see also Descartes) Kolb, Peter, 123 Caput bonae spei hodiernum, 123 Ko¨nigsberg, 37, 61, 73, 75, 161–2, 184, 188–90, 234 Ko¨rber, Samuel, 162 Korff, Nikolaus von, 185 Knobloch, Charlotte von, 136 (see also Kant) Knutzen, Martin, 13, 40, 74, 161–2 De commercio mentis et corporis, 13 Elementa philosophia rationalis seu logicae, 13 Systema causarum efﬁcientium, 40 Vernu¨nftige Gedanken von den Cometen, 13 Wahrheit der christlichen Religion, 13 Krafft, Fritz, 89 Kuiper, J. G., 114–15 Kypke, 185 Lagrange, Joseph de, 92, 210 Lambert, Johann Heinrich, 13–14, 126– 9, 135 correspondence with Kant, 226–7 Cosmologische Briefe, 13–14, 226, 229 Criterion Veritatis, 226 Neues Organon, 14, 226–8 ¨ ber die Methode, 226 U La Mettrie, Julien Offray de, 155, 210 L’homme machine, 155

Index 341 Lange, Joachim, 5, 98, 142–7 Caussa Dei, 5, 145–6 Laplace, 92, 114–15, 127, 154–5 (see also Kant-Laplacian hypothesis) cosmogony, 114–15 Exposition du syste`me du monde, 92, 114–15 Me´canique ce´leste, 92 The´orie analytique des probabilite´s, 92, 154–5 law of acceleration. See laws of motion law of the equality of action and reaction. See laws of motion law of errors, 28 law of inertia. See laws of motion (see also inertia) law of the lever, 137 laws of motion, 12, 21–23, 57, 68–69, 137, 142, 149–50 ﬁrst law (inertia), 21–3, 53, 68, 149 second law (acceleration), 22, 149 third law (action and reaction), 68–9, 149, 231 laws of nature, 100, 111, 155 Laywine, Alyson, 9–10, 69, 150, 241, 244 Leibniz, 19–28, 38–42, 47, 48, 56–70, 81, 89, 107–9, 131, 137–9, 145–8, 162–77, 188, 210–12 Body and Force, 177 Brevis demonstratio, 25–6, 47 on causation, 139–42 correspondence with Catelan, 27–8 correspondence with Clarke, 26, 30 correspondence with Wolff, 109 De rerum originatione radicali, 139, 206 Discours de la me´taphysique, 57, 140, 205 on dynamics, 24–6, 30, 33, 38–46, 49–50, 96, 162 on force, 24–6 (see also living force) Hypothesis physica nova, 57 Letter to Contess Elisabeth, 177 on mass, 21 on metaphysics, 177 Monadologie, 58, 162, 164, 166 Nouveaux Essais, 245–6 Principes de la nature et de la grace, 58, 140, 177

Protogaea, 58, 75 on space, 164–5 Specimen dynamicum, 21, 26, 30, 57 on substance, 205 Syste`me nouveau, 140 The´odice´e, 27, 58, 75, 188 on truth, 134 Leibnizian-Wolfﬁan School Philosophy, 5– 12, 59, 64–5, 68–9, 79, 97, 102, 111, 151, 162 decline of, 210, 222 and Kant, 132–3, 189, 231, 240–4 on mathematics, 19 on metaphysics, 19 Lesser, F. C., 102–3 Insectotheologie, 103 Lithotheologie, 102 Testaceotheologie, 103 Lessing, Gotthold Ephraim, 37, 54, 123 lever, 24, 29–30, 48 (see also law of the lever, simple machines) life, 117–21 evolution of, 118 extraterrestrial, 117, 120–1 intelligent, 129 light, 85 limestone, 76 linear momentum, 34 Lisbon, 74–5 living force, 18–35, 48–52, 59–70, 81– 2, 172–3 (see also energy, force) controversy of, 18–19, 24 as force vive, 26, 32 issue of, 19–20 as kinetic energy, 22, 33–4, 48, 78 measurement of, 21–2 as mv2, 22–38, 44–5, 48, 51–4, 64– 5 and viviﬁcation, 51–55, 65, 186–7 as work, 22, 31–4, 48, 53 Locke, John, 226 Essay concerning Human Understanding, 226 logic, 13, 78, 131–8, 186, 231 and metaphysics, 135 louse, 101 lutheran, 61, 99 MacLaurin, Colin, 28 magnetism, 87 (see also force)

342 Index magnitude. See quantity Mairan, J. J. Ortous de, 29, 47 man. See humans Mariotte, Edme, 78 Mariotte gas law, 78 Mars, 93 Marty, Franc¸ois, 69 Marx, Karl, 234–5 mass, 19–22, 33, 44, 57, 169, 173 (see also body) liquid, 83–4 simple, 21 materialism, 155 mathematics, 23, 46–55, 58, 61–66, 78, 89–94, 211, 213, 218 as exact science, 92 and metaphysics, 221–24 matter, 21–3, 34, 43, 84–6, 112–13, 119–20, 168–74 (see also body, mass, quantity) active, 34, 46, 110–11, 130, 168–74 composition of, 164–75, 187 divisibility of, 163, 168–75 measure of, 21 primordial, 113–114 and rationality, 119–20, 124 unfolding of, 110 Maupertuis, Pierre Louis M. de, 28, 116, 123, 162–3, 210–11 Preuve de l’e´xistence de Dieu, 211 Maxwell, James Clerk, 35 Mayer, Robert von, 83 Dynamik des Himmels, 83 mechanics, 20, 29–36, 97–8, 107 (see also Descartes, Galileo) and metaphysics, 51–5 Meier, Georg Friedrich, 59 Mendelssohn, Moses, 12, 134, 181, 211– 12, 229, 233–5, 240, 242 (see also Kant) Abhandlung u¨ber die Evidenz, 12, 211– 15 Review of Dreams of a Spirit-Seer, 181 Review of Only Possible Argument, 215 on truth, 134 Menz, F., 103 Rana-Theologie, 103 Mercurians, 120–1 metaphysics, 4, 32, 48–51, 58–60, 78– 80, 96–106, 161–79, 181–208, 211– 12, 231–232, 240–44

assumptions of, 7, 95 concepts of, 213–217 critique of, 11–13, 176–7, 211–18, 240–4 deﬁnitions in, 220 dogmatic, 240–4 and knowledge, 212–228 and logic, 135 and mathematics, 221–24 and mechanics, 51–5 and natural science, 4, 9–11, 13–14, 167, 174–179 possibility of, 217 procedure of, 11–12, 46, 63, 213–28 questions of, 4 task of, 12, 90, 176 (see also being, ontology, rational cosmology, rational psychology, rational theology, science) meteorites, 76 meteorology, 77–8, 90 method in metaphysics, 11–12, 46, 63, 213–28 methodology, 23, 58–62, 88–95, 184, 194 and measurement, 48 and the paradigm of mechanism, 79 Milky Way, 89 formation of, 115–17 rotation of, 115–16, 125 structure of, 125 mind, 40 (see also mind-body interaction, soul) constitution of, 118 dependency on material density, 119– 21, 124 human, 118–19 mind-body interaction, 10, 12–13, 38, 40, 119, 140–5, 154 miracles, 99–105, 107, 111, 192 (see also miraculum restitutionis) miraculum restitutionis, 101, 105 (see also miracles) mode of cognition, 49 molecular medium, 84–88 (see also ether) momentum, 22, 29, 31, 33–4, 53 monad, 40, 108, 141–5, 161–79, 210 (see also entelechy, monadology, particle, substance) and active matter, 130

Index 343 extensive magnitude of, 170–1 force ﬁeld of, 170–1 physical, 168–79 space of, 170 monadology, 10, 42 linking ontology and cosmology, 175 monism, 140 Moon, 80–4 moral sense theory, 230 motion, 21–4, 29–34, 42, 44–7, 51–2, 68, 79–81 absolute, 165–6, 187 animal, 87 as autokinesy, 34 circular, 166 conservation of, 23–4, 49, 104 free, 22 inertial, 165, 187 loss of, 68, 104, 125 orbital, 82–3 perpetual, 26, 42–3, 51–2, 68, 81 (see also perpetuum mobile) planetary, 89, 93–4 as a process, 22 quantity of, 24 as a relation, 24 relative, 166, 187 and rest, 21–2, 30, 68 retarded, 33 as a state, 22, 186 types of, 44 virtual, 29, 33 Mu¨ller, Jakob Friedrich, 162 Namibia, 123 natural philosophy, 57, 78, 222 natural science, 4–5, 11, 51, 90, 213 and metaphysics, 4, 9–11, 13–14, 167, 174–179 nature, 23–4, 46, 51–2, 56–7, 61–70, 73–110, 161–79 beauty of, 71, 98, 102, 110, 111 and biodiversity, 77, 117–18 book of, 23 and chaos, 112, 124–5 consistency of, 93, 128–38 contingency of, 99–100 design of, 96–110 (see also teleology) and determinism, 79, 95, 100, 128, 130, 137–8 diversity in, 71, 110, 117, 124–5

elements of, 161–79 entropic tendency of, 105–6, 124–5 evolution of, 127 fertility of, 110, 124–5 goodness of, 109–10 harmony of, 93, 98–106, 196 model of, 17–18, 79–80, 89, 93–8, 104–7, 126, 142 order of, 41, 71, 98–101, 104–5, 107, 110–11, 118, 125, 196 organic, 118 perfection of, 12, 38, 41, 71, 106– 110, 118, 125 purposive development of, 79, 97–8, 106–10, 124–7 (see also teleology) self-organization of, 117, 127 simplicity of, 93 uniformity of, 93 unity of, 79, 129, 137, 193, 196, 243 utility of, 98–103 (see also cosmos, laws of nature, universe) nebular hypothesis, 7, 113–117, 126–7 (see also planetary system) Kantian version of, 114 Laplacian version of, 114–15 Weizsa¨cker-Kuiper version of, 114 necessity, 154–160 absolute, 150 geometric, 143–6 hypothetical, 100, 143 natural, 143, 146 relative, 150 negation, 132–33 Neo-Kantians, 6 Newton, 19, 21–34, 38–43, 61–73, 79– 97, 104, 114–15, 120, 124, 137–8, 152, 163–5, 172, 174–8, 210, 219– 20 Account of the ‘‘Commercium Epistolicum,’’ 5, 176 De aere et aether, 112 De motu, 21 on force, 19, 34, 97, 110–13 Hypothesis Explaining the Properties of Light, 86 on inertia, 22, 186 Letter to Richard Bentley (25 Feb 1693), 85–6 on mass, 21 on metaphysics, 176–7

344 Index Newton (continued ) on method, 219–223 and the model of nature, 106–7, 126, 142 Opticks, 68, 87–8, 112–13, 124, 219 Principia (1st ed.), 22 Principia (3rd ed.), 4–5, 10, 12, 21, 29, 43, 66–8, 87–94, 111–12, 136, 165, 174–6, 219 Questiones quaedam philosophiae, 86 on space, 81, 165 Scholium generale, 67, 87, 104, 220 on teleology, 104–6, 110–11 Newtonianism, 7, 10, 17, 68 Newtonians, 5, 12, 26, 28, 35 nexus elementorum, 143 nexus elementum, 143 nexus rerum, 100–1, 105, 110–11, 143– 5 (see also being) and determinism, 156 Nieuwentyt, Bernhard, 102 Het regt gebruik der Werelt beschowingen, 102 Nouvelles de la Re´publique des Lettres, 26 occasionalism, 7, 140–1, 151 (see also causation) ocean, 82–3 primeval, 75–6 Ockham’s razor, 12 ontological argument, 7, 191–208, 214– 17, 224 (see also God, ontology) material condition of, 201–8 ontology, 4, 12, 19, 41, 60–6, 73, 89, 99–106 orbital eccentricity, 93–94 Origen, 108 Papin, Denis, 26–7, 48 Paris Academy, 28 particle, 42–44, 80–7 (see also monads) spatial, 42–3, 81–2 Pascal, Blaise, 92 Pemberton, Henry, 28 pendulum experiment. See experiment perfection, 12, 38, 41, 71, 106–10, 188 (see also nature, teleology) perpetuum mobile, 26, 37, 48, 53 (see also motion)

perturbations and gravity, 93–4 lunar, 94 planetary, 93–4, 103 Peter the Great, 28 Petersburg problem, 28 Peterson, Johann Friederich, 74 Petty, William, 92 Political Arithmetic, 92 philosophy, 5, 50, 61–64, 231 philosophy of nature, 5, 39, 50, 57–8, 62–3, 67 and determinism, 154–5 and rational theology, 197 phoenix of nature, 124–5 physical inﬂux, 7, 10, 13, 38–41, 54–55, 129–30, 149–54, 157–60 (see also causation) physical processes, 149–54 physico-theological argument. See argument from design physico-theology, 12, 97, 102–107, 111, 191–3 (see also teleology) physics, 4–5, 12, 57, 63–70 (see also science) and freedom, 128, 138, 148 and metaphysics, 176 Newtonian, 4–5, 10, 19–21, 32, 56, 66–70, 79–96, 104, 162 nonquantitative, 88–95, 99 and purpose, 128 Pietismusstreit, 143 Pietists, 10–13, 58–63, 79, 89, 98–9, 106, 133, 146, 154, 222 on natural science, 11 on teleology, 98–99, 106 planets, 75, 86 (see also Mars, Saturn, Uranus) formation of, 113–14 proto, 114 intelligent life on other, 117–21 telos of, 118 plate tectonics, 76 plenum, 43, 81 (see also principle) Plouquet, Gottfried, 233 Observations, 233 plurality of worlds, 41–2 pneumatic laws, 238–40 points, 163, 171–5 Poleni, Marchese G., 27

Index 345 Polonoff, Irving, 10, 221 Portugal, 74–5 Pope, Alexander, 116, 197–8 Essay on Man, 71, 188 possibility, 60, 79, 132–6, 198–208, 224–5 precritical project, 3–11, 17, 175–6, 194, 209–210 bloom of, 126, 178 crisis of, 179, 214–46 development of, 4, 50, 62, 79–84, 95– 6, 107 rejection of, 6–7, 11 unity of, 194, 197 pre-established harmony, 7, 38–41, 129– 30, 140–7, 150–4, 160, 241 pressure, 29, 76 pressure zones, 78 Priestley, Joseph, 34 Disquisitions relating to Matter and Spirit, 34 principium (see also principle) cognoscendi, 146 essendi, 131, 146 ﬁendi, 131 inconiungibilium, 137, 233 inseparabilium, 137, 223 principle (see also principium) of coexistence, 133, 137, 150–4, 167, 175 of conservation, 24, 57 (see also conservation, motion) of continuity, 65–6, 186 of contradiction, 4, 132–9, 143, 223, 232 of determining reason, 133, 137–42, 147, 150, 156 of effect, 132 of the excluded middle, 132 of the identity of indiscernibles, 131, 164 of individuation, 131 of inertia, 68, 186–7 (see also inertia) of plenitude, 81, 141, 164 of reciprocity, 132 of succession, 133, 137, 149–7, 175 of sufﬁcient reason, 4, 132, 137, 143, 146–7, 164 Priority dispute, 5 probability theory, 27–8, 92 (see also mathematics)

Prussia, 162, 185, 188–90 Prussian Academy of Sciences. See Berlin Academy purpose, 17, 79–80, 95–108, 128 (see also teleology) quality, 48–50, 88–95 quantity, 48–50, 88–95 of mass, 120 of matter. See quantity of matter of motion, 21–7, 33–4, 48–52, 66–8 scalar, 34 of strength, 29 vector, 29, 34 quantity of matter, 20–2, 63–4 as mass, 21 as size, 21 as weight, 21 racism, 121–4 Rappold, C. H., 103 Locusta-Theologie, 103 Rathlef, E. L., 103 Akridotheologie , 103 ratio essendi, 91 ratio ﬁendi, 91 rational cosmology, 4, 12–13 rational psychology, 4, 12–13 rational theology, 4, 10, 12–13, 183, 189–208 rationalism, 41, 79 rationality, 118–121, 151 and matter, 119–20, 124 and philosophy of nature, 197 reality, 67 unity of, 241–3 Regnard, Jean-Franc¸ois, 123 Reich, Klaus, 207 relation, 42, 63–4 Remond, Nicolas, 162 repulsion (see also force) lateral, 113–14 resistance, 22, 42–5, 69, 171 inﬁnitely small, 80–2 rest, 21, 22, 30, 68 (see also motion) Reusch, Johann Peter, 59, 132 Systema Metaphysicum, 132 Reuscher, John, 134–5, 199 Richter, J. G. O., 103 Ichthyotheologie, 103

346 Index Rohault, Jacques, 169 Rohr, B. de, 102 Phytotheologie, 102 Rorarius, Hieronymus, 151 rotation axial, 56 of bodies, 166 and deﬂection, 76 of Earth, 73, 77–8, 80–4 and ecliptic plane, 114–15 of galaxies, 115–17 of Milky Way, 115–16, 125 of universe, 113, 117 Rousseau, Jean-Jacques, 123, 230–1 Contract social, 189 Emile, 189 Discours sur les arts et les sciences, 189 Ru¨diger, Andreas, 63, 98–99 Russia, 162, 185, 188 Russian Academy of Science. See St. Petersburg Academy salt, 112 San people, 123 Saturn, 90, 125 and its intelligent inhabitants, 121 moons of, 125 Saxony, 162, 185 scalar quantity. See quantity Schelling, Friedrich Wilhelm Joseph von, 8 Schirach, A. G., 103 Melittotheologie, 103 Schmucker, Josef, 74, 194, 199 Schneider, Werner, 98, 126 Schopenhauer, Arthur, 8, 115 Schultz, Franz Albert, 61 science, 50–1, 61, 84, 90, 99, 103, 106, 111, 125 and religion, 193 Segner, Johann, 78 Einleitung in die Naturlehre, 78 Seidel, C. M., 102–3 Bombyco-Theologie, 103 seismology, 76 sensory perception, 87 Seven Years War, 162, 185, 188–90 Shaftesbury, Anthony Ashley Cooper, 230

Shea, William, 97, 112, 115, 126 Shell, Susan Meld, 9–10, 41–2, 121, 238 simple machines, 21, 24, 29 simplicity, 93 size as quantity of matter, 21 of cosmos, 71 Sodom, 75 soil, 76–7 solar radiation, 78, 120–1 solar system, 91, 104 (see also planets) and ecliptic plane, 114–15 formation of, 113–17, 120 modern conception of, 125 organization of, 114 soul, 41–2, 96, 118–19, 154, 157, 213, 239–44 (see also mind, substance) freedom of, 144, 147–8 immortality of, 144–5 material nature of, 118 simplicity of, 144–5 space, 38, 41–4, 63–4, 69, 80–4, 150, 161–79 absolute, 42, 81, 164–6, 187–8 abstract, 64 and continuum, 187 divisibility of, 168–75 empty, 42–3, 69, 80–2, 86, 164–5 geometric, 168–70, 224 ideal, 164, 167 as inertial frame, 165–6 monadic, 170 particles of, 42–3, 81–2 real, 166 relational, 42–3, 164, 167, 187 substantive, 165, 167, 187 three-dimensionality of, 41, 69 speed, 19–20, 32, 42–3 Spener, P. J., 98 spin deceleration, 83–4 Spinoza, Baruch, 222 Ethica, 222 spirits, 239–44 St. Petersburg Academy, 28, 59 stars, 75, 91, 101, 113 static law, 120, 123–5, 193 statics, 29 statistics, 92 (see also mathematics)

Index 347 Stiebritz, Johann Friedrich, 59, 163 Sua´rez, Francisco, 151 Disputationes metaphysicae, 151 substance, 12, 24, 38–42, 45, 69, 85, 105, 134, 143, 149, 157, 161–179 (see also monad) subtropics, 77 sulfur, 75–6 sulfur dioxide, 77 Sulzer, Johann, 123, 211, 235 sun, 43, 77, 80–4, 94, 101, 115 Su¨ßmilch, Johann Peter, 235 Sweden, 74 Swedenborg, Emmanuel, 181, 234–44 Arcana coelestia, 235–9 synthetic a priori, 4, 217–18 telelogy, 7, 19, 68, 76, 96–113, 194–5 and the design of nature, 96–110 extrinsic, 110–111 and ﬁnal causation, 130 and ﬁnal causes, 91, 98 and ﬁnal ends, 104–6, 111, 126 and ﬁnal means, 104–5, 110–13, 126 immanent, 106–110, 114, 126, 195, 213, 217 joining mechanics and metaphysics, 126 and Newtonian mechanics, 114 and physico-theology, 102–6, 111 and science, 126 and the usefulness of nature, 98– 103 (see also anthropocentrism, entelechy, nature, purpose, telos) telos, 99–110 textbook authors, 59–60 theodicy, 42 theology, 58–61, 76, 97–106, 111, 163, 210 (see also rational theology) thermal expansion, 77–8 thermal springs, 76 three body problem, 94 Thomas Aquinas, 98 Summa theologica, 98 and teleology, 98 Thomasius, Christian, 58–9 Thu¨mmig, Ludwig Philipp, 59

tides, 79–84 time, 42, 149–50 times-squared law, 25, 30, 38, 47 Toland, John, 34 Christianity not Mysterious, 137 Letters to Serena, 34 Tonelli, Giorgio, 8, 42, 98, 126 tropics, 77 truth, 58–62, 131–8, 213, 223 coherential, 134–5 correspondence view of, 134–5 in metaphysics, 220–28 tsar Peter III, 188–9 tsarina Elizabeth, 185, 188 Tschirnhaus, Ehrenfried Walther von, 222 Medicina Mentis, 222 tsunami, 75 Tunguska event, 76 Ueberweg, Friedrich, 6 unfolding. See matter universal gravitation. See gravitation universe, 38–41, 68, 79, 85, 89, 93–106, 112–13 (see also cosmos, world) center of, 113, 116, 124 cyclical, 124–7 decaying, 124–5 deterministic, 155 evolving, 113–17 expanding, 124–5 multiple, 41–2 rotating, 113, 116 University of Ko¨nigsberg. See Albertina Unzer, Johanna Charlotte, 59 Uranus, 115 velocity. See speed vis impenetrabilis, 152 inertia, 152 (see also force) mortua. See force (dead f.), momentum motrix, 39, 173–4 viva. See living force vitalism, 35, 127 viviﬁcation. See living force void. See space volcanoes, 76–7

348 Index Voltaire (Franc¸ois Marie Arouet), 12, 75, 97, 101, 123, 210, 237 Candide, 12, 75, 237 E´le´ments de la philosophie de Newton, 12 Micromegas, 12 Poe`me sur le de´sastre de Lisbonne, 75 Wallis, John, 25 Ward, Keith, 238 warmth, 85 water, 75, 112 Watkins, Eric, 9, 10, 49, 206–7 Wegener, Alfred, 76 weight, 21–2, 48 (see also quantity of matter) Weizsa¨cker, C. F. von, 114–115 Weymann, Daniel, 233 Bedencklichkeiten, 233 De mundo non optimo, 233 Wieland, Christoph Martin, 123 wind, 77–8, 185–6 (see also meteorology) coastal, 77 monsoon, 7–8, 73, 77–8 passat, 77 trade, 77 Wo¨chentliche Ko¨nigsbergische Frage- und Anzeige-Nachrichten, 84 Wolff, 11, 27, 39, 40, 47, 53, 59–60, 64– 5, 68–9, 79, 99–106, 131–7, 151, 156–7, 162, 210, 212, 222 (see also Leibniz)

Anmerkungen zur Deutschen Metaphysik, 143 on causation, 142–8 Cosmologia generalis, 69, 99–100 Deutsche Metaphysik, 4, 59, 101, 131, 143, 240 Deutsche Teleologie, 99, 101, 104 on metaphysics, 11 on natural science, 11 Philosophia prima sive ontologia, 60, 131, 135 Philosophia rationalis sive logica, 135 philosophical development of, 142–3 and the Pietists, 143 Psychologia rationalis, 40, 143, 151 on the soul, 144–5 on teleology, 99–102, 106 on truth, 135 world (see also universe) harmony of, 141, 154, 191 work, 22, 31–4, 48, 53 (see also energy, living force) Wren, Christopher, 25 Wright, Thomas, 115–16, 125, 226 on cosmogony, 115–16 New Hypothesis of the Universe, 115, 226 Wright-Kant hypothesis, 116 Wundt, Wilhelm, 8 Zeno of Elea, 163 Zorn, J. H., 102 Petinotheologie, 102