Psycho-Physical Dualism Today: An Interdisciplinary Approach

Until quite recently, mind-body dualism has been regarded with deep suspicion by both philosophers and scientists due to the widespread identification of dualism in general with one particular version of it: the interactionist substance dualism of Réné Descartes. This traditional form of dualism has, ever since its first formulation in the seventeenth century, attracted numerous philosophical objections and is now almost universally rejected in scientific circles as empirically inadequate. During the last few years, however, renewed attention has begun to be paid to the dualistic point of view, as a result of increasing discontent with the prevailing materialism and reductionism of contemporary scientific and philosophical thought. Awareness has grown that dualism need not be restricted to its traditional form and that other varieties of dualism are not subject to the difficulties commonly raised against Descartes’ own version of it. Psycho-Physical Dualism Today provides philosophers, scientists, their students, and the wider general public with an up-to-date overview of current developments in dualistic conceptions of the mind in contemporary philosophy and science. CONTRIBUTORS: Alessandro Antonietti, Friedrich Beck, Antonella Corradini, Carl Johnson, E. Jonathan Lowe, Uwe Meixner, David S. Oderburg, Ian J. Thompson, Franz von Kutschera, Henry M. Wellman ALESSANDRO ANTONIETTI is a professor of cognitive psychology and head of the Department of Psychology at the Catholic University of the Sacred Heart, Milan. ANTONELLA CORRADINI is associate professor of philosophy of human sciences at the Catholic University of the Sacred Heart, Milan. E. JONATHAN LOWE is professor of philosophy at the University of Durham.

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PSYCHO-PHYSICAL DUALISM TODAY

“Alessandro Antonietti, Antonella Corradini, and E. Jonathan Lowe have put together a compact and accessible overview of the mind-body problem. It elegantly integrates scientific and philosophical perspectives and gives a cogent overview of the current state of the field. The method of presentation nicely recapitulates the interactive nature and open-minded spirit of inquiry that this subject matter demands. This book genuinely advances us toward the goal of a coherent understanding of the relationship between psychic and material realities.” —JEFFREY M. SCHWARTZ, author of The Mind and the Brain

ANTONIETTI, CORRADINI, AND LOWE

Philosophy • Psychology

PSYCHO-PHYSICAL DUALISM TODAY AN INTERDISCIPLINARY APPROACH

EDITED BY

ALESSANDRO ANTONIETTI, ANTONELLA CORRADINI, AND E. JONATHAN LOWE

8/20/08 12:27:27 PM

Psycho-Physical Dualism Today

Psycho-Physical Dualism Today An Interdisciplinary Approach

Edited by Alessandro Antonietti, Antonella Corradini, and Jonathan Lowe

LEXINGTON BOOKS A division of ROWMAN & LITTLEFIELD PUBLISHERS, INC.

Lanham • Boulder • New York • Toronto • Plymouth, UK

LEXINGTON BOOKS A division of Rowman & Littlefield Publishers, Inc. A wholly owned subsidiary of The Rowman & Littlefield Publishing Group, Inc. 4501 Forbes Boulevard, Suite 200 Lanham, MD 20706 Estover Road Plymouth PL6 7PY United Kingdom Copyright © 2008 by Lexington Books 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 the publisher. British Library Cataloguing in Publication Information Available Library of Congress Cataloging-in-Publication Data Psycho-physical dualism today: an interdisciplinary approach / edited by Alessandro Antonietti, Antonella Corradini, and E. Jonathan Lowe. p. cm. Includes bibliographical references and index. ISBN-13: 978-0-7391-2384-3 (cloth: alk. paper) ISBN-10: 0-7391-2384-X (cloth: alk. paper) eISBN-13: 978-0-7391-3100-8 eISBN-10: 0-7391-3100-1 1. Mind and body. I. Antonietti, Alessandro, 1960– II. Corradini, Antonella. III. Lowe, E. J. (E. Jonathan) B105.M53P79 2008 147’.4—dc22 2008024518

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Contents

Introduction Alessandro Antonietti, Antonella Corradini, and E. Jonathan Lowe Part I: 1

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Psycho-Physical Dualism: Scientific Approaches

Developing Dualism: From Intuitive Understanding to Transcendental Ideas Henry M. Wellman and Carl N. Johnson

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2

Must Psychologists Be Dualists? Alessandro Antonietti

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3

Mind, Brain, and Dualism in Modern Physics Friedrich Beck

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Discrete Degrees Within and Between Nature and Mind Ian J. Thompson

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Part II:

Psycho-Physical Dualism: Philosophical Perspectives

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Mutual Dependencies of the Mental and the Physical Franz von Kutschera

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The Reductio of Reductive and Non-reductive Materialism— and a New Start Uwe Meixner

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A Defence of Non-Cartesian Substance Dualism E. Jonathan Lowe v

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143 167

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Contents

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Emergent Dualism Antonella Corradini

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Concepts, Dualism, and the Human Intellect David S. Oderberg

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Index

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About the Editors

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Introduction Alessandro Antonietti, Antonella Corradini, and E. Jonathan Lowe

For many years mind-body dualism has been considered with suspicion, both by philosophers and scientists. Such a position in the philosophy of mind raised several criticisms in the philosophical field and was conceived as misleading in many scientific disciplines. However, in recent time more attention has been paid to the dualistic point of view, not least because of a widespread discontent with physicalistic monism and its dominance on the cultural scene. As known, the difficulties that physicalism encounters stem from the essentially subjective nature of mental phenomena. Physicalistic science aims, for its intrinsic constitution, at grasping the objectivable aspects of reality, so that the analysis of the subjective experiences as such is not in line with the objective parameters of its procedures. According to this position, science can make subjective experiences the subject matter of its inquiry only by scrutinizing them from the viewpoint of their physical bases, first of all the biological and neurophysiological ones. To be sure, the difficulty of pursuing a scientific analysis of subjective experiences does not preclude the possibility of undertaking a scientific study of the objective correlates of mental phenomena. However, to maintain that the dimension of mental subjectivity can also be examined from this point of view does not necessarily amount to claiming either that the mental is reducible to its physical basis, or that it is identical with it, or that it is a merely illusory phenomenon, as eliminativists do. A thorough and deep examination of the resurgent dualistic currents of thought must focus on how these try to meet the difficulties, arising from the subjectivity of the mental, the different kinds of physicalistic monism are faced with. This is a difficult and complex task, since the problem of subjectivity as the hallmark of the mental can be subdivided into further problems regarding the various ways vii

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in which the subjective nature of mental phenomena manifests itself. These can be grouped into two orders of issues. On the one hand, there are the problems concerning the intentional nature of mental events and the consequent phenomenal character of the correlated experiences. On the other hand, attention must be paid to the problem regarding the causal powers inherent to mental phenomena. As far as the first order of problems is concerned, it presents various facets, even if all aspects are related to the topic of intentionality. Originally, in fact, intentionality means directionality and there are directional phenomena (of an informational kind, that is to say, in a broad sense, of a cognitive kind) that can be naturalized. They can be understood as structured processes of re-elaboration of the information coming from the sense stimuli which causally affect the subject. However, inasmuch as the intentional object becomes more and more complex, the very nature of the cognitive relation changes, ceasing to be a mere re-elaboration of information. As a consequence, at a certain degree of complexity the cognitive relation becomes resistant to naturalization. Two reasons can be mentioned to explain why it is so. The first aspect is related to the content of the intentional act. If the act’s content is abstract, that is to say, it does not coincide with a concrete exemplification of it, but represents a general scheme including an infinite number of its possible exemplifications, then the act acquires a new cognitive significance which consists in its subjectivation. The cognitive act changes from a simple process of informational elaboration to the act of a subject who grasps the object insofar as it appears to her. The second aspect is a consequence of the cognitive act’s becoming subjective. If the apprehension of the object coincides with its appearing to the epistemic subject, this latter must be able to grasp the object as something different from herself, and this presupposes that the subject is constituted in the unity of her self-consciousness (Ich denke). In other words, the capability of grasping the objects as appearing to the epistemic subject implies that the subject’s selfconsciousness is a totality which is different from the whole range of the knowable objects. From these two aspects, then, other characteristics derive which are hardly compatible with a naturalization programme about intentionality. From the subject’s capability of grasping the objects in their abstract universality derives first of all the subject’s capability of entertaining the idea of the totality of the existing things. But, then, inasmuch as the subject is self-conscious, she is also conscious of her being an element of the totality of the existent things, that is to say, she is conscious of her existing (Dasein). In fact, if the subject is able to represent to herself the totality of the existing things, she is also aware that beyond it there is nothing. Thus, by having the awareness of herself as a part of the whole, she is also conscious of herself as an existing entity. This implies that she is not simply aware of being a part of the environment in which she lives, that is to say,

Introduction

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in the language of contemporary semantics, of existing as related to a world, but she is aware of existing in an absolute way. The second order of problems deals with the issue of mental causation, about which monistic conceptions have not put forward hitherto plausible solutions. Can mental processes cause physical events? Physicalism has always tried to explain mental causation by resorting to a causal relation between the neurophysiological basis of the mental phenomenon and the neurophysiological process correlated to the produced physical event. For example, the cause of a subject’s raising her arm is not her decision of doing so, but the action exerted by the neurophysiological basis of the act of decision upon the cortical process which in its turn causes the arm rising. However, this picture of human decision and action is overtly incompatible with the common conviction that we cause our actions, that we are responsible for causing them. Such a conviction would implausibly turn out to be outright fallacious, if deliberation processes were the epiphenomenal result of physical processes. In other words, the problem of mental causation is still more thorny for a physicalist if seen from the standpoint of the explanation of the human action. In fact, within an intentional model of action explanation, that is to say, within a non-naturalistic model referring to the final notion of cause, actions are not caused by Humean antecedents, but are chosen in the light of reasons based on intended values and ends. It does not seem that any naturalistic model is able to give account of these fundamental features of action and decision. The field of action explanation is also the most suitable context for treating the crucial topic of the distinction between property dualism and substance dualism. Property dualism asserts the in-principle irreducibility of mental to physical properties, but it also maintains that both kinds of properties belong to the same substance. For substance dualism, instead, the bearer of the mental properties (the mental substance) is different from the bearer of the physical properties (the physical substance). Substance dualism, therefore, implies not only the difference of mental and physical properties, but also of their respective substrates. Now, a further difficulty that pushes towards a dualistic stance derives from the fact that monism implies the existence of only one kind of substance, the material substance or the body. However, the self whom we refer to in the most simple everyday self-reflective activities does not seem to coincide with our own body. We say, as a matter of fact, “I am responsible for this action,” but not “My body is responsible for this action.” It is a conviction deeply rooted in our subjective experience that the self is endowed with a body, but is not the body, since the self is also the substrate of higher-level phenomena such as the unitary consciousness. The problems mentioned so far are objects of inquiry by the contributors to the present volume, according to the different standpoints which are involved in an interdisciplinary project. The book is divided into two parts.

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The first part concerns how dualism is, or may be, currently considered in some scientific domains, like physics, psychology, and the neurosciences. The second part is devoted to the exposition and defence of five different ways of being a philosophical dualist. The difference of viewpoint—the scientific and the philosophical one—has of course far-reaching consequences both on the different ways of dealing with the same issues and on the distinctiveness of the issues under scrutiny. The fundamental topic examined by the physicists Beck and Thompson regards in particular the second order of problems mentioned above, that is to say the problem of mental causation, considered from the standpoint of the image of the world provided us by quantum mechanics. At central stage in the contributions of the psychologists Antonietti and Wellman and Johnson are respectively the non-reductive relationship between psychology and the neurosciences and the analysis of the developmental data about children’s attitude towards dualism. As far as the latter point is concerned, in the first chapter Henry Wellman and Carl Johnson describe the developmental trend of naïve dualism, namely, of that common sense stance which is shared by adults almost worldwide and that leads people to conceive mental states and processes as radically different from material objects. A large amount of empirical evidence supports the notion that infants reveal an early awareness of the distinction between mental and physical aspects of the reality. By one year of age children show to be able to catch the intentionality underlying some human behaviours so to induce observers to infer that they perceive a mental activity at the basis of other persons’ actions. Later children exhibit a series of responses proving that they attribute to mental activity features— such as immateriality, intangibility, modificability through thinking— which are not attributed to concrete things. A clear dualistic ontology is thus implicitly acquired by children around the age of four. At the same time children manifest to have a more articulated view of the mental world: they perceive subtle differences among mental states and realise the connections among mental states and between mental states and behaviour. A sort of naïve psychological theory seems to be possessed by children since their beliefs are coherent and internally well-structured. As children grow, their intuitive understanding of mental life and of the relationships between mind and physical entities becomes object of reflections. As a consequence, their psychological conceptions become more elaborated and explicit. For instance, children are engaged in issues concerning the relative independence of mind and brain and their reciprocal influences. These reflections constitute the basis of further conceptual developments which induce children to elaborate the idea of supernatural entities such as the soul, even if other motivations are involved in these ideas. In fact, while the idea of mind, as opposed to body, arises to predict and explain agents’ behav-

Introduction

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iours, the idea of the soul emerges within an interpretative attitude which serves the need to give meaning to the existence. At the end of the developmental trajectory which is outlined in the chapter, it is clear that most persons share a dualistic view which plays the role of a conceptual scheme which frames and biases the further theorizing about the nature of the psychological and physical properties of reality. Alessandro Antonietti’s contribution takes as starting point the conclusion of the previous chapter. Must common sense psycho-physical dualism also be shared by psychologists? The question is addressed at an epistemologicalmethodological level. The aim is in fact to discuss if the distinctiveness of psychological knowledge requires its object, that is to say mental activity, be investigated through notions and explained by means of conceptual models which are qualitatively different from those applied by the neurosciences. It is argued that psychology makes use of peculiar descriptions and analyses which are also employed by the neurosciences to circumscribe their research domain. Furthermore, such descriptions and explanations cannot be discarded even though the progresses of the neurosciences might provide us with an exhaustive and detailed report of all what happens in the brain. Thus, the problem of relating the psychological description and interpretation of mental activity to the corresponding neurobiological processes comes to the fore. The most obvious operation to be carried out is identifying systematic correspondences between mental experiences and biological structures and processes highlighted by the neuroscientific research. Such correspondences cannot be seen as confirmations of the validity of the psychological models, but as suggestions that are useful to orientate psychological studies towards new directions which should allow psychologists to corroborate findings within their domain. Thus, the dualistic co-presence of psychological and neuroscientific discourses appear to be necessary at this stage of the development of the two forms of knowledge. An actual integration of the analysis of mental phenomena and of the concurrent cerebral processes seems to be a task to be accomplished in the future thanks to the adoption of radical novel conceptual paradigms. The other two scientific contributions to this volume make plausible that, starting from the results of quantum physics, a dualistic worldview including autonomous mental causation is possible. Friedrich Beck argues that a dualistic dimension can be found in quantum mechanics as regards the particle vs wave nature of microscopic entities. This implies that different and complementary points of view have to be adopted according to what has to be described and explained. Moreover, Beck notes that probabilistic concepts have been introduced in the description of nature to the effect that single physical processes fail to produce unique output and fail to be completely determined and predictable. Since what happens in the brain at the micro-level has to be regarded as a set of single events, each of these events

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has to be conceived on the basis of a probability field. The core mechanism of synaptic transmission, that is, exocytosis, has such a feature and it is not impossible that the probability that exocytosis occurs can be modulated by mental influences. Due to the openness of the physical world, brain-mind interactions are compatible with the existing scientific laws. Even if the changes which are introduced in this way in the neural machinery are of extremely low intensity, their effects can be amplified immediately within the highly interconnected network of the nervous system (exocytosis can be seen as a modulator process which has not to produce by itself the energy, but has to regulate the whole dynamics of the energy exchanges within the brain) so to produce the cerebral activation needed to perform actions. Ian Thompson emphasizes the role of the concept of a disposition. A dispositional property can be explained by means of other dispositions but not in terms of structural properties, because of its categorial irreducibility. Hence it is possible to sort dispositions in hierarchies so to show how a given disposition derives from lower-level dispositions. It is worth noting that, even though a disposition can be generated by other dispositions (in any case, however, dispositions are not the result of the rearrangement of their components), they constitute discrete levels within the hierarchy, so that the essential differences between dispositions are preserved. As far as psycho-physical dualism is concerned, we should conceive mental processes as higher-level dispositions, internally articulated (for instance, the “disposition to learn” is related to the derived “disposition to read books”), that, to be implemented, need lower-level dispositions involving physical actions (such as “disposition to walk toward a library”) which in turn involve—we can figure out—even more fine-grained dispositions concerning the brain activity (such as “disposition to activate the supplementary motor area in the cerebral cortex”). In this manner “psychological” dispositions can be linked to behavioural and neural dispositions. Such a link allows us to understand how mental states can exercise causal influence on the body: bodily actions are lower-level implementations of higher-order (mental) dispositions. In this version of dualism it is argued that mind and body are distinct ontological substances connected to each other as derivate dispositions. According to Thompson, the mind predisposes the brain to perform some physical processes which correspond to the intended mind’s goals; in other words, the mind selects a function to be carried out by the brain through spatiotemporal patterns of neural activation. The brain processes, in turn, restrict the action of the mind. In short, the propensities which can be identified in the cerebral machinery are the effects of mental causations and mental acts are conditioned by brain processes. The reflections put forward by the physicists Beck and Thompson find an echo in the first philosophical contribution to the volume by Franz von Kutschera. The author, after criticizing idealism on the basis of the argu-

Introduction

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ment that there exist physical phenomena which are not correlated to mental phenomena, also rejects physicalism for three basic reasons. While the first and the second reasons point respectively at the inderivability of consciousness, and at the higher cardinality of belief states over physical states, the third relies on an argument deriving from quantum physics. According to it, the properties of a system (for instance property F or G) do not exist without an observer. The system only displays dispositions to generate to a certain degree of probability a positive result in a F-observation or in a G-observation. F and G are therefore secondary and not primary qualities. Thus, if we assume that physical objects are characterized by qualities, these are secondary qualities, so that a physical world without subjects cannot exist. Von Kutschera argues that the reciprocal dependence between the physical and the mental which comes to the fore in quantum physics is a constitutive feature of the psychical life. He defends a polar dualism, according to which the psychical life develops between the mental and the physical poles. The mental depends on the physical since, as Fichte affirms, the mental activity par excellence, that is to say, self-consciousness, occurs through reflection on intentional activities directed at the object, which is originally the external physical world. The physical, then, depends on the mental because, as we gather from quantum physics, the world we have experience of is not a world per se, but a world for us. The main aim of Uwe Meixner’s essay is to show that the difficulties inherent in physicalistic monism can be overcome only through acknowledgment of the presence in the human being of two irreducible dimensions, the physical and the mental one. Meixner’s main argument develops in the following way. Materialistic monism is either reductive or non-reductive. Reductive materialism implies the claim that all mental events are physical events. This claim is, however, contradicted by the phenomenology of psychical life. Non-reductive materialism, on the other hand, either includes the claim that all mental events are physical events or does not include it. In the first case it is contradicted by the phenomena, as for reductive materialism. In the second case, either it is agnostic about the claim that all mental events are physical events or, instead, includes the claim that some mental event is not physical. The first alternative, that is to say, agnosticism, condemns nonreductive materialism to insignificance, while the second alternative lets non-reductive materialism coincide with dualism. Thus a new start is needed, which seeks to unify dualistically conceived phenomenal intentionality—that is to say, intentional experience—and dualistically conceived mental causation—that is to say, causation not only by non-physical mental events but also by non-physical mental agents. In fact, the desired unification is feasible from an evolutionary—indeed, naturalistic—point of view. E. Jonathan Lowe’s defence of non-Cartesian substance dualism starts with the critical discussion of two arguments put forward by neo-Cartesian

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substance dualism, i.e. the conceivability argument and the indivisibility argument. Lowe proposes then two alternative arguments, the argument of replacement and the argument of the unity of the self. According to the latter, the self is the subject of all and only its mental states, but neither the body as a whole nor any part of it could be the subject of all and only its mental states; hence the self cannot be identical with the body or with any part of it. To this argumentation could be objected that the self, however not identical with the whole body, is nevertheless identical with a part of it, that is to say with the brain. But, on Lowe’s view, an asymmetry obtains between the self and the brain. We can say that: (x exists) (x is the self and x is the substrate of all mental acts), while we cannot say that: (x exists) (x is the brain and x is the substrate of all mental acts), because the brain is a compound, thus it is not a unitary entity capable of being the substrate of all mental acts. Only its singular parts (including the non-proper part, if there are any functions which are carried out by the brain as a whole) are the substrates of the singular mental states. As regards the problem of the causal closure of the physical world, the fact that certain physical effects are the consequences of personal decisions does not represent, according to Lowe, a violation of such a principle. Decisions are in fact free acts, that is to say, non-caused acts, which are however explainable through the logic ruling intentions. In her contribution, Antonella Corradini proposes a dualistic variant of emergentism. As known, according to emergentism, the mental dimension is emergent upon the physical one, i.e. mental phenomena are new with respect to their neuro-physiological basis. However, to say that mental phenomena are emergent also means that they arise from their underlying physical basis and are dependent on it for their persistence. For these reasons, the notion of emergence offers in the view of many philosophers a convincing middle way between reductionism and dualism. On the one hand, it seems able to avoid reductionism, as emergence is conceived as a new kind of relation; on the other hand, it seems also able to avoid dualism, as emergentism stresses the dependence of mental phenomena upon the physical ones. The author, after scrutinizing various concepts of emergence starting from the British Emergentists, shows however that emergentism cannot coherently be supported without admitting that the underlying basis be only a necessary condition of the mental dimension, but not a sufficient one. In order to allow the mental to emerge from its biological basis, a non-material dimension of reality is needed, which is endowed with ontological independence and exists from the very beginning of the emergent process. It follows from this that, if emergentists want to realize their non-reductionistic purposes, emergence must be understood as a dualistic relation which, moreover, plausibly requires not only a property dualism, but a distinctive kind of emergent substance dualism.

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Among the philosophers, David S. Oderberg is the one who places the most emphasis on the issue of the cognitive capacities of the human being. He insists upon the categorial difference between intellective and sensory knowledge. On Oderberg’s view, the intellect can grasp a potentially infinite number of categories, and, within each category, an infinite number of exemplars. Instead, organs like the eyes or the ears can receive only a categorically limited number of kinds of colours and sounds, and, within each kind of sensory stimulus, only a finite number of exemplars. The physical organs of sight and hearing are finite, that is to say, they are limited as regards the kind of information they can grasp. This does not hold for the intellect, which, however extrinsically limited because of the lack of sensory information, nevertheless is not so intrinsically. As a consequence, there is a clear-cut distinction between the higher activities of the intellect and lower mental functions such as feelings and sensations. From this Oderberg derives the thesis of the immaterial nature of the soul, but with a qualification. We are not able to say positively what the immaterial nature of the soul consists in, in the same way as negative theology cannot positively say anything about the nature of God. We can only maintain that the higher functions of the human mind, as the intending of the universals, cannot be purely material, since acquisition and possession of concepts implies the existence of a non-material dimension of reality.

I PSYCHO-PHYSICAL DUALISM: SCIENTIFIC APPROACHES

1 Developing Dualism: From Intuitive Understanding to Transcendental Ideas Henry M. Wellman and Carl N. Johnson

1. INTRODUCTION Lay adults worldwide (non-philosophers, non-scientists, non-theologians) evidence a naïve, or intuitive dualism. This sort of dualism affirms the commonsense notion of a world of real objects and events “out there,” distinct from a mental world of thoughts and ideas “in here.” It is, in the terms of this volume, a psycho-physical dualism and one that affirms a number of subjective-objective distinctions. Here are three central yet commonplace distinctions, reflective of this naïve dualism: 1. Thoughts are different from things. A thought about a tree is mental and immaterial; a tree is physical and concrete. Relatedly, beliefs are different from actuality and imagination is unconstrained by reality. One can believe the earth is flat, although it is actually spherical; one can imagine unicorns, perfect vacuums, eternal youth, and life after death. 2. Mental attitudes are individual and subjective. I can think rainy days are gloomy; you can think they are crisp and refreshing. 3. Mental acts are not bodily behaviors. My body may be chained, but my thoughts can be free. Thus, mental acts and events are private. Your thoughts, desires, and feelings can be hidden and at odds with your objective reports, expressions, acts. Equally, one’s body functions (reflexively, involuntarily) quite apart from one’s thoughts, desires, and intentions. 3

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Philosophers have long pointed out that these distinctive characteristics of mental kinds of things represent a quality of “aboutness” or “intentionality” (cf. Brentano 1973; Searle 1983). In common parlance intentional means “on purpose,” but in the wider philosophical sense intentional states encompass all mental states “directed to” or “about” other things—an intention about a cookie but also a belief, desire, or feeling about a cookie. Purposes, beliefs, desires, emotions, and the like all mark a distinctive kind of subjective, intentional orientation of beings to the world. Over the last twenty years, cognitive-developmental psychologists have provided rich empirical data about the origins of intentional concepts of this sort, and thus of everyday psycho-physical dualism. In this chapter we offer an overall account of the childhood development of these ideas. In our account, naïve psycho-physical dualism is a worldwide characteristic of early childhood thinking, clearly apparent in experimental studies with and in natural observations of three-, four-, and five-year-olds. Early in life, a foundational explanatory system develops—an intuitive psychology or “theory of mind”—which provides preschool children with a practical framework for dealing with ordinary human intentionality. Somewhat later, this intuitive framework in turn provides the basis for naïve, reflective ideas, which stretch beyond the limits of ordinary experience. That is, a basic capacity to think about the intentionality of persons serves to frame reflective thinking about mind, about existence, about spirit, and about supernatural beings. Thus, in what follows, we shall first describe the development of preschool children’s intuitive capacity to distinguish psychological kinds of states, entities and beings. On this basis, we will then give an account of the emergence of reflective ideas about natural and supernatural intentionality as they appear in middle childhood. In the end, we will claim that this everyday combination of intuitive concepts and reflective ideas is the fodder for philosophical and theological thought.

2. EARLY INTUITIONS Contemporary empirical research addressing naïve dualism in young children has resulted in numerous studies yielding a clear picture. The picture is one of early awareness of how psychological versus physical phenomena are distinct while nonetheless being connected. These early-achieved insights begin in infancy and become well-established in the preschool years. That preschool children firmly distinguish world and mind was at first surprising because Piaget’s early work had established quite the opposite view. Piaget (1929) claimed that young children are adualistic, rather than dualistic, in that they fail to segregate the physical and the psychical, the subjective and the objective, the mental and the real. In his account, this

Developing Dualism: From Intuitive Understanding to Transcendental Ideas

5

dualism had several consequences, including: childhood animism—the attribution of motives and psychological causes to physical phenomena (e.g., clouds)—and childhood realism—the attribution of real physical properties to mental phenomena (e.g., dreams). According to Piaget, for young children dreams are real external pictures seen with the eyes and thinking is literally overt speech (with thoughts akin to the voice in the sense of puffs of air emitting from the mouth). Thus, “Childhood realism is characterized by two confusions, quite distinct from each other though mutually contributory. First, there is the confusion between thought and the body; thought for the child is an activity of the organism—the voice—it is thus a thing among things and its essential characteristic is material action. . . . Secondly, there is confusion between the sign and the thing signified, the thought and the thing thought of. From this point of view the child cannot distinguish a real house, for example, from the concept or mental image or name of the house” (Piaget, 1929, 55). Piaget offered a credible developmental position—naïve dualism only develops in middle childhood (around seven or eight years) after an initial period of confusion. Given that ideas, dreams, and mental images are subjective, private, seemingly abstract entities and experiences, young children could certainly misunderstand them. Children could take ideas, dreams and the like to be material things, like rocks and trees, or especially insubstantial material things like clouds, shadows and moving pictures. That is, young children could plausibly conceive of all things—even “abstract things” such as thoughts and dreams—as types of physical objects (see Keil 1979), and then must come to distinguish the abstract from the physical, and mentality from the world. However, contemporary research, based on improved methods for more systematically probing the ideas of younger preschool children, has produced a very different conclusion: quite young children are firm psycho-physical dualists. 2.1 Infant Understanding of Intentionality Even young infants (three-, four-, and five-month-olds) distinguish between animate and inanimate events and entities. For example, they discriminate between displays of mechanical versus animate motions (Bertenthal et al. 1985), between hands reaching for and contacting objects versus wooden or metal rods doing so (Woodward 1998). If six-month-old infants see a physical object move and then stop and become completely still they lose interest; but if they see a human face being expressive and then become completely still they become upset (Muir and Hains 1993). Moreover, infants prefer to imitate the movement of people and fail to imitate parallel movements of objects (Legerstee 1991, Meltzoff 1995). While impressive, an infantile animate-inanimate distinction need not require or manifest

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any sense of psychological entities or states versus physical ones, it need not encompass specifically psycho-physical distinctions. It requires only distinguishing animate, human acts and entities from inanimate ones on the basis of certain overt, objective features that differentiate the two, such as the presence or absence of self-propelled movements, distinctive action contingencies, and so on. Toward the end of the first year of life, however, infants manifest initial understandings of persons as clearly more than physical bodies or overt movers. Persons now seem arguably not just animate beings but psychological beings. Specifically, at about one year infants appreciate that (some) actions are intentional in the sense of goal-directed and that (some) connections between persons and things are intentional in the sense of experiential and subjective. Generally, somewhat before twelve months infants start to do things like point to objects for others—both to share attention (known as protodeclarative pointing) and to request things (proto-imperative pointing)— track others’ eye-gaze to objects (to achieve joint attention), and moderate their own acts towards an object depending on someone else’s emotions about that object (known as social referencing). Although suggestive of understanding others in terms of their goals and experiences, such everyday actions have “leaner,” alternative interpretations as well (Baldwin and Moses 1996; Moore and Corkum 1994). Fortunately, more controlled, experimental demonstrations are more definitive. Consider a study by Phillips and Wellman (2005), using a habituation-dishabituation paradigm. In this sort of method infants see something again and again. Initially they look attentively, but as they become habituated, they look less and less. Then they are shown something different. If infants see this additional event as similar to the initial one, they remain uninterested and look at it very little. But if they see it as different, novel, or surprising, they look much longer—they dishabituate. During habituation in the Phillips and Wellman study, infants saw a person reach over a barrier and grasp a ball, and then do this again, and again. Once the infants were habituated, the barrier was removed and they were shown two test events. One test event showed the person execute a direct reach for the ball; the other event showed an indirect reach, identical in trajectory to the habituation reaching (but now with no barrier). These test events contrast two different construals of the person’s actions, one in terms of goals or intentions and one in terms of the physical motions of the body. If, in habituation, the infant construes the actor’s action in terms of its physical movement (the arm and hand up and then down in an arc), then the indirect reach should be expected regardless of the barrier (as it repeats the same movement) whereas the direct reach will stand out as novel. In contrast, if the infant initially construes the action as being goal directed (as the actor going as directly as possible to get the goal object), then when the barrier is removed the direct reach is the expected action be-

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cause the actor continues to directly seek the goal. Under this second construal it is the indirect reach that would be more attention-worthy because (although the actor’s arm movement remains the same as during habituation) the actor does not seem straightforwardly goal-directed. In fact, eight-, ten- and twelve-month-olds look longer at the indirect reach test events (see Phillips and Wellman 2005; Gergely et al. 1995; and Sodian, Schoeppner, and Metz 2004 for similar data). They dishabituate to the indirect reach (even though it is showing the exact same arm movement as in habituation) and do not dishabituate to the direct reach (even though it actually shows a different physical arm movement). This pattern, along with appropriate control conditions, shows that infants construe the reach as goal directed. Other methods further demonstrate infants’ emerging understanding of intentionality. For example, Carpenter, Akhtar, and Tomasello (1998) studied infants’ imitation of intentional and accidental actions. In this study, fourteenand eighteen-month-old infants watched an adult model several two-action sequences on objects (e.g., pushing a button and then moving a lever). One action (sometimes the first action, sometimes the second) of each sequence was marked vocally by the adult as intentional (“There!”), and one action was marked vocally as accidental (“Whoops!”). After each adult presentation, infants were then given the objects and so a chance to act on them themselves. Infants imitated almost twice as many of the adult’s intentional actions as her accidental ones and only very rarely imitated the entire two-action sequences (see also Olineck and Poulin-Dubois 2005). This shows that they differentiated between the two types of actions, and, moreover, they preferred to reproduce what the adult meant to do and not her actual surface behavior (see also Meltzoff 1995). As these examples indicate, by twelve months infants distinguish an actor’s overt actions from psychological goals and intentions. Indeed, identical overt acts can be interpreted as goal-directed or not. Beyond assessing infants’ understanding of intentions, as distinct from movement, recent studies have examined infants’ understanding of emotion and perception (Barna and Legerstee 2005; Phillips, Wellman and Spelke 2002). Here too the issue is whether emotions and attention are construed in terms of external expressions or overt glances versus in terms of the persons’ internal experiences and interests. In an especially provocative study, Tomasello and Haberl (2003) examined infant’s understanding of perceptual experiences. Infants twelve and eighteen months old interacted with three objects. Critically, a target adult joined in these interactions for two of the objects, but not the third. After these initial interactions, the three objects were shown together on a tray, and the target adult said to the infants, “Oh, wow! That’s so cool! Can you give it to me?” while gesturing ambiguously in the direction of the objects. To be clear, all three objects were now “old” for the infant, but one was “new” to the target adult. Infants gave the target adult the object that

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was new for him. Thus they understood that even though the adult was currently looking toward all three objects, he was attending to and referring to the one that he had not previously experienced, the one that was new to him. By giving him that object, infants showed some understanding of, and tracking of, the target adult’s experiences and thereby provided evidence of recognizing something of the subjectivity of these experiences, namely that prior experiences can critically differ from one person (infant) to another (target adult). Repacholi and Gopnik (1997) provide a different example of infant appreciation of individuated, subjective experience. They had eighteenmonth-olds taste two snacks to evoke negative and positive preference: broccoli (negative) and goldfish crackers (positive). Then an adult, facing the child, tasted each snack saying, “Yum” and smiling at one snack, but saying, “Eew” and frowning at the other. In a Match condition the adult liked the crackers and disliked the broccoli, matching the child’s preference. In a Mismatch condition she liked the broccoli instead. Then the adult held her hand halfway between the two snacks and said, “I want some more, can you give me some more?” Eighteen-month-olds overwhelmingly gave the adult more of what she, the adult, had liked, even in the Mismatch condition. Thus, children demonstrated an understanding of desires as subjective—realizing that the adult wanted broccoli, contrary to their own preference for crackers. (And it is not the case that infants simply gave the adult the snack the infant did not like—and perhaps wanted to keep for herself—because in the Match condition, infants gave the adult the crackers.) In sum, by twelve and eighteen months of age, infants reveal an understanding of the intentionality of (some) psychological states, in the philosophical sense of intentional “aboutness.” Goal-directed action and emotional/perceptual experience are both intentional—reaching to get a ball is about the ball and liking crackers is about the crackers. Appreciation of persons’ intentional experiences thus reveals an early sensitivity to at least some psycho-physical distinctions.

2.2 EARLY CHILDHOOD DUALISM Infant understanding of intentionality is evident in non-verbal inferences that are made about preferences, intentions, and emotions. With the emergence of language children begin to explicitly talk about such states in ways that express a rich and definitive psycho-physical dualism. Children’s early language often includes emotion terms, like happy and sad, as well as desire terms such as want, wish, and like. The key question, however, is whether children use these terms to refer to mental-intentional

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states. Young children could certainly be generally ignorant of or confused about such states and thus mistakenly take emotion or desire terms to refer to external aspects of a person’s actions, appearance, or situation instead. A term like happy could refer only to a person’s smile or laughter. A term like want could refer merely to overt actions such as getting or seeking. More specifically, the young child’s understanding of emotions could be confined to the notion that certain situations simply elicit corresponding emotional reactions (e.g., birthdays make one happy). Call this a situationist understanding of emotion in contrast to a dualist conviction that emotional reactions do not follow directly from eliciting situations, but are subjective. (e.g., If you want a birthday, having one makes you happy; if I want to avoid birthdays, the same occurrence can be sad or depressing.) A related issue concerns an action-disposition versus internal-experiential conception of emotion. If I fear snakes, I’m likely to avoid them; if I am sad, I’m likely to cry. Emotional states are often associated with typical actiondispositions. Thus, two possibilities can be distinguished. One is that early conceptions of emotion are limited to discerning situation-action scripts; the other is that young children recognize that emotion states exist separate from, or even in contrast to, external situations. With situation-action scripts, children could understand that certain situations or stimuli lead regularly to certain actions (of instrumental or expressive sorts). Emotion terms therefore would simply refer to such script-like situation-action regularities. A child with only such a situation-action understanding of emotion terms might talk about “emotion,” largely appropriately, by using terms like happy and sad to refer to such scripts, without any deeper understanding of subjective-experiential states. Within philosophy there are arguments that emotional term meanings may actually decompose into no more than this (Ryle 1949). Early childhood understanding of desires could proceed similarly. Initial conceptions of desire, and initial understanding of terms such as want and like, could refer to situation-action scripts where overtly desirable entities regularly lead to certain actions such as seeking, finding, obtaining, and the like. In contrast to this situationist-behavioral possibility, from their earliest talk about emotions and desires young children demonstrate an awareness of the distinctly subjective-experiential status of desires and emotions. In everyday conversation the clearest evidence for this comes when children produce contrastives such as: Adam:

Want some? [to adult]

Adult:

No. I don’t want some.

Adam:

OK. But I want some.

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In this conversation the child distinguishes two different desires about the same physical reality—you want some, but I don’t. In comprehensive analyses of everyday conversations children as young as two years old have been found to regularly produce such contrastives (Bartsch and Wellman 1995; Wellman et al. 1995). All the following conversational contrastives come from two-year-old children (from Bartsch and Wellman 1995, or Wellman et al. 1995). Father:

Marky’s mad at your Daddy. (Mark is Ross’ brother)

Ross:

But I’m happy at my Daddy!

______________________ Adult:

You don’t like it?

Abe:

No . . . You like it?

Adult:

Yes, I do.

Abe:

But I don’t like it.

______________________ Peter:

I wanna come out. But I can’t come out.

______________________ Abe:

I like Michael. I like Michael, Mommy.

Mother: Do you want to go outside and play with Michael? Abe:

No. Not right now.

______________________ Child:

“I was sad. But I didn’t cry.”

In these contrastive discourses children make several intentional distinctions. The first three excerpts above contrast one person’s subjective experience with that of another—about the exact same physical object (e.g., Daddy), one person is mad but another is happy. Other contrastives contrast desire or emotion with overt action: “I wanna come out; but I can’t come out”; “I was sad; but I didn’t cry.” Such data demonstrate key aspects of a naïve psycho-physical dualism. This early dualism includes the understanding that people possess internal psychological states distinct from the physical world, because children distinguish such states from the situational occurrences that may elicit such states and distinguish such states from the behaviors and expressions that may result from them. Moreover, children remark that different persons possess different psychological states, even in the same situation and about the same overt objects and events.

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Controlled experimental investigations with one-and-a-half- and twoyear-olds, such as the “yum-eew” study by Repacholi and Gopnik (1997) described above, reveal the same dualist convictions (see also Wellman and Woolley 1990). Emotions and desires are core psychological phenomena; distinguishing the subjective-experiential nature of such states represents a major milestone in children’s understanding of the psychological nature of persons. 2.2.1 Representing Representation Young children’s naïve psycho-physical dualism is not, at first, as extensive as it will become. Consider the three distinctions listed on our first page. They predominantly focus on the status of mental representations (thinking, imagining, believing) instead of the states of intentions, desires or emotions. Piaget’s examples and studies also focused on children’s ideas about representational kinds of things—thoughts, dreams, and names. Considerable research has been directed to these distinctive kinds of representational mental states—states that represent some state of affairs (e.g., the world, or a fictional alternative) as one way or another. In this case, the most well-studied topic concerns children’s understanding of thoughts in the form of beliefs and false beliefs. Many studies have now been conducted assessing children with one version or another of (what have become) standard false-belief tasks. There are many differing false-belief tasks, but a classic one is as follows (Wimmer and Perner 1983): The child is told a story about a character, Maxi, who puts his chocolate in the drawer and goes away. While Maxi is gone (and can’t see), the chocolate gets switched to the cupboard. Maxi comes back and he wants his chocolate. The child is asked, “Where will Maxi look for his chocolate, the cupboard or the drawer?” (Or, “Where does Maxi think his chocolate is?”) Note that correct answers require reasoning about subjective psychological states related to, but also independent from, world states. Maxi’s chocolate is in the cupboard; he thinks it is in the drawer. Where will he look? Correct answers—saying that Maxi will look in the drawer—show that children understand that thoughts and reality diverge: people regard the world not just as it is, but as they mentally represent it. Correct answers also show that children understand people’s thoughts differ—I know the chocolate is in cupboard, Maxi thinks it is in the drawer. These are two core aspects of a naïve dualism. Because so many studies have been conducted using various false-belief tasks, several meta-analyses have been conducted to consider the overall patterns. In one comprehensive set of analyses, Wellman, Cross, and Watson (2001) included more than 150 studies encompassing almost 600 false-belief conditions and task variations. Children were variously asked to

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judge behavior or thoughts—where will Maxi look? What will he think? And they were asked to make judgments about real-life humans, videotaped humans, toy figurines, story characters, and so on. A clear and systematic finding emerged: Performance goes from below chance (consistently choosing on the basis of reality) to above-chance (consistently choosing on the basis of beliefs) during the preschool years. By five and six years children are largely correct; on a vast array of false-belief situations they judge and explain correctly. Going backwards to two and three years there is clear below-chance performance. Children make the classic false-belief error—they say Maxi will look for his chocolate where it now really is. Any experimental task must use some specific materials, particular language, and questions, thereby encompassing specific task details and demands. But the studies in these meta-analyses systematically vary these materials, demands, and features. The analyses show that some of these features make false-belief tasks relatively harder or easier. But, most importantly, all tasks show the same general trajectory of development; children proceed from systematic false-belief errors to above-chance performance some time in the preschool years (Wellman et al. 2001; Liu, Wellman, Tardif and Sabbagh, 2008) albeit somewhat earlier or somewhat later depending on the task details. Thus, even the simplest, most child-friendly tasks show this basic development. This basic pattern of development is also evident across widely different countries and cultures. Figure 1 summarizes this evidence from Wellman et al.’s (2001) meta-analysis. Although different cultures and countries show somewhat different timetables for understanding false beliefs, the general pattern of early developing understanding appears to be universal. Understanding of false beliefs appears as early as three and a half years and as late as six or seven, but in all countries and languages studied to date (including children in non-literate traditional, indigenous groups and communities) children come to manifest systematically correct false-belief performance and judgment. In doing so they evidence understanding of key psycho-physical distinctions: internal psychological representations contrast (at times) in content and influence with external physical realities and diverge (at times) from person to person. In parallel studies, researchers have also demonstrated that preschool children are coming to distinguish between pretense and reality (e.g., Harris and Kavanaugh 1993), fictional imaginings and factual occurrences (e.g., Woolley 1995), perceptual appearance versus underlying reality (e.g., Flavell et al. 1983), dreams versus pictures (e.g., Woolley and Wellman 1992), and more. Studies on these topics are less frequent than the voluminous research on false belief, and are more likely to have been conducted only in Anglo-European societies (e.g., U.S., Canada, Britain, Australia, Ger-

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Figure 1.1. Increases in false-belief performance displayed for children in different countries (from the meta-analysis of Wellman, Cross & Watson 2001). Data are percent correct, but transformed via the logit transformation so that the developmental trajectories appear as linear. With this transformation, chance performance is 0, minus numbers are below chance, positive numbers are above chance.

many, Austria). Yet studies conducted in other cultures and languages yield similar findings, including preschool understanding of appearance-reality in China (Flavell et al. 1986) and Japan (Gardner et al. 1988), childhood understanding of dreams versus realities in Africa (Shweder and Levine 1975), and so on. Taken together the research reviewed thus far further suggests that children appreciate the subjective-experiential character of emotions and desires in

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advance of understanding the subjective-experiential nature of representational mental states such as beliefs and knowledge. Studies directly addressing this issue confirm this developmental sequence (Wellman and Woolley 1990; Gopnik and Slaughter 1991; Wellman and Liu 2004) not only in English-speaking locales but in China (Wellman et al. 2006), Germany (Kristen et al. 2006), and even for deaf children (Peterson et al. 2005). In studies of children’s everyday conversations, talk about emotions and desires in subjective-experiential ways has also been found to occur before talk about beliefs and knowledge (Bartsch and Wellman 1995; Bretherton and Beeghly 1982) and this is also true for children in China acquiring Mandarin or Cantonese (Tardif and Wellman 2000), and for deaf children acquiring sign (Anderson and Reilly 2002). As children come to distinguish desires, emotions, beliefs and the like, it is important to recognize that they are coming to understand how psychological phenomena are interconnected. In other words, children do not simply develop individual concepts of mental kinds, they develop intuitive “theories,” in the sense of coherent understandings based on constructs and inferences that define and implicate one another. For example, at this preschool age children understand that perception and sensation relate to, and shape, an agent’s beliefs, desires, and emotions (e.g., Lagattuta and Wellman 2001; Wellman et al. 2000). Indeed, recall that in false-belief tasks, false belief and ignorance arise because the protagonist has not seen a crucial transformation. Similarly, desires arise out of background urges and diminish with satiation (e.g., Gopnik and Slaughter 1991; Moses et al. 2000) and children’s judgments reflect an understanding of this link. Beliefs and desires, of course, link to and shape action—Maxi (mistakenly) searches where his chocolate is not. Children judge that such mental states not only influence action, they also influence an agent’s emotions (e.g., Harris 1989; Wellman and Banerjee 1991). By the preschool years, then, the intuitive distinctions of infancy have coalesced into the more coherent, intuitive theory of the three-, four-, and five-year-old. 2.2.2 Mental Versus Real Entities In the studies and findings discussed so far, in talking about and making judgments about actions or emotions or beliefs, children have been shown to readily distinguish intentional psychological states from external objects, situations, actions, or expressions. Additional research has focused more directly on children’s judgments about the distinctive nature of mental as opposed to physical kinds of things. These studies assess whether children believe that thoughts and ideas are non-material, subjective, “mental” things in contrast with substantial, objective, physical objects. For example, what if three-, four-, and five-year-old children are told about one person who

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has a dog versus another person who is thinking about a dog, and then are asked to judge which “dog” can be seen, touched, and petted? Even threeyear-olds correctly make these judgments (Harris et al. 1991; Wellman and Estes 1986, Wellman et al. 1996). These studies show that children understand that standard physical objects (e.g., a dog) are material (can be touched), externally perceptible (can be seen with the eyes), and public (can be seen by someone else) whereas mental entities (e.g., a thought about a dog) are immaterial, not externally perceivable, and private. Ordinary physical entities have certain objective, behavioral-sensory properties that mental entities do not. Consider children’s response that a thought-of dog cannot be seen, touched or petted whereas a dog can. Of course, a dog that has run away (and so is physically absent) also cannot be seen or touched, but is physically real. And a person’s gall bladder cannot be seen or touched (under ordinary circumstances), and furthermore it is internal and hence private, yet it is nonetheless a physical thing, rather than a mental thing. Perhaps young children see ideas and thoughts as physical (yet “absent”) in the way that an object gone away, or an object hidden inside a container, is physical yet imperceptible. Relatedly, young children might hold still other subtle realistic misconceptions. For example, ideas and dreams might indeed be conceived of as physical things but as special, insubstantial types of physical things, perhaps like smoke, or shadows, or air. Piaget (1929), in fact, quotes older preschoolers as saying that thoughts are smoke, air, shadows, lights, as well as external pictures seen with the eyes. As Keil (1979) expresses it, childhood realism “does not necessarily mean that ideas and dreams must have the properties of the things thought or dreamt about” but only means that children “think that all things are types of physical objects” (28). To examine these possibilities, Estes, Wellman and Woolley (1989) had three-, four-, and five-year-old children make judgments about mental entities, about corresponding physical objects, about absent physical objects, and about such real but intangible things as sounds, smoke, air, and shadows. In these studies children made judgments of whether the various entities could be touched, or seen with the eyes, and so on, but also, critically, they were asked to explain their answers. Indeed, the children said that mental entities could not be seen or touched, but also (appropriately) said that absent objects could not be seen or touched, that air could not be seen or touched, and so on. However, they explained these judgments very differently in different cases. Children explained that mental items cannot be touched in part because of their peculiar reality status; “It’s not real;” “It’s not really anything.” In contrast, physical items, even insubstantial physical things, like smoke, were nonetheless explained as real. In addition and essentially, young children explained that mental entities cannot be touched because of their mental identity—“just a dream,” “only pretend,”

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“only in his mind.” In contrast, absent, not-possessed real objects cannot be touched because they are gone away, they are not there. That is, they have a distinctive status in terms of location-possession, not in terms of mental identity. Children in these studies often also say mental entities cannot be touched, or are not real, because they are inside the person, only in his “head” or “mind.” But consider the case of a real physical object that is absent because it is inside a person—such as a raisin swallowed now in the stomach. In a set of studies comparing a person (John) thinking of a raisin or a jellybean versus a person who swallowed a raisin or a jellybean, three-, four-, and five-year-old children appropriately distinguished these in their judgments and reasoning (Watson et al. 1998). About raisins and jelly beans, these young children answered “Yes” there is really a jelly bean inside John, and “Yes” if a doctor looked inside John with a special (Xray) machine, he would see a raisin inside. About thought-of raisins or jellybeans, however, young children answered “No” there is not really a jellybean inside John (not even “really inside John’s head”), and “No” if a doctor looked inside John with a special (X-ray) machine, he would not see a raisin. The judgments for mental items in the previous studies (and many others) had a negative conceptual bias: mental entities can not be touched, can not be seen, are not real; beliefs can be false. Yet, for adults, mental experiences also possess positive or affirmative aspects when contrasted to objective reality. Crucially, they afford the possibility of imaginary thought. One can think of things that are nonexistent, impossible, or fantastical; that were not, or are not, or could not be real or objective. What of children’s understanding of the possibility of thoughts about imaginary things, a further way that the mental and the real differ? Three-, four-, and five-year-olds affirm certain positive features of mental entities that also distinguish them from their physical counterparts. For example, young children judge that “No” really there are no “ants that can ride a bicycle” (or “spoons that fly”), but judge that “Yes,” they can “close their eyes and think about an ant that rides a bicycle” (or “think about a spoon that flies”) (Wellman and Estes 1986; Harris, Pasquini, Duke, Ascher and Pons 2006). Moreover, preschool children judge that mental entities—say a mental image of a balloon—can be changed “just by thinking.” Real objects—say a balloon—cannot (Estes et al. 1989; Estes 1998).

2.3 INTERIM SUMMARY In sum, young children worldwide evidence a firm intuitive psycho-physical understanding of mental states that separates the realm of the mental from

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the realm of overt, real, objective behaviors and objects. This understanding begins with simpler instances of contrasting intentions, desires, and emotions with external reality and develops into a fuller understanding of the distinctive representational world of beliefs, dreams, and ideas. In this, preschool children come to understand that mental-representational kinds of things are both less than and more than the real: they cannot be touched or seen, are not material, yet they include the fantastical and the fictional— events and things not possible in the real world of physical objects and occurrences. The mental, unlike the real, can be false or imaginary, can be nonmanifest in action or expression, can be influenced “just by thinking.” In short it has a distinctive kind of “intentional” existence. This naïve psychophysical dualism of early childhood is intriguing in its own right. For example, it encompasses an intuitive ontology and has a notable coherence, worthy of description as naïve theory, that supports a multitude of inferences and explanations. The breadth and systematicity of intuitive psycho-physical dualism is equally important in providing the basis for reflective ideas, which go beyond the boundaries of ordinary intuition. It is this development to which we now turn.

3. FROM INTUITIVE UNDERSTANDING TO REFLECTIVE IDEAS Beyond framing the everyday existence of intentional agency, we argue that initial intentional conceptions provide the basis for reflective ideas that extend beyond intuitive experience. Reflection in this sense extends beyond the intuitive in two fundamental directions: immanent (that is, in-dwelling in the body) and transcendent. In the first case, children develop a more elaborate and explicit psychology, grounded in developing ideas about the causal dependence of the mind on the physical brain. Based on early appreciation of the existence of intentional mental acts and states, children develop explicit ideas about the nature of “mind” and “brain” and the existence of unconscious cognitive processes. In the second case, children entertain the possibility of intentionality extending beyond the ordinary constraints of reality, including ideas about life after death, souls, and supernatural beings. In this second sense, intuitive understanding provides the ground for naïve metaphysical and theological ideas. How do reflective ideas about the mind differ from the intuitive mentalistic understandings we have just described? Our distinction between intuitive and reflective ideas owes a debt to Sperber’s discussions of intuitive versus reflective beliefs (Sperber 1996; 1997). Sperber describes intuitive beliefs as the products of “spontaneous . . . perceptual and inferential processes (that) paint a commonsense picture of the world” (1996, 89). Reflective beliefs then stem from “interpretations” of intuitive beliefs derived

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by explicit reasoning or derived from an explicit external source (e.g., a teacher). In our thinking, first-order concepts of intentionality, the early developments we have described above, are intuitive in something like this sense. But Sperber also claims that intuitive beliefs are “fairly superficial, more descriptive than explanatory” (89). To the contrary, and as we have outlined, young children’s early concepts of intentionality themselves penetrate to deep, nonobvious properties of mentality and are richly explanatory. They are intuitive yet theoretical. So, in our view, early in life, basic inferential processes provide for the development of organized conceptual systems that serve to practically explain and predict ordinary actions, objects, and events and serve to distinguish intentional states from physical ones (Wellman 2002). Nonetheless these organized conceptual systems can be usefully termed intuitive, and thus the province of intuitive ideas, in the sense that they constitute the way in which agency is initially experienced. Very early in development, psychological agency appears to the child to be a straightforward part of experienced reality along with and in contrast to physical causality. Rapidly achieved in childhood, these ideas simply frame commonsense childhood understanding of the world. Because children engage in but are unaware of this underlying cognitive framing, mental as well as physical kinds of things appear to be simply given, constituting the indubitable nature of reality. Hence, children are intuitive psycho-physical dualists. Reflective ideas, in contrast, are derived from these first-order conceptions and mark attempts to understand or comprehend them (rather than simply employ them). Reflective ideation, thus, takes these first-order intuitive conceptions as object, and functions to consciously construct further conceptual systems about them (Johnson 2000). To consider this development further, compare the intuitive theory that underlies commonsense understanding with the reflective ideas of philosophers. Intuitive concepts of mind and matter provide a ground for philosophical reflection. What is intentionality about? How does mind differ from the real world? However, philosophical thought about mind or matter is distinctively a second-order process that is consciously theoretical and analytic. That is, philosophers engage in rigorous efforts to critically examine, generate, and systematize intuitive (and reflective) ideas. But we contend that there are also everyday, naïve reflective ideas. Everyday reflective ideas are not so developed as philosophers’, but they too reflect on the nature of the mental and physical worlds (as given in intuitive thinking). They originate in childhood from naïve cognitive reflective tendencies. Thus, for example, children have early first-order experience with the nature and existence of thoughts and things, as described above; in contrast the nature and existence of “mind,” “brain” or “soul” must be reflectively inferred. In his early work, Piaget (1929) was distinctly concerned with children’s spontaneous reflective understandings. He took care to distinguish his interest in children’s reflections from their intuitive understanding (see John-

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son 2000). To elicit spontaneous reflections, he deliberately asked children questions that extended beyond their intuitive experience (e.g., “What does it mean to think?” “What do you think with?”), with the goal of exploring “how their ideas are formed in response to certain questions and principally in what direction their spontaneous attitude of mind tends to lead them” (123). Piaget regarded these naïve reflective attitudes as “children’s philosophies,” distinguishing these fragmentary tendencies from the more formulated collective ideas of adults and the still more systematically elaborated theories of philosophers. In any case, reflective ideas extend beyond the basic intuitions of younger children. As we see it, intuitive appreciation of the intentional provides the groundwork for reflective ideas. Intuitive ideas are thus a necessary, but not sufficient, condition for reflective ideas, which require as well either spontaneous reflection (of the sort that interested Piaget) and/or the input of collective ideas. Consider, for example, children’s developing understanding of the concepts “mind,” “brain,” or “soul.” These are reflective in referring to things that extend beyond direct experience as constituted by intuitive theories. But they are also terms and constructs shaped by collective ideas and practices, in one language community or another. In direct contrast to Piaget’s emphasis on children’s spontaneous reflections, Harris and Koenig (2006) have recently emphasized how much of children’s knowledge about the world comes from cultural information that extends beyond their personal experience. In their view such knowledge is necessarily derived from input from others, which they term testimony; having no direct experience with things like brains and souls, children essentially rely on information from others. In our view, collective ideas from external sources are undoubtedly important, but so too are spontaneous ideas. Understanding collectively presented ideas and notions is a constructive process, a process that draws upon a background of spontaneous inferences. The key point, that we will elucidate in what follows, is that children’s reflective ideas about mind, brain, soul, and God—whether inspired spontaneously or collectively—are only possible because of, and are dependent on the groundwork of, early-achieved, intuitive, mental-state understanding. 3.1 Immanent Ideas about Mind and Brain We have described how, during the preschool years, children become competent in making inferences about the interplay of intentions, perceptions, desires, and beliefs in understanding human action and in distinguishing thoughts from objects or from overt actions. Now, we will consider how this intuitive theory expands into the development of explicit ideas about the nature and function of the mind as well as the brain.

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The term “mind,” rather than “brain,” is more commonly used by young children in everyday language (Wellman and Hickling 1994; Courriveau, et al. 2005). But children begin to respond sensibly (although not accurately) to questions about both the brain and the mind toward the end of the preschool years. In doing so, children tend to misidentify brain and mind as the same sort of thing, and use both to refer to the faculty of intellect. More generally, children’s early-achieved intuitive capacity to distinguish particular mental states and acts, such as feelings, intentions, and thoughts, provides the ground for more general ideas about distinct “faculties” of mind, particularly sensation, volition, and intellect. “Faculties” of mind have been commonly distinguished from ancient times (Maher 1915) as generalizations over more particular kinds of states and experiences. Similarly, childhood generalizations emerge that are direct extensions of intuitive understanding. However, in addition, thinking about such generalized mental faculties helps generate explicit, still more general, reflective consideration of the mind (and brain). To illustrate, Johnson and Wellman (1982, Experiment 2) asked children in first, third, fifth and ninth grades whether they could perform various kinds of functions without a brain, and separately without a mind. Items included mental acts (think, remember), perception (see, hear), feelings (feel interested, feel happy), voluntary action (walk, talk), and involuntary behavior (breathe, sneeze). The youngest children in this and other research (see, e.g., Richert and Harris 2006) respond identically when asked about the brain and the mind, conceiving them as exclusively needed for purely “mental” acts. More specifically, in the early school years children tend to explain that they only need eyes to see, ears to hear, and legs to walk, just as they only need the brain (and likewise the mind) to think or remember. By fifth grade children are generally aware that the brain is necessary for all functions (although less so for involuntary action), while they distinctly regard the mind as exclusively necessary for mental acts and feelings (Johnson and Wellman 1982). While even the earliest ideas about brain function are partly culturally communicated (e.g., “use your brain” or “he’s brainy”), they equally reflect the limits of children’s intuitive understanding. Dependent on a first-order, intuitive awareness of mental states, children initially have no idea that brain processes may underlie all experience and behavior—walking, breathing, seeing, in addition to thinking. Moreover, children initially assume that most of the time people (self included) go about their business without thinking at all (Flavell, Green and Flavell 1995). Thus, one key to later developmental changes is the more reflective awareness that “thought” is not merely an occasional (conscious) mental occurrence, but rather streams along constantly. Equally, thought can be seen to underlie all perception and action. Thus, in middle childhood, after age seven or eight or so, children explain that the brain is needed to see and walk because the brain

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“tells you what you see” and “tells you where you are going” (Johnson and Wellman 1982). One manifestation of these later middle-childhood developments is that children come to both differentiate and integrate the concepts of mind and brain. Although first graders judged the brain and mind to be functionally equivalent (as mental), Johnson and Wellman (1982) found that that they nonetheless inferred that they were separate things in the head. And, when asked if a person without a brain could have a mind (or vice versa) young children said “yes.” By third grade, however, children judged the brain and mind to be either completely interdependent (i.e. a person could not have one without the other) or judged the mind to be singularly dependent on the brain (i.e., a person could not have a mind without a brain, although they could have a brain without a mind). With regard to ontological status, when Johnson and Wellman (1982) asked children to separately judge whether the brain and mind could be seen and touched upon opening the head, the percentage of children who consistently judged the mind to be intangible and invisible in contrast to the brain being tangible and visible was .00, .25, .62 and .92 for grades 1, 3, 5 and 9 respectively. Similarly, Corriveau, Pasquini and Harris (2005) found that five- to seven-year-olds exhibited considerable confusion about the potential visibility (and thus materiality) of the brain versus the mind. Thus, in later childhood, as children come to differentiate the conscious “mind” from the unconscious-functioning brain, they also distinguish the ontological status of the mind and brain. Children’s initial reflective ideas about the mind (and brain) as the seat of exclusively mental activities (the intellect) are confirmed and extended in studies where children are asked to imagine the consequences of a brain transplant. In various, replicated studies (Johnson 1990; Gottried, Gelman and Schultz 1999; Corriveau et al. 2005), children have been asked to make inferences about the consequences of imagined brain transplants, such as between a pig and a person, or between two people. For example, in Johnson’s (1990) original study, children in kindergarten through fourth grade were told a story about the attributes of a pig named Garby, who, unlike the child participant loved to sleep in slop (versus in a bed), had pig friends (versus child friends) and so forth. Children were then asked to pretend that something happens to Garby: “We’ll pretend to take your brain out of your head (referring to the child participant) and put it inside Garby’s head.” Results in this and other studies consistently show that until about second grade (about age seven or eight), children typically fail to recognize the profound consequences that such a transplant would have on a person’s whole being and identity. That is, while children at this age first acknowledge that the brain is needed for the capacity to think, they do not conceive the brain as essentially containing one’s personalized mental contents (my memories, thoughts), behavioral dispositions (my preferences), and

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identity. Thus, children recognize that you need a brain in order to think, but they judge that a different brain would not result in one having different thoughts, memories, preferences and the like. Indeed, young children are equally unimpressed when asked about the consequences of transplanting the entire insides of a person (Gottried et al. 1999). Not until age seven to eight years do children typically grasp that the brain (or some sort of insides) is essential to a person’s whole being and identity. These transplant studies point to the difference between the intuitive awareness that mental states happen privately, “inside,” and the reflective idea that such states are essentially dependent, for their identity, on “something” inside the body. The intuitive preschool awareness that mental states—desires, feelings, thoughts, and so on—are private kinds of things does not include the idea that something in the body is necessary for such states nor that such embodiment individualizes mental states. Only gradually do children acquire the idea that all these different activities and faculties are more deeply dependent on a functioning brain/mind, and that the mind has a “mind of its own” (Wellman and Hickling 1994). The data we have discussed are undoubtedly influenced by culture. Knowledge about brain function is certainly a cultural achievement; across history and societies there have been different ideas about where mental attributes are grounded in the body (Wierzbicka 1992)—in the head, in the heart, in the viscera. Nonetheless, all cultures, it seems, distinguish faculties like perception, linked with external body parts, from thinking, located internally. In this regard, fixing on the brain per se for the embodiment of mind is a collectively sponsored reflective idea. Still, there appear to be universal ways in which the limits of intuitive understanding shape development of reflective ideas. In our account, intuitively evident differences in kinds of intentionality (seeing vs. thinking) readily lead to ideas about faculties (sensation vs. intellect) which are grounded externally (eyes, ears) as well as internally (brains, hearts) in the body. Based on a limited initial sense that mental acts happen occasionally, not consistently, children first construct a very impoverished idea of the mind identified with a faculty of intellect, with no awareness that mind is generally important for human intentionality and identity. That idea, we propose, is a universally later-developing folk achievement. 3.2 Transcendental Tendencies Paralleling their developing ideas about the inner workings of the mind/brain, school-age children are also developing ideas about the possibility of intentionality transcending the boundaries of the body altogether. Indeed, increased appreciation of the mind as more mental versus the brain as more bodily is instrumental for forming and acquiring transcendental

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ideas. Three illustrations of this transcendental possibility are described in the subsections that follow. First, we review evidence that children spontaneously tend to infer that mental functions can continue after physical death. Second, beyond reflective understandings of “mind” (as we have just discussed it) we consider evidence that children develop the concept of “spirit” or “soul.” Finally, children readily imagine the possibility of supernatural agency, in which intentionality is freed from (i.e., transcends) its ordinary constraints. 3.2.1. Transcending Death During middle childhood, not only do children increasingly conceive of the dependence of ordinary mental and behavioral function on a physically functioning embodied brain (integration); they also increasingly appreciate numerous distinctions between mind, body, and behavior (differentiation). Increasing differentiation of the mind from the brain and the body allows children to increasingly, and intriguingly, imagine the possibility of mind transcending the death of the body. By the early school years children come to understand that death terminates bodily functions, is applicable to all living things, and is irreversible (Slaughter, et al. 1999). Yet, in a series of studies, narrating the death of a (anthropomorphized, cognizant) mouse character, Bering and Bjorklund (2004) found that while elementary school children typically recognized that death terminates bodily functions, including function of the brain, they nonetheless tended to infer that mental states would continue. Children’s ideas in this regard, at first blush, appeared remarkably disjointed. For example, when asked whether the dead mouse could get sick again, be alive again, or have a working brain, children overwhelmingly said no. But when asked parallel questions about whether the mouse would still feel sick, or know he’s alive, or think, children overwhelmingly said yes. Children’s ideas about death thus appeared to depend upon whether they were thinking about the physical organs of the body/brain or more purely focusing on spontaneous acts of mind. Harris and Gimenez (2005) pursued this further and their data present a more comprehensive picture. They asked children, ages seven and eleven years, about the consequences of death of a grandparent in two different contexts, one medical, the other religious. Given the medical context, children at these ages typically claimed that all functions, bodily and mental functions, ceased. Given the religious context, in contrast, they tended to claim that mental functions would continue after death. Thus the data showed contextual differences (religious-medical) and “functional” differences (body versus mind). Finally and importantly, the data also showed clear developmental trends: younger children were more likely to think all

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functions cease at death, older children less so. In sum, the oldest children were most likely to deny that functioning ceased at death, they were mostly likely to deny it for mental (over bodily) functions and in the religious (over the medical) context. And to the extent that younger children ever denied the cessation of function with death, it was for mental functions in the religious context. Similarly, Polling and Evans (2004) show a rudimentary biological understanding of death in preschool and early school-age children that precedes a transcendental belief in continuations of some functions beyond death, which is more likely to be invoked by older children and adults, and for humans rather than for non-human animals. In these studies the youngest children (who are old preschoolers) seem to easily focus on cessation of bodily function, operating perhaps with a simple (intuitively grounded) biological rule—death eliminates all functions. Other evidence suggests that most young children abide by this intuitive understanding when explicitly presented with causal information that signals biological death (e.g., killing). Presented with stories of the killing of animals and people, Barrett and Behne (2005) found that four-year-old German as well as Shuar children (from the Amazon region of Ecuador) were well aware that death, unlike sleep, would eliminate mental as well as motor functions. However, the data also show spontaneous ideas about mind transcending death in somewhat older children, as well as developmental and contextual differences in doing so. These reflective ideas are especially and increasingly apparent as children move into middle childhood. This general picture of developing reflective thinking about “immortal” possibilities holds, amidst intriguing variation, across cultures. Astuti and Harris (2006) report Vezo children in rural Madagascar exhibit a grasp of the finality of death well before they begin to entertain the idea that mental functions could persist after death. In this case this developmental pattern appears to follow the course of cultural exposure. Early on, Vezo children are richly exposed to the consequences of bodily death (including the rotting of corpses) while they are protected from ideas about spirits (deemed inappropriate for children). Nevertheless, once youth begin to imagine the spirit world, their ideas appear to draw on intuitive divisions between body and mind. Thus, like Bering and Bjorklund (2004), Astuti and Harris found that for older children cognitive functions (knowing, remembering, missing one’s children) were judged more likely to continue after death than psycho-biological functions (seeing, hearing, feeling hungry). Notably, Vezo participants judged the spirit to be most likely to continue after death, as compared to the mind (less likely) and body (least likely). In sum, children commonly develop two reflective notions about death. On the one hand, as they become increasingly aware that the mind is contingent on the body, they can infer the mind’s death. On the other hand,

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they also come to imagine mentality operating independent from the body. These two notions operate with regard to different mental faculties and contexts. As Aristotle long ago noted, mental contents in the form of sensations, like seeing, hearing and feeling hungry, have obvious bodily causes. The faculty of intellect (thoughts, memories, dreams), however, is not so clearly embodied. Thus, when ideas about transcending death (of the body) begin to appear, they appear most readily for faculties that focus on those distinctive acts of mind most removed from bodily constraints. 3.2.2 The Idea of Soul In religious traditions, the faculty of a person that most likely transcends death is the spirit or soul. And in the Vezo data (from Astuti and Harris 2006) children distinguish spirit and mind in their responses. In focusing on children’s concepts of mind, however, developmental researchers have largely neglected the matter of soul or spirit. In part, this neglect seems to rest on an accepted Cartesian tendency to refer to mind and soul interchangeably (cf. Bloom 2004). More careful attention, however, shows that for lay adults and for children these ideas are separable and distinct. In two experiments, Richert and Harris (2006) found that children’s idea of soul differs from their idea of mind and brain. In the first experiment, children ages four to twelve years were presented with a vignette describing a ritual baptism of a baby and then asked about the difference the baptism would make. They were asked about the location of the difference— whether outside (visible and tangible) or inside—and whether the baby’s mind, brain or soul would be different after the baptism. Even the youngest group of children (age four to six) showed some awareness that baptism results in an invisible/intangible change inside the body that distinctly changes the soul. Across ages, children regarded baptism as mostly changing the soul, somewhat changing the mind, but having almost no effect on the brain. In their second experiment, Richert and Harris (2006) more directly probed children’s ideas about properties and functions of the soul as compared to the mind and brain. Modeled after Johnson and Wellman’s (1982) study, children were asked whether various kinds of functions—cognitive, non-cognitive, and biological—would continue without the presence of a brain, mind, or soul. Children were also asked whether babies have these faculties, whether they change and develop over time, and whether the baby would be the same if this faculty was taken away. The results consistently showed that children did not identify the soul and mind. While school-age children readily judged that cognitive function would be disrupted without a brain or mind, they typically judged that such functions would continue undisrupted without a soul. The brain and mind were also more often

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judged to change and develop than the soul. In response to open-ended questions, children distinctively associated the soul with spiritual functions, such as moral purpose, life force and invisible spirit. Earlier we argued that developmentally the idea of mind originates from thinking about mental attributes and faculties. It is part of a causalexplanatory theory of human behavior. Conceivably, the idea of “soul” may be just one more reflective step beyond “mind.” However, we want to argue for the plausibility of a more radical proposal. This proposal emphasizes instead something like the classic idea of soul as constituting the essential unitary “I” that lies behind the multifarious states and faculties attributed to it. On this account, an initial reflective idea of soul would not be directly derivative from the idea of mind. Unlike Descartes, children do not infer that their soul exists because thinking exists (“I think therefore I am”). On the contrary, the idea of soul derives from a more rudimentary consciousness of existence (“I am therefore I am”). Bloom (2004) suggests that an intuitive notion of soul is evident in infancy, manifest in data showing that five-month-olds do not expect intentional agents to be limited by the constraints of material existence (Kuhlmeier, Bloom and Wynn 2004). The larger body of evidence, however, supports the more likely conclusion that infants originally conceive of agents as both material and intentional (Spelke, Woodward and Phillips 1995; Saxe, Tzelnic and Carey 2006). Thus, as we described it earlier, infants early on see human agents as compounds of physical matter and mental form—intentional agents engaged in behavioral actions. Only later do children reflectively construct an idea of the soul. On this later-developing account, while the ideas of mind and soul both stem from an understanding of intentionality, they may be constructed within fundamentally different conceptual frames. The idea of mind develops within a causal-explanatory framework that serves to explain human behavior. The idea of soul may develop instead within an interpretive framework that gives weight and meaning to individual existence. Along this line, Jesse Bering (2003, 2006) has argued that a folk idea of the soul rests on construction of an existential conceptual domain, which draws upon but is distinct from children’s understanding of mind. This existential domain rests upon the capacity “to represent intentions at higher orders of recursiveness” (e.g., “She knows that I know that she knows,” and so on) which enables conscious reflection upon the meaning of life experiences (Bering, 2003, 8–9). Beyond inferences about intentional behavior, a separable existential theory-of-mind (EtoM), is, on this proposal, a system that is uniquely about the intentional meaning of individual existence. At the heart of this proposal is a reflective turn of the sort we have been characterizing. In this reflective extension, an intuitive capacity to think about purposes in particular (for someone’s specific acts) turns to thinking

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about purposes more generically. This can be seen, for example, in children’s reflecting on why natural kinds exist—such as the initial origins of dogs or birds or humans (Evans, 2001; Kelemen, 2004). But additionally, human beings commonly wonder “why am I here?” puzzling over the meaning and purpose of individual existence. In his account Bering (2006) emphasizes that the idea of an essential individual “kind” in the case of persons may be unique because kind concepts otherwise define categories (e.g., species) not individuals. The self thus emerges as a distinctive ontological entity in the world, generating (spontaneously and collectively) a constellation of ideas all its own. This is an important part, Bering contends, of why “mind” and “soul” have differing developmental paths. This specific account is admittedly speculative; however, there is clear emerging evidence that young school-age children construct different ideas about mind and soul or spirit. The more basic and less speculative point is that ideas of both mind and soul spring from spontaneously and collectively fueled reflection over an initial intuitive understanding of intentionality. 3.2.3 Supernatural Beings The capacity to reflect on the existence of intentionality, independent from its normal embodiment (evident in both reflective ideas about a soul and reflective ideas about mentality after death), provides the basis for widely imagining the existence of supernatural beings. The recent cognitive science of religion (McCauley and Whitehouse 2005) has focused on how such ideas are naturally formed and readily acquired, spread, and retained—the “naturalness of religion” hypothesis (Barrett 2002; Boyer 1994). As Boyer (1994) summarizes, ideas about supernatural beings appear to be created (naturally) in the following way: 1. Start with the basic idea of an intentional agent. 2. Disembody it and further modify it in an unusual way (e.g., make it infallible, or omnipotent). 3. Use such supernatural beings to account for difficult to explain occurrences (difficult given intuitive naïve psychology, physics and biology), for example, how someone in a death-like coma came back to life. 4. Have others persuasively use them for those explanatory purposes too, plus engage each other in practices that make supernatural beings and actions memorable and important via special rituals, secret practices, and compelling emotional “pageantry.” In this account, clearly, cognitions begin ordinary; understanding (all) agents and beings starts out from a simple intuitive awareness of the intentional agency of living bodies. Thinking about supernatural beings is thus

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grounded in understandings of ordinary beings, embellished via ordinary processes of cognition. Developmentally, (using such ordinary processes) children can and do reflectively generate new ideas, ideas about the extraordinary, and they can process teachings about and collective ideas about the extraordinary. Thinking about supernatural beings, in particular, thus arises reflectively from imagining intentionality apart from its particular natural embodiments. This capacity to readily imagine supernatural possibility appears to develop at the end of the preschool years. At this point, children begin to spontaneously distinguish between ordinary and extraordinary, or ‘magical’, causation (as shown, e.g., in research by Rosengren and Hickling 1994), readily imagining the possibility of all sorts of superpowers. At the same time, collective ideas of supernatural beings (God, superheroes, and the like) are presented to children and stand out as cognitively attractive and memorable, making them easily spread and retained over time. As Boyer (1994) has emphasized, these ideas are marked by cognitively viable combinations of intuitive and counterintuitive properties. Supernatural attributes are distinguished as “special” only against a background of otherwise ordinary intuitive constraints. Violation of (some, not all) constraints makes these beings special, while the intuitive background makes them intelligible. Thus, on this account, supernatural ideas emerge reflectively but, necessarily, against a background of intuitive constraint. For example, consider the development of children’s ideas about the “otherness” of God. In an influential study, Barrett, Richert and Driesenga (2001) demonstrated that just as children come to appreciate the constraints of ordinary human knowledge and belief, they recognize that God has “other” powers. The “surprising contents” task, a standard measure of children’s understanding of false-belief, was used to compare children’s inferences about God versus Mom. Children were presented with a cracker box which they readily expect to contain crackers. The box was then opened to reveal that it contained small rocks (surprising contents). Closing the box again, children were then asked to infer what Mom, or God, would think is in the box, when first presented with it shut and unopened. Before age 4, Barrett found that children assumed that Mom and God alike would share knowledge of reality (the classic false-belief error, and thus a general failure to understand false belief). After age five, however, when children recognized the limits of human knowledge (Mom would be mistaken) they allowed a more “special” power to God, who would know the contents. This finding, demonstrating children’s awareness of God’s “special” mental power, has been replicated with Maya children in Mexico (Knight, Sousa and Barrett 2004). It has also been extended to the attribute of “immortality” (as discussed earlier, but in this case God’s immortality) and to include children who distinctly lack religious instruction. As an example, Gimenez-Dasi, Guerro and Harris (2005) asked three- to five-year-old

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Spanish children, raised in either religious or secular schools (which parents selected deliberately for being secular), to judge the capacities of a friend and those of God. They not only asked about knowledge constraints (including the surprising contents task) but also biological constraints regarding mortality. Extending the previous work, they found that at age five years, children not only distinguished God as special in terms of knowledge but also in terms of immortality. Moreover, children readily picked up this idea of God even in the absence of deliberate religious tuition. It is important to recognize the simplicity of these initial ideas about supernatural powers. There is no evidence that children have any elaborate ideas about “omniscience” or “immortality.” Rather, they are able to begin to imagine the absence of a particular intuitive constraint. In this regard, supernatural beings are constituted by selectively marking one or more intuitive constraints as “not” operative. This mark is counterintuitive in the sense we have described throughout this chapter—in contrast to first-order intuitive understanding of intentionality and psycho-physical dualism. Because they are (moderately) counterintuitive such ideas are highly salient and easily acquired. While salient, it is also important to recognize that these supernatural attributes are at first largely empty of meaning in themselves. And indeed they are hard to grasp consistently and meaningfully for most folk. Thus, while God’s radical otherness is commonly acknowledged and explicated in theological theory, such ideas appear to have much less impact in ordinary religious practice among adults as well as children. In this regard, Barrett and Keil (1996) asked adults to make judgments about God’s qualities in two contexts. When simply asked about God’s powers, adults readily distinguished God as radically other—for example, completely omniscient and unconstrained by perceptual limitations. But when asked to make inferences about God in a narrative context, they inevitably interpreted exceptional acts to occur within other more ordinary constraints—for example, God could only attend to a few prayers at once. In other words, the radically counterintuitive idea of a completely unlimited Being was empty or noninfluential when trying to make sense out of God’s behavior in context. As theologians have long noted, not much can be said about a Being who is completely “other.” Without limits, agency loses its purpose, meaning, drama and sense. And, developmentally, it is from limits—the constraints that intuitive psychology attributes to the ordinary mind and lives of intentional agents—that ideas of the supernatural arise as reflection imagines the suspension of those ordinary limits.

4. CONCLUSION In this chapter we present a developmental story, anchored in empirical data as to the accomplishments and discoveries of childhood. In this story, intuitive concepts originally frame the understanding of everyday agents,

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actions, objects, and events. These intuitive concepts then provide the input for more explicit reflective ideas about both immanent psychology (mind/brain) and transcendental possibility (supernatural intentionality). To summarize, our developmental story has four overlapping levels. First of all, the infant cognitive system rapidly manifests a variety of processing distinctions that serve to make practical sense of a world of objects and agents. During the preschool years, these initial intuitive processes and awarenesses become organized into relatively coherent intuitive theories that frame children’s ordinary understanding of intentional agents (as well as biological entities and physical objects in the world). In particular, an intuitive theory of mind provides a first-order understanding of belief-desire agency. In the preschool years intuitive theory primarily frames the child’s “reality.” Yet, the output and structure of these intuitive theories also provide a stimulus for reflective ideas. These originally fragmented reflective notions, consisting of both spontaneous and collective ideas, emerge particularly in middle childhood. Beyond the generation of reflective ideas, however, stands the capacity to think critically about these reflective ideas themselves. Critically thinking about reflective ideas can eventuate partially (in lay adults) or more fully (in philosophers and theologians) in truly reflective theory. This requires thinking about theoretical possibilities, independent of intuitive assumptions. In Piaget’s terms, possibility (ideas) becomes higher than actuality (intuition), which opens the door to radical revision of the very nature of assumed reality. Reflection at this highest level also exposes deeply incoherent, reflective ideas. Immanent and transcendent ideas that originally function in different contexts for different purposes (e.g., medical and religious) may be considered together. Having conceptually divided the world into essentially different kinds of things, the final ontological questions concern how these things are connected together. How is it that mind and body, soul and matter, ideas and reality are related? Is mind just a product of matter (materialism), or is matter a reflection of mind (idealism)? Is ultimate reality material or spiritual? We have not addressed this fourth phase of reflective theory in our chapter. But other chapters in this volume do so. We have concentrated instead on earlier developments. Why? These earlier developments are intriguing in their own right and they set the infrastructure for any later reflective theorizing. Reflective questions and reflective theorizing—evident in societies worldwide and throughout human history—are framed by ideas that are grounded in the intuitive understandings of childhood.

ACKNOWLEDGMENTS Support for the preparation of this chapter was provided by NICHD grant HD-22149 to Wellman.

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Estes, D., H.M. Wellman, and J.D. Woolley. 1989. “Children’s understanding of mental phenomena.” In Advances in Child Development and Behavior, edited by H. Reese. New York: Academic Press, 41–87. Evans, E.M. 2000. “The emergence of beliefs about the origins of species in schoolage children.” Merrill-Palmer Quarterly 46 (2): 221–54. ———. 2001. “Cognitive and contextual factors in the emergence of diverse belief systems: Creation versus evolution.” Cognitive Psychology 42: 217–66. Flavell, J.H., F.L. Green, and E.R. Flavell. 1986. “Development of knowledge about the appearance-reality distinction.” Monographs of the Society for Research in Child Development 51 (Serial No. 212). ———. 1995. “Young children’s knowledge of thinking.” Monographs of the Society for Research in Child Development, entire serial No. 243. Flavell, J.H., X-D. Zhang, H. Zou, Q. Dong, and S. Qi. 1983. “A comparison between the development of the appearance-reality distinction in the Peoples Republic of China and the U. S.” Cognitive Psychology 15: 459–66. Gardner, D., P.L. Harris, M. Ohomoto, and T. Hamazaki. 1988. “Japanese children’s understanding of the distinction between real and apparent emotion.” International Journal of Behavioral Development 11: 203–18. Gelman, S.A. 2003. The essential child. New York: Oxford University Press. Gergely, G., Z. Nadasdy, G. Csibra, and S. Biro. 1995. “Taking the intentional stance at 12 months of age.” Cognition 56: 165–93. Gimenez-Dasi, M., S. Guerro, and P.L. Harris. 2005. “Intimations of immortality and omniscience in early childhood.” European Journal of Developmental Psychology 2 (3): 285–97. Gopnik, A., and V. Slaughter. 1991. “Young children’s understanding of changes in their mental states.” Child Development 62: 98–110. Gottried, G.M., S.A. Gelman, and J. Schultz. 1999. “Children’s understanding of the brain: From early essentialism to biological theory.” Cognitive Development 14: 147–74. Harris, P.L. 1989. Children and emotion. Oxford: Basil Blackwell. Harris, P.L., E. Brown, C. Marriot, S. Whithall, and S. Harmer. 1991. “Monsters, ghosts and witches: Testing the limits of the fantasy-reality distinction in young children.” British Journal of Developmental Psychology 9: 105–23. Harris, P.L., K. Donnelly, G.R. Guz, and R. Pitt-Watson. 1986. “Children’s understanding of the distinction between real and apparent emotion.” Child Development 57: 895–909. Harris, P.L., and M. Giminez. 2005. “Children’s acceptance of conflicting testimony: The case of death.” Journal of Cognition and Culture 5: 143–64. Harris, P.L., and R.D. Kavanaugh. 1993. “Young children’s understanding of pretense.” Monographs of the Society for Research in Child Development 58, (Serial No. 231). Harris, P.L., and M.A. Koenig. 2006. Trust in testimony: How children learn about science and religion. Child Development 77: 505–24. Hickling, A.K., and H.M. Wellman. 2001. “The emergence of children’s causal explanations and theories: Evidence from everyday conversation.” Developmental Psychology 37: 668–83.

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Johnson, C.N. 1990. “If you had my brain, where would I be? Children’s understanding of the brain and identity.” Child Development 61 (4): 962–72. Johnson, C.N., and H.M. Wellman. 1982. “Children’s developing conceptions of the mind and brain.” Child Development 53 (1): 222–34. Johnson, S.C. 2000. “The recognition of mentalistic agents in infancy.” Trends in Cognitive Sciences 4: 22–28. Keil, F.C. 1979. Semantic and conceptual development. Cambridge: Harvard University Press. Kelemen, D. 2004. “Are children ‘intuitive theists’? Reasoning about purpose and design in nature.” Psychological Science 15: 295–301. Knight, N., P. Sousa, J.L. Barrett, and S. Atran. 2004. “Children’s attributions of beliefs to humans and God: Cross-cultural evidence.” Cognitive Science 28 (1): 117–26. Kristen, S., C. Thoermer, T. Hofer, G. Aschersleben, and B. Sodian. 2006. “Skalierung von theory of mind Aufgaben” (Scaling of theory of mind tasks). Zeitschrift für Entwicklungspsychologie und Pädagogische Psychologie 38: 186–95. Kuhlmeier, V.A., P. Bloom, and K. Wynn. 2004. “Do 5-month-old infants see humans as material objects?” Cognition 94 (1): 344–59. Kuhlmeier, V., K. Wynn, and P. Bloom. 2003. “Attribution of dispositional states by 12-month-olds.” Psychological Science 14: 402–8. Lagattuta, K.H., and H.M. Wellman. 2001. “Thinking about the past: Early knowledge about links between prior experience, thinking, and emotion.” Child Development 72: 82–102. Legerstee, M. 1991. “The role of person and object in eliciting early imitation.” Journal of Experimental Child Psychology 51: 423–33. Liu, D., H. M. Wellman, T. Tardif, and M.A. Sabbagh 2008. “Theory of mind development in Chinese children: A meta-analysis of false-belief understanding across cultures.” Developmental Psychology, 51, 105–35. Maher, M. 1915. Psychology Empirical and Rational. New York: Longmans Green and Co. McCauley, R.N., and H. Whitehouse. 2005. “Introduction: New frontiers in the cognitive science of religion.” Journal of Cognition and Culture 5: 1–13. Meltzoff, A.N. 1995. “Understanding the intentions of others: Re-enactment of intended acts by 18-month-old children.” Developmental Psychology 31: 838–50. Moore, C., and V. Corkum. 1994. “Social understanding at the end of the first year of life.” Developmental Review 14: 349–72. Muir, D.W., and S.M.J. Hains. 1993. “Infant sensitivity to perturbations in adult facial, vocal, tactile, and contingent stimulation during face to face interactions.” In Developmental neurocognition: Speech and face processing in the first year, edited by B. de Boysson-Bardies, S. de Schonen, P. Jusczyk, P. McNeilage and J. Morton, 171–86. Dordrecht: Kluver. Olineck, K.M. and D. Poulin-DuBois. 2005. “Infants’ ability to distinguish between intentional and accidental actions and its relation to internal state language.” Infancy 8: 91–100. Peterson, C.C., H.M. Wellman, and D. Liu. 2005. “Steps in theory of mind development for children with autism and deafness.” Child Development 76: 502–17.

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Phillips, A.T., and H.M. Wellman. 2005. “Infants’ understanding of object-directed reaching.” Cognition 98: 137–55. Phillips, A.T., H.M. Wellman, and E.S. Spelke. 2002. “Infants’ ability to connect gaze and emotional expression to intentional action.” Cognition 85: 53–78. Piaget, J. 1926. The Language and Thought of the Child. New York: Harcourt, Brace and World. ———. 1929. The child’s conception of the world. London: Routledge and Kegan Paul. ———. 1972. Insights and illusions of philosophy. London: Routledge and Kegan Paul. Polling, D.A., and E.M. Evans. 2004. “Are dinosaurs the rule or exception? Developing concepts of death and extinction.” Cognitive Development 19: 363–83. Repacholi, B.M., and A. Gopnik. 1997. “Early reasoning about desires: Evidence from 14- and 18- month olds.” Developmental Psychology 33: 12–21. Richert, R.A., and P.L. Harris. 2006. “The ghost in my body: Children’s developing concept of the soul.” Journal of Cognition and Culture 6 (3-4): 409–27. Rosengren, K.S., and A.K. Hickling. 1994. “Seeing is believing: Children’s explanations of commonplace, magical and extraordinary transformation.” Child Development 65: 1605–26. Ryle, G. 1949. The concept of mind. London: Hutchinson. Saxe, R., R. Tzelnic, and S. Carey. 2006. “Five-month-old infants know humans are solid, like inanimate objects.” Cognition 101 (1): B1–B8. Searle, J.R. 1983. Intentionality. Cambridge: Cambridge University Press. Slaughter, V., R. Jaakkala, and S. Carey. 1999. “Constructing a coherent theory: Children’s biological understanding of life and death.” In Children’s understanding of biology and health, edited by M. Siegal and C. Peterson, 71–96. Cambridge: Cambridge University Press. Sodian, B., B. Schoepper, and U. Metz. 2004. “Do infants apply the principle of rational action to human agents?” Infant Behavior and Development 27 (1): 31–41. Sperber, D. 1996. Explaining culture: A naturalistic approach. Oxford: Blackwell. ———. 1997. “Intuitive and reflective beliefs.” Mind and Language 12 (1): 67–83. Tardif, T., and H.M. Wellman. 2000. “Acquisition of mental state language in Mandarin- and Cantonese-speaking children.” Developmental Psychology 36: 25–43. Tomasello, M., and K. Haberl. 2003. “Understanding attention: 12- and 18-montholds know what is new for other persons.” Developmental Psychology 39: 906–12. Watson, J.K., S.A. Gelman, and H.M. Wellman. 1998. “Young children’s understanding of the non-physical nature of thoughts and the physical nature of the brain.” British Journal of Developmental Psychology 16: 321–35. Wellman, H.M., A.T. Phillips, and T. Rodriguez. 2000. “Young children’s understanding of perception, desire, and emotion.” Child Development 71: 895–912. Wellman, H.M. 2002. “Understanding the psychological world: Developing a theory of mind.” In Handbook of Childhood Cognitive Development, edited by U. Goswami, 167–87. Oxford: Blackwell. Wellman, H.M., and M. Banerjee. 1991. “Mind and emotion: children’s understanding of the emotional consequences of beliefs and desires.” British Journal of Developmental Psychology 9: 191–214. Wellman, H.M., D. Cross, and J. Watson. 2001. “Meta-analysis of theory of mind development: The truth about false belief.” Child Development 72: 655–84.

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Wellman, H.M., and D. Estes. 1986. “Early understanding of mental entities: A reexamination of childhood realism.” Child Development 57: 910–23. Wellman, H.M., F. Fang, D. Liu, L. Zhu, and G. Liu. 2006. “Scaling of theory of mind understanding in Chinese children.” Psychological Science 17: 1075–81. Wellman, H.M., and D. Liu. 2004. Scaling of theory of mind tasks. Child Development 75: 523–41. Wellman, H.M., P.L. Harris, M. Banerjee, and A. Sinclair. 1995. “Early understanding of emotion: Evidence from natural language.” Cognition and Emotion 9: 117–49. Wellman, H.M., and A.K. Hickling. 1994. “The minds “I”: Children’s conception of the mind as an active agent.” Child Development 65: 1564–80. Wellman, H.M., M. Hollander, and C.A. Schult. 1996. “Young children’s understanding of thought-bubbles and of thoughts.” Child Development 67: 768–88. Wellman, H.M., A.T. Phillips, and T. Rodriguez. 2000. “Young children’s understanding of perception, desire, and emotion.” Child Development 71: 895–912. Wellman, H.M., and J.D. Woolley. 1990. “From simple desires to ordinary beliefs: The early development of everyday psychology.” Cognition 35: 245–75. Wierzabicka, A. 1992. Semantics, culture and cognition: Universal human concepts in culture-specific configurations. New York: Oxford University Press. Wimmer, H., and J. Perner. 1983. “Beliefs about beliefs: Representation and constraining function of wrong beliefs in young children’s understanding of deception.” Cognition 13: 103–28. Woodward, A. 1998. “Infants selectively encode the goal object of an actor’s reach.” Cognition 69: 1–34. Woolley, J. D. 1995. “Young children’s understanding of fictional versus epistemic mental representations: Imagination and belief.” Child Development 66: 1011–21. Woolley, J.D., and H.M. Wellman. 1992. “Children’s conceptions of dreams.” Cognitive Development 7: 365–80.

2 Must Psychologists Be Dualists? Alessandro Antonietti

1. INTRODUCTION In order to legitimate the autonomy and the worth of their field of study and intervention, do psychologists, as researchers and/or professionals, have to share the psycho-physical dualism which, implicitly or explicitly, permeates the Western worldview (Astington, 1993; Wellman, 1990)? This is the question on which the present chapter is focussed. To understand the aim of this chapter, it might be worthwhile starting from a fictional example. Let’s imagine that in a certain village to know what the weather is like, you have to turn to the meteorologist P, who can normally successfully forecast whether there will be rain, wind, or it will be colder the following day. To predict such weather, P observes the tracks left by the seagulls in flight, the reflections of the light on the waves of the river, the shape of the clouds, the position of the leaves on the trees etc. P’s forecasts are based upon the regular co-occurrences of these phenomena (for example, “If the seagulls fly low, then there will be rain the next day”) but the knowledge that sustains this is not just based upon of conditional clauses (“If . . . then . . . “); it also includes causal links (“It is the approaching storm that frightens the seagulls, which then fly close to their nests”). Such knowledge is internally organised, from a conceptual point of view, in a systematic manner and includes hypothetic entities which explain the phenomena in their own way (“The seagulls perceive the nearing storm because they can feel the vibrations—the hypothesised unobservable entity—that the thunder produces in the distance.” It is knowledge that may appear to us to be rather questionable, but which has its reason to be, and from a formal point of view may not be very different from structures of knowledge we trust more. 37

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At a certain point in time, another meteorologist N arrives in the same village, bringing with him a set of instruments that measure the temperature of the environment, the pressure of the atmosphere, the degree of humidity in the air etc. By means of these instruments N too starts to provide weather forecasts, which are as reliable as P’s. N’s weather forecasts depend upon elements that are different from those upon which P depends: the measuring of physical parameters, mathematical calculi etc. P and N make the same forecasts, but they apply different methods and different explicative concepts. With N’s arrival, does it still make sense to ask P what the weather will be like? It may be that there are some inhabitants of that village—the younger maybe—who are fascinated by N’s instruments and who think he stands for the future. The technology and mathematical apparatus used by N stand for precision, certainty, knowledgeable power. To the inhabitants N can be considered as being more “scientific” than P. It is likely that from now on these people will turn to N for the weather forecast. It is, however, also probable that some of the other people living in this village will continue to turn to P, out of habit, or for the opposite reasons mentioned earlier (love of tradition, lack of confidence in innovation, the idea that technology is “cold” and “not human” etc.). Besides the impressions and connotations associated to the two people and the type of methods and knowledge they employ, why should one prefer P to N? A first reason might be the following: in order to make his forecast, P collects data (the gulls’ flight, the shape of the clouds, the waves in the river etc.) which can be collected also by the naïve people living in that village. In order to forecast the weather, instead, N collects data (air pressure etc.) which cannot be recorded directly without employing certain tools and he processes such data according to procedures which cannot be understood by common people. Secondly, the “methods” applied by P are more accessible than the “methods” used by N: they are cheaper (they do not even cost anything), less cumbersome, more practical. Thirdly, P makes reference to knowledge that is more intuitive and closer to common sense. In order to give an account of his forecasts, P uses concepts (gulls’ fear, vibrations spreading through the air) which can be easily comprehended also by people of the village. By contrast, N interprets his data and supports his explanations by means of concepts that cannot be immediately understood by naïve people. Besides these differences, which concern mostly the process of knowledge diffusion and reception (and thus pertain to external history or the sociology of knowledge), is there any other reason which structurally differentiates the two kinds of forecasts made by P and N and which justifies the validity of the procedures and notions employed by P, making them worthwhile to the same extent as the procedures and notions employed by N?

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The procedures and notions used by P might, per se, be made rigorous so as to allow them to become precise and reliable as those used by N. For instance, the shapes of the clouds might be observed by means of a sophisticated system of pattern matching which could lead P to classify them in a highly analytical manner. The reliability of such a system of classification might be assessed by comparing the judgments made by different observers and by measuring the rate of inter-observer agreement. However, even if the procedure employed by P became more and more sophisticated, so reaching the same levels of accuracy as the procedures employed by N (and thus resulting as equally “scientific”), they still continue to be applied to something (for instance, the nuances of the colours) which is different from that (for instance, the pressure of the air) to which N applies his procedures; therefore P would proceed in a different manner to N. The knowledge elaborated by P (by considering “knowledge” as the complex of the procedures employed, the kind of data collected, and the interpretations drawn) might be led, from an abstract point of view, to match the same scientific requirements which are satisfied by the knowledge elaborated by N, even if the former knowledge had a different referent than the knowledge elaborated by N. P would encounter serious difficulties and would risk being no longer authorized to operate, if N succeeded in showing that data (the shapes of the clouds, the colour of the leaves etc.) on which P grounds his forecasts and the subsequent interpretations (“Gulls are afraid of the incoming storm”) can be adequately described and explained by means of the same elements (air pressure etc.) to which N makes reference. In this case, apart from the historical-sociological remarks mentioned previously or the idiosyncratic reactions of his “customers” (who might love what is familiar, enjoy the gulls’ flight, be fascinated by the water reflexes etc.), we cannot understand how P could defend his difference from N. Thus, the crucial question is: is there something, in the knowledge elaborated by P, that is not included in the knowledge elaborated by N and which N cannot take into account? The example of the two meteorologists shows blatant analogies with the relationships between psychology. Psychology—whose analogue is the meteorologist P—describes and explains human situations and conducts by making reference to mental experiences (sensations, memories, emotions etc.). Nowadays a different kind of knowledge (corresponding to N in the example) tries to give an account of such situations and conducts by making reference to reuptake of neurotransmitters, modifications of synapses etc. Psychology, in the course of its history, has shown to be able (at least in some fields) to improve its research procedures by leading them to reach high methodological standards, in order to be accepted as scientific. Thus, the competition between psychology and neurosciences does not concern

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this level, namely, the level of the precision and reliability of the research procedures: both disciplines employ valid methodologies, with both potentialities and limits, which can be improved (even though the social representation of the two disciplines induces people to believe psychology as less “scientific” than the neurosciences). The competition concerns another level: if neurosciences succeeded in showing that what is investigated by psychology can be described and explained in an adequate manner in biological terms, they, at least, would place themselves as an alternative to psychology. Moreover, if their appeal (for extrinsic reasons: fascination due to the novelty, to the technological apparatus etc.) and (for intrinsic reasons) their heuristic power led them to appear as superior to psychology, the neurosciences would be a candidate to substitute in the future the (to-beeliminated) psychological knowledge. It seems therefore that a form of psycho-biological dualism, at least on the epistemological level, is needed in order to allow psychology to defend its autonomy and legitimacy in front of the neurosciences. To set the question, in this chapter first of all it will be made clear what is the kind of reality that psychology intends to investigate and/or on which it intends to intervene and what is the specificity of the approach to that kind of reality that psychology intends to follow (§ 2). Then it will be shown how psychology, to study that kind of reality, carries out descriptions and analyses that have to be referred to by who is interested in investigating what happens in the brain (where “brain” for the sake of conciseness is taken to mean that complex of neurobiological structures and processes activated under certain circumstances; we must not forget that the whole body, and not only the brain, is the actual biological counterpart of the mental experience: Northoff, 2003) (§ 3). Thus, a form of descriptive dualism seems to be necessary not only to psychologists but also to neuroscientists. The subsequent step will be to argue in favour of the thesis according to which the psychological descriptions and analyses of mental experience cannot be eliminated even if the description of the concurrent neurobiological processes would be exhaustive (§ 4). Hence, the above mentioned dualism would not be only a preliminary and provisional stance, to be abandoned once the neurosciences reach a sufficient completeness, but would be necessary to support the autonomy of psychology. At this point we should understand what is the relationship between psychological knowledge, elaborated in an autonomous way, and neuroscientific knowledge. The first possibility is to set systematic correspondences between mental experiences and biological structures and processes highlighted by neuroscientific research (§ 5). What might psychology obtain from such correspondences? It will be maintained that psychology can obtain not confirmation of the validity of its theoretical models, but suggestions useful to orientate inquiries towards new directions that cannot be

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identified only on the basis of the psychological analysis. What is suggested by neurosciences has to be investigated and proved subsequently on the level of mental experience through methods peculiar to psychology. Therefore, also the correspondences between mental experience and concurrent cerebral processes continue to refer to a form of dualism. Such dualism occurs again when we move from the level of the description and analysis of the phenomena to that of their explanations (§ 6). Also at this level the models concerning cerebral activity can only suggest possible mental relations and dynamics which have to be interpreted in psychological terms. Hence, until new paradigms—where not only correspondences between the conceptual system of the neurosciences and that of psychology might be highlighted but an actual integration of the description and explanation of the mental experience and of the brain activity—might be proposed, psychologists will be needed to share, explicitly or implicitly, a dualistic view which constitutes the general background of their investigations and interventions.

2. FEATURES OF THE MIND If a psychologist is asked what he/she is studying (if he/she is a researcher) or what he/she is trying to evaluate, transform, improve, support, and so on (if he/she is a professional), it is likely that the answers make reference— explicitly or implicitly—to the mind, namely, to a set of sensations, feelings, thoughts, memories, desires etc. which occur in a person. It might be that the psychologist is interested in assessing the mood of the workers within a factory, that he/she is requested to enhance learners’ motivation in a school setting, that he/she should detect the emotions induced by an advertisement, that he/she has to train teenagers to perceive possible risks while driving a car, or that he/she wishes to record the levels of performance in remembering recent events by elderly people under a pharmacological treatment. In all these cases the psychologist is engaged in the description, measurement, or manipulation of a mental state, process, or experience. Sometimes these states, processes, experiences are qualified as “subjective.” This adjective is employed to stress the fact that mental states, processes, experiences are always “first-person” experiences (Searle, 2004), namely, belong to an individual who can make reference to them through the pronoun “I.” The adjective “subjective” can be accepted if we agree that it does not involve necessarily some connotations which are usually associated to it. For instance, “subjective” does not mean necessarily “qualitative”: mental experiences show qualitative differences but also aspects which can be quantified. Related to this comment is the fact that the subjectivity of a mental experience does not prevent us to study it in an objective manner,

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by conceiving as “objective” the possibility that tools and concepts defined in an univocal manner are employed; the subjectivity of mental experiences does not mean that they can be investigated so as to yield descriptions and conclusions that are intersubjectively valid. As noted by Baker (2000), human persons, having a first-person perspective, can be investigated also by empirical sciences. The subjectivity of mental experience does not involve being arbitrary, ambiguous, idiosyncratic, inexpressible etc. with the impossibility of reaching an intersubjective agreement as a consequence. In other words, the fact that mental experiences are first-person experiences does not mean that they fail to be reported by the individual in a manner which leads all other persons to understand the same thing and/or that other people can catch and reconstruct them in an univocal way. A mental experience can be studied in an intersubjective manner without making a reification, that is, considering it as a thing, separated from the whole individual which it belongs to and abstracted from the personal meaning that one attributes to it (such a reification would be, according to Uttal (2004, 5), the basic mistake of dualism). The third comment concerns the tendency to consider a subjective experience as intimate, as something which occurs in the inner of the individual. Some aspects of mental experience share this feature but other aspects involve behavioural manifestations which cannot be meant purely as overt “translation” of what happened in the covert and inner space of the mind. Some mental experiences are structurally linked to their “external” manifestation, which is a constitutive part of them (e.g., Gallagher, 2005; Overton, Müller and Newman, 2007; Pfeifer and Bongard, 2007). After having set these specifications about the subjectivity of mental experiences, we have to characterise them better. By following the phenomenological tradition (e.g., Gallagher and Zahavi, 2007; Marbach, 1993), mental experiences can be conceived as the result of that peculiar way according to which humans interact with reality which is called “intentionality.” When I have something in front of me, on the one hand a physical relationship is set between it and me: what I have in front of me influences me since, for example, it sends physical waves toward my sensory organs and I influence it since I can manipulate it physically (I can move it, for instance). On the other hand, a relation of a different nature is set: something is present to me, has a meaning for me, my consciousness is occupied by it. Something is in me in an intentional form when I, besides the possible physical actions and reactions which occur between it and me, seize a meaning in it. What is present intentionally to me can be a concrete object or an abstract thought object (ens rationis). It can be present intentionally to me in a perceptive, remembered, imaginative etc. manner and can be more or less connoted emotionally. Let’s hypothesise I am sitting in front of a fireplace. Between myself and the fireplace there is a relationship of the

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physical kind: for example, the heat coming from the fire changes the temperature in my body. With a same kind of relationship that is just as physical I can change the flames: by blowing air I can make them bigger. An intentional relation is also involved, though: I can clearly see the fire, it reminds me of what it looked like the evening before, I try hard to imagine it another colour, I feel relaxed etc. It is I who, in different ways (perception, memory, imagination) and in ways that are more or less conscious, enter into a relationship with that hole in the wall of the room, which, by assuming a certain form and a certain emotive nuance, comes to mean a fireplace to me. Once made clear how the mind is conceived here, we may wonder if that is not what psychology simply intends to investigate. Some psychological schools might disagree. In fact, if a psychologist shared a systemic or sociocultural theoretical and operational frame of reference, he/she would be induce to share the opinion that she he/she has to analyse and (maybe) change not the individual mind, but the whole context in which the individual is included, the network of relationships and interpersonal dynamics the individual belongs to, the roles, norms, schemata which are working in a certain environment and pertain to a given worldview. Even in this case, however, the psychologist—if he/she were different from a sociologist, an anthropologist, or a historian—must make reference to what these extraindividual elements induce in the individual’s mind. For instance, the interpersonal dynamics may be considered (and actually psychologists judge them so) as more or less functional by making reference to the levels of anxiety, frustration, aggressiveness etc. that they induce in the individual. As another example, the way in which people react to technological innovations in everyday life surely depends on the extent to what the values of efficacy and productivity are shared in their culture, but the actual acceptance or rejection of such innovations lastly depends on the personal meaning—what people think, believe, feel about them—individuals attribute to them. The socio-cultural and systemic perspectives stress the fact that mental experience might have not only an endogenous, internal origin, but that it might be elicited, emphasized, modulated by external factors; however, such factors have to be considered, if they are taken into account within a psychological point of view, with reference to their effects on the individual’s mind. Thus, even through perspectives which are not primarily focussed on the individual experience but on the environmental and cultural aspects, the mind can be conceived as the general term which denotes the object of the investigations and of the interventions carried out by psychologists. After having settled that mental experiences are the term of reference of psychology, it is important to stress the fact that they are something real. Somebody might note that they are widespread phenomena, but illusory. However, even if we assumed the perspective of who maintains that mental

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experience is the way in which processes that have actually a different nature appear to people, we would have to understand why such illusion is almost universal and has survived so long time and why so many persons are convinced that mental experiences are real and they are so attracted to them, by making reference to them so often in their talks and in their interpretation of everyday-life events, and spend so much time in communicating to one another such experiences and reflecting upon them. One might reply that this happens because persons need to illude themselves by believing that they feel, remember, desire etc. Such a need, however, should be an actual psychological phenomenon, and thus should merit investigation. Since people are so engaged with mental experiences—so much so that a specific discipline was created to study them—and with the conviction that they need to be understood, there is need to investigate all of this and to explain why and how people are so heavily influenced by this illusion. Psychologists are concerned with the mind. According to a first, simplistic view of the system of science psychologists seem to be in a position similar to that of botanists who are concerned with plants, zoologists who are concerned with animals, astronomers who are concerned with planets and stars etc. A view which states that a certain discipline corresponds to a peculiar category of objects should cast no problem to psychologists. However, we note that the mind, which psychologists intend to study, belongs to an individual entity which is also a physical body, and, as a body, it becomes the object of other disciplines (biology, medicine etc.). In order to keep the stance according to which each specific object corresponds to a given discipline psychologists should share the idea that the object (the mind) they investigate exists together with another object (the body) investigated by other disciplines. In this sense, a dualistic view, according to which humans are composed by a mind and a body, should be necessary to support the autonomy of psychology with respect to the other disciplines which are concerned with human beings. However, one might maintain that the scientific disciplines differ from one another not on the basis of the object they are concerned with, but on the basis of the aspects of that object they consider. For example, a discipline might be concerned with electromagnetic waves. They are produced by different objects. Thus such a discipline should investigate objects which, according to a previous view, belong to different disciplines. For instance this discipline might investigate stars—which, according to the previous view, should be investigated by astronomy—as well as torpedoes— which should belong to zoology. It is obvious that stars are not composed by electromagnetic waves. Electromagnetic waves are an aspect of stars and a specific discipline is identified in order to study it. As far as psychology is concerned, one might maintain that it investigates some aspects of human

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beings which are different from those investigated by other disciplines. The object, meant as an individual entity, is the same (the human being), but the aspect investigated by psychology is different from the aspects investigated by disciplines such as biology or medicine. A different version of dualism, focussed on properties rather than substances, seems to be shared by psychologists all the same, if they wish to be different from scholars of other disciplines interested in studying the human being. At this point someone might argue that the mental aspects investigated by psychology are not different in nature from the aspects investigated by the other disciplines. This is a notion which nowadays is widely shared in philosophy but also in science. Specifically, today psychology has to face the attempt by some disciplines (in particular, the neurosciences) that mean to investigate the mental aspects of human beings as if they were properties of the brain. The question whether the mind is actually something distinct—on the level of the substances and/or on the level of the properties—from other aspects of an individual (the body) is not addressed here. This question pertains to philosophy and will be discussed deeply in the subsequent chapters of this book. More modestly here we address the question whether the mind—in any case it can be conceived at the ontological level—can be studied by psychology through an approach (or a set of approaches) which is specific, namely, different from the approaches followed by other disciplines. In particular, by considering how the question is addressed nowadays, we wonder whether psychology can study the mind according to its own perspective, distinct from the neurobiological approach. Are psychologists legitimated to investigate sensations, memories, emotions etc. by making reference to what people perceive, think, feel, decide etc. (or show or report to perceive, think, feel, decide etc.)? The question is therefore set at an epistemological-methodological level. The question is if psychology can be considered legitimately an autonomous form of knowledge. An autonomous form of knowledge means a form of knowledge which derives from the application of specific research procedures and instruments and is based on a specific kind of data, and provides specific genders of explanations. As far as procedures and instruments are concerned, are psychologists legitimated, for example, to apply interviews where people are asked to report feelings, questionnaires asking to express their opinions, experimental tasks through which it is tried to infer reasoning during problem-solving, observational procedures aimed at identifying the agents’ intentions? Or do the psychological research instruments and methods have to be conceived not only as less informative and powerful than those applied by neurobiology, but also as though they might be supplanted by them? As far as data are concerned, the question is if the above mentioned procedures allow researchers to collect peculiar kinds of data which extend our understanding

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of human beings, which produce a gender of knowledge that cannot be acquired in other ways. As far as explanations are concerned, the question is if the interpretative models proposed by psychology can be considered as peculiar with respect to those proposed by the neurosciences. In order to legitimate itself as an autonomous discipline, psychology has to defend a certain kind of distinction between its methods and knowledge and those of other disciplines which are concerned with the same entity (the human being). A certain kind of epistemological-methodological dualism seems to be needed in order to allow psychology to be distinct from other disciplines. Furthermore, such a dualism should make clear not only the difference between psychological knowledge (conceived as a networked set of procedures, data, and explanations) and other genders of knowledge, but also should ground psychological knowledge so as to avoid that it appears “inferior” to the knowledge elaborated by other disciplines. In short, it is a dualism that should guarantee both the distinction and the equal power of the psychological research procedure, data, and explanations with respect to the neurosciences. Finally, it has to be a specifically psychobiological (or psycho-physical) dualism since the peculiarities of psychology with respect to the neurosciences concern the fact that psychology is focussed, among the various dimensions of human being, on mental experiences. Psychology investigates a phenomenon which is actually experienced by humans—the intentional relationship to meaning—using its own research instruments and explicative concepts, by trying to adhere to the features directly shown by mental experiences. In this sense it is a peculiar epistemological-methodological dualism. As regards a diamond even, a form of dualism (or pluralism) can be recognised: a discipline may focus, with its own research instruments and concepts, on the molecular structure and another discipline on the financial value. Financial descriptions, analyses, and explanations about a diamond are distinct and autonomous with respect to those concerning its physical composition and in this sense a dualism exists between the two forms of knowledge (economics and mineralogy). However, in the case of the diamond, economics maps some features (commercial value etc.)—which diamond itself fails to show—onto the diamond; it is thanks to the fact that the diamond is included in a network or relations that it comes to have some properties that then economics conceives in a certain way. As far as psychology is concerned, this discipline is different from neurosciences not because it “imposes” some features to mental experiences which they come to possess in an extrinsic way, due to the fact that they are included in a system of relations and then conceptualised in a peculiar way; the features attributed to mental experiences that psychology investigates are features taken directly and originally to be mental. In this sense the epistemological-methodological dualism between psychology and neuroscience is a specific psycho-biological dualism.

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Such a dualism concerns a crucial issue for psychology since the survival of the disciplines depends on it. If what is investigated by psychology can be investigated better by the neurosciences, psychology risks becoming an approximate and “primitive” discipline which may be accepted temporarily, owing to a lack of alternatives, but which may eventually cause it to disappear when the neurosciences will exhibit a profound, complete, and systematic description of the biological basis of the mind. This is a fundamental issue since it concerns the justification of the current way of operating by psychologists and of the proposal, addressed to the next generations, to engage them in the study of this discipline. Otherwise, it would be more honest to encourage young people to cultivate the neurosciences and to make reference to them to help those in need, for instance, to change the mood of workers in a company, to enhance motivation in school learning, enhance emotions elicited by an advertisement, foster the perception of risk in car driving, or lengthen the span of memory in older people. In order to save their future, psychologists should be dualists.

3. NEED FOR PSYCHOLOGICAL DESCRIPTIONS In face of the challenge addressed by the neurosciences to psychology, the first remark concerns the fact that neuroscientists need psychology in order to understand what they have to investigate if they wish to say something about mental experiences. If someone is interested in developing a “neuroscience of subjective experience” (Solms and Turnbull, 2002), the nature of the subjective experience has to be taken into account. One suggested analogy (Jackson, 1982) is that of a neuroscientist who knows all there is to know about how the nervous system works but has always lived in a room in which he/she has only had visual experiences in black and white. If that neuroscientist came out of his/her room and saw colours for the first time, he/she might say: “So that’s what is meant by yellow or by green, the sight of which activates certain areas in the brain and triggers off that particular physiological process.” Having a personal and direct experience of colours would thus add something to his/her knowledge of the human mind; his/her previous knowledge—expressed solely in terms of the working of the brain—being incomplete could not be an exhaustive explanation of the mental phenomenon. In this way, even if a complete neuroscientific description of the brain activity accompanying mental life were possible, this would still have something that the description would not include. This was the conclusion which was usually drawn from this thought experiment. But there is another, more fundamental implication. Without having an experience of colours (also simply in black and white), the neuroscientist can only relate specific brain reactions to different values

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of the frequency of the electromagnetic waves coming from external objects (the physical counterparts of the experienced colours). Without any notion of the mental effects (perceiving colours) of the differences in the frequency of the waves, such a relation between brain activity and frequency values is meaningless. If we are interested in assessing the possible function of such a relation, we are induced to wonder: why should the brain react differently according to the specific values of the frequency of the electromagnetic waves? If I associate colours to the frequency values of the electromagnetic waves I understand why it is important for a person to distinguish stimuli on the basis of such features. Colours, for instance, allow people to distinguish ripe fruit from unripe (we must not forget, however, that the functional meaning of mental experience does not concern only the individual but also the system of social relations and the groups in which the individual is included: Barlow, 1987); otherwise the relation between brain processes and frequency of the electromagnetic waves is only a curious fact lacking any significance for the improvement of knowledge. And also if, for some reasons, such a relation were relevant to any field of knowledge, it would not concern psychology, since no mental aspect (such as the perception of colours) would be taken into account. It would have nothing to do with psychology, if I fail to mention in such relation something which happens in the mind (like, for instance, the finding that different levels of pollution in the atmosphere associated to different rates of nail growing has nothing to do with psychology, even if it might be interesting to the study of the environmental influence on biological processes). The pure relation between electromagnetic waves and brain processes concerns, on the one hand, physics and, on the other, neurobiology, with no relevant space for psychology. In conclusion, we have to acknowledge that a description of the mental experience is necessary to understand the function of neural processes when we try to relate the latter to the physical conditions which elicited them. If I want to relate reality X to reality Y (for example, if I want to relate the experience of seeing yellow to the activation of certain receptors in the retina, and so forth), I have to know what the first is in order to place it in relation to the second. In order to illustrate the need of psychological descriptions for neuroscientific research, let us consider the following concrete example. In a study (Camille et al., 2004) concerning the psychological dynamics involved in decision-making, the subjects’ emotive states were measured by asking subjects to evaluate their own feelings as well as by recording their skin conductance response. Subjects were involved in a task in which they had to choose between two bets (for example, betting either in a game where there is only a 50 percent chance of winning $50 and a 50 percent chance of losing $50 or betting in a game where there is a 20 percent chance of winning $200 and an 80 percent chance of losing $50). Having the possibility of knowing, having placed the bet, the results of both games, participants were

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seen to be upset if they lost the bet (the experience of “disappointment”) and were further wrought when they learnt they could have won, had they chosen the other game (the experience of “regret”). It also emerged that patients with lesions to the orbitofrontal cortex did not experience regret and were not able to understand which bets were more worthwhile to choose (ending up, unlike normal participants, as losers). In agreement with the previous considerations, it is worth underlining that to find out that the orbitofrontal cortex is involved in regret, a psychological understanding of this emotive state must be presumed, otherwise certain experimental situations that lead to disappointment (“I only know that I have lost, but I don’t know what would have happened if I had chosen the other bet”) and to regret (“I know I have lost and that I would have won if I had chosen the other bet”) could not be set up. Neither would it be possible to qualify the psychological difference between the two situations. In fact one could simply distinguish them according to the amount of information made available to subjects after their decisions. Thus, it is the psychological description (and perhaps an implicit psychological theory) of the mental experience which leads us to maintain that the two experimental situations (knowing vs. not knowing the outcome of the alternative choice) differ psychologically (and the authors were indeed interested in assessing relationships between brain structure and psychological processes underlying decision) with respect to the emotional reactions (respectively, regret vs. disappointment) but not to the amount of information available. Somebody might raise the objection that, in order to obtain the definitions and distinctions requested to plan neuroscientific investigations, commonsense psychology is enough and a specific scientific discipline is not needed. It can be argued that, for instance, astronomy started from a naïve inspection and that the description of the sky was enough, at least at the beginning, to address the astronomers’ attention toward some planets and stars whose actual features were discovered subsequently thanks to the progresses of the astronomical inquiry, allowing people to go beyond initial appearances. In short, the descriptions produced by common sense are enough for a discipline which tries to go beyond the direct appearance of the phenomena (and neurobiology might share such a goal: to find what occurs behind the emotions, perceptions, decisions etc. of the human beings). However, things are not so simple. The definitions suggested by common sense are not always a relevant starting point. They have to be discussed and clarified. Disciplines such as psychology are useful to circumscribe, analyse, and distinguish phenomena. For instance, molecular biology needed the preliminary work carried out by Mendel to identify some basic principles of hereditary transmission whose grounds were later explained in terms of the DNA structure.

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Thus, a first standpoint is that psychology is necessary to define and describe the mental experience which the neurosciences wish to deal with. For as long as a detailed and fine analysis of mental experience will be necessary, psychology will exist. As previously noted, mental experiences, even if illusory, are in any case a phenomenon, something that occurs, and the way they manifest themselves thus deserves being taken into consideration, even if the aim is to overcome the phenomenological description and to discover something further, different in nature, beyond them. So, it is likely that UFOs are illusory entities. However, being victim of such an illusion is an actual phenomenon which it is not useless to investigate. For instance, analysing the reports of people who alleged to have seen an UFO may help researchers in devising a taxonomy of these illusory experiences that, in turn, may be useful to identify the specific optical phenomena which yield such illusions. But is what psychology accomplishes in defining and describing mental experiences only a preliminary task that, once carried out, leads psychology to be discarded and be replaced by the neurosciences? We have no reason to claim that a phenomenology of mental experiences can be complete in the future, so that further psychological analyses might be redundant. Thus, we can predict that psychology will not exhaust its task. Moreover, even if we reached an exhaustive knowledge of all the details of the mental experiences in all kinds of individuals, we have to admit that mental processes (as well as the biological ones: Wexler, 2006) always change because of modifications in the socio-cultural environment. Since the environmental transformations are endless, psychology will have always space to update its descriptions of the mental life which will develop under new circumstances. Thus we can predict that psychology—as a discipline useful to provide a precise description and analysis of the mental phenomena whose biological counterparts have to be studied—will be always needed in the future. Therefore we are induced to acknowledge the necessary co-presence of two conceptual and linguistic systems. As recognised by Freeman (1999), the dynamic of cerebral processes can be described in neurobiological terms—and even, according to this neuroscientist, in mathematical terms— as well as through linguistic expressions which make reference to the phenomenological features of the corresponding mental experiences. In any case, various neuroscientists (e.g., Damasio, 1999) admit that is useful and legitimate to distinguish two levels of description, the mental and the biological ones. The psychologist who describes the mental phenomena by means of his/her instruments and concepts has to share a dualist stance since he/she puts her data about mental experience next to the data that the neuroscientist will acquire by studying the brain functions concurrent to that experience.

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4. PSYCHOLOGICAL DESCRIPTIONS CANNOT BE ELIMINATED Once settled that psychological descriptions are needed to identify correspondences between mental experiences and neurobiological processes, we have to understand if, after having acquired the psychological definition of the mental phenomenon to be investigated, such a definition can be put aside and only the description of the neurobiological process kept. By hypothesising that a psychological description of mental life (or even of only a limited field of mental life) which is definitive and not further updatable will be reached, can such a description be discarded when an adequate description of the corresponding biological processes is obtained? If we go back to the example of the meteorologists, it could be said that in principle the description of atmospheric conditions in terms of physical processes— as carried out by N—may cover in a complete and exhaustive manner the description carried out by P. Once the necessary knowledge is acquired—a method which may be long and require much progress—the new meteorologist could describe the reflections of the light on the waves of the river, the colour changes of the leaves, the shapes of the clouds, the gulls’ reactions in terms of physical processes. An equivalence between the naïve terms used by P in his forecasts and those used by N is actually plausible. Might there also be an equivalence between the psychological descriptions of mental experiences and those of the concurrent neurobiological processes? Someone considers the relationship between the mental and the concurrent neural process to be analogous to the relationship between water and H2O, gene and DNA, or between clouds and mass of water drops in suspension. In all these cases, the name is different but the substance is identical (i.e. water and H2O are the same thing). The same would apply to the relationship between the mind and the brain: the mind is just a different name—generally considered a more “primitive,” less “scientific” term because it is based on the appearance instead of on the true nature of things— for that which is concealed behind it at a deeper level, namely, the brain. The objective is thus gradually to eliminate the terminology and the conceptual apparatus of psychology and replace it with the neurobiological one, just as terms from old theories in the past were pushed aside by new theories (as happened for the concepts of “phlogiston” or “ether”). Various objections to these arguments have been made. Firstly, the proposed analogies are rather different. For instance, the relationship between gene and DNA concerns an abstract entity (the gene) referring to something concrete whose specific biological counterpart has been identified; once such a counterpart was identified, gene became a pure verbal label referring to a sequence of nucleotides. In the water-H2O relationship, the first term

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can be substituted by the description of its atomic structure (for example, if we are interested in considering the therapeutic properties of certain thermal waters) whereas in other circumstances (as the case of evaluating the aesthetical qualities of a waterfall) the first term implies a set of aspects which it is not so useful to substitute with descriptions in terms of atomic structure. After this remark, even assuming that it is possible in principle to “translate” mental experiences into neurobiological processes, there would still however be a gap which cannot be filled. It might be objected that eliminating the terms used to describe a scientific theory is not the same as eliminating an experience. Phlogiston is a conceptual construct, after all, whereas a mental phenomenon like pain is a real element of experience. When science replaces the concept of “phlogiston” with concepts which refer combustion to alteration in the molecular structure, thus replacing a way of conceiving and denominating a phenomenon with another way considered to be more evolved, it is not replacing one reality with another (the objects which burn due to the lack of the presumed phlogiston they contain are the same objects which burn following structural modifications at the level of atomic particles). The concepts, abandoned or current, refer to real processes or entities but their replacement concerns a change in the way of understanding or modelling such processes or entities, not a change in their ontology. While in the scientific study of physical realities it makes sense to move from appearance (e.g. “cloud”) to a “deeper” reality (“mass of water drops”), where the mind is concerned it is not a question of going from appearance to a deeper reality, because the subjective appearance is the essence of the mind (Kripke, 1980; Nagel, 1986). Painfulness is not a contingent property of pain; painfulness is the essence of pain; there are no appearances beyond the sensation itself; if I feel pain, the sensation of the pain is all I feel; it is a non-sense to say that the pain is actually a neural process. It is a non-sense since we understand how the properties of water can be connected to the atomic structure of the molecule H2O, but we cannot understand how mental phenomena can be connected to biological processes. Sperry (1991) proposed the following image to explain how a property can be related to another kind of properties. Let us take a wheel. The shape of the wheel is given by the physical characteristics of the atoms making it up. However, when the wheel goes into action, the behaviour of these atoms is not regulated merely by the internal characteristics of the atoms themselves, but is affected by the action of the shape of the wheel which each atom has contributed to determine. The same—Sperry argued—could be said to happen for the relationship between the brain and the mind: the mind is not made of a different substance from the brain; the mind is generated by neural structures and by their workings. As a reality of a higher

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order which emerges from the brain, it has specific features which allow us to recognise that it has a holistic power of retroaction on the elements making it up. However, in this case too—just as for the similarities between H2O and water, between gene and DNA, or between cloud and mass of water drops—it may be observed that even though the emerging properties of the wheel cannot be explained with the characteristics of the atoms making it up, they are at least of the same genre (being spatial, mechanical, energy characteristics) as the characteristics of the single atoms, so that it is not impossible for me to comprehend how the first can derive from the second. In the case of the mind, however, its presumed emerging properties are of a different genre and therefore the shift from the brain to the mind remains difficult to conceive. If I am feeling pain, even if the neurosciences could describe all that happens in my nervous system while I am in such a mental state, I would fail to find in these descriptions some fundamental aspects of the experience I am living. It is true that also in the description of water as “water” there are some aspects of the water which I fail to find in the description of water as “H2O” (for example in the description of the molecule I cannot find properties such as liquidity or transparency), but these aspects can be in principle “translated” into the description of the molecular structure (I can understand, given a combination of certain atoms, how the substance is liquid or transparent). In this case the description in terms of atomic structure produces advancement in the knowledge of water with respect to the naïve description. Such advancement occurs thanks to a substitution of concepts, but of concepts belonging to the same fields since they make reference to entities which share the same basic features (spatial extension, weight etc.). In the case of pain, on the contrary, the features of such a mental experience have no direct relation with the corresponding brain processes: in the neurons and in their functioning there is nothing which can be “translated” into the experience of feeling pain. In the neurobiological process, besides the temporal coincidence between the two orders of events, there is nothing which leads us to understand how pain can be equivalent to it. It is the case of two radically different conceptual systems so that it cannot be conceived how a system can be “translated” into the other one, apart from the mere chronological factor (when I feel pain, certain processes co-occur in my nervous system). In other words, by making reference again to the above mentioned study by Camille et al. (2004): in the way in which the orbitofrontal cortex and its functioning are described, there is nothing that can be related directly to feeling regret. The authors detected a co-occurrence: when the orbitofrontal cortex is intact and normally working, regret occurs; when the orbitofrontal cortex is damaged, regret does not occur. The description of what the individual is feeling—regret or disappointment—includes aspects which are

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not “translated” in the correlated cerebral basis (the orbitofrontal cortex). Moreover, I fail to imagine what further neurobiological data might allow me to comprehend in a deeper way what feeling regret or disappointment really means, whereas I can imagine how a deeper knowledge of the atomic structure of the molecule H2O can lead me to understand better the properties of water. Let us consider a further case. Sanfey et al. (2003) employed the so-called Ultimatum Game in which the participant is told that a person—whose name is mentioned and whose face is shown—has won $10. Such a person has to share the money with the participant and can decide how much of this sum she can keep, and how much of it she can offer the participant. The participant can either accept the offer or refuse it. If she accepts it, both participant and proposer will get the money (in the measure forecast by the deal); if he/she does not accept it, then neither will get the money. Generally, participants accept fair offers (the proposer keeps $5 or $6 and the participant is offered $5 or $4 respectively), so that they both get the money. Almost half the number of participants refuse unfair offers (the proposer keeps $8 or $9 and offers the participant only $2 or $1 respectively), even if that means that the participant does not get any money at all, which is presumably worse than getting some. In actual fact, in this game the ways in which the $10 are shared out were manipulated by the experimenters who tried participants with fair and unfair offers in order to study their reactions, especially following unfair offers. Faced with unfair offers, participants must decide whether to accept or refuse them. If they accept, they win a small sum of money; if they refuse, they do not get anything at all. In the former case, however, they appear to be cynical opportunists who care little about what others think of them, while in the latter they prove to care about their social reputation which means they have “personal dignity” and consider the unfair offer an offence which necessitates the greedy proposer’s being punished (“I won’t get the $1 or $2, but you won’t get the $8 or $9 either”). These are, more or less, the mental processes that develop in participants before they decide whether to accept or refuse offers, processes that can be intuited by most of us in that same situation and which find confirmation in the participants’ accounts of their experience and thoughts during the Ultimatum Game. In the study in question the activity of the brain during the period in which subjects were deciding whether to accept or refuse an unfair offer was recorded by means of the functional magnetic resonance (fMRI). The results showed that three cerebral structures were selectively activated in this situation: the bilateral anterior insula, the dorsolateral prefrontal cortex, and the anterior cingulate cortex. What can be gathered from these findings? That pondering unfair money offers is neurobiologically different— and thus apparently psychologically different too—from pondering fair

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offers. Is this a true discovery? It does not really seem possible that a true contribution towards a better understanding of the psychological dynamics of decision-making can be obtained from this research. The study included however further information. Following a further careful analysis of the structures when unfair offers are refused or accepted, it has been seen that the anterior insula is activated more in the case of a refusal than in the case of an acceptance, whereas the dorsolateral prefrontal cortex is activated more in the case of an acceptance as opposed to a refusal. In other words, when one accepts, the dorsolateral prefrontal cortex is activated more than the anterior insula; when one refuses, the anterior insula is activated more than the dorsolateral prefrontal cortex. If we observe only the differential patterns of activation in the cerebral cortex described above, what conclusions might we reach? That different decisions (accepting or rejecting the unfair offer) are supported by different neurobiological processes. The actual meaning of these processes is obscure if we omit the description of what presumably occurs in the individuals’ minds (privileging gains with no care of personal and others’ emotive issues or renouncing money in order to save social reputation or because of the failure to inhibit anger). The description of the neural responses is very poor and the report of the mental reactions includes a lot of aspects which are neglected by the former. There is no need to improve the description of the neurobiological processes. Even an extremely deep and detailed analysis of what happens in the brain during the choice of either accepting or refusing the offer would fail to include what the psychological analysis of the mental experience can provide.

5. THE ROLE OF NEUROBIOLOGICAL DATA By summarising: the psychological descriptions reside next to the neurobiological ones by showing a specificity that the neurosciences fail to include completely in their conceptual systems. We might share such a dualism of approaches and limit ourselves to identify psycho-biological correspondences: when I live a certain mental experience, concurrently I record certain brain processes. The psychological and neuroscientific discourses can flow in parallel, each making reference to its own methods, data, and concepts. Is it possible to go beyond and imagine an exchange between the two disciplines? Actually the existence of two parallel corpora of knowledge is antieconomical. By referring again to the example of the two meteorologists: from a theoretical point of view the knowledge possessed by P includes aspects which are not included in the knowledge possessed by N; however, from a practical point of view, what use would two meteorologists be to inhabitants of one place, when both provide the same information obtained

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in different ways? If P contacted N, might the knowledge of the former benefit from such a contact? Is there a way that the knowledge acquired from one discipline might be related to the knowledge acquired from another in order to produce reciprocal advantages? A first form of exchange has been already considered: psychology lends to the neurosciences the description of the mental life whose cerebral counterparts will be investigated by the latter. Is an exchange in the opposite direction possible; that is, can the neurosciences give psychology anything? Psychology does not only describe mental experience, but also analyses them, namely, tries to identify various aspects and components within them and to place them in some sort of order (for instance, in a hierarchical way). Furthermore, psychology tries to relate mental experiences to one another and to relate them to external factors. Can neurobiological data play a role in these operations? Let us consider what the neurobiological studies previously reported can offer in this direction. Camille et al. (2004)’s study led authors to conclude that “regret [ . . . ] is reported by normal subjects as more intense than disappointment” (1169) and that “emotions related to experiencing gains or losses are not independent from the alternative outcomes since it is the counterfactual thinking between the obtained and unobtained outcomes that determines the quality and the intensity of the emotional response” (1169). These conclusions are rather banal from a psychological point of view and could have been drawn using other means: that my emotive state following my decision depends on my knowing or not knowing the results of the alternative decision and that to experience regret is more intense than to experience disappointment are assertions that can be reached through personal introspection, observation, and everyday interactions with other people. The same is true of some conclusions drawn in Sanfey et al. (2003)’s study described above. It is worth noting that in this case the three structures activated by the unfair offers have a known role in other situations: the anterior insula is activated in correspondence with negative emotions like anger and disgust; the dorsolateral prefrontal cortex is activated during goal maintenance and executive control; the anterior cingulate cortex is activated in the detection of cognitive conflicts. If such structures are active when a subject receives an unfair offer, it is possible to argue that the psychological experiences/processes that such structures are associated with (respectively, anger-disgust, executive control, and cognitive conflict) are present in the mind of such a subject. By keeping in mind the roles of each neural structure, these are the assertions that can be read in Sanfey et al.’s article: • “Emotional influences are important in human decision-making” (1758); • “Neural representations of emotional states guide human decisionmaking” (1757);

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• “[During the Ultimatum Game] the steady task representation of money maximization [is present]” (1757); • “An unfair offer is more difficult to accept” (1757); • “In the Ultimatum Game the conflict between cognitive and emotional motivations [occurs]” (1757); • “Higher cognitive demands may be placed on the participant in order to overcome the strong emotional tendency to reject the [unfair] offer” (1757).3 We might indeed wonder whether such assertions, obtained through the analysis of the neurobiological responses and by considering what is known about their role in other circumstances, are not actually already heritage of folk psychology and could not simply have been obtained asking subjects to relate what they had experienced and thought during the game. This is an example of how less useful neurobiological data might be in the understanding of mental processes. However, if we consider a study carried out subsequently, it may be noted that the Ultimatum Game and the investigation of the parallel cerebral activity can lead to some interesting conclusions from a psychological point of view. When differences occur between believing that an unfair offer comes from a human being or a computer—as shown by Rilling et al. (2004)—unfair offers made by the computer—as might have been predicted—did not arouse as high a percentage of refusals as did offers made by human beings. However, it emerged that the same cortical structures were activated—albeit at different intensities—in the two situations (computer vs. human partner). This suggests that subjects recognise that a computer has some form of intentionality, providing new information which induces further exploration in order to understand the psychological processes implied. This is an example of how neurobiological data may suggest something which is relevant from a psychological point of view and merit to be furthered by psychological inquiry. Another example shows how neurobiological knowledge can suggest unexpected psychological distinctions. In Dickhaut et al. (2003)’s experiment participants were asked to choose between two lotteries. For example, they were asked whether they preferred to play in lottery A in which—given an urn containing thirty red balls, thirty blue balls, and thirty yellow balls— they could win $30 if a blue or red ball was extracted and $0 if a yellow one was extracted, or play in lottery B in which—given the same urn—they could win $50 if a red ball was extracted, $6 for a blue, and $4 for a yellow. In actual fact, according to the expected values, the two lotteries pay the same amount (lottery A: $30 X 1/3 + $30 X 1/3 + $0 X 1/3 = $20; lottery B: $50 X 1/3 + $6 X 1/3 + $4 X 1/3 = $20) and were thus “objectively” equivalent. Subjects, however, tended to prefer lottery A because it appears less

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risky owing to the slight differences among the three possible results (the preferred lottery is clearly the one in which $20 can be won whatever ball is extracted; in this case there is no difference and thus no risk). The experimenters manipulated the two lotteries from which subjects had to choose in order to evaluate the effects of two variables: • the degree of certainty/risk (offering subjects the choice either between two risky lotteries or between one risky and one certain lottery); • the type of result (offering subjects pairs of lotteries in which they could either only win or only lose). By measuring the aversion to risk (i.e. the frequency with which the lottery whose results showed the slightest differences was chosen), it was seen that the aversion was greater in relation to wins than to losses, without significant differences between risky and certain lotteries. In short, the observations made (behavioural datum) proved that when there is a chance of winning, one tends to avoid risk, whereas when there is a chance of losing there is no particular aversion to risk. The neurobiological result obtained by means of the PET showed, however, that when subjects had to choose between two risky lotteries, it was prevalently the ventral system that was activated in the chance of a win; in the chance of a loss, it was the dorsal system. When having to choose between a risky and a certain lottery, there were instead no differences in the activation of the cortical system. On the one hand, therefore, the behavioural datum showed that decisions are not influenced by the context (risk vs. certainty), whilst, on the other, the neurobiological datum implies that decisions are influenced by the context. In this case the neurobiological information amplifies what has already been acquired through the behavioural findings in that it highlights a difference that the latter does not show. It is as though the behavioural description (at least the one based upon subjects’ choices) was too ‘rough’ and as though in the decisional process are really involved, as revealed by the PET, “finer” aspects which are taken into account by the cerebral apparatus. The examples reported above indicate that neurobiological evidence— even though it fails to include aspects which can be described only on the psychological level—can be related to mental experience in order to encourage a furthered psychological description. However, such evidence cannot be used as a proof of what it suggests. The proof has to be acquired on the psychological level. Let us consider this case. In the visual cortex a ventral pathway has been identified which corresponds to the codification of the object’s characteristics (the “what” of the perceptum) and a dorsal pathway corresponding to the codification of the object’s localisation (the “where”)—with the ensuing double dissociation: with neurological damage to the ventral pathway, the subject knows where the object is, though he/she

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does not know what it is; damage to the dorsal pathway leaves the subject able to identify the object but not to know where it is located. These data are used as evidence for the existence of two separate mental modules of representing spatial information (Ungerleider and Mishkin, 1982). According to an alternative perspective, however, the data could mean that there is a single perceptual mode which, in normal conditions, is accompanied by two integrated neural pathways. When one of the two is found to be deficient, perception gathers the spatial information in a distorted way, through an intentional act which leaves “out of focus” either the object or its position, according to the type of neurological damage. Thus, a non-modularist view of the mind could still be supported even though the neurobiological counterpart shows specific “localisations.” Pally (2001) outlined another interesting perspective in which—within a psychological school very different from those till now considered, namely, psychoanalysis, where psycho-biological correspondences are also questioned (e.g., Wilkinson, 2006)—we can find the attempt to support, and possibly widen, the description and explanation of mental phenomena thanks to neurobiological data. This author, by trying to link some classical psychoanalytical tenets to recent neuroscientific findings, stressed, for instance, that the acknowledgment that subcortical limbic networks develop early in infancy and then miss plasticity (so that subsequent events fail to modify them, and consequently such networks produce a permanent effect of the subsequent development of the individual) confirms the psychoanalytical thesis that early mental experiences influence deeply the subsequent life of a person. Another corroboration of psychological theses by neural data would be the following: when we perceive a current scene we carry out a pattern matching with models of analogous situations stored in memory; this is why we tend to see in the present what we perceived in the past and this would explain the possible confusion between past and present. This pattern matching would be similar to the psychoanalytic transfert: it would explain the tendency to interpret current situations by reliving them as if they were painful or difficult situations of the past; also in the case of the transfert the present would be distorted on the basis of what happened in the past and stored in this way in the memory. It is worth noting that what Pally relates are not psychoanalytical constructs, on one hand, and neurobiological data, on the other hand, but psychoanalytical constructs and cognitive interpretations of neurobiological data. For instance the correspondences between unconscious processes and cerebral structures are mediated by the cognitive construct of the “implicit memory” which in turn is an interpretation of experimental data showing that some stimuli lead the individual to emit behaviours which can be explained by assuming that previously presented information is still active in the mind, even if it fails to be consciously recognised. Thus, it is incorrect to say that neurobiological data

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support psychoanalytical hypotheses; such a support is instead provided by a psychological (cognitive) knowledge which can be partially related to neurobiological data. Overall, the considerations made above lead us to maintain that neuromental correspondences are unlikely to have a probative function for psychology. They may have a circumstantial function (maybe even strongly circumstantial); that is, they can play an interesting heuristic role: they can point to the presence of specific differences between phenomena previously considered homogeneous or to the existence of a relationship between two mental activities, but these specificities and relationships must be established on a psychological level. Neuromental parallelisms thus constitute an interesting source of conjectures which must however be verified by psychology in the context of mental (and not neural) phenomena and which must be explained in psychological (and not neurobiological) terms. It is important to evaluate each case separately, considering the limits imposed by the artificial nature of the procedure of enquiry and the type of neuromental concomitance in question, to see how far the neuroscientific evidence contributes to developing hypotheses on mental activity. If man is a psycho-biological unit, it is to be expected that a distinction or a relation which is revealed on the level of the biological processes corresponds to a distinction or a relation on the level of mental experiences. By taking one of the two perspectives (neuroscientific or psychological) certain differences or relationships can be better perceived. What is perceived in one perspective may then be found and proved in the other. Just as the neurosciences are constantly drawing from psychology conceptual constructs in order to investigate their biological basis (and fine psychological descriptions can suggest possible differences to be found on the level of neural processes), in the same way psychology can draw from the neurosciences suggestions about distinctions and relationships in order to investigate their psychological reality. It would thus seem that the extent to which neurobiological data contribute to developing interesting hypotheses about the mental experience cannot be in general terms determined a priori, but must be evaluated case by case.

6. WAITING FOR NEW PARADIGMS Psychology does not confine itself to the description of mental experiences and to the study of the relationships between one another and with external conditions. Psychology wishes to explain mental experiences. To this purpose it proposes some models and theories. As far as models and theories are concerned, is there a chance they may be tackled using the explanatory models proposed by neurosciences? Also in this case the question

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arises whether psychological explanations can be considered distinct and autonomous with respect to those proposed by the neurosciences, and so does the question whether exchanges between the two kinds of explanations are possible. Returning to Camille et al. (2004)’s study described previously, the aim of the study, on the psychological level, was not only to carry out a differential description of regret and disappointment; the aim was also to relate the emotional response (regret or disappointment), the cognitive processes, and the individuals’ choices and to explain such relations. What are the psychological conclusions that the authors could draw from this study? They are the following: • “Regret and disappointment are elicited by two different counterfactual comparisons characterized by two different levels of personal responsibility” (1169); • “Regret reinforces the decisional learning process” (1169). Certain conclusions—as noted above—are banal from a psychological point of view. Other conclusions do not derive directly from the data, but are based on inferences: what participants were thinking about after having made a decision was not directly analyzed in the research; that subjects developed counterfactual reasoning—which consequently regulated their emotive state that in turn influenced their acquisition of information—is thus fruit of hypotheses which are highly likely but still very different from empirically supported statements. The findings in this experiment—in the light of the well-known connections of the orbitofrontal cortex with the sensorial areas (related to the acquisition of information), with the limbic system (related to the emotions), and with the prefrontal cortex (related to reasoning and the planning of behavioural conduct)—induces one, partly on the basis of empirical evidence and partly on likely inferences, to elaborate some hypotheses on the emotional and cognitive dynamics of decision-making. According to the authors of this study, it is possible to hypothesize that, once aware of the result of the alternative decision (psychological process linked to sensorial areas), the subject accomplishes a sort of counterfactual reasoning (“If I had chosen the other bet, then . . . ”) (prefrontal cortex) which provokes a sense of personal responsibility (“I could in actual fact have made the other choice, why didn’t I? I wasn’t careful etc.”) which generates regret (limbic system), which in turn stimulates the subject to distinguish which bets are advantageous, leading the subject to make the “right” choice and thus end up a winner. It is clear that this research aims to provide information as to the relationship between regret and disappointment, about the relationship between

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emotive responses and reasoning, and between these and decision-making. The neurobiological data, according to the authors, would posit the existence of relationships within and between these mental experiences (regret, disappointment, reasoning, perception of personal responsibility, decision). As noted previously, these relationships are not, however, proven by the neuromental correspondences found, but they are suggested, in the form of a set of hypotheses, by such correspondences. The relationships suggested by the neurobiological datum would need, however, to be proven on the psychological level by introspective accounts, analysis of linguistic expressions, and so on. Apart from the fact that this network of relationships between emotion, cognition, and decision is the result of conjectures but not of evidence, what can be said about the explanation offered regarding decision-making grounded on this network of relationships? Can knowing what happens in the nervous system when a particular mental experience takes place be considered an explanation of that experience? These types of acquisitions certainly constitute progress in the knowledge of bodily mechanisms (conceptualised according to the current frameworks of biomedical disciplines). These acquisitions also represent progress in the knowledge of psycho-somatic correspondences, described on the basis of the framework of parallelism between psychological constructs and neuroanatomical or neurophysiological constructs. According to many authors (e.g., Malabou, 2004), these correspondences produce also an advancement of the knowledge about mental experience. It is, however, doubtful that in themselves they constitute progress on the level of interpreting the mind if they are unable to clarify the specifically psychological significance of the neurobiological element. As noted critically by Horgan (1999), it is not enough to take a patient, record his/her brain activity, and write a scientific paper reporting that it has been found that a mental process is disrupted when there is a neurological deficit affecting one. Nobody can deny that the work of the mind is accompanied by the work of the brain. In general terms we can say that each mental act corresponds to a biological process. These correspondences are not surprising if the human being is conceived as an individual undergoing mental experience with its whole body. Our bodies are not an indistinct biological plasma; like other organic beings, the body is a structure that is highly differentiated internally and whose functioning is highly organised. It is therefore obvious that the counterparts of an articulated and finely differentiated mental life are specific biological processes. It would be surprising if our mental acts were accompanied by biological activities without any specificity or regularity. It is not surprising to learn that when a person lives certain types of mental experiences, particular structures, specific forms of functioning, and so on are activated in his/her nervous system. Such correspondences are to be expected.

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Investigations designed to identify specific neural counterparts of psychological phenomena remind us that the mind is intrinsically connected to the body and therefore dependent on the characteristics of the body and the processes developing in it. Mental activity is not something that is juxtaposed to or goes beyond biological activity. It is the execution of the activity of the same individual in which the biological activity is taking place. When I see an object, it is not as though, on the one hand, the chain of neurophysiological reactions are triggered by electromagnetic waves striking the retina of my eyes, and, on the other hand, the figure of the object arises in my mind. Instead, it is I who perceive the object, with my body (and the physiological processes that occur in it). The object appears to me—in an intentional, i.e. non-physical way—and reveals its meaning. Memories, sensations, thoughts, and emotions are not internal psychological states which are accompanied by neural processes. For example, going red with shame is not an emotion—a mental content—to which a somatic transformation corresponds; it is not something which lies within, above, next to, or behind the biological processes. Going red (and all the neurophysiological reactions occurring together with this experience) is our shame, our way of placing ourselves in a certain situation, the way with which this situation takes on meaning for us, the nuances that our intentional relation to the environment acquires in this circumstance. What we call “mind” and “body” act in synergy according to the form taken by the individual’s relationship with the world. Man is a physical being who performs acts (which we qualify as mental) through which he intends meanings. These acts are performed by the whole psycho-bodily being of man and are completed in/through/with the physical-bodily structure of this being (and thus are influenced by/benefit from the characteristics— limits and opportunities—of this structure and are not indifferent to the specific anatomical and physiological features of this structure). The meanings which are intended do not however reside within man in the same way as physical objects do. They reside there in that they are a sense which makes itself felt. The task of psychology is thus to explain how this sense makes itself felt (how it is experienced, how it is manifested, how it is acted out) and to identify the conditions which influence it (the elements which facilitate or hinder it, orient, colour and modulate it in certain particular ways). Neurobiological evidence can offer interesting ideas. To help us with an analogy, in music the analysis of the mathematical relationships between the notes do not explain to me the sense of a melody but can highlight characteristics of the system of notes of which the melody is composed, characteristics whose counterpart I can then search for in the meaning I perceive in the melody. In the same way, the study of the brain can highlight characteristics of the neurobiological events whose counterpart I can investigate in terms of correlated psychological meaning.

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The true challenge to psychology is therefore finding an adequate manner to take into account what the neurosciences report, going beyond the simple juxtaposition of the respective contributions (psychology describes a given mental act and the neurosciences tell us what happens in parallel in the brain). Such a juxtaposition fails to produce an actual progress in our knowledge of the mind. It is necessary to go beyond the solution of the plurality of the levels or interpretations (a certain mental phenomenon is explained by the neurosciences by making reference to the cerebral activity and by psychology in terms of subjective experience) which is equally unsatisfactory. The attempt might be to show how the neurobiological datum, once related to mental acts, is enlightened with psychological meaning, so permitting to broaden the understanding of the way in which humans make sense of reality. Normally, as already shown, the contribution of the neurosciences is meant mainly as the possibility to identify a specific brain structure or process corresponding to a specific mental experience. Alternatively, besides this rather localisationalist perspective—which induces to conceive mental phenomena in terms of modular structures, pathways, networks—we may imagine a different contribution by the neurosciences: they, by investigating the cerebral functioning, might find a possible psychological meaning in that functioning. For instance, research about the so-called mirror neurons (Iacoboni and Mazziotta, 2007), besides showing specific localisations of these brain elements, stress aspects of mental life such as the functional organisation of the representation of movements and the close relation between perception and action. On the one hand, in fact, the finding that the same cerebral structures are activated both when the individual performs a movement addressed to reach a given goal (grasping food, for example) and when the individual watches another individual performing such movement allows us to understand that functionally different movements have different representations, whose cerebral counterparts can be identified. On the other hand, however, this finding has also implications concerning the way in which meaning is constructed in the mind. First of all it suggests that the comprehension of objects is based upon the motor affordance shown by the objects: things are perceived according to the possibility of action they allow. Secondly, actions are interpreted in a holist and functional way: movements are not understood thanks to the analysis of the distinct motor units which constitute the overall movements but thanks to the identification of the goal to which the movement is addressed. Thirdly, this finding suggests that behaviours are understood on the basis of an internal reproduction of the actions seen being performed by other people. Mirror neurons, in fact, do not react to the physical features of stimuli but to functional meaning they have for the individual. Mirror neurons allow individuals to link the observed movements to their own movements and so to become aware of their mean-

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ing. Mirror neurons are at the basis of a kind of pragmatic, immediate, implicit comprehension which does not need conceptual or linguistic mediation. This leads to suppose that the understanding of other people’s actions—at least in the case of the observation of another person’s behaviour and of the inference of his/her scopes—is not “theoretical” since it is grounded on the automatic selection of action strategies which are compatible with the context and which belong to the individual’s motor repertoire (Rizzolatti and Senigaglia, 2006). This is an example of the suggestions a neurobiological datum offers the psychological interpretation of a mental process. In this case what is important is not the identification of detailed distinctions which exist, in parallel, at the level of the brain and at the level of mental experience. What emerges here is the invitation to seize a “psychological” meaning in the cerebral machinery and to recognise how the mental act of comprehending is closely related to the motor dimension. This type of integration and co-penetration of neurobiological data and psychological meaning may require deep changes in the conceptual structure of science. As Chalmers (1995) maintained, a new ontology might be needed where it is assumed that the mind is a fundamental entity of the world like mass, space, time. Science would need, according to Chalmers, new psycho-physical principles which, even if they do not interfere with the well-established physical laws, introduce some supplements indispensable to explain the relationships between physical processes and mental experiences. As Lloyd (2004) stressed, for decades, the drums of philosophy, psychology, and the neurosciences claimed that the mind is the brain and that the brain is the mind. This might be true; it must be true. But how can it be true? While we are waiting for new paradigms which allow to overcome the gap between description of the brain functioning in terms of structures, modules, pathways, networks and the description of mental experience in terms of intentional acts highlighting meanings, psychologists are forced, on the epistemological-methodological level, to be dualists.

BIBLIOGRAPHY Astington, J.W. 1993. The Child’s Discovery of the Mind. Cambridge, MA: Harvard University Press. Baker, L.R. 2000. Persons and Bodies: A Constitution View. New York: Cambridge University Press. Barlow, H. 1987. “Single neurons, communal goals, and consciousness.” In Cognition, computation and consciousness, edited by M. Ito, Y. Miyashita and E.T. Rolls, 120–37. Oxford: Blackwell. Camille, N., G. Coricelli, J. Sallet, P. Pradat-Diehl, J.-R. Duhamel, and A. Sirigu 2004. “The Involvement of the Orbitofrontal Cortex in the Experience of Regret.” Science 304: 1167–70.

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Chalmers, D.J. 1995. “Facing Up to the Problem of Consciousness.” Journal of Consciousness Studies 2: 200–19. Damasio, A.R. 1999. The Feeling of What Happens: Body and Emotion in the Making of Consciousness. New York: Harcourt. Dickhaut, J., K. McCabe, J.C. Nagode, A. Rustichini, K. Smith, and J.V. Pardo. 2003. “The Impact of the Certainty Context on the Process of Choice.” Proceedings of the National Academy of Sciences 100: 3536–61. Freeman, W.J. 1999. How Brains Make Up Their Minds. London: Weidenfeld and Nicolson, Orion Press. Gallagher, S., 2005. How the Body Shapes the Mind. Oxford: Oxford University Press. Gallagher, S. and D. Zahavi 2007. The Phenomenological Mind. New York: Routledge. Horgan, J. 1999. The Undiscovered Mind. How the Human Brain Defies Replication, Medication, and Explanation. New York: Simon and Schuster. Iacoboni, M., and J.C. Mazziotta. 2007. “Mirror Neuron System: Basic Findings and Clinical Applications.” Annals of Neurology 62: 213–18. Jackson, F. 1982. “What Mary Didn’t Know.” Journal of Philosophy 83: 291–95. Kripke, S. 1980. Naming and Necessity. Oxford-New York: Oxford University Press. Lloyd, D. 2004. Radiant Cool. A Novel Theory of Consciousness. Cambrige, MA: MIT Press. Malabou, C. 2004. Que Faire de Notre Cerveau? Paris: Bayard. Marbach, E. 1993. Mental Representation and Consciousness: Towards a Phenomenological Theory of Representation and Reference. Dordrecht: Kluwer. Nagel, T. 1986. The View from Nowhere. New York: Oxford University Press. Northoff, G. 2003. Philosophy of the Brain. Amsterdam: Benjamins. Overton, W. F., U. Müller, and J.L. Newman. 2007. Developmental Perspectives on Embodiment and Consciousness. Hove: Psychology Press. Pally, R. 2001. The Mind-Brain Relationship. London: Karnac Press. Pfeifer, R., and J. Bongard 2007. How the Body Shapes the Way we Think. Cambridge, MA: MIT Press. Rilling, J. K., A.G. Sanfey, J. Aronson, L.E. Nystrom, and J.D. Cohen. 2004. “The Neural Correlates of Theory of Mind within Interpersonal Interactions.” NeuroImage 22: 1694–1703. Rizzolatti, G. and C. Senigaglia 2006. So Quel Che Fai. Il Cervello Che Agisce e i Neuroni Specchio. Milano: Raffello Cortina. Rockwell, W.T. 2005. Neither Brain nor Ghost. A Nondualistic Alternative to the MindBrain Identity Theory. Cambridge, MA: MIT Press. Sanfey, A. G., J.K. Rilling, J.A. Aronson, L.E. Nystrom, and J.D. Cohen 2003. “The Neural Basis of Economic Decision-Making in the Ultimatum Game.” Science 300: 1755–58. Searle, J. R. 2004. Mind. A Brief Introduction. Oxford: Oxford University Press. Solms, M., and M. Turnbull. 2002. The Brain and the Inner World: An Introduction to the Neuroscience of Subjective Experience. New York: Other Press. Sperry, R.W. 1991. “Il Problema della Coscienza a una Svolta: Un Nuovo Paradigma per la Causazione.” In L’automa spirituale. Menti, cervelli e computer, edited by G. Giorello and P. Strata, 97–117. Roma-Bari: Laterza.

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Ungerleider, L., and M. Mishkin. 1982. “Two Cortical Visual Systems.” In Analysis of Visual Behavior, edited by D. J. Ingle, M.A. Goodale and R.J.W. Mansfield, 549–86. Cambridge, MA: MIT Press. Uttal, W.R. 2004. Dualism. The Original Sin of Cognitivism. Mahwah, NJ: LEA. Wellman, H.M. 1990. The Child’s Theory of Mind. Cambridge, MA: MIT Press. Wexler, B.E. 2007. Brain and Culture: Neurobiology, Ideology, and Social Change. Cambridge, MA: MIT Press. Wilkinson, M. 2006. Coming into Mind: The Mind-Brain Relationship. New York: Routledge.

3 Mind, Brain, and Dualism in Modern Physics Friedrich Beck

1. DUALISM: A HISTORICAL SURVEY Since its very existence, mankind has been preoccupied with the mysterious putative relation between the material body and the immaterial mind. In what follows I will refer to the incommensurability of these two concepts as the “mind-brain duality” of human existence. At this stage, however, we have just introduced a distinction and no assumptions have been made about the possible interaction between the mind and the body. In Pre-Socratic philosophy, the mind, like the body, was thought of as being material, in the form of air or fine dust penetrating the body. Aristotle, however, interpreted the mind as immaterial but interacting with the body, causing the principle of life. At the same time Hippocrates, the important physician of the ancient world, held that the brain was the interpreter of consciousness in that it directs the motions of the body and was thus the messenger of the mind. This is the earliest manifestation of mind-braindualism and interactionism. Greek natural philosophy had no problem with such an interpretation of cause and effect! During the scholastic period of the early Christian Occident not much changed from the ancient Greek ways of thinking about the mind-brain problem. Only at the end of the Renaissance period, when philosophy turned towards rationalism, was the question taken up again. It was the great French philosopher and mathematician René Descartes (1596–1650) who established his well-known statement cogito ergo sum (Descartes 1644). This was the shortest possible formulation of a duality, which he assumed to be realized by the interaction of an immaterial mind, the “res cogitans,” with the material brain, the “res extensa.” This position is known as “Cartesian dualism” 69

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and is an interpretation of the mind-brain duality which is, even today, a controversial position within the mind-brain debate. 1.1 The Establishment of the Mechanistic Worldview Ever since the work of Galilei, Kepler and Newton led to the idea that phenomena in nature should be explained causally there has been an enormous progress within science. No mysterious rules govern the motion of stars; it is, however, governed by Newton’s second law with gravitation as the force. “No action without cause” was the rule of nature, and it even became a methodological structure for reasoning outside of the physical sciences. This development culminated towards the end of the nineteenth century, when classical physics in the form of Newton’s mechanics and Maxwell’s electrodynamics established a complete, closed and strictly causal1 description of the world, not allowing for any form of freedom: the world unwinds like clockwork. Materialism was born! It manifests itself most clearly in Laplace’s daemon: If you were to give a sufficiently powerful mind the momentary initial conditions of the whole world, he could calculate the whole future unambiguously! Charles Darwin added: “Why is thought being a secretion of the brain more wonderful than gravity a property of matter?” There was no room left for Descartes’ dualism, and it has never really recovered from this basic defeat. As a consequence, materialism still prevails as the preferred view of most neurophysiologists. Not everybody, however, accepted materialistic thinking. Too strong was the belief, based on personal experience, that self-consciousness governs our actions in the world, and that this requires the ability for free, responsible and non-predetermined decisions. Natural scientists, however, were quite aware that such a non-materialistic view was in conflict with the then known laws of nature which our bodies, including the brain, are governed by as material biological objects. The difficulty could not be better expressed than in an address by the neurophysiologist and science philosopher Emil Du Bois-Reymond, which he presented in 1872 at the German scientists and physicians meeting: There occurs at a certain point of evolution of life in the world, which we do not know and whose determination is of no importance in this connection, something new and hitherto incommensurable. Something which is, like the nature of matter and force and like the first motion, mysterious [ . . . ] This new mystery is consciousness. I shall now, as I believe in an unambiguous manner, outline that not only by our present-day knowledge consciousness can not be explained out of its material conditions, what apparently everybody would admit, but that by its own nature, it will be never explainable from these conditions. (Translated by the author).

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Du Bois-Reymond ended his talk with the apodictic prognosis “ignorabimus.” The “mystery,” as stated by Du Bois-Reymond, has survived up to the present. It has been rationalized by the Austrian-British philosopher Karl Popper (1902–1994) in his “Three-World-Classification” of all existence which is needed for a complete description of the existing world as it appears to us in its whole complexity (Popper 1972; see figure 3.1). World 1 is the material world of all physically existing things; World 2 is the immaterial world of conscious experiences; while World 3 is the world of our cultural heritage, manifested in books, philosophical, religious, artistic, scientific and social structures. It should be emphasized that World 3 is the only one of the categories which unambiguously separates homo sapiens from his evolutionary predecessors. There has been considerable misunderstanding of Popper’s three worlds insofar as worlds one and two have been construed as physically separated, instead of categorically separated. This misunderstanding produced severe criticism of Popper’s classification, ascribing to him a primitive version of Cartesian dualism. Popper, however, was very well aware of the epistemological problems with mind-brain duality, and shortly before his death he realized that his position was unsatisfactory and took the discussion up again (Popper et al. 1993; Lindahl & Århem 1994; Beck 1996a). It must, however, be emphasized that on the basis of classical physics, there is no solution of Du Bois-Reymond’s mystery.

Figure 3.1. Tabular representation of the three worlds of Karl Popper (Popper 1972), comprising the physical world and the world of our experience.

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The assumption of freedom of choice in human decisions and actions must then, in a rational understanding of the world, be regarded as an illusion, resulting from the dynamical uncertainty of the highly complex, nonlinearly coupled systems that the brains of members of highly developed species are (Roth 2000; Singer 2005).

2. QUANTUM MECHANICS: THE REVOLUTION OF PHYSICAL DETERMINISM Towards the end of nineteenth century the strong belief in the causally closed nature of the physical world as described by classical physics came into question. No solution could be found for the problem of black body radiation until Max Planck (1885–1947) realized that the assumption of discrete energy levels in the atomic surroundings could solve the problem. This was the start of the greatest revolution in physical science since Newton! More examples followed quickly after: Einstein’s (1905) explanation of the photo effect—the ejection of electrons from metals by radiation—by means of the revolutionary assumption that, in addition to being an electromagnetic wave, light also at the same time behaves like a particle. This was later supplemented by Louis de Broglie’s (1892–1987) claim that, equally, classical particles (e.g., electrons) also possess the character of waves, an assumption that was shortly after verified by experiment. These steps marked a complete breakdown of the classical macroscopic description of physical objects according to which they are exclusively either particles or waves! Nils Bohr (1885–1962) was the first to realize that with this development something completely new had entered our understanding of the microscopic atomic world, and he called this new conception particlewave-dualism. If the two concepts (particles and waves, which are in classical physics mutually exclusive) are independently from each other essential for a complete description of quantum objects, then this widening of attributes for physical objects is called complementarity.2 Complementarity in quantum physics is an astonishing parallel to the mind-brain duality mentioned earlier! Here, we learned that it is not sufficient to describe the world using a closed and, according to our macroscopic experience, logically consistent system of concepts, but that we have to employ different and complementary viewpoints, depending on what we want to explain! What is the price we have to pay for applying this dualistic concept in the description of the microscopic world? The consequence can be demonstrated in a very simple experiment without employing any particularly technical vocabulary. The experiment is schematically depicted in figure 3.2. A beam of particles (e.g. electrons), described according to de Broglie’s

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Figure 3.2. A particle wave incident on a wall with two open slits, A1, A2. Behind the slits secondary waves are propagating with complex amplitudes A1 and A2. At the screen detectors measure for ensembles of many particles the intensity |A1 + A2|2 which is schematically sketched by the dotted figures. For a single event (one single dot) the outcome is undetermined. (The distance between the openings must be of the same order as the de Broglie wavelength of the particles.)

hypothesis by a plane wave, hits a screen with two slits, whose distance is of the order of the wavelength of the particle wave. As one knows from optics, behind the slits two interfering waves A1 and A2 are produced which generate an interference pattern |A1 + A2|2 on the screen S. What does this wave description of a beam of particles mean? If we put particle counters, one besides the other, along S, the number of particles in each counter is proportional to the intensity of the interference pattern. So far this experiment is completely analogous to the corresponding one with light: it concerns wave diffraction. The counters, however, detect particles, one after the other, and not continuous waves. What do the waves then mean? Since the number of particles in the counters is proportional to the intensity of the interfering wave on S, the intensity measures the frequency of the particles. Particlewave dualism introduces a probabilistic element into the description of nature! Now, what happens if one reduces the intensity of the particle beam, so that finally only one particle hits S at a time? Now the location of the particle hitting the screen is completely undetermined. Since a complete description of the microscopic quantum world cannot restrict itself to ensemble-dynamics, but has to describe the single event as well, quantum

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dynamics for the latter is of a non-causal nature (in the sense of strong causality, see Note 1). The basic difference between classical and quantum dynamics can be made clear on a somewhat more abstract basis in a simple diagram without entering into the formal subtleties of the theory. The generation of a physical process consists of preparing an input (the initial conditions) followed by a more or less complicated process, leading to an output (the result) which depends on the initial conditions and the dynamics of the process. The output can be observed by (a filtering) measurement. For simplicity, we restrict the distinguishable components of the output to only two states (figure 3.3). In classical dynamics the output is unique (strict determinism), which means the result is either state I or state II: excluding states (figure 3.3(A)). The very essence of a quantum process is, contrary to this, that the output is

Figure 3.3. Schematic diagram of classical and quantum evolutions. (A) excluding states (classical determinism), (B) interfering states (quantum indeterminism).

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not unique (no strict determinism), we have neither state I nor state II, but a coherent superposition of both states: interfering states (figure 3.3B). In both cases the time development of the system is given by partial differential equations of first order in the time variable (Newton’s or Maxwell’s equations in the classical case, Schrödinger’s equation in the quantum case) which describe the dynamics in a strictly causal way: the initial conditions determine uniquely the output. The non-causal element in the quantum case enters through the von Neumann state collapse which occurs if one tries to realize the output state, either by a measurement, or by letting the output state undergo a successive process. Then the coherent superposition α˙|state I> + β ˙|state II> collapses into either |state I> with probability |α|2 , or |state II> with probability |β|2 , and |α|2 + |β|2 = 1 For the single event—and it has to be emphasized once more that quantum mechanics is a theory for the single event, and not, as is sometimes claimed, an ensemble theory3—the probabilities are highly irrelevant (except for sub-states with zero probability which will never show up in single experiments or probability one which always show up). The outcome is completely unpredictable (provided that not all but one of the probabilities are zero, which would imply the one left is equal to one).4 This constitutes the non-computable character of quantum events (Penrose 1994).

3. DUALISM REVISITED It is evident that deterministic logic on which Cartesian dualism depends, with its interactionism (mind-brain interaction via the pineal gland), and which conflicts starkly with the materialistic view based on the closed world of classical physics, no longer applies if elementary quantum processes play a decisive role in brain dynamics. We all believe in determinism in our daily life: If—then is integral to the way we normally reason. Each action has its cause—If one turns the starter key, then the engine starts. If it does not, one asks for the reason. Less deterministic statistical reasoning is a powerful tool for predicting the consequences of an event where not all the necessary information is available, and therefore has been replaced by more or less appropriate statistical assumptions (e.g., in statistical mechanics). But since

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Newton and Leibnitz’s invention of the differential calculus, physics attempted to translate causal thinking into the basic physical laws through the deterministic differential action in the time development of a physical process. Quantum mechanics has a more subtle relation to determinism. In classical physics, two objects are required to describe a process in the microworld: the particle, as a dynamic object, and its accompanying wave field that describes development over time. The wave field obeys the Schrödinger equation, a deterministic differential equation of the first order in time, completely analogous to Newton or Maxwell’s classical equations for the motion of particles or fields. The wave field, however, is a probability field determining the probability distribution of an ensemble of particles. Thus, quantum mechanics is deterministic as an ensemble theory. However, as outlined in the previous section, it is non-causal for the single event, since probabilities realize themselves only in the frequency of a large number of identical processes. This difference is of less importance in microscopic physics because most experiments have an ensemble character, since they are performed using a large number of particles (c.f. the diffraction experiment in the previous section) or they have an identical reproduction of the same setup many times. The key point of quantum mechanics is that the probability concept is an ab initio building block of the theory, and not, as in classical physics (e.g., in statistical mechanics), an aid to replace unobserved degrees of freedom by statistical assumptions. This probabilistic character of the theory is a consequence of Bohr’s particle-wave dualism. Both classically exclusive concepts are needed for a complete description of quantum processes which introduces the concept of complementarity into microphysics.5 To be relevant to brain activity, the question becomes whether quantum processes play a decisive role in such activity. If so, processes in the brain have to be regarded as single events since they are unique and not the repetition of a large number of identical events. Then, however, the non-causal and non-predictable nature of quantum mechanics applies to brain activity, replacing Cartesian dualism with the more subtle quantum dualism outlined in the previous paragraph. In section 4 we will outline in which part of the neuronal net quantum processes could regulate its dynamics. 3.1 Hidden Variables In order to derive a quantitative result from the particle-wave dualism, Heisenberg introduced a “Gedankenexperiment.” Suppose that we had to determine the location of a particle, let’s say an electron. We would use light in a kind of microscope to generate a microscopic “picture” of the electron. But since light possesses, in addition to its wave characteristics, characteristics of particles (particle-wave dualism), light transfers momentum to the

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electron, thus preventing the exact determination of its location. This led Heisenberg to derive _ his “uncertainty relation” between momentum p and location x: Δp ˙ Δ ≥ h / 2, where –h is Planck’s constant divided by 2, and Δ, Δp are the measuring uncertainties of location and momentum of the particle. In other words, the conjugate variables of a particle, location x and momentum p (both of which are needed in classical physics to uniquely define the initial conditions of particle motion), can never be measured arbitrarily sharply, as a consequence of the finite value of Planck’s constant h. This leads to the indeterminacy in, e.g., particle motion. Some physicists, like de Broglie and, most prominently, David Bohm, tried to reintroduce classical reality into microphysics by arguing that, though we cannot measure location and momentum together sharply, these parameters for the particle nevertheless exist in reality, and they called them “hidden variables.” That this view is misleading can be seen most strikingly by the stability of atoms, which would be unstable without the so-called localization energy which follows from the uncertainty relation, since the electrons would fall into the nucleus because of the attractive Coulomb force. Another example is the experimentally possible realization of the classical Einstein-PodolskyRosen (EPR) “Gedanken”-experiment which shows with overwhelming likelihood that hidden parameters do not exist (Aspect 1999). As a consequence, quantum reality requires the particle-wave dualism and thus indeterminacy! As a consequence, quantum processes are structurally different from the so-called “deterministic chaos” whose future is also unpredictable because its dynamics depends sensitively on the initial conditions. These can never be obtained in a measurement (with error margins) precisely enough to solve the equations of motion unambiguously.6 The full set of classical variables, however, is defined for such systems without uncertainty, which means the dynamics is still deterministic.

4. NEOCORTICAL ACTIVITY Figure 3.4A illustrates the universally accepted six laminae of the neocortex (Szentagothai 1978) with two large pyramidal cells in lamina V, three in lamina III, and two in lamina II. The pyramidal apical dendrites finish in a tuft-like branching in lamina I (figure 3.5A). There is agreement by Fleischhauer, Peters and their associates (Schmolke and Fleischhauer, 1984; Peters and Kara 1987) that the apical bundles, diagrammatically shown in figure 3.5B, are the basic anatomical units of the neocortex. They are observed in all areas of the cortex in all mammals that have been investigated, including humans. It has been proposed that these bundles are the cortical units for reception (Eccles 1990), which would give them a pre-eminent

Figure 3.4. (A) Three-dimensional construct by Szentagothai (Szentagothai 1978) showing cortical neurons of various types. There are two pyramidal cells in lamina V and three in lamina III (one being shown in detail in a column to the right), and two in lamina II. (B) detailed structure of a spine (sp) synapse on a dendrite (den); st, axon terminating in synaptic bouton or presynaptic terminal (pre); sv, synaptic vesicles; c, presynaptic vesicular grid (PVG in text); d, synaptic cleft; e, postsynaptic membrane; a, spine apparatus; b, spine stalk; m, mitochondrion. (Gray 1982)

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role in brain activity. Since they are composed essentially of dendrites, the name dendron was adopted. Figure 3.4B illustrates a typical spine synapse that makes intimate contact with an apical dendrite of a pyramidal cell. The ultrastructure of such a synapse has been intensively studied by Akert and his associates (Pfenninger et al. 1969; Akert et al. 1975). The inner surface of a bouton confronting the synaptic cleft (d in figure 3.4B, the active site in figure 3.6A) forms the presynaptic vesicular grid (PVG) (figure 3.6A–E). Figure 3.6B is a photomicrograph of a tangential section of a PVG, showing the dense projections in triangular array, and with the faint synaptic vesicles fitting snugly in hexagonal array. The spherical synaptic vesicles, 50–60 Å in diameter, with their content of transmitter molecules, can be seen in idealized drawings of the PVG (figure 3.6C

Figure 3.5. (A) Drawing of a lamina V pyramidal cell with its apical dendrite showing the side branches and the terminal tuft, all studded with spine synapses (not all shown). The soma with its basal dendrites has an axon with axon collateral before leaving the cortex. (B) Drawing of the six laminae of the cerebral cortex with the apical dendrites of pyramidal cells of laminae II, III and V, showing the manner in which they bunch in ascending to lamina I, where they end in tufts. (Beck & Eccles 1992)

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and D). They arrange themselves in a hexagonal array on the active zone (Pfenniger et al. 1969; Akert et al. 1975). A nerve impulse propagating into a bouton causes a process called exocytosis. Each incoming nerve impulse results in at most a single exocytosis from a PVG (figure 3.6F and G, figure 3.7). Exocytosis is the basic unitary activity of the cerebral cortex. Each exocytosis of synaptic transmitter substance results in a brief excitatory postsynaptic depolarization (EPSP). Summation by electrotonic transmission of many hundreds of these milli-EPSPs is required for an EPSP large enough (10–20 mV) to generate the discharge of an impulse by a pyramidal cell (figure 3.8). The impulse will travel along its axon to make effective excitation at its many synapses. This is the conventional macro-operation of a pyramidal cell of the neocortex, and it can be satisfactorily described by conventional neuroscience, even in the most

Figure 3.6. (A) Scheme of a nerve terminal, or bouton, showing the active site with cross linkages forming the PVG, which is drawn in Inset. (B, C) Tangential section through the presynaptic area. (D-E) Active zone (AZ) of mammalian central synapse showing geometrical design. SV, synaptic vesicle; VAS, vesicle attachment site; PA, presynaptic area. (F) Synaptic vesicle in apposition. (G) Exocytosis (Pfenninger et al. 1969; Akert et al. 1975; Gray 1982; Kelly et al. 1979; modified in Eccles (1994).

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Figure 3.7. Different stages of synaptic vesicle propagation: (a) filling, movement towards the presynaptic membrane, docking. (b) stages of exocytosis. Note the essential role of Ca2+ after depolarization by a nerve impulse (Kelly et al. 1979).

complex design of neuronal network theory and neuronal group selection (Szentagothai 1978; Mountcastle 1978; Edelman 1989). Exocytosis has been intensively studied in the mammalian central nervous system, where it is also possible to refine the study by utilizing a single excitatory impulse to generate EPSPs in single neurons that are being studied by intracellular recordings. The initial studies were on the monosynaptic action on motoneurons by single impulses in the large Ia afferent fibres from muscle (Jack et al. 1981). More recently it was found that the signalto-noise ratio was much better for the neurons projecting up the dorsospino-cerebellar tract (DSCT) to the cerebellum. The successful quantal resolution for DSCT neurons and motoneurons generates confidence in the possibility of success for the much more difficult analysis of neurons of the cerebral cortex, which provides the key structures of neural events which relate to consciousness. The signal-to-noise ratio was so low in the studies of CA1 neurons of the hippocampus that so far only three quantal analyses have been reliable in the complex deconvolution procedure by fluctuation analysis (Sayer et al. 1990). For a systematic review, see Redman (1990). A key result of these observations is the fact that

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Figure 3.8. Impulse processing in a pyramidal cell (shown to the right). Upper trace: normal background and increased nerve activity. By filtering via synaptic exocytosis it produces reduced EPSPs, shown in the lower trace. The summed EPSP at the soma (excitation curve in the lower part) is not strong enough in normal background activity to produce an impulse discharge. This happens only with increased activity. (Beck & Eccles 1992, sketch due to Helena Eccles, private communication).

exocytosis occurs with probabilities much smaller than one for each impulse reaching the synapse.

5. QUANTUM VERSUS CLASSICAL BRAIN DYNAMICS In the brain there is an interplay between micro- and macrostructures. The latter consist of pyramidal cells, dendrites and their bundles (dendrons), and electrochemical transitions; on the other hand, microstructures involve synaptic membranes and microtubules. Nerve impulses, propagating along nerve cells, are independent of external stimuli or internal brain activity; they always present and constitute a stochastic background in the brain. Recent investigations suggest that the neuronal net stays close to instability, and in this way can be switched between different states by minute action (Freeman 1996). In order to control such a system, a stable regulator has to be present which generates a coherent pattern in the active cortical unit. As was outlined in the previous section, according to the cortical ultrastructure, synaptic action qualifies as such a regulator. This has been demonstrated in various biochemical studies of the influence of drugs and anesthesia on the ion channel properties of the synaptic membrane (Flohr 1995; Hameroff 1998), and also on the role that synaptic dysfunction plays in mental diseases like schizophrenia, or Alzheimer’s disease. The all important regulatory function of spine synapses results from the fact that exocytosis, the release of transmitter molecules across the presynaptic membrane, occurs only with probabilities much smaller than one upon each incoming nerve impulse (Redman 1990). We therefore regard exocytosis as a candidate for quantum processes to enter the neuronal network, and in this way regulate its performance (Beck and Eccles 1992).

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Micro- and macrostructures in the brain are clearly separated by time or, correspondingly, energy scales. The macrostructure is typically characterized by the fact that the brain lives in hot and wet surroundings of T ≈ 300°K. This raises immediately the question of quantum coherence vs. thermal fluctuations. As is well known, as soon as thermal energies surpass quantal energies, classical thermal statistics prevails. To quantify this situation, two characteristic energies can be defined: (i) the thermal energy per degree of freedom Eth = 1 kbT 2

with kb: Boltzmann’s constant.

(ii) the quantal energy, defined as zero point energy of a quasiparticle of mass meff which is localized over a distance Δ q. From Heisenberg’s uncertainty relation (Section 3.1) it follows (using the equal sign)

Equ =

( )

–h / 2 (Δp)2 ≅ 2meff Δq

2

1 2meff

These relations define two energy regimes Equ >> Eth :

quantal regime

Eth >> Equ :

thermal regime

An estimate with typical numbers: T = 300° K, localization distance Δq ~ 1Å, and a critical separation, Ec, between the two regimes, following from Equ = Eth = Ec ≈ 1.3˙10-2 eV, results in a critical quasiparticle mass meff ≈ 0.04 MH ≈ 75 me where MH is the mass of a hydrogen atom, and me is the electron mass.7 This indicates that the dynamical mass of a quantum transition, if robust against thermal fluctuations, has to be much smaller than the hydrogen atomic mass. Biomolecules whose masses lie in the range of kD do certainly not qualify for quantum effects as a whole. We can also derive a critical frequency, – h ωc = Ec , and a signal time, τ = 2 π/ωc , ωc ≈ 2 ⋅ 1013 s-1 ; τ ≈ 0.3 ps These results show unambiguously that quantum processes at room temperature involve frequencies in the picosecond scale, or smaller. This, in turn, means they correspond to electronic transitions, like electron transfer or changes in molecular bonds (e.g., breaking of a hydrogen bridge).

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Our analysis leads to the consequence that in brain dynamics two well separated regions with different time scales exist: (i) The macroscopic, or cellular, dynamics with time scales in the milliand down to the nanosecond range. (ii) The microscopic, or quantal, dynamics with time scales in the pico- to femtosecond range. The large difference in time scales makes it possible to deal with quantum processes in the isolated individual microsites, dynamically decoupled from the rest of the neuronal net. On the other hand, the enormous time scale difference explains why the usual biochemical and biophysical studies, usually performed in the macroscopic cellular dynamics, do not need the introduction of quantum considerations. To uncover the need, one has to employ ultra-short time spectroscopy (Vos et al. 1993). The analysis presented here shows that quantum processes in the brain could be playing a decisive role in brain activities if the latter enter the dynamics of the cortical neuronal network. As outlined in the previous section, exocytosis with its quantal emission character qualifies as just such a process. We therefore regard exocytosis as a candidate by which quantum processes enter into, and thus regulate, brain dynamics (Beck and Eccles 1992).

6. THE QUANTUM TRIGGER MODEL Synaptic exocytosis is the biochemical and biophysical process which enables the regulating function of spine synapses. The decisive process for the release of transmitter molecules is the opening of an ion channel in the presynaptic membrane. The biophysical mechanism for this is presumably a conformation change in the electronic structure of the membrane. Based on this, the quantum trigger model was developed by Beck and Eccles (Beck and Eccles 1992). An incoming nerve impulse excites a metastabe electronic configuration of the membrane molecules which is separated by a potential barrier from the state in which a time-dependent cascade leads to exocytosis. The dynamics along this electronic process of conformational change can be described by a quasiparticle which represents the collective degrees of freedom along this motion. The crucial assumption is that surpassing the potential barrier is achieved by a quantum mechanical tunnel effect:8 in this way quantum physics is introduced into brain dynamics. As has been shown in the previous section, the mass of the quasiparticle must be restricted to the order of several electron masses to secure that tunneling survives thermal fluctuations. This, however, means that ion channel dynamics as a whole can not be responsible for quantum processes in the brain.9

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A realization of the quantum trigger for synaptic exocytosis is possible by an electron transfer process in biomolecules (Beck 1996b). The step which initiates this process is an energetic excitation, regulated by the action potential, of a donor D with subsequent transport of an electron to the acceptor A, producing the polar system D+A–. This is accompanied by the rearrangement of the molecular coordinates, leading to unidirectional charge separation and, over several further electronic transitions with increasing time constants, to the opening of the ion channel for exocytosis. Such a process has indeed been observed in the biological reaction centers of bacteria (Vos et al. 1993). Further experimental investigations (ultra-short time spectroscopy on the microscopic time scale as discussed in the last section) have to be performed using isolated nerve cells to establish if the quantum trigger (Beck and Eccles 1992) is indeed the decisive process in synaptic transfer. One result, however, is undoubtedly true: if quantum processes play a predominant role in the brain, such that quantum interference with its principal indeterminacy becomes active in spite of the stochastic nature of the neuronal net, this is only possible on the time and frequency scales which were derived in the previous section.

7. SPATIOTEMPORAL STRUCTURES IN THE NEURAL NET The “hard problem” in brain research is the binding problem, characterized by coherent activity of specific topological areas (e.g., the visual cortex) in the brain (Posner et al. 1985; Singer 1990; Corbetta et al. 1990; Eccles 1994). Activated brain areas are characterized by an increase in regional cerebral blood flow, as has been demonstrated in radio-xenon technology (Roland 1981), or more recently by positron emission tomography (PET, Pardo et al. 1991). Activation generates most complex spatiotemporal patterns which characterize specific perceptions (visual, audible, taste or touch) or intentions (silent thinking, moves, figure 3.9). These patterns are intimately related to memory and the learned inventory of pyramidal cells (Kandel and Schwartz 1982). In the neural bundles (“dendrons,” cf. figure 3.5), which comprise the active area, there are thousands of modifiable synapses which have to act cooperatively to generate the increased action potential needed to bring out the observed activity, (figure 3.8). Since the exocytosis probability of single synapses can change (increase or decrease) only when there are incoming nerve impulses, there has to be a constant (stochastic) background activity which will be modulated coherently by a large number of synapses. The foregoing discussion suggests a research program to look for spatio-temporal patterns in the neuronal net, together with their regulation by synaptic action and possibly diffusive couplings between nerve cells.

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Figure 3.9. Positron emission tomography (PET) scans of the cerebral cortex of conscious human subjects performing four intellectual tasks relating to words. (Images taken by Dr. Marcus Raichle in 1992.)

Several authors concerned with quantum brain dynamics attribute longrange coherence in the neuronal net to macroscopic quantum states. The most serious of these approaches has been presented by Hameroff and Penrose (1996); see also Schwartz et al. (2005). None of these papers gives, however, an explicit dynamical framework that shows how such states could preserve their coherent structure against thermal fluctuations at room temperature. On the basis of the empirical evidence (Freeman 1996; Spitzer and Neumann 1996), and successful modeling (Haken 1996), we would rather attribute long-range cooperative action in the active zones of the brain to nonlinear dynamics of a driven open system. Such a system is far from thermal equilibrium and possesing dynamic instability, so it can organize itself by external stimuli in a variety of synchronous activity patterns (Gray et al. 1989). Synaptic exocytosis in such a system serves as regulator, and the coherent cooperation of the many synapses in the dendrons (active area) produce the spatiotemporal patterns above noise. We regard this as the proper approach to transform quantum action to the macroscopic template in the

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active brain. Quantum action and subsequent state reduction in the individual synapse produce the non-algorithmic binding in cortical cells. Figure 3.10 presents a schematic sketch of three bundles of pyramidal cells (dendrons) surrounded by their spatial patterns which are produced temporarily by cooperation within the individual cells. Since these patterns are activated by perception and intention, as well as in ideation (Ingvar 1990), they represent the basic units of consciousness. To give them a name which expresses their unparalelled importance, Eccles (1990) coined the term “psychons.” The physiological mechanisms of pattern formation and signal transduction in the brain are not yet fully understood. Nevertheless, the recent rapid progress in uncovering many facets of nonlinear dynamics in biological systems (cf., e.g., Goldbeter 1996) offers hope that there will be substantial progress in our understanding of large-scale brain dynamics in the near future. A most promising approach to combine noisy structures with the enhancement of regular signals is presented by the observation of stochastic resonance (Gammaitoni et al. 1998). A recent study of stochastic resonance in a neuronal net (Jung and Mayer-Kress 1995) is presented in figure 3.11. It shows for increasing noise levels (a to d) the time development of spiral waves in the excitable medium generated by an initially firing set of elements. The results show clearly the constructive influence of noise on coherent pattern formation (“stochastic resonance”). The combination of quantum tunneling states with

Figure 3.10. Coherent couplings of bundles of dendritic pyramidal cells (dendrons) to form spatiotemporal patterns (Eccles 1990).

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Figure 3.11. Spatio-temporal pattern formation in a twodimensional excitable neuronal net model by stochastic resonance. Shown is the formation of spiral waves out of an initially firing set of elements. From left to right: snapshots of firing patterns of elements in position (i,j) with i,j = 1,…,400 as time evolves. (a), noise turned off, (b)–(d), increasing noise level (Jung & Mayer-Kress 1995).

noisy surroundings has recently also been studied by Grifoni and Haenggi (1996). The important role of quantum events does not, however, depend on the exact nature of these large-scale structures, it relies solely on the concept of state superposition in microscopic molecular transitions.

8. CONTROVERSIES Most neuroscientists do not see the need to incorporate quantum processes in the dynamics of the human brain. The reason for this is that recent rapid success in experimental brain research, made possible by modern image-

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processing, like positron emission tomography (PET) and, most recently, dynamic magnetic resonance imaging, reveal spatiotemporal patterns which can be understood with classical molecular dynamics, acting in the neuronal net. This is in agreement with biochemical experimental investigations, e.g., in neural firings and synaptic activity, restricted, however, to the macromolecular time scale of micro- to nanoseconds. Consequently, these researchers adhere to the belief that brain dynamics is a strictly deterministic process, leaving no room for any form of dualism, or, consequently, the notions of “free will,” self-determined decisions, etc. (see, e.g., Roth 2000, Singer 2005). “Free will,” in the context of this viewpoint, is an illusion, extremely useful, though, since it gives confidence in human behavior, but it is not compatible with neuronal determinism. A strong support for this materialistic explanation of brain activity was delivered by the exciting and intensively discussed Libet experiment. In its original form (Libet et al. 1983) the experiment demonstrated that unconscious electrical processes in the brain (occurrence of the so-called readiness potential) preceded conscious decisions to perform volitional acts. This implies that unconscious neuronal processes precede and cause volitional acts which are retrospectively interpreted as being consciously motivated by the acting person. Consequently, seemingly volitional brain activity is driven by physiological, deterministic processes, and free will is illusionary! Benjamin Libet himself was completely shocked by his results, since he conducted the experiment to proove the existence of free will. In a later experiment, he weakened this surprising consequence by asking the subject to revoke the volitional act immediately after it was decided on, and he registered the time of revoking. This came after the occurrence of the readiness potential, so Libet argued that free decisions have at least a stopping power for mental acts, initialized before by the unconscious build-up of the readiness potential. Experiments of the Libet type have subsequently been performed several times, and in different laboratories. The results were similar, but revealed large fluctuations in the sequence of the time signals, casting doubt on the statistical significance of the results. Furthermore, it has been argued that the simple decision to move a finger necessarily within a given time interval does not relate to moral or self-conscious free decisions. Such a decision could rather be the one to take part in the experiment or to refuse. Consequently, physiological and philosophical doubts remain with respect to the Libet experiment, and the question of its relevance with respect to determinism or indeterminism of brain activity is by no means finally settled. In view of this situation, there is no compelling reason to claim that Libet’s experiment is a proof of the non-existence of free will. Finally a word concerning the equally controversial question about which point in evolution hominids became human beings. Evolution is an extremely slow process, and the development from anthropoids to homo sapiens

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took several millions of years. In consequence, there is no jump in the development, and no definite point at which the transformation occurred. The criterion of homo sapiens is believed to be self-consciousness, but one has to admit that higher mammals also possess conscious activity. They are able to learn and to produce simple tools. If quantum processes are essential for mind-brain duality and located in the regulating function of spine synapses, as argued here, this structure should have also developed continuously in evolution, and so should already be functioning in higher vertebrates. Consequently, their behavior should be equally unpredictable. The truly unique property of homo sapiens, not present in any earlier species, is, however, the ability to develop ever more complex communications in speech and written words, communicating their experience to the next generations, and so developing a cultural heritage: Popper’s World 3 (cf. figure 3.1). This property leads to a cultural evolution, parallel but much more rapid than the biological evolution, and which is definitive of mankind.

9. CONCLUSION Modern physics in the microscopic domain of matter has revealed a duality of classical incommensurable entities: the wave-particle-dualism. The waveand the particle picture are both simultaneously needed for a complete description of the microscopic structure: complementarity. In the emerging theory of quantum mechanics, this dualism expresses itself as complex state vectors which are probability amplitudes, introducing indeterminism to the time evolution of the actualities, i.e. into the future outcome of a physical process (actualities evolve into propensities). For a single event, the outcome is not predictable. In consequence, if quantum processes do play a decisive role in the regulation of brain processes, these processes are not predictable and the brain is not a deterministic object. This establishes for a sequence of events the difference between past and future: The past is known (by events which have occurred in reality) while the future is unknown (since the possible events which are determined by the time evolution of the state vector possess only a certain potentiality combined with a probability of occurrence). It establishes the dualism in modern physics. This is all that physical science can contribute to the debate of mental dualism. It is, however, remarkable that physics has taught us that two classically incommensurable pictures have to be used complementarily for a complete description of a microphysical situation, and that the price for this is non-determinacy. As we pointed out right at the beginning, a similar dualism exists between the physical brain and the immaterial mind: if both concepts are needed for a complete description of human self-consciousness, and if they are used simultaneously, no prediction of human actions is possible. The basic difference between these two concepts of duality is, however, that the

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qualia of consciousness is not a matter of science, but belongs to philosophical, ethical or religious reasoning. Science can, however, provide logical concepts (e.g., the uncertainty in the description of future processes in the microscopic world) that are essential to make discussions beyond the limitations of science possible: complementarity must be introduced if a complete picture of the world is to be established! In this way, the “ignorabimus” of Du Bois-Reymond (cf. Section 1.1) has been turned into a hopeful “non ignorabimus” through the possibility of quantum physics playing a decisive role in brain dynamics. For this, we present a physiologically realistic model (see Section 6 and the Appendix). The basic assumptions of the quantum trigger model (Beck and Eccles 1992) are: • Quantum processes in the hot and wet environment of the brain are only possible at the microscopic level of (electron) transitions in the pico- to femtosecond time scale. • Spine synapses are important regulators of brain activity, filtering the ever-present firings of nerve impulses. • Exocytosis, the release of a transmitter substance across the presynaptic membrane, is an all-or-nothing event which occurs with probabilities much smaller than one. • A model, based on electron transfer, relates exocytosis to a two-state quantum trigger, leading by quantum tunneling to the superposition of two states, followed by state reduction (collapse into one definite final state). • The coherent coupling of synapses via microtubular connections is still an open problem. The quantum trigger can, however, initialize transitions between different macroscopic modes (stochastic limit cycles, Grifoni and Hänggi 1996). • The quantum trigger opens a doorway to a better understanding of the relations between brain dynamics and consciousness.

ACKNOWLEDGMENTS My interest in brain dynamics was evoked by the late Sir John Eccles in a vivid discussion on brain and quantum physics. This began our close collaboration in which John Eccles presented the essential physiological data of brain functioning on which basis I developed the quantum trigger model for synaptic exocytosis. The result was our 1992 paper on quantum aspects of brain activity and the role of consciousness which appeared in the Proceedings of the National Academy of Science, USA, (Beck and Eccles 1992). I am deeply indebted to John Eccles for leading me into a fascinating field of interdisciplinary research.

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NOTES 1. Causality is understood in this article as strong causality: i.e. completely specified initial conditions will lead to a unique, completely determined final result. In humanities, a weaker concept of causality is often used, in the sense “no action without cause.” This may be called weak causality, and it allows an indeterministic outcome even for completely specified initial conditions. 2. Attempts have been to incorporate particle-wave dualism into a classical concept by introducing “hidden variables.” According to recent experiments these attempts have been ruled out (see chapter 3). 3. Von Neumann, in his introductory book on the foundations of quantum mechanics (von Neumann 1955), expresses this rather drastically: “The everything leveling of the law of large numbers obscures completely the real nature of the single process.” 4. In coin tossing the knowledge that the occurrence of either side is 1/2 does not help in any way to predict the outcome of a single toss. 5. In several, mostly popular, books on quantum mechanics, particle-wave dualism is explained by claiming that, corresponding to which question we ask, microscopic particles manifest themselves either as particles or as waves. This obscures the fact that both pictures have to be used simultaneously for a complete description of a microscopic object. (In the formal establishment of quantum mechanics, classical canonical variables have to be replaced by non-comuting operators in the space of quantum states.) 6. Systems producing deterministic chaos are in many cases non-integratable, which means that no analytic solution is possible. The numerical solutions produce uncertainties at each time step of the integration algorithm. 7. The original paper (Beck and Eccles 1992) contained an error in listing this quantity; the later given values are, however, correct. 8. Quantum tunneling allows the penetration of potential barriers with a kinetic energy less than the barrier height, but only with a certain tunneling probability per time less than one, which is an outflow of the uncertainty relation. Thus, tunneling is a typical quantum process and does not exist in classical mechanics. It has first been applied by G. Gamow to describe the radioactive α-decay of atomic nuclei. 9. A more formal outline of the quantum trigger model will be given in the Appendix.

BIBLIOGRAPHY Akert, K., K. Peper, and C. Sandri. 1975. “Structural Organization of Motor End Plate and Central Synapses.” In Cholinergic Mechanisms, edited by P.G. Waser, 43–57. New York: Raven. Aspect, A. 1999. “Bell’s Inequality Test: More Ideal than Ever.” Nature 398: 189. Beck, F., and J.C. Eccles. 1992. “Quantum Aspects of Brain Activity and the Role of Consciousness.” Proceedings of the National Academy of Sciences USA, 89: 11357–61. Beck, F. 1996a. “Mind-Brain Interaction: Comments on an Article by B. I. B. Lindahl and P. Århem.” Journal of theoretical Biology 180: 87–89.

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Beck, F. 1996b. “Can Quantum Processes Control Synaptic Emission?” International Journal of Neural Systems 7: 343–53. Corbetta, M., F.M. Miezin, S. Dobmeyer, G.L. Shulman, and S.E. Petersen. 1990. “Attentional Modulation of Neural Processing of Shape, Color and Velocity in Humans.” Science 248: 1356–59. Descartes, R. 1985. Principles of Philosophy. In The Philosophical Writings of Descartes, edited by J. Cottingham, R. Stoothoff, and D. Murdoch. Cambridge: Cambridge University Press. Eccles, J.C. 1990. “A Unitary Hypothesis of Mind-Brain Interaction in the Cerebral Cortex.” Proceedings of the Royal Society (London) B240: 433–51. Eccles, J.C. 1994. How the Self Controls Its Brain. Berlin, Heidelberg, New York: Springer. Edelman, G.M. 1989. The Remembered Present: A Biological Theory of Consciousness. New York: Basic Books. Freeman, W. 1996. “Random Activity at the Microscopic Neural Level in Cortex (“Noise”) Sustains and is Regulated by Low-Dimensional Dynamics of Macroscopic Cortical Activity (“Chaos”).” International Journal of Neural Systems 7: 473–80. Flohr, H. 1995. “An Information Processing Theory of Anesthesia.” Neuropsychologia 33: 1169–80. Goldbeter, A. 1996. Biochemical Oscillations and Cellular Rhythmics. Cambridge: Cambridge University Press. Gammaitoni, L., P. Hanggi, P. Jung, and F. Marchesoni. 1998. “Stochastic Resonance.” Review of Modern Physics 70: 223–87. Gray, E.G. 1982. “Rehabilitating the dendritic spine.” Trends in Neurosciences 5: 5–6. Gray, C.M., P. König, A.K. Engel, and W. Singer. 1989. “Oscillatory Response in Cat Visual Cortex Exhibit Inter-Columnar Synchronization Which Reflects Global Stimulus Properties.” Nature 338: 334–37. Grifoni, M., and P. Hänggi. 1996. “Coherent and Incoherent Quantum Stochastic Resonance.” Physical Review Letters 7: 1611–14. Haken, H. 1996. “Noise in the Brain: A Physical Network Model.” International Journal of Neural Systems 7: 551–57. Hameroff, S., and R. Penrose. 1996. “Orchestrated Reduction of Quantum Coherence in Brain Microtubules—A Model for Consciousness.” In Toward a Science of Consciousness: Contributions from the 1994 Tucson Conference, edited by S. Hameroff, A. Kaszniak and A. Scott, 507–40. Cambridge, MA: MIT Press. Hameroff, S. 1998. “Anaesthesia, Consciousness and Hydrophobic Pockets⎯A Unitary Quantum Hypothesis of Anaesthetic Action.” Toxicology Letters 100–101: 31–39. Ingvar, D.H. 1990. “On Ideation and ‘Ideography.’” In The Principles of Design and Operation of the Brain, edited by J.C. Eccles and O. Creutzfeldt, 433–53. Experimental Brain Research, Series 21. Berlin, Heidelberg: Springer. Jack, J.J.B, S.J. Redman, and K. Wong. 1981. “The Components of Synaptic Potentials Evoked in Cat Spinal Motoneurons by Impulses in Single Group Ia Afferents.” Journal of Physiology (London) 321: 65–96. Jung, P., and G. Mayer-Kress. 1995. “Spatiotemporal Stochastic Resonance in Excitable Media.” Physical Review Letters 74: 2130–133. Kandel, E.K., and J.H. Schwartz. 1982. “Molecular Biology of Learning: Modulation of Transmitter Release.” Science 218: 433–43.

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Kelly, R.B., J.W. Deutsch, S.S. Carlsson, and J.A.Wagner. 1979. “Biochemistry of Neurotransmitter Release.” Annual Review of Neuroscience 2: 399–446. Libet, B., A.G. Curtis, W.W. Elwood, and K.P. Dennis. 1983. “Time of Conscious Intention to Act in Relation to Onset of Cerebral Activities (Readiness-Potential): The Unconscious Initiation of a Freely Voluntary Act.” Brain 106: 623–42. Lindahl, B.I.B., and P. Århem. 1994. “Mind as a Force Field: Comments on a New Interactionistic Hypothesis.” Journal of Theoretical Biology 171: 111–22. Messiah, A. 1961. Quantum Mechanics I. Amsterdam: North Holland. Mountcastle, V.B. 1978. In The Mindful Brain, edited by F.C. Schmitt, 7–50. Cambridge, MA: MIT Press. Pardo, J.V., P.T. Fox, and M.E. Raichle. 1991. “Localization of a Human System for Sustained Attention by Positron Emission Tomography.” Nature 349: 61–64. Penrose, R. 1994. Shadows of the Mind: An Approach to the Missing Science of Consciousness. Oxford: Oxford University Press. Peters, A., and D.A. Kara. 1987. “The Neuronal Composition of Area 17 of the Rat Visual Cortex. IV. The Organization of Pyramidal Cells.” Journal of Computational Neurology 260: 573–90. Pfenninger, K., C. Sandri, K. Akert, and C.H. Eugster. 1969. “Contribution to the Problem of Structural Organization of the Presynaptic Area.” Brain Research 12: 10–18. Popper, K.R. 1972. Objective Knowledge: An Evolutionary Approach. Oxford: Clarendon Press. Popper, K.R., B.I.B. Lindahl, and P. Århem. 1993. “A Discussion of the Mind-Brain Problem.” Theoretical Medicine 14: 167–80. Posner, M.I., S.E. Petersen, P.T. Fox, and M.E. Raichle. 1985. “Localization of Cognitive Operations in the Human Brain.” Science 240: 1627–31. Redman, S.J. 1990. “Quantal Analysis of Synaptic Potentials in Neurons of the Central Nervous System.” Physiological Review 70: 165–98. Roland, P.E. 1981. “Somatotopical Tuning of Postcentral Gyrus During Focal Attention in Man. A Regional Cerebral Blood Flow Study.” Journal of Neurophysiology 46: 744–54. Roth, G. 2000. “The Evolution and Ontogeny of Consciousness.” In Neural Correlates of Consciousness, edited by T. Metzinger, 77–97. Bradford Book: MIT Press. Sayer, R.J., M.J. Friedlaender, and S.J. Redman. 1990. “The Time-Course and Amplitude of EPSPs Evoked at Synapses Between Pairs of CA3/Ca1 Neurons in the Hippocampal Slice.” Journal of Neuroscience 10: 626–36. Schmolke, C., and K. Fleischhauer. 1984. “Morphological Characteristics of Neocortical Laminae When Studied in Tangential Semi-Thin Sections Through the Visual Cortex in the Rabbit.” Anatomy and Embryology 169: 125–32. Schwartz, J., H. Stapp, and M. Beauregard. 2005. “Quantum Physics in Neuroscience and Psychology: A Neurophysical Model of Mind/Brain Interaction.” Philosophical Transactions of the Royal Society B 360: 1309–27. Singer, W. 1990. “Search for Coherence: A Basic Principle of Cortical SelfOrganization.” Concepts in Neuroscience 1: 1–26. ———. 2005. “The Brain—An Orchestra Without a Conductor.” In Max Planck Research, 14–18. 3/2005. Spitzer, M., and M. Neumann. 1996. “Noise in Models of Neurological and Psychiatric Disorders.” International Journal of Neural Systems 7: 355–61. Szentagothai, J. 1978. “The Neuron Network of the Cerebral Cortex: A Functional Interpretation.” Proceeedings of the Royal Society (London) B 201: 219–48.

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Von Neumann, J. 1955. Mathematical Foundations of Quantum Mechanics. Chapter IV. Princeton: Princeton University Press. Vos, M.H., F. Rappaport, J.C. Lambry, J. Beton, and J.-L. Martin. 1993. “Visualization of Coherent Nuclear Motion in a Membrane Protein by Femtosecond Spectroscopy.” Nature 363: 320–25.

APPENDIX: THE QUANTUM TRIGGER MODEL Exocytosis as a whole is, as was outlined in section 5, a macromolecular process which serves as a regulator in the neuronal net. Our quantum trigger model is based on the observation that the probability of exocytosis is, after an activating nerve impulse, in many cases much smaller than one. This gives a hint that quantum processes might be involved in the triggering process. A nerve impulse entering a spine synapse excites in the biological reaction center of the presynaptic membrane (cf. figure 3.4B) a metastable energy state which is separated by a potential barrier V(q) from the state which leads irreversibly to exocytosis. With q we denote a collective coordinate which describes the path along the electronic and molecular conformational changes between both states. The motion along this path can be characterized by a quasiparticle with the effective mass meff (given by the dressing of the electronic motion through the couplings to the complicated conformational degrees of freedom). The quasiparticle can then quantum mechanically tunnel through the barrier V(q). As pointed out in Section 5, the effective mass meff must not be larger than several electron masses to avoid a dominant influence of thermal fluctuations. The quasiparticle assumption allows a model description of the complicated molecular transition as an effective single-particle problem whose solution is determined by the one-dimensional Schrödinger equation i –h ∂ Ψ(q;t)  –h2 ∂2 Ψ(q;t)  V(q) ˙ Ψ(q;t)  ∂t 2meff ∂q2

(A 1)

Figure 3.A1 (A) shows schematically the initial state at t = 0 (after the activation by an incoming nerve impulse), and in (B) at the end of the activation period, t = t1. The assumption is that the activated state persists during a time period t1 before it recombines. t1 belongs to the macroscopic time scale (micro- to nanoseconds) as defined in Section 5. At time t1 the state (represented by the wave function) has developed into one part which still resides left of the barrier (in region I) and another part residing to the right (in region III). Now we can separate the wave function into two parts, left and right of the barrier: Ψ(q;t1)  Ψleft (q;t1)  Ψright (q;t1)

(A 2)

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Figure 3.A1. (A) initial state (t = 0) of the quasiparticle in the potential V(q). The wave function is localized to the left of the barrier. E0 is the energy of the activated state from which the tunneling process starts. (B) After time t1 the wave function has parts at both sides of the barrier. a, b, turning points of the classical motion inside and outside the barrier.

These are the coherent amplitudes, as described in Section 2. State reduction transforms the wave function into two separated components, Ψleft, Ψright, which determine the probabilities probability for exocytosis

pex (t1)  ∫| Ψright |2 dq

probability for inhibition

pin (t1)  ∫| Ψleft |2 dq

(A 3)

To arrive at numbers for these quantities (in order to check the physiological soundness of the model), we can calculate the tunneling by using

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the WKB-approximation (Messiah 1961). As a result, we obtain the transmission coefficient T as

{

b

T  exp  2∫ a

√ 2meff [V(q)E0] – h

}

dq

(A 4)

with E0, energy of the activated initial state, V(q)  E0, effective barrier height. As typical quantities we take as effective barrier height 0.05 to 0.1 eV (this secures to be above thermal fluctuations (cf. Section 5), and quasiparticle masses between 2 and 10 electron masses. With these estimates the transmission coefficient comes out to be in the region T  10-1 to 10-10 (this wide span reflects the exponential dependence of the transmission coefficient on the effective barrier height, Equation A4). For a crude estimate of the exocytosis probability pex(t1) (Equation A3) one can use the so-called Gamow approximation by calculating the frequency of hitting the barrier per unit time which is given by ω0  E0 / –h, and multiplying this quantity with the activation time t1 and the transmission coefficient T. pex (t1)  t1ω0 T.

(A 5)

With a transmission coefficient in the mid-range, T ~ 10-7, an activation time between 1 and 5 nanoseconds, and activation energy E0 of 0.5 to 1 eV, one obtains exocytosis probabilities in the range between 0 and 0.7, in agreement with measured values of this quantity (Jack, Redman, and Wong 1981).

4 Discrete Degrees Within and Between Nature and Mind Ian J. Thompson

Examining the role of dispositions (potentials and propensities) in both physics and psychology reveals that they are commonly derivative dispositions, so called because they derive from other dispositions. Furthermore, when they act, they produce further propensities. Together, therefore, they appear to form discrete degrees within a structure of multiple generative levels. It is then constructively hypothesized that minds and physical nature are themselves discrete degrees within some more universal structure. This gives rise to an effective dualism of mind and nature, but one according to which they are still constantly related by causal connections. I suggest a few of the unified principles of operation of this more complicated but universal structure.

1. INTRODUCTION Questions about the nature and interaction of mind or soul and body have been much debated since Plato, who argued that the soul cannot be the “harmony of the body,” but must have its own existence. In the seventeenth century, this commonly held view was articulated and codified by Descartes, who proclaimed that there were two kinds of substances: thinking substances which are our souls, and extended substances which constitute the physical world. Since then, some kind of dualism has been almost universally assumed in folk psychology, morality and religion, while at the same time almost universally condemned in cognitive psychology, philosophy and neurobiology. Modern philosophers tend to ritually deny dualism, and use Descartes’ formulation as a convenient target for their discontent. 99

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To rationalize their dissatisfaction, a variety of questions have been asked and arguments presented. Some of the questions raised against dualism are based on empiricism: that we never see minds in nature, and science has no need for non-material causes. Some object from methodology that modern science must assume all causes are part of nature, and that in any case physics can be defined as the basic science of all causes. Others are puzzled when trying to understand dualism: how can there be a non-substantial substance, how do (can?) mind and body interact? Some want to keep everything unified, and say that there must be unity at the heart of nature, not an irreducible multiplicity, and that we do not want to fragment our “person” into multiple parts: we are a whole! Does not Descartes relegate our body to be mind-less, feeling-less? Of course, there are equal or greater problems with materialism that led us into the whole discussion, since our minds seem so obvious to us, but so obscure to science. What is mind?—that is the perennial debate. In the last decade there has been renewed interest in consciousness, but very often with the contexts of functionalism, supervenience, or “non-reductive physicalism,” so that the causal closure of the physical world is maintained. Many problems then arise as to how our ideas, decisions, affections have any influence in the world. The challenge I want to meet in this paper is to conceive coherently of multiple kinds of substances existing, so they can interact with each other, yet without all these kinds being reduced or conflated into one kind. How is this possible? Is it possible for mind and body to be of such multiple kinds? Could minds and bodies conceived like this be in general agreement with the assumptions of folk psychology as well as of neurobiology? My proposed answers will depend on developing the concept of multiple generative levels of dispositions, and then showing that there are many kinds of linked dualisms or discrete degrees within physical nature, possibly also within minds, and then plausibly between nature and minds. The links will arise from causation as more generally conceived, but this causation will not look more like collisions of billiard balls, more like non-local “resonances” or “correspondences” as I will explain. Many people have noted that there are several aspects of quantum mechanics which are reminiscent of mental properties. Quantum processes are indeterministic, non-local, and consciousness could have a role in initiating measurements. Walker (1970) and later Eccles (1977, 1989) have suggested that mental events influence or bias at least some physical outcomes within the range allowed by quantum mechanics. However, quantum mechanics makes very precise predictions for the probabilities of those outcomes, and, furthermore, the evolution of these probability distributions is completely deterministic. If there were external mental input, it would have to change the proba-

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bilities of different outcomes (Saunders 2000 and Brecha 2002), and hence change the probability rules of quantum physics. Other scientists and philosophers (e.g., Wigner (1962), Popper (1977), Faber (1986), Toben (1974), Squires (1990), Donald (1990), Stapp (1977), among others) have believed that the problem of measurement can only be solved by introducing some basic notion of an observer, presumably a conscious observer, and that this indicates an essential role of consciousness in the physical world. Since, however, the “measurement problem” can perhaps be solved within physics, by theories of decoherence (Giulini 2003) or of propensities (Maxwell 1988), the role of consciousness in measurement has little direct bearing on the problem of how the mind and brain function together. Finally, Marshall (1989) and Clarke (2006) think that the non-locality of, for example, Bose-Einstein condensates is suggestive of mentality, and therefore these condensates could be the carrier of consciousness. However, all psychological details of mental structure and operations would then be derived from this quantum structure, so that all human life (from mathematics and logic to arts to psychopathology) would have to be implicit in Schrödinger’s equation. Personally, I find it extremely implausible that the quantum mechanics of patterns of excitations of Bose-Einstein condensates exactly and mechanically determines the interaction patterns of ideas, images and meanings in the human mind. Despite the shortcomings of these theories of quantum effects in the brain, I still believe that quantum physics is important in our understanding of its function. To show this, I am going to take a different approach, and develop a dualism that is non-reductionist, as Eccles and others do, so that the mind is (in some way) distinct from the brain. But I want to then see how they could be intimately connected (still). Psychologists and neuroscientists are aware of the close functional dependence of minds and brains, that physiological changes very readily affect the mind in many ways, and that mental intentions and attitudes affect both the normal and abnormal functioning of the nervous system. A good theory ought to be based on sound principles, cast light on the above phenomena, and contribute constructively to psychology.

2. DISPOSITIONS We need therefore to go back to basics, and consider some rather fundamental questions about dispositions and causation in the sciences. I will be using the terms “power,” “potential,” “capability,” “capacity,” “propensity” and “cause” as examples within the category of “dispositional properties of objects.” It is a common belief that modern science does away with those obscure notions of “disposition” and “potentiality,” in favor of an analysis of the

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component structure of the things concerned and their functional relationships, but many philosophers (Molnar 2004) have realized that the truth is quite different. As explained in Thompson (1988), dispositional properties can only be explained or reduced to other dispositions, not to entirely static or structural properties. That is, dispositions have a “categorical irreducibility,” as it is impossible to explain them away in terms of other categories such as space, time, form, process, material, property etc. For suppose that the exact shape and size of an object were known, the shapes and sizes of all its constituents, along with a list of these facts at every time. We would still not know enough about how or why the object would change over time or on interactions. Still less could we predict how it would respond to a new experimental test. There seems no way to avoid some kind of irreducibly dispositional properties of physical objects. In psychology, much theorizing is done using functionalist explanations, but Klein (2004) shows that the realistic interpretation of any functions must be in terms of dispositions. 2.1 Ontology of Dispositions We next consider a kind of “ontology of dispositions,” where what is necessary and sufficient for the dispositional causation of events is interpreted realistically, and postulated to exist. Thompson (2005) shows how this leads to a concept of “generic substance” (Aristotle’s underlying “matter”) as being constituted by dispositions, not just being the “bare subject” for those dispositions. That is, the substance of an object is constituted by the set of underlying dispositions or propensities for how it can act or interact. If furthermore we describe the forms of objects according their spatiotemporal range, then this form is best viewed as a field, and substances themselves are best conceived as “fields of propensity.” I have described elsewhere (Thompson 2005) that then we can try to understand some of the more mysterious quantum features of nature, such as the nature of measurement interactions and non-localities, and as well as the duality of wave and particle descriptions. 2.2 How Dispositions Change Most examples of dispositions in philosophical discussions are those, like fragility, solubility, radioactive instability, whose effects (if manifested) are events. If a glass exercises its fragility, it breaks. If salt shows its solubility, it dissolves, and the manifestation of radioactive instability would be a decay event detected with a Geiger counter. However, physicists want to know not merely that these events occur, but also how the dispositions themselves may change after the manifestation event. In the cases above, the fragility of the parts or the stability of the nuclei may change as a result of the manifestation events, and it is an important part of

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physics to describe the new (changed) dispositions as accurately as possible. Sometimes, new dispositions may be ascribable after an event which could not have been ascribed before the event. The fragments of a broken glass may be able to refract light in a way that the intact glass could not. The existence of some of these new dispositions may perhaps be successfully explained as the rearrangement of the internal structures of the objects under discussion, when these are composite objects. The refraction by pieces of broken glass, in contrast to the original smooth glass, has obvious explanations in terms of the shapes of the new fragments. Science is largely successful in explaining such dynamical evolutions of empirical dispositions of natural objects: it bases its explanations in terms of changes in their structural shapes and arrangements of their parts, along with the fixed underlying dispositions or propensities of these parts. It is from the dispositions of these parts that, according the structure, all their observed dispositions and causal properties may be explained. The existence of new dispositions by rearrangement of the parts of an object may be taken as non-controversial. However, it appears that not all dynamical changes of dispositions occur by rearrangements of parts, and these are what in this paper I want to call “derivative dispositions.”

3. DERIVATIVE DISPOSITIONS IN PHYSICS There are some cases, to be listed below, where new dispositions come into existence without there being any known parts whose rearrangement could explain the changes. The next section gives some examples of what appear to be such derivative dispositions, and this is followed by a more general analysis of how these might work. If there turns out to be a sequence of derivative dispositions, then the combined structure will be termed a set of “multiple generative levels,” as will be illustrated. 3.1 Energy and Force If we look at physics, and at what physics regards as part of its central understanding, one extremely important idea is that of energy. Physics talks about kinetic energy as energy to do with motion, and potential energy as to do with what motion would happen if the circumstances were right. More specifically, if we look at definitions of force and energy which are commonly used to introduce these concepts, we find definitions like • force: the tendency F to accelerate a mass m with acceleration F/m, • energy: the capacity E to do work, which is the action of a force F over a distance d, and • potential energy field: the field potential V(x) to exert a force F = -dV/dx if a test particle is present.

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As Cartwright (1983) points out, force is not identical to the product ma, because it is only the net force at a point which can have an effect. An individual force is only by itself a tendency which may or may not be manifested. It is a disposition, as is energy generically, as well as potential energy. Furthermore, we may see a pattern here: • potential energy field: the disposition to generate a force, • force: the disposition to accelerate a mass, and • acceleration: the final result. I would like to take this as an example of two successive derivative dispositions, where the effect of one disposition’s operation is the generation of another. An electrostatic field potential is a disposition, for example, the manifestation of which—when a charge is present—is not itself motion, but is the presence now of a derivative disposition, namely a force. The manifestation of a force—when acting on a mass—may or may not occur as motion, as that depends on what other forces are also operating on the mass. The production of a force by a field potential does not appear to be something that occurs by means of the rearrangements of microscopic parts, but appears to be more fundamental, and almost sui generis. It appears that field potentials, force and action form a set of multiple generative levels, and this situation is clearly in need of philosophical inspection. Admittedly, many physicists and philosophers often manifest here a tendency to say that only potential energy is “real,” or conversely perhaps that “only forces are real,” or even that “only motion is real,” and that in each case the other physical quantities are only “calculational devices” for predicting whichever is declared to be real. Please for a while apply a contrary tendency to resist any of these reductive conclusions. 3.2 Hamiltonians, Wave Functions, and Measurements In quantum physics, energy (the total of the kinetic and potential energies) is represented by the Hamiltonian operator. This operator enters into the ^ Schrödinger wave equation H ⌿ (x,t)=ih-δ⌿ (x,t)/δ t, which governs all quantum wave forms ⌿ (x,t). It thus generates all time evolution, and hence all fields of probabilities for measurement outcomes. The principal dynamics in quantum physics are specified by knowing what the initial state is, and what the Hamiltonian operator is. These remarks apply to quantum mechanics as it is practiced, by using Born’s statistical interpretation and then naïvely saying that the quantum state changes after a measurement to one of the eigenstates of the measurement operator. (This is the much discussed “reduction of the wave packet,” which we may agree at least appears to occur.)

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We may therefore consider quantum physics in the following “realistic” way. We have the Hamiltonian which is to do with total energy, which is somehow “active” since it is an operator which operates on the wave function and changes it. The Schrödinger equation is the rule for how the Hamiltonian operator produces the wave function, which is a probabilistic disposition (a propensity) for action. This wave function (in fact its squared modulus) gives a probability for different of macroscopic outcomes of experiments, and the wave function changes according to the specific outcome. Such is the structure of quantum physics as it is practiced, and we may observe a sequence of derivative dispositions in operation: • Hamiltonian operator: the fixed disposition to generate the wave function by evolving it in time, • wave function: the probabilistic disposition (a “propensity wave”) for selecting measurement outcomes, and • measurement outcome: the final result. It appears again that we have multiple generative levels, with the set of {Hamilton→wave function→selection event}. Note here also that the final result is not a disposition, but the last of a sequence of derivative dispositions. For completeness, therefore, we have included such a “bottom line” within the concept of multiple generative levels. Admittedly, again, reductionist tendencies may be applied here as well. Most commonly, it may be denied that there are distinct measurement outcomes in any ontological sense, and that they may only be approximately defined within a coarsegrained “decoherent history.” Advocates of the Many Worlds Interpretation, or of Decoherence theories, take this view. Others such as Bohr take the opposite view, and hold that only the measurement outcome is real, and that the Hamiltonian and wave function are calculational devices and nothing real. These views in tension will be discussed later. 3.3 Virtual and Actual Processes Taking a broader view of contemporary physics and its frontiers, we may further say that the “Hamiltonians, wave functions and measurements” of above describe just the dispositions for a class of “actual processes.” The Hamiltonian is the operator for the total energy, containing both kinetic and potential energy terms. However, we know from quantum field theory (QFT) that, for example, the Coulomb potential is composed “in some way” by the exchange of virtual photons. Similarly, we also know from QFT that the mass in the kinetic energy part is not a “bare mass,” but is a “dressed mass” also arising (in some way) from many virtual processes. This

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again suggests the theme of my paper: that the Hamiltonian is not a “simple disposition,” but in fact is itself derivative from some prior generative level. In this case the needed generative level could be called that of “virtual processes,” in contrast to that of “actual processes.” The class of virtual processes, as described by QFT, have many properties that are opposite to those of actual processes of measurement outcomes. Virtual events are at points (not selections between macroscopic alternatives), are interactions (not selections), are continuous (not discrete), are deterministic (not probabilistic), and have intrinsic group structures (e.g., gauge invariance, renormalization) as distinct from the branching tree structure of actual outcomes. All these contrasts suggest that virtual processes should be distinguished from actual events. The guiding principles have different forms: virtual processes are most commonly described by a Lagrangian subject to a variational principle in a Fock space of variable particle numbers, whereas actual processes, as discussed above, deal with the energies of specific observable objects leading to definite measurement outcomes. 3.4 Pregeometry and the Generation of Spacetime Field theories such as QFT still use a geometric background of space-time, and there is currently much speculative work in quantum gravity research to determine how this spacetime might arise. Wheeler started interest in “pregeometry”: the attempt to formulate theories of causal processes which do not presuppose a differentiable manifold for space-time. Rather, his aim was to encourage speculation as to how space-time might arise. Most commonly, the task has been taken as showing how space-time may turn out to be a “statistical approximation” in some limit of large numbers of hypothetical pregeometric processes. Proposals have involved spinors by Penrose (1987); “loop quantum gravity” as described for example in Rovelli (1998); Table 4.1. Relation between discrete degrees and physical processes. In each degree, the second column gives the derivative disposition that is operating to produce the dispositions of the next degree down in the sequence. The pregeometric degrees are speculative, but are widely believed to be necessary in some form.

Discrete n

Derivative Disposition for Producing n-1 Degree

Physical Process

7–9 6 5 4 3 2 1

Pregeometric? variational principle virtual particles virtual events energy quantum objects events (the end)

spinor loops? Lagrangian field propagators field interaction vertices Hamiltonian wave function measurement selection

Pregeometry? Virtual processes

Actual processes

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and “causal sets” according to Brightwell et al. (2003). If some pregeometry could be identified, I would speculate that a good way of seeing this would be as a distinct pregeometric level within a structure of derivative dispositions. That is, instead of spacetime being a statistical approximation (in the way thermodynamics is a statistical approximation to molecular gas theories), it should be better imagined that spacetime is an aspect of derivative dispositions that have been generated by “prior” pregeometric dispositions. This is admittedly speculative, but it does follow the pattern of some current research, so I use it as an example of how the philosophical analysis of dispositions may yet interact fruitfully with modern physics. This appears to be useful particularly since the very aim of “deriving spacetime” has itself been called into question by Meschini (2005). 3.5 Summary of Physical Discrete Degrees Table 4.1 collects and collates the discrete degrees that have been discerned so far in physics. The degrees appear to be in groups of three. The lowest (1–3) describe the operation of “actual processes” as in nonrelativistic quantum mechanics governed by the Schrödinger equation with its Hamiltonian, its wave function and boundary conditions, and the actual selection of alternatives after measurements or decoherence. The next triple (4–6) describes analogous functions, now with virtual rather than actual particles. There is a governing variational principle, now the Lagrangian, there are fields describing virtual particles, and there are interaction vertices when virtual particles are produced or absorbed. The similarity of corresponding 1–3 and 4–6 triples will be discussed later in the section on correspondences. Finally, it is now frequently speculated that there is another degree of pregeometric processes of some kind, but no one is sure what they consist of. Using the logic of discrete degrees, I would imagine that they are an internal triple (7–9) with again analogous internal structures.

4. PSYCHOLOGY 4.1 Levels of Causal Influence There are many examples of apparent derivative dispositions in everyday life, in psychology, in particular in cognitive processes. Such dispositions are involved whenever the accomplishment of a given disposition requires the operation of successive steps of kinds different from the overall step. The original disposition on its operation therefore generates the “derived dispositions” for the intermediate steps, which are means to the original end. An original “disposition to learn,” for example, can generate the derived “disposition to read

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books,” which can generate further “dispositions to search for books.” These dispositions would then generate dispositions to move one’s body, which in turn lead ultimately to one’s limbs having (physical) dispositions to move. These successively generated dispositions are all derived from the original disposition to learn, according to the specific situations. Another example of sequential and derivative dispositions is the ability to learn. To say that someone is easy to teach, or that they are musical, for example, does not mean that there is any specific action that they are capable of doing. Rather, it means that they are well disposed to learn new skills (whether of a musical or general kind), and that it is these new skills which are the dispositions that lead to specific actions. In this I follow Broad (1925): that there are “levels” of causal influence. We might allow that particular dispositions or intentions are best regarded not as the most fundamental causes, but as “intermediate stages” in the operation of more persistent “desires” and “motivations.” The intention to find a book, for example, could be the product or derivative of some more persistent “desire for reading,” and need only be produced in the appropriate circumstances. Broad would say that the derived dispositions were the realization of the underlying dispositions. The pattern of “underlying propensity/distribution/result” for “mental sub-degrees” shows the steps by which deep motivational principles (purposes) in an “interior mind” lead to action. These purposes come to fruition by means of discursive investigation of ideas, plans and alternatives in what can be called a more exterior “scientific discursive mind,” as constrained by existing intellectual abilities. The actions by the sensorimotor mind select one outcome among many, as constrained by bodily conditions. Moreover, psychologists who have investigated perceptive and executive processes within the sensorimotor stage realize that these are far from simple. What we see, for example, is very much influenced by our expectations and desires, as well as being constrained, of course, by what is in front of our eyes. They would agree that there are subsidiary degrees of expectation, presentation of alternatives and resolution even during “simple” sensations. 4.2 Piaget’s Cognitive Stages In attempting to describe the phenomena of mental development in children, Piaget (1926, 1962) has distinguished five broad stages. These, as shown in Table 4.2, are first the sensorimotor stage (ages through one), followed by the preconceptual (two to three years) and intuitive (four to six years) stages. (The preconceptual and intuitive stages together are called the “preoperational” stage.) Then come the operational (seven to eleven years) and formal (twelve to sixteen years) stages, while the “creative stage” (ages

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seventeen years and up) is a sixth stage postulated by Gowan (1972) as an extension of Piagetian theory. We may very briefly summaries these stages as follows: Sensorimotor Stage: The sensorimotor stage consists of the twelve or eighteen months before the stage 1 structures can be properly constructed and manipulated. At the end of this time, the child has a mental map of objects and his place among them, but this map only includes what he sees. Preconceptual Stage: These years involve building up concepts at stage 2 representing events and episodes as single entities. Procedures are built up to recognize such events while observing successive positions of objects (at stage 1), and to use subject-object sentences to express these features linguistically. Intuitive Stage: In this second half of the preoperational stage, the child begins to see relations between objects, and can use categorizing words (such as colors, shapes etc.) though not systematically. The child still can only imagine one relation at a time, so she cannot examine her own consistency over time, cannot see one-to-one correspondences, and cannot see a series as a whole. Operational Stage: The child can now imagine reversible operations, oneto-one correspondences, and series of relations, so he or she can come proficient in operations with group structures (such as rotations, reflections), matter conservation properties, classes according to property abstractions related as elements in a lattice, and numbers. Formal and Creative Stages: The final stages 5 and 6 were designed to correlate with Piaget’s “formal” stage, and with Gowan’s (1972) proposed continuation with a further “creative” stage, but the details here become less specific. What is known can be summarized by postulating first a distinct stage 5 in which whole sequences of abstract plans can be formulated and explored. Gowan’s extension calls for a stage with the ability to formulate meta-theoretic notions, to think about theories, create them, and discuss the meaning, interpretation and application of formal theories as if they were individual cognitive entities in an additional stage 6. Such processes would enable us to formulate and implement life-long goals. 4.3 Developmental Stages as Discrete Degrees A good understanding of the cognitive dynamics underlying Piagetian stages is still being sought, but the logical structures are becoming clearer (Commons 2002). Thompson (1990) proposed a multilayer network architecture in which there are links within discrete parts of the network as in connectionist theories, but in addition that there pattern-directed rules combining the distinct network “layers.” Piaget’s developmental

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Table 4.2. Relation between discrete degrees and Piagetian stages. During each stage n, at the approximate ages shown, the child is learning to relate the concepts listed in the row n-1 below, and is constructing the concepts in a given discrete stage n.

Discrete Stage n

Cognitive Structures Forming n by relating n–1

Developed in Piaget/ Gowan Stage

During Ages

6 5 4 3 2 1 0

meta-theories, paradigms plans, models, formalisms classes, series, numbers single relations sentences objects sensory and motor systems

creative formal operational intuitive preconceptual sensorimotor (initial biology)

17– 12–16 7–11 4–6 2–3 0–1 –0

psychology was used to suggest specific semantic contents for the individual layers, along the lines suggested in Table 4.2. This layered structure of cognitive network stages allows the separate layers to function simultaneously, so that the stages themselves can be well described as partially independent discrete degrees of cognitive activities. We must insist that the stages are not merely “structures,” as they are not merely mathematical, but structures of something substantial. So we should postulate that they are different kinds of dispositional substances identified naturally by the different dispositions for change at each stage. 4.4 Stages as Derivative Dispositions in Reverse Order The above series of stages is generally thought of according to their order of cognitive development during childhood. It is now fruitful to turn the order around, and look at the series of stages starting with the top “creative” or “goal oriented” stage. Given this stage, carrying out a certain goal first requires entertaining plans in abstraction for possible sequences of acts. Usually, we think and make plans before we act. Then, having made a plan, we need to formulate the individual operations, and apply our abstract arguments to specific problems and situations. This is to use concepts at the operational stage. Then, given an operational formulation, we need to think of causal sequences of events (preoperational thought), which in turn we use to produce real actions by close-coupled feedback loops at the sensorimotor stage. If we use the criteria above, when we discussed levels of causal influence, this view of Piagetian stages suggests that the stages, from the top down, should therefore themselves be regarded as discrete degrees which are the forms of operation of successive derivative dispositions. We next investigate the general form that these might take.

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5. LOGIC OF DISCRETE DEGREES 5.1 Generative Sequences We now consider the concept of “multiple generative levels” more generally from a philosophical standpoint. The first general idea is that they are a sequence {A → B → C →...} in which A “generates” or “produces” new forms of B using the present form of B as a precondition. We say that B derives from A as its manifestation. Then B generates C in the same way. This sequence may perhaps continue until an end Z, say, where nothing is active. This rough scheme does not tell us, however, how A, B, etc. might be changed as a result of their operation. This appears to occur often, as for example according to naïve quantum theory when a wave function is changed after it generates a particular measurement outcome. It would be good if we had the philosophical principles for a general scheme which might explain the (apparently mysterious) logic of the “reduction of the wave packet.” In order to formulate such a general scheme, let us extract some guidelines from our example derivative dispositions listed above. To do this, we will need to first distinguish the concepts of principal from instrumental and occasional causes.

5.2 Principal, Instrumental, and Occasional Causes In the present paper, I want to allow both dispositions and previous events to be causes, although in different senses. Thus I recommend that distinctions ought to be made between all of the following: • the “Principal Cause”: that disposition which operates, • the “Occasional Cause”: that circumstance according to which dispositions operate, and • the “Instrumental Cause”: the origin of the occasional cause. The instrumental cause is thus a previous cause, and is that by means of which the principal cause operates. The overall pattern is therefore that “principal causes operate according to occasional causes, which arise from instrumental causes.” All three kinds of causes appear to be necessary for any event in nature, for example when a stone is let fall: the principal cause is the earth’s gravitational attraction, the occasional cause is our act of letting go, and the instrumental cause is the muscle movements in our fingers releasing the stone. Its hitting the ground is thus caused by our letting go, but only as an instrumental and then occasional cause. Many common uses of “cause” (including that of Davidson 1967) refer to occasional causes rather than principal causes, as it

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is only in the “occasional” sense that events can be said to be causes. Previous events cannot be efficacious causes, Emmet (1984) points out, in the sense of “producing” or “giving rise to” their effects, since events per se are not themselves powers. The instrumental cause is a genuine causal contributor, and may be said to “set the stage,” by creating suitable conditions (namely, the occasional cause) for the operation of the principal cause. Whenever any potentiality is exercised to produce a particular outcome, future potentialities must depend on the detailed outcome. Suppose for example that, at the moment, I have the potentialities of moving left or right; if I actually move left, say, then this influences (by restriction to a fixed history) what I can do from now on. This implies not that actual outcomes are dispositions to change causes, but, on the view above, that they are simply the occasional causes for the future operation of causal influences. 5.3 Causal Sequences in Physics Consider now an electron of fixed charge and mass moving in an electrostatic potential, according to classical electrostatics. At a given place x, the derivative of the potential V(x) gives the force, and the force gives acceleration which in turn changes the velocity of electron, and it moves to a new place. In our framework of derivative dispositions, we see that the potential is one disposition which generates another disposition, namely the force. It does so, moreover, according to the place of the electron. The electrostatic potential is therefore the principal cause of the force, and the place of the electron is the occasional cause. A place by itself is never an efficacious cause, but it can be said to be the circumstance by means of which the potential generates the force. Note that we never have forces causing potentials to exist where they did not before, and (again) places are never themselves dispositional. Let us generalize by surmising the set of generative levels Potential → Force → Places, such that the principal causation is always in the direction of the arrow, and the only apparent “backward” causation is with the occasional cause. The only feedback “back up the sequence” is with the conditional aspect of certain occasions, and how the operation of prior dispositions somehow still depends on particular occasions as preconditions. Consider secondly the quantum mechanical evolution of a system from time t0 that is subject to measurement selections at various later times t1, t2 etc. The quantum mechanical story is as follows. The initial quantum state Ψ(t0) is evolved according to the Schrödinger equation by the Hamiltonian H for t|2. The new state Ψ(t1+) is then evolved similarly for t
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the next measurement. Seen in terms of derivative dispositions, the Hamiltonian is the disposition to evolve an initial state Ψ(t0) to new times t, generating Ψ(t) = exp(⫺iHöt / –h)Ψ(t0). A new Ψ(t) is itself another disposition, namely a propensity to produce measurement outcomes with the various probabilities pλ = ||2. The final results are the discrete selection events at the times of measurement. These discrete events have themselves only a residual causal power, that to definitely influence the future evolution of the wave function. In that sense, they are “occasional causes” according to which other dispositions may operate. The principal dispositions are first the Hamiltonian operator that starts the whole process and then the wave functions considered as fields of propensity for different selection events. Summarizing the quantum mechanical case, we see that here again, the principal causes act “forwards” down a set of multiple generative levels, yet act conditionally on certain events. These events thereby become occasional causes. Because the wave functions before a measurement event are the cause of that event, those wave functions are thereby the instrumental cause of the new wave functions after the measurement. 5.4 Conditional Forward Causation From our examples, we may generalize that all principal causation is “down” the sequence of multiple generative levels {A → B →...}, and that the only effect back up the sequence is the way principal causes somehow still depend on certain occasions in order to operate. Let us adopt as universal this asymmetric relationship between multiple generative levels: that dispositions act forwards in a way conditional on certain things already existing at the later levels. The only power that later stages have is to restrict the earlier stages in this way. We regard this as a simple initial hypothesis, and will have to observe whether all dispositions taken as existing in nature follow this pattern. We may therefore surmise that A, the first in the sequence, is the “deepest underlying principle,” “source,” or “power” that is fixed through all the subsequent changes to B, C, etc. Conditional forward causation, the pattern we saw from physics, would imply that changes to B, for example, come from subsequent operations of A, and not from C, D, . . . acting in “reverse” up the chain. We would surmise, rather, that the subsequent operations of A are now conditioned on the results in B, C, D, etc. The operations of A are therefore the principal causes, whereas the dependence of those operations on the previous state of B is via instrumental causation, and the dependence on the results in C, D,. . . is via occasional causation. I would like to suggest that this is a universal pattern for the operation of a class of dispositions in nature, namely those that do not follow from the rearrangement of parts of an aggregate object.

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5.5 Reductionism and Dispositional Ontologies In all the apparent examples of multiple generative levels given here, many physicists and philosophers of physics will often want to assert the particular “reality” of one of the levels, and say that the prior levels are “merely calculational devices” for the behavior of their chosen “real” level. For example, some assert in electromagnetic theory that only the field tensors (incorporating the electric and magnetic vector fields) are “real,” and that the vector potential (incorporating the electrostatic potential) is a calculational device with no reality. To this end, they note the gauge uncertainties in the vector potential, which for electrostatics is the arbitrariness in setting the level of zero potential energy. Against this, many have noticed that the scattering of electrons in the Bohm-Aharonov experiment is most succinctly explained in terms of the vector potential, not the field tensor. It turns out that it is loop integrals of the vector potential which carry physical significance. I conclude that there are non-trivial physical and philosophical questions about the relative “reality” of potentials and forces, questions which require not immediate preferences but considered responses. We also saw how reductionist tendencies may be manifest in quantum theories. “Decoherent history” accounts of quantum mechanics want to keep the wave function according to the Schrödinger equation, and deny that macroscopic outcomes occur in a reality and only allow them to be approximate appearances. The founders of quantum theory such as Bohr and Wheeler, however, took the opposite view, that an electron is only “real” when it is being observed—when it makes the flash of light at a particular place—not while it is travelling. In their opposite view, the Hamiltonian and wave function are calculational devices and nothing real, having only mathematical reality as portrayed by the mathematical name “wave function.” The views which make prior or later levels into “mere” calculational devices can be critiqued from the point of view of dispositional ontology. This view encourages us in general to not invoke arbitrarily mathematical rules for the laws of nature, but, as Mumford (2005) suggests, replace the role of laws by that of the dispositional properties of particular objects. For now, this paper simply explores the theories which result if all the stages of operation of derivative dispositions are given whatever kind of own existence is necessary for realistic interpretations. That is, just as in quantum mechanics we argue that the world must have propensities, wave functions, energies, and virtual process all existing in some manner, so we assume in general that members of a set of discrete degrees all exist in their own right.

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5.6 Correspondences between Degrees Note that there are detailed constituent events in both of any pair of prior and produced degrees. Because of all these microscopic events, we should expect that there will be successive principal causations from the prior degree reciprocating with sequential constraints by the produced degree. This gives rise to an alternation of principal and occasional causes that will repeat itself longest if the patterns of the constituent events are most similar in the two degrees, and they do not get out of step. By a sort of survival of the fittest, this in the long term gives rise to correspondences of function between adjacent degrees. We may conversely say that the functions in distinct degrees sustain each other in a kind of “resonance” when they are most similar in the patterns of their constituent events. There is much detail here to be learned by theorizing and observing. Discrete degrees are not of a continuous substance with each other, but, we see, have therefore functional relations that make them “contiguously intertwined” at all stages, and at many levels of detail at each stage. Some of these corresponding structures have been seen already, where similarities in the internal structures of actual and virtual processes were noted.

6. MIND AND NATURE AS DISCRETE DEGREES? In previous sections I have argued that there are discrete degrees of derivative dispositions within both the physical and mental realms. The next hypothesis to consider is that the physical and psychological are themselves discrete degrees, so that physical dispositions as a whole are derivative from mental dispositions, at least within living and/or thinking organisms. That is, we entertain the view that the dualism of mind and body is not an ad hoc division, but one that logically follows from the kinds of causation that exists within a universe in which there are both minds and bodies as distinct ontological substances connected as derivative dispositions. To see whether this works in practice, we have to consider the detailed requirements of any theory of psychology. At the simplest level of generalization, in order for people to have functioning minds connected at least with their brains, minds must be able to • implement intended functions by feeling and thinking, then using motor areas, • establish permanent memories, presumably by means of permanent physiological changes, • form perceptions using information from the visual and auditory (etc.) cortexes, and • be able to follow “internal” trains of thought/feeling/imagining without necessarily having any external effects.

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One way that these requirements can be most simply accomplished is by means of the ideas presented so far, formulated in the following three principles: I. Some physical/physiological potentialities (both deterministic or indeterministic according to quantum physics) are derived dispositions from minds as their principal cause. That is, minds predispose the dynamical properties of some physical objects. II. That the dispositional capacities of the mind are consequentially restricted (and hence conditioned) by their actual physical effects, by means of occasional causation. III. That the pattern of I and II is repeated for individual stages of more complex processes. These principles together give what has been called Conditional Forward Causation, or “top-down causation.” Note that we do not have a fourth “bottom-up” principle that neural events directly cause events to occur in the mind. We do not have general matter → mind causation, although something resembling this does arise, namely selection. This is not causation in the sense of principal causation as producing or generating the effect, but is occasional causation as being a necessary prerequisite. A strong argument for these three principles is that they are already similar to what is known already to happen in physics. According to quantum field theory, for example, we saw how virtual events predispose the ordinary quantum wave function. These virtual events operate deterministically, and describe the operation of the electric, magnetic, nuclear and gravitational forces. They are not the actual events of quantum mechanics, as those are the definite outcomes of events like observations. Rather, they are a “prior level” of “implicit events” whose operation is needed in order to derive or produce the potentialities for events like observations. The principle (I) states the analogical result that mental events themselves are a “prior level” of “implicit events” whose operation is needed in order to produce the potentialities for physical events. The argument for the principle (II) is more general. This principle can also be seen as the law according to which your future life is restricted and influenced by your past actions (by selection). Physical events are in this way the necessary foundations for permanent mental history and structure. Principle (III) has an important corollary connected with the observations of the above section on correspondences: IV. That the mind predisposes the brain to carry out those functions which “mirror” or “correspond to” the mind’s own functions.

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This is because mental functions involve intermediate steps, and these intermediate mental steps predispose suitable intermediate physical steps (by I), and are in turn conditioned or confirmed by them (by II). Thus the sequence of physical steps should follow the sequence of mental steps, and the overall function of the physical process will be analogous (in some sense) to the overall function of the mental process. Examples of this “mirroring” or “corresponding” can be illustrated by the similarities between minds and physics already seen in the previous sections. If we compare Tables 4.1 and 4.2, we see considerable structural similarities in the way they have internal discrete degrees. Table 4.3 brings together these similarities, and we see that the order of the columns is the same in the mental and physical cases. I claim that just such similarities should be expected by the principles of correspondences, if indeed minds and nature are individual discrete degrees within a broader structure of multiple generative levels. According to those principles, we should expect that at each stage the mental derivative dispositions (i.e. the particular ideas) have similar functional relations among themselves as do the corresponding physical derivative dispositions. Such functional relations should be a fruitful source of scientific predictions that may be investigated experimentally. Let us then see how these principles enable the mind and brain to function together: • The particular functions selected by the mind to be carried out by the brain will be the establishment of spatiotemporal patterns of neural activity that may then be “decoded” in the motor cortex to lead to the desired activities, by the principle (I). Principle (IV) establishes a criterion for the overall functioning of this decoding. Table 4.3. Hypothesis of similarities between the discrete degrees within mental and physical processes. The order of the columns is the same in the mental and physical cases. On each row, the mental derivative dispositions (i.e. the particular ideas) are claimed to have similar functional relations among themselves as do the given physical derivative dispositions.

Corresponding Derivative Dispositions Discrete Degree

Mental

Physical

6 5 4 3 2 1

Creative Formal Operational Intuitive Preconceptual Sensorimotor

variational principle as Lagrangian virtual particles as field propagators virtual events as field interaction vertices energy as Hamiltonian quantum objects as wave function events as measurement selection

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• Permanent physiological changes lead to permanent memories in the mind, by the principle (II). (It is an empirical question which physiological changes are relevant, but principle (IV) will be a guide.) • Perceptions are formed by the sensory cortex areas deterministically forming particular patterns of neural activity, so that these physiological effects can select the subsequent perceptual content of the mind. The process here is rather subtle. The mind must have a “general disposition” to see/imagine any of its possible percepts; the role of the sensory cortex is to select the particular content, by means of principle (II). Thus we have the general psychological observation that “we see only what we are capable of and disposed to see.” • To be able to follow “internal” trains of thought/feeling/imagining without necessarily having any external effects, the mind must be able to produce physiological effects which do not have significant behavioral consequences. Presumably, much of the cerebral cortex can function in a way “loosely connected” with the motor areas, in order to provide the foundation for a set of permanent mental structures capable of “internal thought.” This theory of mind and brain connection establishes an intimate relation between them. It is not a relation of identity, or a relation of aspects or points of view. It is more a relation of inner and outer, or cause and effect: propensities in the brain are the causal product of mental actions. As Bowden (1947) wrote: “the role of the psychical in relation to the physical (in the living organism) is essentially the relation of the potential or incipient to kinetic or overt action.”

7. REPLIES TO COMMON ARGUMENTS AGAINST DUALISM 7.1 The Assumption of Naturalism Let us next see how we can reply to some of the early questions often raised against dualism. The first set of questions from empiricism are that “we never see minds in nature, and science has no need for non-material causes.” However, the meaning of “non-material” has changed considerably over the last century, to the extent that Clarke (1995) claims that no idea of “material” is present in modern physics. Certainly, the successive ideas of electromagnetic fields (Pockett 2000 and McFadden 2002), wave functions (Eddington), virtual fields (Jibu 1995) and zero-point motion (Lazslo 1993) have become progressively less material, and each of these has its advocates being the carrier of consciousness. However, according to the physics view of above, these are sub-degrees still within the physical. To find minds, we have to go further back in the causal analysis.

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Some today object from methodology, that modern science must assume all causes are part of nature, and that in any case physics can be defined as the basic science of all causes. This is the oft-quoted “presumption of naturalism.” However, modern science is quite capable of postulating and understanding that which it cannot see or feel, as long as it has a rigorous intellectual structure that enables us to make deductions, and eventual partial testing. Many scientists say that they will follow “wherever science leads them,” and that “perhaps we will gradually get used to the weird ways of our cosmos and find its strangeness to be part of its charm” (Tegmark 2003). If we are to have a unified account of discrete degrees that brings together theories of mind and physics, then there will definitely be predictive power and testable consequences. The fact that there is no fully fledged scientific account including dualism tells us merely that we lack the imagination to make even a possible such theory. We thus need a specific theory: one that could be verified or refuted like other scientific theories, and fail or prevail. A theory would link disparate pieces of evidence together, and then scientists think they can begin to properly understand. Rather than asserting that there are non-substantial substances (a contradiction in terms), we now rather hold that there are different kinds of substances, with rather different properties and capabilities. Only if all substances are taken to be necessarily those of contemporary physics would we find contradiction in the substantiality of minds. This “mental substantiality” is simply the statement that minds exist as individual beings in some world of similar beings, at least for a while, and that other aspects of mind or thought are properties or modes of action of these substances. The biggest puzzle for everybody is how can mind and body interact, or at least influence each other in some way, in agreement with our obvious abilities to perceive and act in the world? Here, we explain the connection between mind and body in terms of correspondences, which are similarities of functional forms. These correspondences are not magic, but each must have an explanation in terms of the constituent processes in each of successive discrete degrees, one producing the next. There is much detail yet to understand here, of how there are asymmetric links of “downward” production and “upward” constraint, but the principles of these features should already be discoverable within physics and psychology. Our challenge today is to formulate a theory of discrete degrees so that they may be recognized in detail. 7.2 Are Minds in Space? Objections are often formulated as to where minds might be in space. Descartes went so far as to say that they are completely unextended, as the opposite of extended physical matter, but does that mean they are unextended

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like a point? Where is that point—in the pineal gland? Most of us would naïvely say that location does not apply to thoughts, but how is this possible, and, if so, how can they affect physical objects which do have locations? The lesson to learn from physics, however, is that our best description of physical process is getting less and less localized. The successive discrete degrees in physics as summarized above are at one end completely definite measurements at specific locations, and further up Table 4.1 become more and more non-local. The non-locality of the wave function is now well known, and quantified. Energy is global property. Virtual processes do not have specific locations or times, since they contribute to potentialities which may never actualize. Then the pregeometric processes themselves are clearly not localized, since they are themselves responsible for in some way “generating” space-time. My proposal about the duality of minds is that they are discrete degree “beyond” or “above” such pregeometric degrees. Such a proposal is not inherently absurd, but follows the pattern we see beginning in modern physics. Thus, minds are not in space, but are part of what produces the degree that generates space. These connections of “produce” and “generate” are clearly linked in the end with specific physical objects, and it is by means of such a generative chain that minds not in space are connected with material objects that are in space. 7.3 Conservation Laws and Closure It is generally taken as a strong indication against dualism that the physical world appears to be causally closed. This is taken from the fact that the total of energy and total momentum appear to be accurately conserved whenever they have been measured in modern physics. These conservation laws do not seem to allow any room for minds to make any difference to evolution of the physical world. We should first note, with Meixner (2005), that there is little or no experimental evidence just where it is needed, namely within living bodies and especially within brains, so the universal application of conservation laws is an assumption of the physical sciences, not a result as it is commonly presented. Various general philosophical arguments for causal closure have been presented, but they all depend on some assumption that is almost identical to the result to be proved. Suppose that physicists found that conservation laws in an object were not conserved in some instances. How would they react? First, they would note that the laws apply only to isolated systems, so they would examine whether the object really was isolated or not, and whether they should look for something further (like a hidden planet) that was producing the effects. Secondly, they could generalize the conservation laws so the new law was satisfied but not the old one. It used to be thought, for example, that total mass and total energy were separately conserved, but, after many sub-atomic experi-

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ments showing the annihilation and creation of massive particles, those separate laws were quietly dropped in favor of a general law of conservation of mass-energy in combination. Note that this example is directly related to having a virtual as well as an “actual” degree in physics. A further “pregeometric” degree would force a further generalization of the conservation laws. At present, energy and momentum conservation are typically “derived” from the invariance of the underlying Lagrangian under small-time and spatial translations respectively. If spacetime were curved, or was being dynamically generated in some way, this invariance would not hold, but physicists would soon come up with a “generalized mass-energy” measure that was still conserved. If, therefore, the non-conservation of energy and/or momentum were found in certain biological or psychological processes, science as we know it would not collapse. Either the influence from other kinds of beings would be ascertained, or a further generalization of the conservation laws would be sought. The only novelty in the proposals here is that these “other kinds of beings” would not be “physical” in the traditional way. I remark that the generalized conservation laws (beyond the pregeometric degree) to take into account these new substances will still be recognizably rational.

8. CONCLUSION By reconsidering the basic metaphysics of dispositions and propensities, we see how to formulate a “dispositional ontology.” After seeing how “derivative dispositions” commonly form discrete degrees in both physics and psychology, we try to see such ontologies as “multiple generative levels,” each discrete degree of which exists in its own manner. Given such a multiple-level ontology, it is then argued that mind and nature are plausibly themselves discrete degrees that are linked together by the same general principles. Thus we have an ontology of multiple kinds of substances that yet operates by unified and universal principles. In this ontology, mind and physical nature are not reduced or conflated, but exist alongside each other in deeply intertwined causal relations. This is effectively a dualism of mind and nature, but in fact they are both part of a more complicated structure that the scientists have already begun to investigate in detail even though they have not yet seen the whole picture.

BIBLIOGRAPHY Bawden, H.H. 1947. “The Psychical as a Biological Directive.” Philosophy of Science 14: 56–67. Brecha, R. 2002. “Schrödinger’s Cat and Divine Action.” Zygon 37: 909–24.

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Brightwell, G., F. Dowker, R.S. García, J. Henson, and R.D. Sorkin. 2003. “‘Observables’ in causal set cosmology.” Physical Review D 67, 084031: 1–8. Broad, C.D. 1925. Mind and Its Place in Nature. London: Routledge and Kegan Paul. Cartwright, N. 1983. How the Laws of Physics Lie. Oxford: Clarendon Press. Clarke, C.J.S. 2006. “The role of quantum physics in the theory of subjective consciousness.” www.scispirit.com/Role_of_QT.pdf. Clarke, C.J.S. 1995. Reality Through the Looking Glass. Edinburgh: Floris Books. Commons M.L., and F.A. Richards. 2002. “Organizing Components into Combinations: How Stage Transition Works.” Journal of Adult Development 9: 159–77. Davidson, D. 1967. “Causal Relation.” Journal of Philosophy 64: 691–703. Donald, M.J. 1990. “Quantum Theory and the Brain.” Proceedings of the Royal Society (London) A 427: 43–93. Eccles, J., and K.R. Popper. 1977. The Self and Its Brain. New York: Springer International. Eccles, J. 1989. Evolution of the Brain: Creation of the Self. London and New York: Routledge. Emmet, D. 1984. The Effectiveness of Causes. New York: State University of New York Press. Faber, R.J. 1986. Clockwork Garden. Amherst: University of Massachusetts Press. Giulini, D., E. Joos, C. Kiefer, J. Kupsch, I-O. Stamatescu, and H.D. Zeh. 2003. Decoherence and the Appearance of a Classical World in Quantum Theory, 2nd ed. Berlin: Springer. Gowan, J.C. 1972. Development of the Creative Individual. San Diego: R.K. Knapp. Jibu, M., and K., Yasue. 1995. Quantum Brain Dynamics and Consciousness. An introduction. Amsterdam-Philadelphia: Benjamins. Klein, C. 2004. “Functions as Dispositions.” www.princeton.edu/~cvklein/papers /dispfunct2De1.pdf. Laszlo, E. 1993. The Creative Cosmos. Edinburgh: Floris Books. Marshall, I.N. 1989. “Consciousness and Bose-Einstein Condensates.” New Ideas in Psychology 7: 73–83. Maxwell, N. 1988. “Quantum Propension Theory.” The British Journal for the Philosophy of Science 39: 1–50. McFadden, J. 2002. “The conscious electromagnetic field theory: the Hard Problem made easy.” Journal of Consciousness Studies 9: 45–60. Meixner, U. 2005. “Physicalism, Dualism and Intellectual Honesty.” Dualism Review 1: 1–20. Meschini, D., M. Lehto, and J. Piilonen. 2005. “Geometry, pregeometry and beyond.” Studies in History and Philosophy of Modern Physics 36: 435–64. Molnar, G. 2004. Powers. Oxford: Oxford University Press. Mumford, S. 2005. “Laws and Lawlessness.” Synthese 144: 397–413. Penrose, R. 1987. Spinors and Space-Time: Volume 1, Two-Spinor Calculus and Relativistic Fields. Cambridge: Cambridge University Press. Piaget, J. 1962. Play, Dreams, and Imitation in Childhood, New York: Norton. ———. 1926. The Language and Thought of the Child. New York: Harcourt, Brace and World. Pockett, S. 2000. The Nature of Consciousness: A Hypothesis. Lincoln, NE: Universe.

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Rovelli, C. 1998. “Loop Quantum Gravity.” Living Reviews in Relativity 1: 1. www .livingreviews.org/lrr-1998-1. Saunders, N.T. 2000. “Does God Cheat at Dice? Divine Action and Quantum Possibilities.” Zygon 3: 517–44. Squires, E.J. 1990. “An Attempt to Understand the Many-worlds Interpretation of Quantum Theory.” In Quantum Theory without Reduction, edited by M. Cini and J.M. Levy-Blond, 151–60. Bristol: Adam Hilger. Stapp, H.P. 1977. “Theory of Reality.” Foundations of Physics 7: 313–23. Tegmark, M. 2003. “Parallel Universes.” Scientific American 288: 40–51. Thompson, I.J. 1990. “Layered Cognitive Networks.” www.generativescience.org/ps -papers/layer7.html. ———. 2005. “Pragmatic Ontology I: Identifying Propensity as Substance.” www .generativescience.org/ph-papers/pragmatic_substance.htm. ———. 1988. “Real Dispositions in the Physical World.” The British Journal for the Philosophy of Science 39: 67–79. Toben, B. 1974. Space-Time and Beyond. New York: Dutton. Walker, E.H. 1970. “The Nature of Consciousness,” Mathematical Biosciences 7: 131–78. Wigner, E. 1962. “Remarks on the Mind-Body Question.” In The Scientist Speculates, edited by I.J. Good, 284–302. New York: Basic Books.

II PSYCHO-PHYSICAL DUALISM: PHILOSOPHICAL PERSPECTIVES

5 Mutual Dependencies of the Mental and the Physical Franz von Kutschera

1. INTRODUCTION The relation of the mental to the physical is not only a central theme of the philosophy of mind but also one of the most important problems of philosophy in general. In his late dialogues that was already the view of Plato. He saw that our answer to this question to a large extent determines our understanding of ourselves and the world around us. In the Sophistes (246a4) Plato compared the battle about the right answer to the gigantomachia. Greek myths tell of the victorious combat of the Olympic Gods against the giants: uncouth, longhaired fellows with beards and tails who rose up to challenge the rule of Zeus. In this battle against the giants the future of the world was at stake, the continuation of culture and the reign of law and order or a relapse into barbarism, brutal force and chaos. Plato uses this mythical picture to describe the battle between the materialists, the “sons of the earth,” as he says, who believe only in what they can touch, and the “friends of ideas” who recognize the reality and importance of the mental and the spiritual. Because of its importance for our conception of reality, the bodymind problem has remained the central problem of philosophy, even until today. This is obscured by the fact that at present materialism has become something like an official doctrine in philosophy and the sciences. It even claims to be the only rational position left. That, of course, is simply absurd since it has been refuted in all its variants so that materialists today are exceedingly reluctant to define their position exactly. The battle between materialists and dualists is not just about a theoretical position either but has also important practical consequences. Materialism eliminates such fundamental ideals as human freedom, human dignity, and human rights. For 127

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materialism moral norms cannot be anything but conventions of behaviour, and all values must derive from subjective interests. Everything that happens in the world is governed by chance and necessity; we, too, are products of chance and necessity, without freedom and without hope of finding a greater meaning for our lives. Plato, then, has seen the significance of the dispute with materialism quite correctly when he characterized it as a “gigantomachia.”

2. MATERIALISM, IDEALISM AND DUALISM The three classical positions towards the body-mind problem are materialism, idealism and dualism. Materialism, roughly speaking, maintains that there is only physical reality, and that the mental is reducible to the physical. Idealism, as the opposite position, maintains that there is only the mental, and the physical is reducible to it.1 Dualism, finally, maintains that both reduction claims are wrong, that the mental and the physical are distinct and autonomous realms and neither is reducible to the other. Besides these three classical positions there is also neutral monism assuming, like materialism and idealism, only one kind of reality. It is to be distinct, however, from the mental as well as the physical which are both supposed to be reducible to it. Since this third reality has never been adequately specified, however, I shall ignore neutral monism here. Before we can discuss the three classical positions we have first to define what is to be understood by “the mental”—the meaning of the term “the physical” is unproblematic since we can simply say that it is the reality treated by physics. Secondly we have to remember that there is not just one materialism but many materialistic positions, and likewise for idealism and dualism. It is wrong, therefore, to say that if both materialism and idealism are refuted dualism must be right. Only special kinds of materialism, idealism and dualism are disjunct and exhaustive alternatives. I shall not distinguish between the mental, the psychical and the spiritual here. The mental, in what follows, includes subjects—or persons, since I shall only talk about human subjects—and their conscious states and acts, i.e. sensations, perceptions, emotions and preferences, acts of imagination, remembering, thinking, judging and inferring. The criterion for the consciousness of these states and acts is that the subject concerned can not be deceived about them. I cannot be mistaken about whether I am presently in pain or whether I believe something right now. The mental, furthermore, comprises products of mental activities, thoughts, e.g., understood not as acts but as their contents. For conceptualists also concepts, propositions, numbers, sets and functions are mental products. The mental, however, shall not comprise such things as the Absolute of Schelling and Hegel,

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which, although they designate it by mental terms like “absolute knowledge” or “pure self,” is really a fiction of neutral monism. Since there are no relevantly different conceptions of the physical the various materialisms differ only as to the concepts of reduction they employ. In the times of logical physicalism it was claimed that the language of psychology could be translated into that of physics while materialists of today speak of a supervenience of psychological properties or states of affairs upon physical ones. But there are many concepts of supervenience by which materialisms differ. The fundamental idea of supervenience is: No mental differences without simultaneous physical differences. This idea can be made precise in numerous ways, however, for instance—as weak supervenience—so that it becomes quite trivial, but also—as strong supervenience—so that it is almost equivalent to a definability of mental terms by physical ones. Here I shall only use a very weak concept of supervenience, that of a global supervenience of states of affairs. Global supervenience means that worlds differing psychologically in some way, e.g., by the same Swede at the same time thinking and not thinking of going to bed, also differ physically in some way, e.g., by an uranium atom decaying or not decaying somewhere in New Zealand. This claim of a global supervenience is so weak that one may doubt whether it still is a materialistic position at all.2 This weakness is an advantage, however, if we aim at a refutation of materialism, since if this claim is untenable so are all the stronger versions of materialism. For a specification of idealism the concept of reduction employed is just as important, of course, but here we also have to deal with the question what subjects are to be considered. A solipsistic idealism, e.g., claims that all physical properties or states of affairs are reducible to the mental properties or states of a single person, while phenomenalism usually refers to the mental properties or states of all persons. Absolute idealisms like that of Berkeley, finally, also count God among the persons whose mental life is considered. In what follows I shall only discuss an idealism for which the mental consists just of human subjects and their mental states, acts and products. If we use the same concept of reduction, namely global supervenience, for all of them idealism, materialism and that version of dualism which only claims the irreducibility of the mental to the physical and vice versa form a set of alternatives one and only one of which must be true. I shall call this dualism weak dualism since dualisms mostly make additional claims.

3. ARGUMENTS FOR WEAK DUALISM According to these preliminary clarifications everything that speaks against materialism and idealism speaks for weak dualism. Therefore I shall argue for dualism in this section by arguing against idealism and materialism. In

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the next section I shall point out some difficulties of Cartesian dualism, and then use the rest of the paper to delineate my dualistic conception. The argument against that type of idealism considered here can be formulated very briefly.3 There are many physical events in the world which no one observes or thinks about, for instance the decay of a certain atom. But then the world in which it decays will differ physically but not psychologically from the world in which it does not decay. A global supervenience of physical upon mental events, then, is highly implausible. An idealist might reply that our empirical distinctions must after all lastly refer to sensual and therefore to mental distinctions. Although that may not be expressible in terms of a supervenience of physical upon mental properties it means that we cannot justify physical distinctions without a psychological basis. This defence overlooks, however, that most of our psychological distinctions in turn refer to physical ones. We distinguish orange and violet colour sensations, for instance, or the assumptions that Vienna lies on the Danube and that Rome lies on the Tiber. The epistemological argument that our picture of the physical world is based on our sensual impressions, moreover, is no support for ontological idealism. While we thus can get rid of this kind of idealism very quickly materialism is a much harder case. For a detailed refutation of materialist positions I have to refer you to Kutschera (1993) and (2003). Here I can only indicate the three most important objections against it: The first one is the underivability of consciousness. It was already emphasized by Leibniz in his Monadologie (§ 17) that even the most detailed information about the functioning of our brains entails nothing about the way we experience ourselves and the outside world. Thomas Nagel (1974) has taken up this idea and pointed out that even the most complete physiological information about bats would not tell us what it is like to be a bat. Frank Jackson (1982, 1986) has argued in that a blind girl who knew all about the processing of optical stimuli in the brain nevertheless would know nothing about how it is to see. Whatever we shall come to know about the human brain, the correlations between neural processes and experiencing, thinking, feeling and remembering will remain inexplicable in physical terms. The second argument against materialism is what I call the argument from dimension. Let S be a set of states of affairs, complete in the sense that together with any state also its negation is in S, and together with a sequence of states also their conjunction.4 Consider now the possible doxastic attitudes of a person P to the states of S, i.e. her beliefs that such and such states of S hold. Such an attitude may be represented by the subset of S containing exactly those states of S P believes to obtain. The set A of possible doxastic attitudes of P to the S-states is then the power set of S, i.e. the set of all the subsets of S, and the set of possible beliefs of P concerning states of S may be represented by the power set of A.5 Now Georg Cantor, one of the pio-

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neers of set theory, has shown that the power set of a set always contains more elements than that set itself. Therefore there are more doxastic attitudes towards the states of a set than there are states in that set. Applied to physical states: There are more possible beliefs about physical states than physical states. Thus not all mental states can possibly be physical states.6 The third argument against materialism I want to mention here derives from physics itself, for materialists not only the basic but the comprehensive theory of all reality. Quantum theory, one of the two fundamental physical theories, is incompatible with reducibility of the mental to the physical. Werner Heisenberg, one of the founders of quantum mechanics, already emphasized that it is characteristic for the domain of the theory that observations always interfere with the observed system. The measurement of the place of a particle, e.g., changes its impulse, and vice versa. If for the sake of simplicity we restrict our considerations to properties an observation of a property F must yield reliable information whether the observed system S has that property at that moment; it must not change S’s being F or not-F. If the observation is an intervention it must therefore change another property of the system, let us say G. Since F and G are incommensurable in that case, i.e. since they cannot be observed at the same time, S’s being F and its being G depends on what we observe. But then we cannot ascribe these two properties to the system itself but only to it in an observation. What we can ascribe to the system itself are only dispositions to yield with such and such a probability a positive result in an F-observation or a G-observation. The states of the system itself are only determined by these dispositions, and therefore the two properties, F and G, cannot be taken as primary but only as secondary qualities of the system. If in the micro-world, the domain of quantum theory, all observations are interventions then George Berkeley’s claim that all empirical properties are secondary is justified after all. Berkeley drew an idealistic conclusion from this claim: If all properties that may be empirically tested are secondary we cannot ascribe an objective constitution to things, a constitution they have themselves, independently of observations. By losing its independence from observations the physical world is revealed as a mere construction out of our impressions. The recognition, however, that all empirical properties are secondary does not give rise to such a radical idealism. It only implies that the constitution we may ascribe to things themselves consists only in dispositions to yield certain results with certain probabilities in observations. Therefore all we can know about the nature of physical things essentially refers to observations and to us as observers. In this sense we can say: No physical world without subjects. The physical world, as we know it, is essentially bound to the mental one. This is the basis of the third objection against materialism: Subjects cannot at the same time be presupposed by the physical world and evolve from it.

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4. CARTESIAN DUALISM AND ITS DIFFICULTIES By “dualism” we mostly understand Cartesian dualism, dualism as it was formulated by Descartes. According to him there are two kind of substances, bodies and souls, which are radically different: While bodies are extended and exist in space but have no consciousness, souls—or as we may also say, subjects—have consciousness and perform conscious acts (which Descartes generally calls cogitationes) but do not exist in space. Cartesian dualism, then, is a dualism of substances. In the sixth meditation (§ 9) of his Meditationes de prima philosophia from 1641 Descartes has an argument for the difference of bodies and souls which, however, already presupposes what it wants to demonstrate. The two worlds, the physical world and the spiritual one, are supposed to be self-sufficient so that there could be a physical world without subjects or a mental world without a physical one. Cartesian Dualism is therefore also a two-world theory. The duality of the substances as well as that of the worlds has been the target of critics since the days of Descartes. The conception of human beings as pairs of substances, as souls connected in some way with bodies, is very far from our everyday conception. We say “Jim thinks of Rome” as well as “Jim weighs 80 kg,” but not “Jim’s soul thinks of Rome” and “Jim’s body weighs 80 kg.” Therefore Peter Strawson (1959) proposed a property dualism in which physical and mental properties are ascribed to the same substances. Cartesian dualism also confronts us with the question how the connection between body and soul is to be conceived. Because the soul does not exist in space we cannot say that it is in the body. The connection, rather, must be a causal one: Soul X belongs to body Y if decisions of X to act result in motions of Y, and stimuli in the sense organs of Y result in sensations in X. Such a causal determination of the connection between bodies and souls, however, confronts us with the second difficulty of Cartesian dualism: how there can be causal interactions between such widely different realms as the mental and the physical. This problem is the mind-body problem in the narrower sense. It is the rock on which, according to a wide-spread belief, Cartesian dualism founders, and even dualism in general. On the one hand we constantly have to do with psycho-physical interactions in everyday life; on the other hand they cannot be accounted for in Cartesian dualism. The problem is not a detailed account of the causal chain that links a visual sensation to a lightning or a bodily movement to a decision to act—that is the task of empirical science—but to show that such interactions are possible on dualist assumptions. Even contemporaries of Descartes, for instance Malebranche, were convinced that this problem is unsolvable. Its difficulties have certainly contributed to the rise of idealism in the eighteenth century, and today the body-mind is still believed to be unsolvable on dualistic assumptions.

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What exactly is the difficulty? Generally speaking it is the presumed autonomy and therefore independence of the two worlds that is incompatible with causal interdependencies. We think of the physical world as causally closed. We assume that every physical event that has a cause at all, that, for instance, is not a chance event, has a sufficient physical cause. Mental events must then be causally ineffective. We even believe that every cause of a physical event is also a physical event, as well as every effect of a physical event. But then causal chains containing one physical event lie completely in the physical world. A sufficiently strong assumption about the causal closure of the physical realm thus suffices to exclude psycho-physical interactions. Two further difficulties have lesser weight. First there is a conception of causality of long standing—it was first stated by Plato—according to which cause and effect must be of the same kind. For Cartesian dualism with its tenet of a radical difference between the mental and the physical there cannot then be causal interactions. Since this Platonic conception plays no role in modern definitions of causality this difficulty is eliminated today. More convincing is the reference to an explanatory gap in all psychophysical explanations. Light that is reflected from a red surface falls on the retina of an observer. There the optical stimulus is transformed into electric impulses which are transmitted to the brain where they have complex physiological effects. But how do these effects result in a red sensation of the observer, in his being aware of the red surface in front of him? Here seems to be a gap that cannot be filled by further neurophysiological findings. Inversely, if we start with a physical effect, for instance that I lift my arm, and follow the chain of its causes we always remain within the physical realm. My arm is lifted because certain muscles have contracted, that was because electrical impulses in the relevant nerves effected certain physiological changes in them, and these electrical impulses in turn have been brought about by neural activities in my brain. But how does my intention to lift my arm bring about these neural activities? Again there seems to be a gap that cannot possibly be bridged. I do not see these explanatory gaps as a decisive objection against dualism. They simply result from insufficient knowledge of the relevant laws. In our first example the event that red light is reflected from a surface and falls on the retina of the observer is, under the given conditions—he is conscious and not colour blind—already a sufficient cause for his having a visual impression of the surface. We are well acquainted with such causal relations from everyday life, and there we do not encounter explanatory gaps. They only arise when we analyze the process of seeing physiologically without knowing appropriate psycho-physical laws to connect its end with conscious experience. We know a host of psycho-physical laws on the macrolevel of everyday experience but only very few and mostly uninformative laws on the micro-level of neurological events. Furthermore we understand

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the psycho-physical connections on the macro-level intuitively because they are part of our general experience while interactions on the micro-level remain unintuitive since we can neither experience nor control our brain processes directly. Thus we understand it much better that someone feels pain who touches a hot stove than someone whose C-fibres fire. Should we know more about neuropsychological correlations causal laws resting on them would also seem much more natural. Such correlations, however, will probably be very complex since psychological distinctions follow criteria that are very different from those we observe in our physiological distinctions. Although we believe in the principal reducibility of biology to physics it is quite out of the question to define biological concepts by physical ones and to work with such unwieldy definitions in biology. Psychological distinctions are still further removed from physical ones, and we have seen that they cannot all be mirrored by physical ones. In the second example we assumed that I lift my arm intentionally. But then the lifting of my arm is an action and therefore an event without a cause.7 The search for physiological and neurological causes for this event is therefore in vain. What we can find are only concomitant processes. If I lift my arm quite a lot happens physiologically, muscles contract and electrical impulses run through nerves, neurons fire in the brain. All that, however, is no cause of my action but only part of it. Neither is my action caused by my intention. An intention alone is not sufficient for an action. Even if I intend to visit a friend this evening all kinds of things may still keep me from doing it. Actions have only reasons, not causes. I may lift my arm for instance because I want to make a remark in a meeting.8 The outcome of this short discussion of the body-mind problem is then: Dualism may only claim an analytic independence of the two worlds, i.e. demand that from physical facts no mental facts follow, and vice versa. It must admit nomological connections between the worlds and may not assume that the physical or the mental world is causally closed. In fact the epistemological problem of whether we can know something about the physical world is harder for dualism than the body-mind problem.9 Like materialism dualism takes a realistic position towards the physical world.10 The basic idea is that in our experiences we have to do with a reality the existence and nature of which does not depend on the existence of human beings, the constitution of their cognitive equipment, and their beliefs. It can be stated in the form that every consistent set of beliefs is compatible with every consistent set of physical states of affairs, or: R1: From our beliefs no physical facts follow deductively. That corresponds to Frege’s dictum: “With the step by which I gain an outer world I put myself in danger of errors.” (Frege 1967, 358) While we cannot be mistaken about what goes on presently in our inner, mental world every assumption about the outer world can turn out to be wrong.

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A much stronger version of realism is the claim: R2: From our beliefs, impressions and sensations no physical facts follow inductively. (Inductively we can infer a state of affairs q from another, p, if for analytic reasons the assumption of p sufficiently increases the probability of q for all subjective probability valuations.) Experience is our only door to the physical world, and impressions are the basis of experience. If R2 were to hold we couldn’t infer anything about physical facts from our impressions. It would then be possible that the physical world is radically different from what our experiences suggest. We couldn’t even exclude that our impressions are just as unconnected with reality as our dreams. This would lead to an uneliminable uncertainty about the reliability of our experiences. Descartes has expressed this doubt very impressively in his Meditationes de prima philosophia where he says: There could be a demon who manipulates our sense impressions so that the world we believe to live in is not there at all. A problem of dualistic realism or independence of physical reality is therefore that it leads into skepticism. If from our experiences nothing follows about the constitution of the outer world, we cannot justify our knowledge claims about it. Of course a realist may assume that there are nomological connections between physical events and our impressions, but he cannot thereby vindicate such knowledge claims. Statements about such connections, after all, are statements about the outer world and their reliability just is the problem.11 The basis for our knowledge claims must then be a priori relations, but they are excluded by R2. If we think of the physical world as something analytically independent from our experiences the epistemic gate to it is closed from the start, and, as Kant pointed out, it would be just an accident if our sensory impressions and the conception of the physical world we form on their basis would really correspond to it. (Kant, Kritik der reinen Vernunft, B 166 seq.) Kant assumed synthetic connections a priori but the price he paid for them was his epistemological idealism, the transformation of physical reality into a world of appearances structured by the forms of intuition and the categories of thinking. Since the forms of our own intuition and understanding are evident for us, as Kant assumed, we know about the structure of appearances and therefore about the physical world. The reality behind these appearances, the thing itself, which causes our impressions, remains utterly unintelligible, however. If we define knowledge minimalistically as true conviction then according to R2 it is still possible for us to know physical facts. But we cannot ascertain in which cases our convictions are true.12 My argument, then, is not: “According to the independence thesis R2 there can be no knowledge about the physical world,” but only: “According to this thesis we cannot justify knowledge claims about the physical world.” This difficulty cannot be overcome

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without giving up R2.13 And that again counts against Cartesian dualism with his claim of an independence of the two worlds. What tells against Cartesian dualism in general is that it separates reality into two parts and postulates a chorismos, in Plato’s words, between them, an abyss of difference. Once reality is cut up in this way we have difficulties to reconnect the parts ontologically as well as epistemologically. That was clearly recognized by Johann Gottlieb Fichte, who emphasized the unity of reality against the Cartesian autonomy of the parts. In his Versuch einer neuen Darstellung der Wissenschaftslehre from 1797–1798 he wrote: “One will always look in vain for a thread between subject and object if one has not conceived them in their union from the very start.” (Cf. Fichte 1971, 528) In his Grundlage der gesamten Wissenschaftslehre of 1794/95 Fichte coined the slogan: “No subject without an object, no object without a subject.” (Cf. Fichte (1971, 103) The physical world, that is to say, exists only for subjects, and the consciousness of subjects always presupposes awareness of an objective world like the physical one. Fichte defended a kind of idealism that faces still harder problems than Cartesian dualism, but his critique may show the way to a dualism which does not postulate two independent but two interdependent worlds.

5. THE DEPENDENCE OF THE MENTAL ON THE PHYSICAL The mental is connected with the physical in many ways. A human being, first of all, is no conjunction of two independent substances, a soul that is the center of the mental life and the body as the subject of physical life, but a single subject which feels and thinks and acts and moves around. Therefore our mental life is dependent in many ways on bodily processes. That holds for all kinds of sensual experience. To see we need eyes, light, and a position among things; to speak we must be able to produce sounds. Pains are mostly located somewhere in the body and characterized by their cause—burning, cutting or pressing. A purely spiritual soul could not feel thirst, hunger, exhaustion, warm and cold, sweet and sour, hard and soft. Secondly, the physical world is the basis for our self-consciousness. It was Fichte again who pointed out that our mental acts have an intentional structure. They are imaginations and thoughts of something, assumptions, hopes and fears of something, judgments that something is the case, doubts whether something is the case, etc. Sensations are non-intentional conscious states, but in general consciousness is intentional. It has propositional contents and objects, which the contents are about. I see, for instance, that Jim crosses the street. Here Jim is the object of my perception,

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and the fact that he crosses the street is the content. Now while I see Jim crossing the street I am aware of my seeing and of the fact that it is I who see him, but my attention is focussed on what I see, on the content and object of the act. However, I can reflect on my act and direct my attention to it and its character. I can also reflect on myself as the subject of the act, for instance, on my motives for observing Jim. The point I want to make is that self-consciousness comes by reflection which is mostly directed to intentional acts. I can also reflect on acts that have myself or another act for an object but reflection must have a basis of intentional acts with external facts as contents. Other persons, too, are part of my external world but I know of them only through their physical appearance. Therefore we can say: No mental life without self-consciousness, and no self-consciousness without intentional acts directed to an external world. In this sense, too, mental life is essentially dependent on the physical.14 The dependence of the mental on the physical is especially evident in the case of language. Even in antiquity the role of language for thought and knowledge as well as for human society and culture was recognized. The characterization of man as zoon logon echon does not only mean the animal that has reason but also the animal that has speech. Language has two main functions: It is a means of communication and of the expression of thought. The role of communication in human life is well known, and also that many forms of human behaviour, interaction and learning would be quite impossible without linguistic communication. Therefore I concentrate on the less evident role of language for the formation of mental contents. If we say that speaking and writing are an expression of thought the idea is generally that thought is independent of language, and linguistic expression is only something external to it. Thinking, however, goes on in linguistic forms from the start. Plato spoke of thinking as “silent speaking” (Theaitetos, 189e6–190a2, cf. also Sophistes, 263e). We think in our native language, we grasp concepts by learning predicates, we make judgments in the form of sentences. “Thinking” is an umbrella term for many mental operations from perceptual differentiation to imagining, remembering, deciding, concluding, planning, and problem-solving. Evidently not all thinking in this broad sense goes on in linguistic form. Without perceptual differentiations we could not even learn a language, after all. Moreover our vocabulary is insufficient to describe all the nuances of colours, sounds, tastes and smells which we can distinguish. Often we understand complex connections by diagrams better than by descriptions, but judging and inferring, at least, always goes on in linguistic forms. For the greater part thinking, then, is bound to language. That language is not only a means for the communication of thoughts, and language and thought rather form an inseparable unity and develop

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together was first emphasized by Wilhelm von Humboldt. He wrote: “Language is the formative organ of thought. The intellectual activity, in itself purely spiritual, internal and passing away without a trace, becomes external by the sound of speech and perceivable by the senses. It and language are therefore one and inseparable. But it must also for its own development enter into a conjunction with the sounds of speech; otherwise thought cannot become distinct and notions not concepts.” (Humboldt 1960, VII, 53) There are two reasons for the necessity of linguistic articulation for the distinctness of thought: First, expressing a thought linguistically means giving it an objective form in which it can be perceived acoustically, or optically in written language. Now, our cognitive competences are best developed for comprehending the outer world. Only in sensual perception are we confronted with well-defined objects; only by it can we make fine and accurate distinctions, which are much more difficult in the field of mental phenomena. Linguistic expression, then, allows additional distinctions for whatever is expressed by correlation with sensible differences. It also makes reflection on them much easier. You cannot distinguish pure emotions or impressions by putting one beside the other and comparing them for, roughly speaking, the mental realm admits of no simultaneity but only of succession. If you describe them linguistically, however, you can compare the descriptions and analyze them even if the emotions and impressions themselves have passed away. Language, then, is not only a means for the expression of thoughts that are themselves independent of it, but thought and language develop together. We do not understand the world intellectually and then express linguistically what we have understood, but we grasp reality, its objects, their differences, properties, and relations in linguistic forms. We shape thoughts linguistically. Language, therefore, is not only one important achievement of humanity among others but the condition of practically all our intellectual life and of our consciousness. A third argument for an essential conjunction of the mental to the physical is the fact that without the physical world there would be no communication, and without communication no community. I have just pointed out the importance of language for communication and community, and language, of course, presupposes the physical world, but now I turn to a still more fundamental argument. Community is more than a plurality of subjects; it is based on communication and interaction. If the subjects couldn’t communicate with each other they could only come to know of each other’s thoughts, wishes, and opinions if their mental life were not private but public, i.e. if the thoughts of each individual would be observable by the others like their movements and actions. But community does not consist in a

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public intellectual life but in the ability to communicate what one wants, to whom one wants and when one wants. Such communication presupposes an objective world beyond the subjective worlds of the mental life of persons. It has to be a common world, i.e. it must be epistemically equally open to all so that they can recognize what goes on in this world, and everyone must be able to act in it, i.e. to interfere in its natural course. Persons communicating with each other finally must exist in this world, they must be part of it and thus observable by the others; otherwise one could not perceive who addresses whom. The third argument for an essential dependence of the mental on the physical then is: Subjects as members of a community need a medium for their communication and must therefore live in a common objective world like the physical one.

6. THE DEPENDENCE OF THE PHYSICAL ON THE MENTAL While the idea of a dependence of the mental on the physical is quite familiar the inverse claim of a dependence of the physical on the mental is most unusual today. From the standpoint of materialism as well as Cartesian dualism the physical world, after all, is the paradigm of an independent reality. In the times of idealism, from Locke to Hegel, i.e. for about 150 years from 1680 to 1830, the intellectual situation was quite different. Epistemological idealism, at least, was then generally accepted. According to it the objects of perception are not physical things but mental entities: impressions and conceptions or pictures of physical things. In Plato’s myth of the cave in the Republic (514a–521b) the captives do not see the things themselves but only their shadows on the wall of the cave. For epistemological idealism we are captives in the cave of our own heads and see only mental shadows of external things. The arguments for epistemological idealism are all of them quite unconvincing (cf. Kutschera [2003], chap. 2). Much more plausible is the idea that the way we perceive external physical things does not only depend on their nature but also on the construction of our own cognitive apparatus: our sensual organs and our intellect. How we see things is determined by an interaction between the external objects and ourselves. It was this idea that led Democritus and Plato to their distinction of primary and secondary qualities, i.e qualities that characterize the things themselves, independently of their being observed, and qualities that things have only relatively to an observation. As we have seen in section 2 Berkeley’s claim that all observational properties are secondary has been confirmed by quantum physics. Therefore we may say: We cannot characterize the nature of the physical world without

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reference to human observation. We can only describe it by dispositions to show up with such and such properties in observations. In this sense we said: “No physical world without subjects.” The world as we experience it and can only describe it is a world not in itself but a world for us.

7. POLAR DUALISM We can sum up the result of the last two sections in Fichte’s words: “No object without a subject, no subject without an object.” Mental and physical reality belong together and are essentially related to each other. If we cut up reality into two autonomous parts as in Cartesian dualism we cannot afterwards plausibly reconnect these parts ontologically and epistemologically. We have thus, as Fichte said, to start from the unity of reality and conceive of its parts as essentially connected. Fichte was an ontological idealist, but some of his ideas can be incorporated into dualism. One of these is the insight that we cannot understand the mental and the physical independently but only by differentiating them from each other. Fichte, as I have already pointed out, was the first modern thinker who recognized the intentionality of many mental acts. In an intentional interpretation of an impression I understand it as an impression of a certain type with a certain content. In this interpretation I distinguish the subjective components of the impression—the subject itself and its sensations and actions—from the objective ones—the content—in such a way that the subjective is the non-objective and vice versa. In adult experience this interpretation is to a large degree automatic. There are, however, cases showing that in principle decisions are involved. Sometimes, for instance, it is not clear whether it is objectively hot or I just feel hot. And sometimes I cannot at first say whether my train begins to move out of the station or the train on the next track. The physical and the mental are determined by differentiation from each other, then. Reality does not consist of the mental, the physical, and combinations of the two, either. There are many phenomena that are more or less mental or physical, respectively. If we describe linguistic behaviour, for instance, we can concentrate more on the phonetic side or on that of conceptual content. Each description has physical as well as mental components. Even if I quote somebody’s utterance verbatim I do not just talk about the sounds he uttered. The phonemes of a language are already determined by the differences in meaning they may transport, and in repeating what he said I present only phonetic matter relevant to his meaning. Another case of an inseparability of physical and mental components are action terms. Often bodily movements are specified by their intentions, and vice versa.

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The arguments I have brought forward thus advocate a replacement of Cartesian dualism by a Polar Dualism which emphasizes the unity of reality and the essential connections between the mental and the physical.

NOTES 1. I am concerned here only with ontological, not with epistemological, idealism, the claim that the objects of our experience are only mental objects such as representations, conceptions, or sense data. 2. Moreover it again comes in different versions which the proponents usually hesitate to specify, knowing that they would thereby become an easy prey for their critics. What I have defined above is analytical global supervenience. A nomological global supervenience takes only worlds into account in which the same laws of nature hold as in our own world. This kind of global supervenience, however, could also be upheld by psycho-physical parallelism, a form of dualism held, e.g., by Arnold Geulincz, Nicole Malebranche and, most prominently, Gottfried Wilhelm Leibniz. Parallelists, to be sure, maintain in addition that there is no causal interplay between the two realms which a materialist would not accept, but global supervenience is neutral with respect to causal relations. Nomological global supervenience just says something about the coexistence of mental and physical states, while causal relations connect earlier with later events. A distinctive materialistic content, then, is only to be found in claims about an analytic global supervenience of the mental on the physical. 3. For the arguments for idealism and their critique cf. Kutschera (2003), chapter 2. 4. S, then, is to be a complete Boolean algebra. 5. In doxastic logic which studies the principles of belief we distinguish between a descriptive and a rational concept of belief. While for the latter there are logical principles saying, e.g., that you cannot at the same time believe a state and its negation, and that together with a state you also believe what follows logically from it, there are no such principles for the first one, to which I refer in the text. Because of the principles for rational belief doxastic attitudes may be represented by a single state instead of by a set of states. In the case of descriptive believes there is no such possibility. For an argument against materialism based on the rational concept of belief cf. Kutschera (1994), 103–10. 6. This is an argument against an analytical global supervenience of the mental on the physical. For an argument against a nomological supervenience cf. Kutschera (2003), 34 seq. 7. This holds in the sense of the modal theory of causation. Cf. Kutschera (1986), 253–81. 8. For the distinction between causes and reasons and between causal and rational explantions cf. Kutschera (1993), chapter 2. 9. Plato already pointed out that the assumption of a chorismos between the mental and the physical leads into problems of interaction as well as of cognition. Cf. his Parmenides, 133a–134e.

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10. This realism is an ontological thesis. Epistemological realism is the opposite of epistemological idealism and maintains that the objects of our experience are physical things and facts. Epistemological as well as ontological realism is the normal conception in everyday life and science. 11. That is the mistake of Evolutionary Epistemology: It presupposes the theory of evolution as a theory about the world in explaining, by selection and adaption, why our impressions must be mainly right. 12. This difficulty was already pointed out by Xenophanes in fragment 34, the first epistemological text in antiquity. 13. How it can then be overcome has been shown in Kutschera (2003), 5.1. 14. This idea is elaborated in Kutschera (2006).

BIBLIOGRAPHY Fichte, J. G. 1971. Sämtliche Werke and Nachgelassene Werke, edited by I.H. Fichte. Berlin 1845/46 and 1834–1835. Reprinted 1971. Berlin: de Gruyter. Frege, G. 1967. Kleine Schriften, edited by I. Angelelli. Darmstadt: Wissenschaftliche Buchgesellschaft. Humboldt, W. von. 1903–1906. Gesammelte Schriften, edited by the Königliche Preußische Akademie der Wissenschaften zu Berlin. Jackson, F. 1982. “Epiphenomenal qualia.” Philosophical Quarterly 32: 127–36. ———. 1986. “What Mary didn’t know.” The Journal of Philosophy 83: 291–95. Kutschera, F. von. 1986. “Bewirken.” Erkenntnis 24: 253–81. ———. 1993. Die falsche Objektivität. Berlin: de Gruyter. ———. 1994. “Global supervenience and belief.” Journal of Philosophical Logic 23: 103–10. ———. 2003. Jenseits des Materialismus. Paderborn: mentis. ———. 2006. “Reflection.” In Analytic Philosophy Without Naturalism, edited by A. Corradini, S. Galvan and E.J. Lowe, 15–23. London and New York: Routledge. Nagel, T. 1974. “What is it like to be a bat?” Philosophical Review 83: 435–50. Strawson, P. F. 1959. Individuals. London: Methuen.

6 The Reductio of Reductive and Non-reductive Materialism— and a New Start Uwe Meixner

This chapter has two parts: a destructive part, which is also somewhat polemical, and a constructive part. In the first part, it is argued that materialism is not a tenable position in the philosophy of mind. In the second part, a dualistically conceived science and philosophy of mind is briefly described.

1. THE REDUCTIO Once upon a time, in the not so long ago good old times, materialism—or physicalism—was a straightforward matter: in the philosophy of mind, it amounted to the thesis that every mental entity is physical, hence that every mental property, every mental event, every mental substance (if there is such a thing) is physical. That was clear enough, though hardly convincing to anyone. For some reason, materialism sounded much more convincing if, for example, the thesis that every mental property is physical was reformulated as the thesis that every mental property is identical to a physical property. The latter thesis is logically equivalent to the former—but no matter, the second thesis simply sounded more convincing than the first, and for that reason it was preferred by those who wanted to be materialists, and even came to be called a “theory”: the identity theory. It didn’t take long and there was not just one identity theory but two of them: one was called the “type-identity theory” and coincided with what had formerly been called “the identity theory”; the other was called the “token-identity theory.” That was the time when matters started to get complicated, since some of the people who wanted to be materialists believed 143

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that the type-identity theory was wrong, but that they could be perfectly good materialists merely by believing in the token-identity theory. Unfortunately, materialism didn’t seem entirely convincing even if it was tuned down to the token-identity theory, that is, to the doctrine that every mental event is identical to a physical event, or in short: that every mental event is physical. Consequently, matters became more complicated. On the one hand, there was the, for some reason entirely non-negotiable, urge to be a materialist; on the other hand, there was the definite need to make the case for materialism philosophically more convincing than it had hitherto been. The outcome was that many who wanted to be materialists believed that they could be perfectly good materialists by merely believing that every mental event is identifiable with a physical event. One might have called this doctrine the “token-identifiability theory,” but to my knowledge nobody ever called it that way. Instead of characterizing their position in terms of identifiability, those who wanted to be token-identifiability materialists chose to characterize their position in terms of reducibility, and considered themselves reductive materialists regarding mental events. The difference is only verbal; for if mental event X is (ontologically) reducible1 to physical event Y, then mental event X is identifiable with physical event Y, and conversely. It didn’t take long and not even reductive materialism regarding mental events seemed entirely convincing. However, since people still wanted to be materialists, they quickly invented non-reductive materialism, and believed they could be perfectly good materialists by merely being non-reductive materialists regarding mental events. This belief is illusory, as I will argue. But first my attention will focus on reductive materialism. In what follows, the phrase “reductive materialism” will be short for “reductive materialism regarding mental events,” and analogously the phrase “non-reductive materialism” short for “non-reductive materialism regarding mental events.” I am, of course, well aware that there is also reductive, respectively non-reductive, materialism regarding properties. I will stick to mental events, since if reductive materialism and non-reductive materialism are not tenable regarding mental events, then they certainly do not seem to be tenable regarding mental properties. There is a fundamental dilemma at the heart of reductive materialism. The dilemma is this: Take mental event X and physical event Y. Either X is identical with Y, or X is not identical with Y. If X is identical with Y, then reducing X to Y (identifying X with Y) is superfluous (though trivially feasible); if, however, X is not identical with Y, then reducing X to Y (identifying X with Y) is false. Hence reductive materialism is false if the token-identity theory is false, and it is superfluous if the token-identity theory is true. Hence reductive materialism is either false or superfluous.

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Proof: Suppose reductive materialism is true. Hence it is true that every mental event is reducible to a physical event. Hence it is true that every mental event is identifiable with a physical event. Hence it is true for every mental event that it is not false to identify it with a physical event. Hence it is true that every mental event is identical with a physical event. Hence the token-identity theory is true. Thus: if reductive materialism is true, then the token-identity theory is also true, or in other words: if the token-identity theory is false, then reductive materialism is also false. Suppose, conversely, the token-identity theory is true. Hence it is true that every mental event is identical with a physical event. Hence it is true for every mental event that it is superfluous to identify it with a physical event (since it is already identical with a physical event). Hence it is true for every mental event that it is superfluous to reduce it to a physical event (since it is already a physical event). Hence reductive materialism, though trivially true, is a superfluous addition to the token-identity theory. This dilemma puts reductive materialists in a rather uncomfortable position, since it was precisely the suspicion that the token-identity theory is false that made them think—given their urge to be materialists—that at least reductive materialism is true and, of course, non-superfluous. But that can’t be. If reductive materialism is true, then the token-identity theory is also true, and reductive materialism is merely a superfluous addition to it. Thus, all that remains for reductive materialists, who believed their position to be an advance over the token-identity theory, is to ruefully return to precisely that theory—which means, however, that any real need to refer to reductive materialism vanishes entirely. There is no call for the reducibility of mental events to physical events (except in a trivial sense) if mental events are physical events to begin with. But the greater problem for reductive materialists, and for materialists in general, is, of course, the fact that the token-identity theory does not seem to be true. This fact points straightway to dualism. What is to be done in this ominous situation? I will look at the main difficulty that throws doubt on the token-identity theory in a moment. But let me first remark that many who wanted to be materialists do seem to have been impressed by that difficulty. Did any of them become dualists? Hardly. Most of them, certainly, still wanted to be materialists, and either turned to non-reductive materialism or to eliminative materialism. I will consider non-reductive materialism below; here a few words need to be said about eliminative materialism, and about its variant, eliminative-reductive materialism. Eliminative materialism (regarding mental events) is the doctrine that there are no mental events. If this were true, then the token-identity theory would be trivially true; this is just a fact of elementary predicate logic. The mentioned main difficulty of the token-identity theory, however, suggests

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that some mental events cannot be integrated into the physical realm. Hence that same difficulty a fortiori suggests that there are indeed mental events, and at least this latter suggestion must be a very persuasive one. Eliminative materialism can be combined with the idea of reductionism in the following way: Though there are no mental events, say the eliminativereductive materialists, there are ersatz mental events, which can serve perfectly well as ersatz referents of the singular and general terms which, to date, are still intended to refer to mental events (in the usual sense) but really do not refer to such entities (since there are no such entities). Thus, ersatz mental events are, so to speak, identifiable with (genuine) mental events; more properly speaking, they fill the roles mental events were intended to fill, but which mental events never filled (since there are no such things). And there is no problem at all about the physical nature of ersatz mental events: they are selected in such a way as to be physical. Eliminative-reductive materialism is no advance over (simple) eliminative materialism since the evidence against eliminative materialism is also evidence against eliminative-reductive materialism. That evidence is also evidence against reductive materialism in the normal sense (discussed above), since it is evidence against the good old, beautifully straightforward token-identity theory. What is that evidence? It is this: There simply seem to be mental events which are not physical. It is not difficult to produce examples of mental events which due to their intrinsic nature just cannot be fitted into the physical world. Here is one: consider your current visual experience. How could this experience—the experience that you can make go away by closing your eyes, but the existence of which you cannot doubt as long as you don’t close your eyes—be a part of the physical world? It cannot be a part of what is physically going on outside of your body, since no part of that section of the physical world can be made to go away by simply closing one’s eyes. And it cannot be a part of what is physically going on inside of your body, since no part of that organic section of the physical world is a manifold of perspectivally organized phenomenal shape and color which bears a complex intentional meaning for a subject of experience: yourself. In fact, nothing in the physical world seems to be identical with your current visual experience. But it constitutes part of the core of the mental phenomena that a self-respecting psychology must save; a self-respecting psychology cannot deny this phenomenon, it cannot ignore it, and it cannot replace it by something else. What remains for a self-respecting psychology but to acknowledge that at least part of its subject matter is of a non-physical nature? These considerations seem entirely obvious. But instead of accepting them those who wanted to be materialists have, at least initially, tried to cast suspicion on the manifest image of the nature of experience and to reverse the natural allocation of the burden of proof. In doing so, they have, at least

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implicitly, relied on some question-begging argument that is more or less like one of the following seven: (1) The argument from causation Only physical events have causal powers. All mental events have causal powers. Hence: all mental events are physical events. (2) The argument from causal closure (version 1) Every mental event causes some physical event, however tiny. What causes a physical event must itself be physical. Hence: every mental event is a physical event. (3) The argument from causal closure (version 2) Every mental event is a sufficient (meaning: exactly sufficient) cause of some physical event, however tiny. Every physical event that has a sufficient cause also has a sufficient physical cause. Every physical event has no more than one sufficient cause. Hence: every mental event is a physical event. (4) The argument from the identity of causal role Every mental event has the same causes and the same effects as some physical event. Events that have the same causes and the same effects (i.e. the same causal role) are identical. Hence: every mental event is identical with some physical event. (5) The argument from complete explainability Every mental event is entirely explainable by physical conditions. What is entirely explainable by physical conditions is itself physical. Hence: every mental event is physical. (6) The argument from explanatory superfluity Non-physical mental events have no explanatory function. There are no Fs if Fs have no explanatory function. Hence: every mental event is physical. (7) The argument from knowability Each mental event is knowable. X is unknowable if X is non-physical. Hence: every mental event is physical. Comments: (I) I have been told that criticism of the arguments (2) and (3) addresses straw men: allegedly, no reasonable physicalist ever proposed arguments such as (2) and (3). What is supposed to be responsible for this is, in each of the two arguments, the first premise, which, allegedly, is unnecessary for physicalism. This defense strikes me as due to an excessive attention to literal formulation. It seems to me, on the contrary, that arguments

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like (2) and (3) are highly popular in the contemporary philosophy of mind. (Regarding (3), compare the presentation and reference given in Crane (1995), 481.) True, in such arguments the second premise is usually not spelled out, but merely ambiguously referred to under the designation “the principle of causal closure of the physical world.” And true, in arguments that are in the spirit of (2) and (3) usually some ambiguous phrase such as “mental events cause—respectively, are sufficient causes of—physical events,” “the epiphenomenality of mental events is not viable,” or “causal interactionism is the only plausible position regarding mental events” is used as first premise (Are these phrases supposed to mean that some mental events cause—respectively, sufficiently cause—some physical event, or that every mental event causes—respectively, sufficiently causes— some physical event?), and the conclusion is formulated in a correspondingly ambiguous manner: “Mental events are physical” (Does this mean that some mental events are physical, or that every mental event is physical?). However, reductive materialists can hardly afford to reject the first premise even if it is formulated precisely as it has here been formulated—because a mental event that does not cause any physical event, or that is not causally sufficient for any physical event, seems suspiciously like a non-physical event. (For if it were a physical event, it seems it could not avoid causing, and being causally sufficient for, at least some physical event.) (II) I have also heard the charge of being a straw-man argument raised against argument (4). But, in effect, it can be found in Davidson (1980), 179. Again, one should not allow oneself to be blinded by an excessive attention to literal formulation. Functionalist reductive materialists argue in the spirit of (4) when they point out that something physical fills a certain causal or functional role (the mental, according to the functionalist paradigm, being considered to be reducible to such roles), which role, it is explicitly or implicitly assumed (usually the latter), can only be filled by one thing; for an early example of such argumentation, see Lewis (1966). At first sight, the first premise of (4) may seem so outlandish to some readers that they can’t believe that any physicalist will propose it. But, in fact, reductive materialists are forced to believe in its truth, whether they propose it or not. For if a mental event did not have the same causes and the same effects as some physical event, it would have to be non-physical (since it certainly has the same causes and the same effects as itself). (III) Perhaps the argument that most people will consider to be the most forceful one among the above seven is argument (5). (I have gathered this impression from various conversations with physicalistically oriented thinkers.) Has not science—the science of the brain, in particular—already shown without any margin of reasonable doubt that every mental event is entirely explainable by physical conditions? If this rhetorical question demands assent to the assertion that science has already effectively shown that

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every mental event is entirely explainable by physical conditions, then assent must be denied; for science has, to date, not effectively shown that every mental event is entirely explainable by physical conditions. Let’s assume that what is meant by a mental event being entirely explainable by physical conditions is this: it is predictable, regarding all its features, from given physical conditions. It is unlikely, but perhaps not totally unrealistic, that science will, at some future time, effectively show that every mental event is predictable, regarding all its features, from given physical conditions. But if it did show this, would it establish that every mental is physical? Leibniz, in effect, assumed on purely speculative grounds that every mental event is predictable, regarding all its features, from given physical conditions. But this did not make him a materialist regarding mental events, though he certainly was a very intelligent man. Did he have a blind spot regarding the mental? I do not think so. Though one may perhaps deduce, say, that something has an electromagnetic nature from its being entirely explainable on an electromagnetic basis, there simply is no justification (physicalistic prejudice aside) for a general principle that allows one to deduce that an X has an F nature from its being completely explainable on an F basis no matter which descriptions are being substituted for “X” and “F.” Rather, the matter has to be decided from case to case, and the case where “X” is replaced by “mental event” and “F” by “physical” does certainly not appear to be a favorable case. Pronouncing oneself to be “convinced” by arguments such as the above seven, in the teeth of absolutely plain phenomena that show that the conclusion of each of the arguments is simply false, seems to me to be among the worst cases of metaphysical dogmatism masquerading as philosophical reasonableness in the history of ideas. The allegation that the premises of the arguments are required to be true by science is not true. Materialism, and materialism only, requires of at least one premise of each of the above arguments that it be true—that’s certainly true, and this, precisely, is what makes each of those arguments question-begging. Accordingly, the argument for materialism that at some point in time really convinces those who will be materialists to become materialists is certainly not any argument which is like one of the above seven. Rather, what convinces them is likely to be the truly irrefutable “argument” that they just want to be materialists. For whatever non-philosophical reasons, they want to adopt materialism as their basic outlook on the world, as their pivot of opinion around which all their other views will revolve. It is not easy for me to understand, as a philosopher, how a person can, in this absolutely fundamental manner, want to be a materialist, given that the rich non-physical nature of experience must be as accessible to him or her as it is to me, or Descartes, or Edmund Husserl, or, for that matter, David Chalmers. How can, for example, Daniel Dennett schematically represent the activity of the conscious human mind as a bubble filled with the physical realizations of words (issuing from the head of a

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cartoon character) and nonchalantly declare that this, basically, is the whole truth about it, as I witnessed him once do during a public lecture he gave at the University of Münster in Westfalen (in 2002).2 What makes him do such a thing? Due respect for the results of science can’t quite explain the matter, I am afraid, nor can it be explained, I hope (for Dennett), by an overly fervent veneration for Saint Ludwig (Wittgenstein), Saint Gilbert (Ryle) and Saint Willard (van Orman Quine) during intellectual adolescence.3 Later in the paper, I will offer some tentative sociological—not philosophical—speculations about why so many philosophers want to adopt such an inherently implausible position as is materialism. For the time being, however, I will accord close critical attention to the nonreductive materialists. Theirs seems to be a more plausible form of materialism, since unlike eliminative, reductive, or token-identity materialists, they do not seem to close, in various ways, their eyes to the phenomena and yet seem to be perfectly good materialists. I do not believe, however, that all of this seeming has something real corresponding to it. For one thing, non-reductive materialism is such a fluid position that some who call themselves “non-reductive materialists” will presumably insist that every mental event is physical. In that case, I wonder what is non-reductive about their allegedly non-reductive materialism; perhaps it’s supposed to be “non-reductive” because it is believed that reduction is not needed, since mental events are taken to be identical with physical events to begin with? A more plausible hypothesis of interpretation is that the non-reductiveness intended is a non-reductiveness of the nonontological—for example, linguistic—sort. In this sense Donald Davidson, a firm believer in the token-identity theory, was a non-reductive materialist. But no matter, those who call themselves “non-reductive materialists,” but believe that all mental events are physical, are subject to the same charge of implausibility that reductive materialists are subject to (who, qua reductive materialists, must, ultimately, believe that all mental events are physical). Comment: What can be gathered from standard literature—say, A Companion to the Philosophy of Mind (1995)—regarding non-reductive materialism and its delimitation against other forms of materialism? According to Horgan (1995), 474, non-reductive physicalism (which is nothing else than non-reductive materialism) does not assume that for physicalism (materialism) to be true “mentalistic psychology must be reducible to physical science via type/type psycho-physical bridge laws expressing either property identities or nomic co-extensiveness of distinct properties.” According to Crane (1995), 482, non-reductive physicalists “think that identity theories are not essential to physicalism, and are objectionable even on physicalist grounds.” However, also according to Crane (1995), the non-reductive physicalists’ reason for rejecting the token-identity theory is quite different

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from their reason for rejecting the type-identity theory: the type-identity theory is rejected because it seems false; the token-identity theory, however, is rejected not because it seems false, but because it “is considered too weak to explain the relation between the mental and the physical” (ibid., 483). I suspect that both Terence Horgan and Tim Crane would include the thesis that every mental event is physical in the setup of each and every form of non-reductive materialism. So, I believe, would Lynne Rudder Baker, who in a draft of her forthcoming piece on non-reductive materialism for The Oxford Handbook for the Philosophy of Mind writes that “[a]ccording to any materialist [her emphasis], every concrete particular 4 is made up entirely of microphysical items.” Since mental events are necessarily concrete particulars and since what is made up entirely of microphysical items is necessarily physical, it follows according to Baker’s characterization of any materialism that any non-reductive materialism includes the thesis that all mental events are physical. I, on the contrary, do not wish to exclude that this thesis can belong to one or another form of non-reductive materialism; but I urge that its invariable inclusion would invariably expose each and every form of non-reductive materialism to the above objection against the token-identity theory. Moreover (but secondarily), the thesis that every mental event is physical has a definite reductive ring to it (since one is prima facie inclined to believe the contrary)—no less so than the thesis that every mental property is physical. Therefore, to call a theory “non-reductive” that still includes the former thesis does not appear to be an entirely proper way of speaking. If non-reductive materialism is to be a plausible form of materialism, it cannot, among other things, assert that every mental event is physical. Prima facie, this leaves two options for a plausible non-reductive materialism: (1) to deny that every mental event is physical; (2) to remain without a definite opinion regarding the question whether every mental event is physical. But no philosopher of mind and no philosophy of mind can afford to remain without a definite opinion regarding the question whether every mental event is physical.5 And adopting agnosticism regarding the nature of mental events must certainly be out of place in the highest degree for anyone who wants to be a materialist, reductive or non-reductive. Hence there is only one option for a plausible non-reductive materialism: to deny that every mental event is physical, or in other words: to affirm that some mental event is not physical. The central problem of non-reductive materialism has now become apparent. Most of those who want to be non-reductive materialists want to adopt non-reductive materialism because they think that non-reductive materialism is more plausible than reductive materialism. But this forces them to assert that some mental event is not physical. For otherwise the position they wish to adopt would not be more plausible than reductive materialism.

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However, the assertion that some mental event is not physical defines a form of dualism—and more than just a minimal form of dualism is implied by it: it is asserted that there is at least one mental non-physical event; but if there is one mental event of the non-physical sort, then, we may take it, there are many. What more is needed for an interesting, non-negligible dualism regarding mental events? It follows that non-reductive materialism—if more plausible than reductive materialism—implies non-negligible dualism (regarding mental events; but I will leave this tag tacit in what follows). If this is the case, why speak of non-reductive “materialism”? Why use that word? That the word sounds attractive to the average Western philosopher cannot be justification enough. Materialism, howsoever one may choose to define it, is an ontological monism. As such it is incompatible with ontological dualism. Clearly, those who want to be non-reductive materialists because they think that non-reductive materialism is more plausible than reductive materialism have a serious problem. How can they be the good materialists they want to be if their position is compatible with nonnegligible dualism, even implies it? The only way to get out of these straits is to deny that the assertion that many mental events are not physical constitutes a form of dualism. This denial is highly disputable; but I will let it pass for the sake of the argument. Instead, dualism is considered to be constituted only by a thesis of independence or separability: by the thesis that some mental event is independent of, or separable from, every set of physical events. It is this thesis that nonreductive materialism—in its reformed interpretation—is taken to be opposed to, being itself the thesis that, although some—even many—mental events are not physical, every mental event is dependent on, or inseparable from, some set of physical events. The invoked relation of dependence or inseparability can be variously interpreted. In recent years, it has mostly been interpreted in terms of supervenience relations of varying modal strengths. Others have spoken of constitution, others again of realization, asserting that every mental event is constituted by some set of physical events, or that every mental event is realized by some set of physical events. The supervenience of mental events on physical events, or the constitution, or the realization of mental events by physical events has been taken to be enough for mental events being “nothing over and above” the physical, which “being nothing over and above the physical” has, in turn, been taken to be enough for materialism, albeit materialism of the non-reductive sort. Unfortunately, all this philosophical cleverness is not enough to remove the strong suspicion that so-called non-reductive materialism (if it is intended to be more plausible than reductive materialism) is not really materialism, but that it is, in fact, dualism. Consider Descartes, the paradigmatic dualist. Descartes did hold that many mental events are not physical. But we have seen that this much is believed by all non-reductive material-

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ists who want to uphold a more credible form of materialism than is asserted by reductive materialists. Hence Descartes’ belief that many mental events are not physical must not, by itself, make Descartes a dualist (by which, remember, I here mean: a dualist regarding mental events). For if it did, then those who consider themselves materialists and believe, like Descartes, that many mental events are not physical would have to be dualists, like Descartes, and would have a thoroughly mistaken self-image; they could not help but be hypocrites in calling themselves “materialists.” But what makes Descartes a dualist regarding mental events if it is not his belief that many mental events are not physical? Did Descartes assert that some non-physical mental event is independent of every set of physical events? Yes and no. It is common to bash Descartes, it is less common to read him carefully. The gist of his philosophy of mind, as articulated in the Meditations, his main work, is this: Descartes did believe, putting it in the modern idiom, that there is some possible world in which his (actual) cogitationes (and he along with them) exist without any physical event existing, and, in fact, without anything physical existing, which, note, entailed for Descartes that his cogitationes (and he along with them) are non-physical entities in the actual world.6 But Descartes did not believe that this possible world is the real world, or that it is easily accessible from the real world: that it is similar or close to the real world. Descartes believed that the possibility of his cogitationes existing without any physical event existing is a possibility indeed—but only a very remote one. As he chooses to express himself, it is a possibility that might have been made real by God. Nothing in his writings suggests that he considers it a possibility which might have come about in the normal course of nature, or which is at least compatible with the laws of nature. So, in a sense, Descartes did believe that some mental event is not only non-physical but also independent of (separable from) every set of physical events. But the notion of independence involved in this belief is very weak, logically speaking. Nevertheless, if Descartes is a dualist (regarding mental events), then it must be this belief, with that same weak notion of independence involved in it, which makes him a dualist. Nothing else could. Descartes is credited with various absurd beliefs, like that there is “mind stuff” besides material stuff, or that the mind is in actual fact (and not only in possibility) free-floating, without any physical basis, or that there are two kinds of substances that are in actual fact totally unrelated to each other. But Descartes didn’t believe any such things. So, if Descartes is a dualist (regarding mental events)—and he is one, or no one is—the sufficient reason for his being a dualist must be found in his belief that some mental event is non-physical and such that there is some possible world, possible in the weakest possible sense, in which that mental event exists without any physical event existing. And, of course, what is sufficient for making Descartes a

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dualist must also be sufficient for making anyone else who accepts it a dualist. Those who want to be non-reductive materialists and consider their materialism to be more plausible than reductive materialism will be happy to agree, I take it. Although they do share with dualists the belief that many mental events are not physical, they do not believe that some non-physical mental event is independent of every set of physical events—and only believing the latter would make them dualists, they say. But they overlook two crucially important points: (1) already the belief that some non-physical mental event is in the weakest way possible independent of all physical events in total makes one a dualist; otherwise one could not consider Descartes a dualist on the basis of what is the essence of his philosophy of mind; (2) if one accepts that some mental event is not physical, then one must also accept that some non-physical mental event is in the weakest way possible independent of every set of physical events. Thus, non-reductive materialists who consider their materialism to be more plausible than reductive materialism are still in the position they wanted to escape from: they turn out to be dualists. Since they believe that some mental event is not physical, they must, in reason, also believe that some non-physical mental event is in the weakest way possible independent of every set of physical events, and this latter belief makes them dualists. Retreating to reductive materialism or even better, to the simple token-identity theory, to honest materialism (but thereby also accepting its inherent implausibility), or to become honest dualists—this, in the end, is the stark alternative non-reductive materialists are confronted with. What must be at issue here is of course the thesis I labeled “(2)” above: the thesis that if one accepts that some mental event is not physical, that then one must also accept that some non-physical mental event is in the weakest way possible independent of every set of physical events. What is the justification for this thesis? Is it justified? Clearly, it would be justified if “some mental event is not physical” logically implied “some non-physical mental event is in the weakest way possible independent of every set of physical events.” Does the former logically imply the latter? In answering this question, it must first be noted (what implicitly has been made use of already above) that the (complex) predicate “X is in the weakest way possible independent of every set of physical events” is logically equivalent to the (likewise complex) predicate “there is some world, possible in the weakest possible sense, in which X exists without any physical event existing” (or in other words: “X is in the weakest way possible independent of all physical events in total”). The proof of this assertion: The direction from left to right: Suppose X is in the weakest way possible independent of every set of physical events. Hence it is in the weakest sense possible that X exists without any set of physical events existing. Hence it is in the weakest sense possible that X exists with-

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out any singleton set of physical events existing. Hence it is in the weakest sense possible that X exists without any physical event existing. Hence there is some world, possible in the weakest possible sense, in which X exists without any physical event existing. [In other words: X is in the weakest way possible independent of all physical events in total.] Note that, by definition, a set exists (in the sense here relevant) if, and only if, it is non-empty and every element of it exists. The direction from right to left: Suppose there is some world, possible in the weakest possible sense, in which X exists without any physical event existing. Hence it is in the weakest sense possible that X exists without any physical event existing. Hence it is in the weakest sense possible that X exists without any singleton set of physical events existing. Hence it is in the weakest sense possible that X exists without any set of physical events existing. Hence X is in the weakest way possible independent of every set of physical events. Hence the question whether “some mental event is not physical” logically implies “some non-physical mental event is in the weakest way possible independent of every set of physical events” would have to be answered by “yes” if it is logically inconsistent to suppose both that X is a non-physical mental event and that there is no world, possible in the weakest possible sense, in which X exists without any physical event existing. Is it indeed logically inconsistent to suppose both that X is a non-physical mental event and that it is in the strongest manner impossible for it to exist without any physical event existing? While it seems entirely consistent to me to suppose both that X is a non-physical mental event and that it is nomologically impossible for it to exist without any physical event existing, the supposition of X being a nonphysical mental event and being nonetheless in the strongest manner unable to exist without any physical event existing does indeed seem logically inconsistent to me. To save themselves from dualism non-reductive materialists will claim the contrary, but note that they must do so without benefit of the slightest shred of evidence, while I can point to the fact that thought moves quite automatically from X being a non-physical mental event to its being possible in the weakest manner that X exists without any physical event existing. This evidence is not entirely conclusive—this is the mere straw that non-reductive materialists may clutch at, if they will, to keep themselves from falling into dualism. I believe that the preceding considerations show that there are no good philosophical reasons for the prevalence of materialism. Put in a nutshell, my argument has been as follows: Materialism is either reductive or non-reductive. Reductive materialism includes the thesis that all mental events are physical. This thesis, however, is contradicted by the phenomena. Non-reductive materialism, in turn, either includes the thesis that all mental events are physical, or it does not. In the first case, it is contradicted by the phenomena, just as is reductive materialism. In the second case, it is either agnostic about the thesis

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that all mental events are physical or, on the contrary, includes the thesis that some mental event is not physical. The former alternative, agnosticism, disqualifies non-reductive materialism from being a full-fledged position in the philosophy of mind; the latter alternative, however, makes non-reductive materialism collapse into dualism in the end. Thus, if intellectual justice—in other words: reason and respect for the phenomena—ruled among the philosophers in the way it ought to rule, materialism could not have the position that it has among the philosophers today. What, then, are the reasons for the prevalence of materialism among the philosophers? One reason, I believe, is that materialism has become, for reasons external to philosophy, a paradigm in philosophy, and materialist philosophers are doing, so to speak, normal science under that paradigm, which situation—since it finally seems to assimilate philosophy to a normal science, like physics or biology—fulfills the deepest cravings of scientifically oriented naïve philosophers and draws them irresistibly towards the paradigm of materialism. In my eyes, turning philosophy into something like a normal science is truly a perversion of philosophy, which ought not to have a paradigm in Thomas Kuhn’s sense. Matters being as they are, however, materialist philosophers will hardly be moved by considerations of what philosophy should be like and will not be ready to relinquish their paradigm without severe crisis, as Kuhn taught us more than four decades ago. But although there are anomalies enough, crisis simply does not develop; instead, the anomalies are merely viewed as occasions for more, and ever more sophisticated, puzzle-solving—in a jargon that is increasingly impenetrable even for many who are philosophically educated. Though the complications have been piling up for decades, there is no pervasive sense so far that something might be wrong with the materialist philosophy of mind. What are the reasons for this situation? For one thing, the contemporary materialists form the largest philosophical community with the same basic outlook that ever existed. Such a group is not easily shaken in that conviction which is the basis of its fundamental unity and, in consequence, of all the considerable professional advantages that accrue to group members from that unity. Moreover, materialism is regarded as a bastion in the struggle of liberal intellectuals against the powerful religious right. It cannot be given up, many of them feel, without relinquishing the cause of intellectual and moral liberty. But that’s a reason for America, not for Europe where the intellectual wars with religion have been over for a fairly long time and where there is no passionate political concern which obscures the quite trivial logical fact that one can be a perfect atheist without being a materialist. Why do European academics, especially the young academics, absolutely want to be materialists, given that materialism cannot be a beacon of light in a dark world for

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them? I am truly puzzled by the fact that so many of them want to be materialists nonetheless. Perhaps they, for some reason, believe that they can’t be analytic philosophers without being materialists—perhaps because famous authorities of analytic philosophy, like W. V. O. Quine and David Lewis, were materialists? But, like all philosophers, these father figures of modern materialism, too, are merely cooking with water, as one says in Germany. They have their basic convictions and what they build on them, and these can be reasonably criticized like everyone else’s basic convictions and what he or she builds on them. Perhaps the attractiveness of materialism, especially for the young analytic philosophers, simply consists in the ominous feeling that they can’t have careers as analytic philosopher if they are not materialists? There may be something to this, but I don’t know, and I do not wish to dwell on this very pessimistic note. Therefore, I come back to more philosophical considerations. Materialism is regarded as being identical with, or implied by, the scientific worldview. But it is never inquired whether there even is such a thing as the scientific worldview. Is not the developing of worldviews the task of metaphysics, not of science? And are there not more worldviews than one that are compatible with science? Indeed, are there not more worldviews than one that are not only compatible with, but actually good for science? Perhaps there is even a worldview that is better for science than the materialistic one? I submit that the dualistic conception of consciousness has done much more for the scientific exploration of consciousness than the materialistic conception ever will. Transposing a simile from Wittgenstein’s Tractatus into the present context, one can fairly say that dualism is the ladder on which science climbs into the exploration of consciousness. But why, in the world, should science throw that ladder away if solely in a dualistic perspective the phenomena become visible that a science of consciousness must want to describe and explain? For a science of consciousness is not trying to correlate brain events with brain events, or brain events with behavior or behavioral dispositions; it is trying to correlate brain events with conscious events, two types of events which for this purpose must be considered to be on different sides of being—at least methodologically, and why, then, not also metaphysically? How can that which is methodologically good for science be metaphysically bad for it, or contrary to its spirit? The esthetic ideas of unity and simplicity are presumably still the most intellectual motives for the materialist’s urge to simplify and unify: to shove entities into categories they do not seem to belong to, to make them the same as entities they do seem to be different from, to eliminate them, if need be, altogether from the realm of being, although they plainly seem to exist—in one phrase: not to accept entities in the way they seem to be. But, as always, the duty of the philosopher is to distinguish where distinction is due. The ideas of unity and simplicity and the unifying, simplifying measures pursuant to

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them have sometimes, in other contexts, been a guiding light in the quest for truth. These ideas and measures, however, cannot, in reason, be a guiding light regarding the truth of the mind if they run counter to phenomenal seeming (that is: to phenomenal seeming that is verifiable as being intersubjectively the same). With regard to the mind, if not in other areas of knowledge, the highest respect must be accorded to phenomenal seeming and to the distinctions inherent in it; for the life of the mind is phenomenal seeming: subjective intentional appearance in all its infinite variety. Take it ontologically seriously. Consider it—the thing itself, not just the ersatz for it that is intolerantly demanded by materialist metaphysical prejudice.

2. A NEW START 7 If subjective intentional appearance is seen in its true, non-physical nature, where will this lead philosophers who formerly wanted to be materialists with regard to the mind (at least)? Normally, these philosophers are adherents of ontological naturalism—the doctrine that only the entities that are countenanced in natural science exist. But they can take comfort from the (often more than merely) methodological dualism of the sciences of the mind. For centuries, the world of the mental, considered to be non-physical, was treated as a part of nature, of the natural order. One simply thought that there is, beside its physical side, a non-physical side to nature—a side to be explored by the natural science of psychology. This idea must be taken seriously again—and one will duly acknowledge that there need not be any conflict between dualism with regard to the mental and naturalism. Although dualism with regard to the mental is compatible with supernaturalism, no former materialist is required to believe in entities that are not countenanced in natural science merely on account of having become a dualist. If there is a non-physical side to nature, then it is natural to ask: what are the relations of the non-physical side of nature to its physical side? This is the subject of psycho-physics, conceived in the broadest manner to include all kinds of psycho-physical correlation research. With regard to the physical side, we have the situation that never before in the history of science psychophysics has been in a better position to pursue its task, since so much more than in earlier times is known about the brain and the nervous system, which constitute the locus of psycho-physical relations. But with regard to the nonphysical side, we are confronted with the fact that mental phenomenology— which can only be based on intersubjective comparison of introspective data—has been severely neglected. An ideal psycho-physics would have a complete mental phenomenology at its disposal, and it would be in the position to specify, for each non-physical mental phenomenon, the physical correlate. It remains to be seen whether nature is such that an ideal psycho-

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physics is feasible (in principle: discounting accidental limitations). To find out about this is entirely up to empirical research. It might very well turn out to be the case that some non-physical mental phenomena do not have a specifiable physical correlate (which would mean one of two things: either they have a physical correlate but it is too complex for specification, or they just do not have any physical correlate). To repeat, to adjudicate this matter is entirely up to—dualistically conceived—empirical research. But what is the nature of the relation that binds the physical correlate X to the non-physical mental phenomenon Y of which it is the physical correlate? A partial answer to this question can be given for non-physical mental events. Let X be a physical event and Y a non-physical mental event; X is a physical correlate of Y if, and only if, X is causally equivalent to Y, where causal equivalence means that X and Y have exactly the same causes and exactly the same effects. Some things should be noted about causal equivalence. (1) Causal equivalence is an equivalence relation, restricted by stipulation to the domain of events (hence it is based on causation qua event-causation); it is therefore a symmetric, transitive and, in the domain of events, reflexive relation. (2) While causal equivalence is a causal relation, the relation of causation cannot hold between causal equivalents (otherwise, one of the causal equivalents would cause itself). (3) How many causal equivalents of a given event there are cannot be decided a priori; but what we know about physical events makes it very likely that there is just one physical causal equivalent of a physical event: the physical event itself. Accordingly, any non-physical mental event has (very likely) at most one physical correlate. For if it had at least two physical correlates, these two physical events would themselves be causal equivalents of each other, and therefore be identical and one after all (see (3) above), and not two. Also, if epiphenomenalism were right and no non-physical mental event caused any physical event, no non-physical mental event would have a physical correlate, since, very likely, every physical event causes at least some physical event. This brings out the fact that, according to the above definition, a physical correlate of a non-physical mental event is a causal correlate of it; under epiphenomenalism, there could not be any causal physical correlates of non-physical mental events (though there still might be physical correlates of such events in a non-causal sense of “physical correlate”). But epiphenomenalism does not seem to be true. What makes some dualists believe in it is the circumstance that they uncritically accept physicalistic a priori assumptions about the causation of physical events (primarily, one or another principle of causal closure of the physical world). There is no good reason for a dualist to share these a priori assumptions. Moreover, non-physical mental events must have physical effects, or else there could be no observation of them by external observers (that is, they would not be

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observationally accessible from the third-person point of view). In view of this, no construal of causation is acceptable—for a dualistic philosophy and science of the mind—that rules out non-physical mental causation of physical events. Fortunately, no such construal is rationally forced upon us: non-physicalistic, metaphysically neutral concepts of causation are readily available.8 It is important to note that research regarding the physical causes of a non-physical mental event is not quite the same as research regarding its physical correlate, though the former research certainly contributes to the latter. This is so because the causes of a non-physical mental event, none of which is identifiable with its physical correlate, will also be the causes of its physical correlate (if it has one). Likewise, the effects of a non-physical mental event, none of which is identifiable with its physical correlate, will also be the effects of its physical correlate. Thus, correlation research regarding non-physical mental events and brain-events is to be regarded as research on a prominent case of causal convergence or causal parallelism. The (dualistic) psycho-physical causal parallelism has a nomic character: it is constituted by psycho-physical laws of nature, and the supreme aim of psycho-physics is to discover these laws of nature. In view of this, it is a misnomer to call the double causations that are essential for psycho-physical causal parallelism “cases of causal overdetermination,” as if something untoward were going on. The truth of the matter is that a non-physical mental event which has a physical correlate cannot—due to the laws of nature— be a cause of event X without its physical correlate also being a cause of X, and vice versa. Psycho-physical causal parallelism (to whatever extent it exists: perhaps only for some non-physical mental events, perhaps for all) is a possibility in nature that will be realized (indeed necessitated) under certain circumstances—in particular, under the circumstance of the existence of sufficiently complex brains, which are the loci and motors of psychophysical causal parallelism. Psycho-physical causal parallelism, therefore, came about in the course of an evolutionary process that happened to favor precisely the coming about of psycho-physical causal parallelism and, by the same token, the development of brains that are capable of producing (non-physical) conscious experiences. It came about on a very broad scale. Hence, it is rather likely that there is a distinct survival advantage attached to having conscious experiences within the framework of psycho-physical causal parallelism. I now turn to considering the question of what this survival advantage may consist in, which, first of all, requires paying close attention to the nature of conscious experiences. (The word “conscious” attached to the word “experience” is a reminder that any experience is per se conscious; it is not a modifier of the word “experience.”)

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Intentional experiences are the most important non-physical mental events, and the most important experiences. The most widespread view regarding intentional experiences is that they are representations. But if this is their nature, it is far from being apparent to us, since, in having intentional experiences, it always seems to us that we are dealing directly with the intentional objects of these experiences (for example, with physical objects; note that the physicalness of the intentional object of an experience does not compromise the non-physicalness of the experience itself; for further explications, see the end of this paper). If they are representations, one should call intentional experiences, “transparent representations,” their transparency meaning precisely that their representational nature is not apparent to us. But perhaps, indeed, this representational nature of intentional experiences is not really there at all.9 In contrast, certain brain-events are undoubtedly representations, and as brain-events undoubtedly nontransparent representations.10 (In view of this, it is hard to understand why intentional experiences could ever have been confused with certain physical events: brain-events.) For X being a representation, it is required that the item that X presents is not directly accessible in X.11 (If X is a transparent representation, then it seems that the presented item is directly accessible in X, though in fact it is not.) Whether or not intentional experiences are representations in this primary sense, they certainly can be representations in a secondary sense, namely, in virtue of their physical correlates being representations—in the abovedescribed primary sense. Why do we, or any other animal, have intentional experiences? Why do we have any experiences? The general answer is already clear: because it is advantageous, from the point of view of biological survival, to have experiences (and, of course, because the laws of nature are such as to allow the possibility of having experiences in the first place, and because the circumstances in the course of natural history were such as to start the actualization of that possibility in the second place). But who, really, is having the experiences? In a secondary sense, it is the experiencing animal (this usage is exemplified at the beginning of this paragraph). In the primary sense, it is the subject of experience that is present in any experience, whether that experience is intentional (that is, object-presenting) or not. The subject of experience is the intrinsic addressee of an experience, the entity that is intrinsically addressed by an experience. Thus, any experience turns out to be per se information for someone. As information for someone, an experience is always, and not only if it is an intentional experience, about something; but it is an intentional experience if, and only if, it is about something in the manner of presenting an object (or objects). We can conclude: the evolutionary advantage of having experiences consists in the fact that each experience is information about something for the

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subject of experience, and hence, derivatively, for the animal—information which more often than not is relevant for the survival (or at least the wellbeing) of the animal. But why do animals need conscious information which is, in the first place, addressed to a subject of experience? Would not blind— unconscious—reactive mechanisms, provided they can be adapted to varying circumstances (by dint of suitable meta-mechanisms), do just as well in steering animals around the pitfalls and to the resources of the mesocosmos they live in? This is the remaining, deep question that must now be tackled. Sometimes the concept of subject of experience is limited to human subjects of experience, since only human subjects of experience seem to be capable of self-consciousness. However, for being a subject of experience it is not necessary to have self-consciousness, let alone the conceptually explicit self-consciousness that is manifested in the spontaneous and sophisticated handling of the pronoun “I.” For a subject of experience to be present, it is already sufficient that an elementary experience—an instance of pain, fear, or hunger—occurs; indeed, it is sufficient that some experience occurs, for, as was said above, every experience is intrinsically addressed to someone— the experience’s subject of experience. As a consequence of this, a subject of experience is connected with every conscious animal (that is, with every animal that has experiences—because some subject of experience is the subject of these experiences). A widespread attitude regarding subjects of experience, human or not, is this: not to take them ontologically seriously in their own right. Sometimes the subject of experience is identified with the animal that has experiences, for example, with the human being.12 This is unobjectionable as long as it is not ignored that there is a more pertinent, primary sense of “subject of experience” in which the animal just isn’t a subject of experience—since the animal is indeed present in its experiences as intentional object, but never, truly, as subject. A genuine subject of experience X—a subject of experience in the primary sense—is connected with an animal Y in virtue of the brain of Y producing (due to natural laws) experiences of which X is the (literal) subject—which entire fact of the matter is precisely the reason why Y, the animal, is a subject of experience in a secondary, derived sense.13 More often than the identification of subjects of experience with the experiencing animals—which is one way of not taking the subjects of experience ontologically seriously in their own right—one encounters, nowadays, the epiphenomenalization or even fictionalization of such subjects. The fictionalization of subjects of experience is incoherent, since it involves the incoherent idea that I, for example, am an illusion of myself. And while it cannot be ruled out logically that evolution took a course that, on a broad scale, produced subjects of experience (in the primary sense) for nothing more than to be innocuous biological superfluities, it does not seem plau-

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sible to assume such a position. The alternative position, however, can only imply that subjects of experience have to some extent in some manner causal powers. The most natural way to accord a causal role to subjects of experience is this: a subject of experience is also a subject of action—of actions that have the general purpose of ensuring the survival of the animal to which it is connected (via the brain), precisely in the informative light of the experiences of which it is the subject. This is the purpose (in the sense that evolutionary biology allows to speak of purpose) that experiences and therewith, ineluctably, subjects of experience have evolved for. Unconscious reactive mechanisms, even if they can be adapted to varying circumstances (by suitable meta-mechanisms), do not do just as well as experiences with an experiencing agent-subject in steering mobile animals around the pitfalls and to the resources of the meso-cosmos they live in (though such mechanisms are quite sufficient for plants and plantlike animals and, of course, do play a large role also in the biological economy of mobile animals). This is so because subjects of experience can, in a sufficient number of cases, act more efficiently to the advantage of the mobile animal than any reactive mechanism, even if the mechanisms concerned are capable of learning “from experience.” This, naturally, leads to two further questions: (1) What must the course of nature be like to allow the causal influence (the action) of subjects of experience on behalf of the survival of their respective animals? (2) How do subjects of experience act (exert causal influence) on behalf of the survival of their respective animals? No answer to these questions is known to be true. Nevertheless, I here offer some speculative suggestions. (1) If the macroscopic course of nature were to a considerable extent indeterministic—that is, if at many moments of time there were several physically possible macroscopically distinguished courses of nature, of which only one becomes the actual course of nature—then the causal influence of subjects of experience on behalf of the survival of their respective animals (in addition to the effects of reactive mechanisms) would fit into the economy of nature very naturally and would make perfect evolutionary sense. (2) The informed actions of subjects of experience on behalf of the survival of their respective animals would, then, consist in recognizing alternative physical possibilities (on the basis of their experiences) and in contributing to the actualization of one of these possibilities (the one considered favorable to the survival of the animal).14 Finally, there is a question that has not been treated in this paper at all so far: Are subjects of experience material or immaterial beings? Whether or not they are material beings, it is clear that they have a main trait of substances: they each figure as numerically the same entity in temporally separated mental events (i.e. experiences), or in other words: they are temporal continuants. But on the other hand, though they are capable of action (another

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trait of substances), it does not seem to be the case that they are also capable (in more than a weakest sense) of independent existence: subjects of experiences appear to be entities whose existence depends not only on the existence of a corresponding brain, but also on the well-functioning of that brain. Nevertheless, subjects of experience can certainly be considered to be substances in a minimal sense. It is not intrinsically absurd to hold that subjects of experience are material substances. Although they are embedded in something immaterial, experiences, this does not automatically make them immaterial, too—no more so than the peculiar embeddedness of, say, certain stones in experiences (as their intentional objects) makes these stones immaterial. Subjects and material objects of experiences are constituents of experiences (and differ from them in ontological category), not parts of experiences (precisely because they are not congruous to experiences with regard to ontological category); only if they were parts of experiences, they would be required to share the immaterial, non-physical nature of experiences. Nevertheless, in view of the fact that a material subject of experience cannot be located anywhere in the brain (the only place for it to be if it were quite literally the “mind-pearl in the brain-oyster” of Dennett (1991), 367), the conclusion seems unavoidable that subjects of experience are immaterial substances.15

NOTES 1. Ontological reducibility alone will be considered here. This restriction is justified, since other kinds of reducibility (explanatory reducibility, linguistic reducibility, theoretical reducibility) have been of interest to materialists only insofar as they considered these reducibilities to imply, or at least contribute to, ontological reducibility. 2. Dennett’s illustrated assertion is, of course, only a concise graphic representation of his position in Consciousness Explained and elsewhere. 3. This is not a polemical invention of mine. “When I was an undergraduate, he [Wittgenstein] was my hero,” says Dennett, who, moreover, acknowledges a debt to Wittgenstein that is “large and longstanding” (see Dennett 1991, 463). In fact, concerning pain (as distinguished from pain-behavior), Dennett declares himself to be “more Wittgensteinian than St. Ludwig himself” (see Dennett 1993, 143). He also sees himself (“a Dennett”) as a cross of “a Quine with a Ryle” (see Dennett 1995, 242). 4. In conversation, Lynne has told me that “concrete particular” should here be taken in the sense of “concrete particular of the natural world.” 5. The mysterian Colin McGinn and the so-called “neutral monists” have a hard time here. McGinn (1999), 230, says: “My whole point has been that mind and brain form an indissoluble unity at the level of objective reality.” (The emphasis is McGinn’s.) But since McGinn is not an ontological idealist, this cannot be taken to imply that minds are non-physical, and brains non-physical, too; and since McGinn is a reasonable man, it also cannot be taken to imply that minds are physical and

The Reductio of Reductive and Non-reductive Materialism—and a New Start 165 non-physical, and brains physical and non-physical, too. For that same reason, it also cannot be taken to imply that minds are neither physical nor non-physical, and brains neither physical nor non-physical, too. But what, then, is implied by McGinn’s assertion of mind and brain forming “an indissoluble unity”? That brains are physical, and minds physical, too? This would mean his return to the fold of the materialists. Perhaps McGinn’s point is that the mind is, like the brain, physical all right, that therefore every mental event is physical, but that we just cannot know how this is possible? This would make him a materialist mysterian or, indeed, a mysterious materialist. 6. If it is a true tacit premise that everything physical is necessarily (i.e. in all possible worlds) physical, then the nexus of entailment that Descartes relied on is indeed there. 7. The ideas presented in this section are treated in much greater detail in Meixner (2004). See also Meixner (2006a). 8. For a rich survey, see Meixner (2001). 9. For more on this, see Meixner (2006b). 10. For an illustration of the contrast between a transparent and a non-transparent representation, consider a sentence in your mother tongue, and a sentence in a foreign language that you can decipher with more or less effort. In the former case, in reading the sentence, you are usually not aware of the sentence being a representation; in the latter case you are invariably aware of this. The extreme of non-transparency in representation is opaqueness, which occurs when something is known to be a representation, but not of what. 11. My use of “to represent” and “to present” (the latter being more general than the former in this use) is unrelated to the distinction in Searle (1983), 46, between representation and presentation. 12. A modified version of this view is proposed in Baker (2000): the human being (which, for Baker, is the same as the human person) is, among other things, the subject of experience, but the human being is not just the human animal (the latter being for Baker the same as the human organism); see (2000), 7, 68. 13. The relationship between human being and corresponding (primary) subject of experience has its own phenomenology, which manifests itself in the thought that the subject of experience is a distinct being inside the human being, chiefly inside the head, and, more indirectly, in every use of the first-person indexical that implies a distancing of what is being referred to by “I” from the rest of the human being (for example, the use of “I” in “I have to take more care of my body”—in contrast to the different use of “I” in “I have to take more care of myself”). 14. Regarding the further description of the causality in question, see Meixner (2004) and Meixner (2007). 15. According to Lowe (1996), subjects of experience are psychological substances (ibid., 10). Lowe does not accept the view that subjects of experience are material substances and has “nothing to say in defence of immaterial substantivalism” (ibid., 8). He therefore appears to be an agnostic about the material or immaterial nature of subjects of experience, because, once it is believed that there are subjects of experience, and that they are all substances, and that it is not the case that some of them are material and some of them immaterial (beliefs I share with Lowe, I believe), the question “are subjects of experience material or, on the contrary, immaterial sub-

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stances?” can only be answered in three (still logically permissible) alternative ways: (1) “All of them are material substances,” (2) “All of them are immaterial substances,” (3) “I do not know whether all of them are material substances, and I do not know whether all of them are immaterial substances (though I do know that either all of them are material substances, or all of them immaterial substances).” Lowe, it seems, does not accept (1) and does not accept (2), and therefore accepts (3); I do not accept (3) and do not accept (1), and therefore accept (2).

BIBLIOGRAPHY Baker, L. R. 2000. Persons and Bodies. Cambridge: Cambridge University Press. ———. Forthcoming. “Non-reductive Materialism.” The Oxford Handbook for the Philosophy of Mind, edited by B. McLauglin and A. Beckermann. Oxford: Oxford University Press. Crane, T. 1995. “Physicalism (2): against physicalism.” In Guttenplan, ed., 479–84. Davidson, D. 1980. “The Individuation of Events.” Essays on Action and Events. Oxford: Clarendon Press, 163–80. Dennett, D. C. 1991. Consciousness Explained. Boston/New York/London: Little, Brown and Company. ———. 1993. “Living on the Edge.” Inquiry 36: 135–59. ———. 1995. “Dennett, Daniel C.” In Guttenplan, ed., 236–44. 1995. Guttenplan, S., ed. 1995. A Companion to the Philosophy of Mind. Oxford: Blackwell. Horgan, T. E. 1995. “Physicalism (1).” In Guttenplan, ed., 471–79. 1995. Lewis, D. 1966. “An Argument for the Identity Theory.” The Journal of Philosophy 63: 17–25. Lowe, E. J. 1996. Subjects of Experience. Cambridge: Cambridge University Press. McGinn, C. 1999. The Mysterious Flame. New York: Basic Books. Meixner, U. 2001. Theorie der Kausalität. Paderborn: mentis. ———. 2004. The Two Sides of Being. Paderborn: mentis. ———. 2006a. “Consciousness and Freedom.” In Analytic Philosophy Without Naturalism, edited by A. Corradini, S. Galvan, E. J. Lowe, 183–96. London: Routledge. ———. 2006b. “Classical Intentionality.” Erkenntnis 65: 25–45. ———. 2007. “Three Tasks for (Hard Interactionist) Dualists.” In Agency and Causation in the Human Sciences, edited by F. Castellani and J. Quitterer, 47–72. Paderborn: mentis. Searle, J. 1983. Intentionality. Cambridge: Cambridge University Press.

7 A Defence of Non-Cartesian Substance Dualism E. Jonathan Lowe

1. SOME VARIETIES OF PSYCHO-PHYSICAL DUALISM Following longstanding tradition, dualism in the philosophy of mind is normally divided into two chief kinds: substance dualism and property dualism, the former maintaining the distinctness of mental and physical substances and the latter maintaining the distinctness of mental and physical properties. Notice that I do not mention as a third kind of dualism one which maintains the distinctness of mental and physical events or states. This is simply because I concur with the generally accepted view that events or states do not constitute a fundamental ontological category, in the way that both substances and properties do, since an event or state just consists in the possession of a property by a substance at a time (see Kim 1980). Consequently, event or state dualism is standardly regarded as being a species of property dualism—and I shall not question that assumption in the following discussion. But what, exactly, are we to understand by a mental or physical substance in this context? Well, by a substance, here, is standardly meant an individual object, or bearer of properties—not, I must emphasize, a kind of stuff. By a mental substance, then, is meant a bearer of mental or psychological properties, while by a physical substance is meant a bearer of physical properties. Thus we can immediately see that, whether we are talking about substance dualism or property dualism, the fundamental distinction in play is the distinction between mental and physical properties. The property dualist holds that mental and physical properties are distinct, while the substance dualist additionally holds that the bearers of those properties are distinct—the implication being that substance dualism entails property dualism (and therefore also event or state dualism), but not vice 167

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versa. All this being so, what seems to be needed at this point is a defensible account of the two key concepts of a mental property and a physical property. These, it seems clear, are distinct concepts, although whether the properties of which they are concepts are themselves distinct is, of course, one of the main points at issue. However, it is one thing to say that these concepts are distinct and quite another to provide an account of that conceptual distinction that would satisfy everyone. In fact, it has proved remarkably difficult to produce an uncontentious characterization of either concept (see Crane and Mellor 1990). Fortunately, though, it is much easier to provide paradigm examples of mental and physical properties which almost all parties to the debate will be happy to accept as such. For instance, pain and desire are universally recognized as being mental properties, while mass and velocity are universally recognized as being physical properties. In what follows, therefore, I shall take it for granted that the conceptual distinction now at issue is a genuine one and that for practical purposes it can be captured by appeal to such paradigm examples. This being accepted, let us return to the topic of substance dualism. The adherents of substance dualism contend that the bearers of mental properties, such as pain and desire, are distinct from—that is, are not to be identified with—the bearers of physical properties, such as mass and velocity. What are these “bearers,” though? Well, the bearers of mental properties might be called, quite generally, subjects of experience—understanding “experience” here, in a broad sense, to include not just sensory and perceptual experience, but also introspective and cognitive states or, in other words, “inner” awareness and thoughts (see further Lowe 1996, ch. 1). Human persons—we ourselves—provide prime examples of subjects of experience, but no doubt we should also include examples drawn from the “higher” reaches of the non-human animal domain. As for the bearers of physical properties, for the purposes of the present discussion I shall mostly be referring to bodies, or parts of bodies—on the understanding that what we are talking about here are not mere lumps or masses of matter, but organized bodies and their parts, the paradigm examples being the human body and its organic parts, such as the brain and the neurons and other kinds of cell making up the brain and central nervous system. In these terms, then, the substance dualist may be construed as holding that a person is not to be identified with his or her body, nor with any part of it, such as the brain. On this view, a person—not the person’s body or brain—feels pain and has desires, even if it is true to say that a person feels pain or has desires only because his or her body or brain is in a certain physical state. The physical state in question—a certain pattern of excitation in nerve cells, say—is not to be identified with the pain or desire consequently experienced by the person, according to the substance dualist.

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At this point, I need to draw an important distinction between two different types of substance dualism. An implication of what I have said so far concerning substance dualism might seem to be that, according to it, a bearer of mental properties—a subject of experience—only bears mental properties, just as a bearer of physical properties, such as a human body or brain, only bears physical properties. This was indeed the view of the most famous substance dualist of all, René Descartes, for whom the human self or ego is an immaterial substance (see Descartes 1984 and, for prominent modern sympathizers, Swinburne 1986 and Foster 1991). However, even if I am distinct from—not to be identified with—my body or any part of it, as Descartes held, it does not automatically follow that I can have only mental, not physical, properties. And, indeed, there is a modern form of substance dualism—which may be called, aptly enough, non-Cartesian substance dualism—which differs from Cartesian substance dualism precisely over this point. According to non-Cartesian substance dualism, it is I, and not my body nor any part of it, who am the bearer of mental properties, just as Descartes maintained. However, unlike Descartes, the nonCartesian substance dualist does not make the further claim that I am not the bearer of any physical properties whatsoever. This sort of substance dualist may maintain that I possess certain physical properties in virtue of possessing a body that possesses those properties: that, for instance, I have a certain shape and size for this reason, and that for this reason I have a certain velocity when my body moves (cf. Lowe 1996, ch. 2, and also Baker 2000). It doesn’t follow that such a substance dualist should allow that every physical property possessed by my body is also possessed by me, however, for some of these properties may entail that the thing possessing them is a body—and the non-Cartesian substance dualist wants to deny, of course, that I am a body. One such property, for instance, would appear to be the property of being wholly composed of bodily parts, which is possessed by my body but presumably not by me.

2. TWO NEO-CARTESIAN ARGUMENTS FOR SUBSTANCE DUALISM Setting aside, for the time being, the distinction between Cartesian and nonCartesian substance dualism, what sorts of arguments can be advanced in favour of such dualism, and how good are they? Some of the best-known arguments have been inherited from Descartes himself and hence their contemporary versions may be described as “neo-Cartesian.” Two neo-Cartesian arguments in particular are worthy of consideration: an argument from the conceivability of disembodiment and an argument from the indivisibility of

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the self. For brevity’s sake, I shall call them the conceivability argument and the indivisibility argument respectively. The conceivability argument has both a strong and weak version, the difference in strength being a difference in the strength of their premises—that is to say, the premises of the strong version of the argument entail those of the weak version, but not vice versa. That being so, one might suppose that the weak version is to be preferred, because it assumes less. The weak version may be reconstructed as follows. (1) It is clearly and distinctly conceivable that I should exist without possessing a body. (2) What is clearly and distinctly conceivable is possible. Hence, (3) It is possible that I should exist without possessing a body. (4) If it is possible that I should exist without possessing a body, then I must be distinct from my body. Therefore, (5) I am distinct from my body. The strong version of the argument replaces premise (1) by (1*) It is clearly and distinctly conceivable that I should exist without any body whatever existing, which clearly entails (1) (cf. Meixner 2004, ch. 3). The historical source of (1*) is, of course, Cartesian doubt about the very existence of the physical world in its entirety—a doubt which at least appears to be coherent and therefore to describe a possible state of affairs. As I say, one might suppose the weak version of the argument to be preferable to the strong version because it assumes less. However, it could be contended that (1) is only plausible, or at least is most plausible, in the context of (1*), on the grounds that it is difficult to conceive of oneself as existing in a disembodied state save under the hypothesis that the existence of the entire physical world is an illusion. Whether we consider the strong or the weak version of the conceivability argument, it presents certain difficulties. Particularly controversial is premise (2), that what is clearly and distinctly conceivable is possible (for wellinformed discussion of this issue, see Gendler and Hawthorne eds. 2002). Let us grant the truth of premise (1*), that it is clearly and distinctly conceivable that I should exist without any body whatever existing, basing this claim on the coherence of Cartesian doubt about the existence of the physical world. The content of such doubt is something like this: perhaps, for all that I know, the entire physical world as it seems to be presented to me in perception is non-existent and that perception is wholly illusory. This is a doubt about the nature of the actual world, amounting to a surmise that the actual world contains no physical objects although it does contain me and my mental states. I am inclined to think that the surmise is at least a coherent, or logically consistent one. But the question is whether this is enough to establish that there is a possible world in which I and my mental states exist but no physical objects exist. Of course, if the surmise is correct, then the actual world is just such a world. But we are not given that the surmise is correct, only that it is coherent. To this it may be replied that it suffices that the surmise could be correct—it doesn’t have actually to be correct.

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But the trouble, I think, is that we simply don’t know whether or not it could be correct, because there may, for all we know, be some reason why it couldn’t be correct—a reason that we haven’t yet thought of. For instance, it might be that there simply couldn’t be a world containing no physical objects, whether or not it also contained me and my mental states. We might sum up this response to the conceivability argument by saying that the trouble with premise (2) is that it illicitly conflates “real” or metaphysical possibility with mere epistemic possibility. That is to say, (2) together with either (1) or (1*) does not serve to ground the truth of (3), that it is possible that I should exist without possessing a body, in the requisite sense of “possible.” The most that can be established by these means is that I might actually exist without possessing a body, in an epistemic sense of “might.” This is the sense of “might” in which we can say, for instance, that there might be an even number greater than 2 which is not the sum of two prime numbers, because we don’t know whether or not Goldbach’s conjecture is true. But in the metaphysical sense of “necessary,” it is either necessarily the case or else necessarily not the case that every even number greater than 2 is the sum of two prime numbers, so the matter is not in this sense a contingent one. Likewise, then, we cannot assume that it is a contingent matter whether or not I possess a body just because it is true that, in the epistemic sense, I might or might not possess a body. Let me pass on now to the indivisibility argument. This may be reconstructed as follows. (6) I contain no parts into which I am divisible. (7) My body is composed of parts. Therefore, (5) I am distinct from my body. I take it that (7) is uncontentiously true. Premise (6), however, may appear to be straightforwardly question-begging, since it simply denies that I possess a property that (7) uncontentiously attributes to my body—namely, the property of being a composite entity—and hence, it may be said, already presumes the truth of the conclusion, (5), that I and my body are distinct. Certainly, if the indivisibility argument is to acquire any persuasive force, an independent reason needs to be advanced in support of premise (6). My own view, I should say, is that premise (6) is indeed true, but that the most plausible argument for its truth requires (5) as a premise, so that (6) cannot without circularity be appealed to in an argument for the truth of (5). If (5) is to be successfully argued for, then, we need to look elsewhere than to the indivisibility argument. I shall suggest an alternative shortly.

3. AN ARGUMENT FOR THE SIMPLICITY OF THE SELF As for my chief reason for thinking (6) to be true—that is, for holding the self to be a simple or non-composite entity—it is that I consider the following argument (and note that its first premise includes (5) as a conjunct) to be

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not just valid but sound (for a fuller account, see Lowe 2001). (8) I am not identical with my body nor with any part of it. (9) If I am composed of parts, then all of those parts must be parts of my body. (10) Anything that is wholly composed of parts of my body must either itself be a part of my body or else be identical with my body as whole. Hence, (11) I am a simple entity, not composed of any parts— which is another way of expressing (6). The crucial premise here is, of course, (8), to which I shall return in a moment. As for premise (9), this should be uncontentious in the context of a debate between substance dualism and its physicalist opponents, since those opponents will naturally agree with (9), holding as they do that I am identical with my body or some part of it, such as my brain. Premise (10) seems equally uncontentious—but more of that in a moment. I should acknowledge, however, that not all substance dualists will be happy to assert premise (9). Some, for instance, adopt the following view of the self: they hold that I am distinct from—not identical with—my body, but am composed of it and another, immaterial entity, my soul. On this view, I am a body–soul composite (for discussion and criticism, see Olson 2001 and Kim 2001). Such a composite is still a “substance”—that is, an individual object or property-bearer—but one which, in violation of premise (9), contains both parts of my body and something else, my soul, as parts. Indeed, Descartes himself sometimes writes as if he endorses this view. I can only say that I find it implausible and unattractive myself. Another kind of substance dualist will reject premise (10), holding that I am wholly composed of parts of my body and yet am not identical with any part of it nor with my body as a whole. This kind of substance dualist sees the relation between me and my body as being analogous to that between a bronze statue and the lump of bronze of which it is made. On this view, I am constituted by, but not identical with, my body (see especially Baker 2000). And, indeed, the example of the bronze statue may be seen as posing a threat to a generalized version of (10). For doesn’t it show that it simply isn’t true that anything that is wholly composed of parts of an object x must either itself be a part of x or else be identical with x as a whole? For the bronze statue, it may be said, is wholly composed of parts of the lump of bronze and yet is neither itself a part of the lump of bronze nor identical with the lump of bronze as a whole. However, here a great deal turns on the question of how, precisely, we are to understand the assertion that the bronze statue is “wholly composed of parts of the lump of bronze.” If the assertion is taken to mean that we can decompose the statue into parts all of which, without remainder, were parts of the lump of bronze, then it is certainly true. For we can decompose the statue into bronze particles, all of which were parts of the lump. But if, instead, the assertion is taken to mean that all of the parts of the statue are also parts of the lump of bronze—which is, mutatis mutandis, the interpretation that I was assuming in proposing premise (10)—then it is far from evident that it is true. For example: the head of

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the statue—assuming it to be a statue of a man—is a part of the statue and yet is not, plausibly, a part of the lump of bronze (see further Lowe 2001). However, is it not open to the constitution theorist to agree, now, with premise (10), interpreted in the manner I intend and instead reject premise (9), although not for the same reason that this was rejected by the proponent of the body–soul composite theory? Cannot the constitution theorist say that, just as the statue has parts, such as its head, that are not parts of the lump of bronze, so I have parts that are not parts of my body—but not because I have any immaterial part or parts, any more than the statue has? In principle, I agree, the constitution theorist could say this. However, I simply don’t see what these “additional” parts could at all plausibly be. The reason why the statue has parts that are not parts of the lump of bronze is that it has parts—such as its head—that are, like the statue, constituted by, but not identical with, a portion of bronze. If, analogously, I were to have parts that are not parts of my body, they would have to be parts that are constituted by, but not identical with, parts of my body—just as, according to the constitution theorist, I am constituted by my body as a whole. But there are, surely, no such parts of me—no parts of me that are related to parts of my body in the way that I am related to my body as a whole. As a self or subject of experience, I do not, for example, have lesser or subordinate selves or subjects as parts of me, each of them associated with different parts of my body—as though I were a kind of collective or corporate self, on the model of a company or club (for more on the latter notion, see Scruton 1989). At least, it certainly doesn’t seem that way to me!

4. TWO NEW ARGUMENTS FOR (NON-CARTESIAN) SUBSTANCE DUALISM Now I need to return to unfinished business—the search for a plausible argument in favour of the main claim of substance dualism, that I am not identical with my body nor with any part of it. This was premise (8) of my argument for the simplicity of the self. We have seen that neither the conceivability argument nor the indivisibility argument is satisfactory for the present purpose. I believe, however, that a much more compelling consideration in favour of (8) is this: (12) My identity-conditions differ from those of my body or any part of it. Entities possessing different identity-conditions cannot be identified with one another, on pain of contradiction (see further Lowe 1989, ch. 4). But what are “identity-conditions”? Speaking quite generally, the identity-conditions of entities of a kind K are the conditions whose satisfaction is necessary and sufficient for an entity x of kind K and an entity y of kind K to be identical, that is, for them to be one and the same K. Thus, for example, the identity-conditions of sets are these: a set x and a

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set y are one and the same set if and only if x and y have exactly the same members. In the case of things that persist through time, their identityconditions will also provide their persistence-conditions, since a thing persists through time just in case that same thing exists at every succeeding moment during some interval of time. Now, there are, of course, notorious difficulties attaching to the question of personal identity, and particularly to the question of what conditions are necessary and sufficient for the identity of the self over time. However, even without being able to settle this question, we may well be in a position to determine that the identity-conditions of the self, whatever they may be, are different from those of the body or any part of it, such as the brain. Here is one sort of consideration that seems quite compelling in this respect. We know already that parts of the human body can be replaced by artificial substitutes which serve the same function more or less equally well, as far as the person possessing that body is concerned. For example, a “bionic” arm can replace a natural arm and serve the person who owns it pretty much as well as the original did. And, indeed, it seems perfectly possible in principle that every part of a person’s biological body should, bit by bit, be replaced in this fashion, with nerve cells gradually being replaced by, say, electronic circuits mimicking their natural function (compare Lowe 1989, 120, and Baker 2000, 122-3). If such a procedure were carried out completely, as it seems it could be, the person whose biological body had been replaced by an entirely artificial one would, very plausibly, survive the procedure and so still exist at the end of it. And yet, clearly, neither that biological body nor any part of it would have survived and still exist. If correct, this shows that the persistence-conditions of human persons are different from those of their biological bodies and their various parts, such as their biological brains, and hence that such persons—we ourselves—are not identical with those bodies nor with any of their parts. In short, it establishes the truth of (8), the main claim of substance dualism. Notice, however, that the foregoing argument for substance dualism—the replacement argument, as we may call it—while it serves the purposes of nonCartesian substance dualism well enough, is not sufficient to establish the truth of Cartesian substance dualism, since the latter maintains that the self possesses only mental properties, not any physical ones. For the replacement argument doesn’t show that the self could survive in a completely disembodied state and hence doesn’t show that the self might exist even in circumstances in which no physical properties whatever, such as shape or mass, could possibly be attributed to it. The conceivability argument does purport to show this, of course, but has been found wanting in persuasive force. As for the indivisibility argument, it, like the replacement argument, cannot be used specifically in support of Cartesian dualism, even setting aside the other difficulties that attach to it—for its conclusion is only that I

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am distinct from my body, not that I lack, or could lack, any physical properties whatever. Although, as we have seen, the indivisibility argument is unsatisfactory, there is another argument that is in some ways reminiscent of it but which, I think, deserves considerably more respect. I also think that it is even more compelling than the replacement argument, since it does not depend upon speculations which at present, it might be said, belong only to the realm of science fiction. I shall call this the unity argument—the unity in question being the unity of the self as the unique subject of all and only its own experiences. The first premise of the unity argument is (13) I am the subject of all and only my own mental states—which is surely a self-evident truth. The second premise is (14) Neither my body as a whole nor any part of it could be the subject of all and only my own mental states. The conclusion is, once again, (8) I am not identical with my body nor with any part of it. Of course, (14) is the crucial premise, so let us see how it might be defended. First, then, observe that my body as a whole does not need to exist in order for me to have each and every one of the mental states that I do in fact have. If, for instance, I were to lack the tip of one of my little fingers, I might as a consequence lack some of the mental states that I do in fact have, but surely not all of them. I might perhaps lack a certain mildly painful sensation in the fingertip—a sensation that I do in fact have—but many of my other mental states could surely be exactly the same as they actually are, such as the thoughts that I am in fact having in composing this essay. Indeed, I could still even have that sensation “in my finger tip,” because the phenomenon of “phantom” pain is a wellattested one. However, I venture to affirm that no entity can qualify as the subject of certain mental states if those mental states could exist in the absence of that entity. After all, I certainly qualify as the subject of my mental states, as (13) asserts, but for that very reason those mental states could not exist in my absence. Mental states must always have a subject—some being whose mental states they are—and the mental states that in fact belong to one subject could not have belonged to another, let alone to no subject at all (see further Strawson 1959, ch. 3, and Lowe 1996, ch. 2). But, as we have just seen, many and quite possibly all of my own mental states could exist even if my body as a whole were not to exist—that is to say, even if certain parts that my body actually possesses were not to exist. This, I suggest, indicates that my body as a whole cannot qualify as the subject of all and only my own mental states and so cannot be identified with me. Now, many physicalists may agree with my reasoning so far, but draw the conclusion that, rather than being identical with my body as a whole, I am identical with some part of it, the most obvious candidate being my brain. However, it is easy to see that the foregoing reasoning can now just be repeated, replacing “my body as a whole” by “my brain as a whole” throughout. For it seems clear that, although I may well need to have a brain in order to

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have mental states, neither my brain as a whole nor any distinguished part of it is such that it needs to exist in order for me to have each and every one of the mental states that I do in fact have. Indeed, even if each and every one of my mental states depends upon some part of my brain, it by no means follows, of course, that there is some part of my brain upon which each and every one of my mental states depends. (To suppose that this does follow would be to commit a so-called “quantifier-shift” fallacy.) And yet I, being the subject of all and only my own mental states, am such that each and every one of those mental states does depend upon me. Hence, we may conclude, neither my brain as a whole nor any part of it can qualify as the subject of all and only my mental states and so be identical with me. Putting together the two stages of this train of reasoning, we may thus infer that (14) is true and from that and (13) infer the truth of (8), the main claim of substance dualism. However, here it may be objected that the foregoing defence of premise (14) depends upon an illicit assumption, namely, that if my body as a whole were to lack a certain part, such as the tip of one of my little fingers, then it—my body as a whole—would not exist. This assumption is unwarranted because it presupposes, questionably, that every part of my body is an essential part of it, without which it could not exist. As it stands, this may be a fair objection—although it should be acknowledged there are some philosophers who do hold that every part of a composite object is essential to it (see, for example, Chisholm 1976, ch. 3). However, I think that the reasoning in favour of premise (14) can in fact be formulated slightly differently, so as to make it independent of the truth of this assumption. The initial insight still seems to be perfectly correct—that, as I put it, my body as a whole does not need to exist in order for me to have each and every one of the mental states that I do in fact have. Thus, to repeat, the thoughts that I am having in composing this essay plausibly do not depend upon my body including as a part the tip of one of my little fingers. Call these thoughts T. Consider, then, that object which consists of my body as a whole minus that fingertip. Call this object O and call my body as a whole B. (It should be conceded here that there are some philosophers who would deny that any such object as O exists (see, for example, van Inwagen 1981)—but that is, to say the least, a controversial claim.) Suppose, now, that it is proposed that I am identical with B, and hence that B is the subject of the thoughts T. Then we can ask: on what grounds can B be regarded as the subject of T in preference to O, given that T do not depend upon B’s including the part—the fingertip—that O does not include? Isn’t the material difference between B and O simply irrelevant to the case that can be made in favour of either of them qualifying as the subject of T? But in that case, we must either say that both B and O are subjects of T, or else that neither of them are. We cannot say the former, however, because B and O are numerically distinct objects, whereas the thoughts T have just one subject—myself. We may conclude,

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hence, that neither B nor O is a subject of T and thus that I, who am the subject of T, am identical with neither of them. This sort of reasoning can then be repeated, as before, with respect to any specific part of B, such as my brain. However we exactly formulate the defence of premise (14), the basic point of the unity argument, as I call it, is that my mental states do not all depend on my body as a whole or on any part of it in the unified way in which they all depend upon me as their subject. This point, it seems to me, is a good one. Indeed, between them, the unity argument and the replacement argument provide, I think, very compelling grounds for belief in the truth of non-Cartesian substance dualism.

5. THE CAUSAL CLOSURE ARGUMENT AGAINST INTERACTIVE DUALISM Now, however, we need to explore certain causal considerations that inevitably arise in the debate between dualism and its opponents. For dualism—whether we are talking about substance dualism or property dualism—is traditionally divisible into interactionist, epiphenomenalist, and parallelist varities. Perhaps the most powerful argument against interactive dualism is the so-called causal closure argument (for further background, see Lowe 2000a, ch. 2). By interactive dualism I mean the doctrine that mental events or states are not only distinct from physical events or states, but are also included amongst the causes and effects of physical events or states. Of course, the causal closure argument can have no force against either epiphenomenalist or non-interactive parallelist dualism, but since even the first and more credible of these positions has relatively few modern advocates, I shall not consider them here (but see, for example, Robinson 2004). In any case, even those who do support them would presumably concede that they would prefer to endorse interactive dualism if they thought that it could meet the physicalists’ objections, so let us concentrate on seeing how those objections can indeed be met, focusing on the causal closure argument. The key premise of the causal closure argument against interactive dualism is the principle of the causal closure of the physical domain. This principle has received a number of different formulations—some of which are really too weak for the physicalist’s purposes (see further Lowe 2000b)—but the relatively strong version of the principle that I shall chiefly consider here is this: (15) No chain of event-causation can lead backwards from a purely physical effect to antecedent causes some of which are non-physical in character (cf. Kim 1993). It may be objected on behalf of interactive dualism that (15) is simply question-begging, because it rules out by fiat the possibility of there being non-physical mental causes of some physical effects. However, as we shall

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see, (15) does not in fact rule out this possibility. Dialectically, it is in the dualist’s interests to concede to the physicalist a version of the causal closure principle that is as strong as possible—provided that it still falls short of entailing the falsehood of interactive dualism—because if the causal closure argument in its strongest non-question-begging form can be convincingly defeated, the physicalist will be left with no effective reply. Weaker versions of the causal closure principle can, of course, be countered by interactive dualists relatively easily, but tend to be countered by them in implausible ways which leave the physicalist with a telling response. To illustrate the latter point, consider the following widely advocated version of the causal closure principle: (16) Every physical effect of a mental cause has a sufficient physical cause. An interactive dualist may accommodate (16) by, for example, espousing the doctrine of interactive parallelism, which maintains that there is a one-to-one correlation between the mental and physical causes of any physical event that has a mental cause, such that both the mental and the physical causes of any such event are sufficient causes of it (for an exposition and defence, see Meixner 2004, ch. 8). (By a sufficient cause of a given event, I mean an event or conjunction of events that causally necessitates the event in question.) The physicalist may object that this doctrine has the highly implausible implication that every physical effect of a mental cause is causally overdetermined by that mental cause and the physical cause that is, suppposedly, one-to-one correlated with it. To this the interactive parallelist may reply that such causal overdetermination is no mere accident but, rather, the upshot of psycho-physical laws, so that the fact that it occurs is a matter of nomic or natural necessity. However, it may nonetheless appear surprising to the impartial bystander that psycho-physical laws of this character should be thought to govern the causal interactions of mind and body, when so many other possibilities are compatible with interactive dualism. The non-interactive parallelist has, it seems, much better reason to suppose that there is a one-to-one correlation between the apparent mental causes of physical events and their actual physical causes, because (traditionally, at least) he sees this as being the upshot of a divinely instituted pre-established harmony between the mental and physical domains. Equally, the physicalist has a perfectly good reason to suppose that there is a one-to-one correlation between the mental and physical causes of physical events, because he identifies those causes, and identity is a one-toone relation par excellence. But the interactive parallelist, it seems, must simply regard it as a brute fact that psycho-physical laws sustain such a one-toone correlation—a fact that is all the more remarkable because so many other arrangements are consistent with the truth of interactive dualism. Neutral parties to the debate could be forgiven for suspecting that the interactive parallelist postulates the one-to-one correlation of mental and physical causes simply in mimicry of the physicalist’s position, with a view

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to denying the physicalist recourse to any empirical evidence of a causal character that could discriminate between the two positions. For wherever the physicalist claims to find evidence of one and the same cause of a certain physical effect—a single cause that is both mental and physical—the interactive parallelist will be able to reply that we in fact have two distinct but correlated causes, one of them mental and the other physical. Let us now consider a version of the causal closure argument against interactive dualism that appeals to the very strong formulation of the causal closure principle embodied in premise (15)—that no chain of event-causation can lead backwards from a purely physical effect to antecedent causes some of which are non-physical in character. Two additional premises are needed. First, (17) Some purely physical effects have mental causes, which the interactive dualist accepts as true, of course. Second, (18) Any cause of a purely physical effect must belong to a chain of event-causation that leads backwards from that effect. These three premises entail the conclusion (19) All of the mental causes of purely physical effects are themselves physical in character, which contradicts the defining thesis of interactive dualism. My defence of interactive dualism will rest upon a challenge to premise (18). Moreover, it will endorse a version of interactive dualism which combines it with the sort of non-Cartesian substance dualism defended earlier.

6. A NON-CARTESIAN DUALIST’S RESPONSE TO THE CAUSAL CLOSURE ARGUMENT What seems plausible is that if we were to trace the purely bodily causes of any bodily event, such as the movement of my arm on a given occasion, backwards indefinitely far, we would find that those causes ramify, like the branches of a tree, into a complex maze of antecedent events in my brain and nervous system—these neural events being widely distributed across large areas of those parts of my body and having no single focus anywhere, the causal chains to which they belong possessing, moreover, no distinct beginnings (see further Lowe 1996, ch. 3). See figure 7.1 below. And yet, my

Figure 7.1.

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mental act of decision or choice to move my arm seems, from an introspective point of view, to be a singular and unitary occurrence which somehow initiated my action of raising my arm. How, if at all, can we reconcile these two apparent facts? It seems impossible to identify my act of choice with any neural event, nor even with any combination of neural events, because it and they seem to have such different causal features or profiles. The act of choice seems to be unitary and to have, all by itself, an “initiating” role, whereas the neural events seem to be thoroughly disunified and merely to contribute in different ways to a host of different ongoing causal chains, many of which lead independently of one another to the eventual armmovement. (For a response to doubts about the “initiating” role of acts of choice, founded on the well-known experiments of Benjamin Libet (1985), see Lowe forthcoming.) Non-Cartesian substance dualism—henceforth, NCSD—can, I believe, enable us to see how both of these causal perspectives on physical action can be correct, without one being reducible to the other and without any sort of rivalry between the two. The act of choice is attributable to the person or self—to me, in this case—whereas the neural events are attributable to parts of the body: and self and body are distinct things, even if they are not separable things. Moreover, the act of choice causally explains the bodily movement—the movement of my arm—in a different way from the way in which the neural events explain it. The neural events explain why the arm moved in the particular way that it did—at such-and-such a speed and in such-andsuch a direction. By contrast, the act of choice explains why a movement of that general kind—say, a rising of my arm—occurred around about the time that it did (compare Lowe 1999). It did so because shortly beforehand I decided to raise my arm. My decision certainly did not determine the precise speed, direction and timing of my arm’s movement, only that a movement of that general sort would occur. The difference between the two kinds of causal explanation reveals itself clearly when one contemplates their respective counterfactual implications. If I had not decided to raise my arm, there wouldn’t have been an arm-movement of that kind at all—my arm would either have remained at rest or, if I had decided to make another movement instead, it would have moved in a quite different way. It doesn’t seem, however, that one can isolate any neural event, or any set of neural events, whose non-occurrence would have had exactly the same consequences as the non-occurrence of my decision. Rather, the most that one can say is that if this or that neural event, or set of neural events, had not occurred, the arm-movement might have proceeded in a somewhat different manner—more jerkily, perhaps, or more quickly—not that my arm would have remained at rest, or would instead have moved in a quite different kind of way. (In other words, in the “closest” possible worlds in which the relevant neural events do not occur, it’s not the case that an arm-movement of the

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given kind does not occur at all, because in those worlds other neural events occur which give rise to a similar arm-movement. They do so because in all of these worlds the agent has the same intention to move his arm in a certain way and succeeds in doing so, albeit in a slightly different way in different worlds.) Mental causation is intentional causation—it is the causation of an intended effect of a certain kind. Bodily causation is not like this. Both kinds of causation need to be invoked to give a full explanation of human action, and NCSD seems best equipped to accommodate this fact. The very logic of intentional causation differs from the logic of bodily causation. Intentional causation is fact-causation, while bodily causation is event-causation (cf. Lowe 1996, 67–68 and, for the distinction between fact-causation and eventcausation, see Bennett 1988, 21). That is to say, a choice or decision to move one’s body in a certain way is causally responsible for the fact that a bodily movement of a certain kind occurs, whereas a neural event, or set of neural events, is causally responsible for a particular bodily movement, which is a particular event. Merely to know why a particular event of a certain kind occurred is not necessarily yet to know why an event of that kind occurred, as opposed to an event of some other kind. Intentional causation can provide the latter type of explanation in cases in which bodily causation cannot. More specifically: an event, such as a particular bodily movement, which may appear to be merely coincidental from a purely physiological point of view—inasmuch as it is the upshot of a host of independent neural events preceding it—will by no means appear to be merely coincidental from an intentional point of view, since it was an event of a kind that the agent intended to produce. It may be asked: But what about the causes of my act of decision or choice? Are these bodily, or mental, or both? My own opinion is that an act of decision or choice is free, in the “libertarian” sense—that is to say, it is uncaused (see further Lowe 2003a). This is not to say that decisions are simply inexplicable, only that they demand explanations of a non-causal sort. Decisions are explicable in terms of reasons, not causes. That is to say, if we want to know why an agent decided to act as he did, we need to inquire into the reasons in the light of which he chose so to act. Since decisions are, according to NCSD, attributable to the self and not to the body or any part of it, there is no implication here that any bodily event is uncaused. It may now be wondered: how is it really possible for mental acts of decision to explain anything in the physical domain, if that domain is causally closed, in the sense defined earlier? Let us recall how, precisely, we defined the causal closure of the physical domain. According to the principle of physical causal closure, I said, no chain of event-causation can lead backwards from a purely physical effect to antecedent causes some of which are non-physical in character. This was premise (15) above. But intentional causation on the

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NCSD model, as I have described it, does not violate the principle of physical causal closure, since it does not postulate that mental acts of decision or choice are events mediating between bodily events in chains of event-causation leading to purely physical effects: it does not postulate that there are “gaps” in chains of physical causation that are “filled” by mental events (compare Lowe 1996, 82). Thus, it is consistent with premise (15) of the causal closure argument and avoids the conclusion of that argument by repudiating, instead, premise (18). On the NCSD model, a decision can explain the fact that a bodily movement of a certain kind occurred on a given occasion, but not the particular movement that occurred. Even so, it may be protested, if physical causation is deterministic, then there is really no scope for intentional causation on the NCSD model to explain anything physical, because the relevant counterfactuals will all be false. It will be false, for instance, to say that if I had not decided to raise my arm, a rising of my arm would not have occurred: for precisely the same bodily movement would still have occurred, caused by the same physical events that actually caused it. Maybe so. But we know that physical causation is not in fact deterministic, so the objection is an idle one. The NCSD model of intentional causation may nonetheless seem puzzling to many philosophers. I suggest that that is because they are still in the grip of an unduly simple conception of causation—one which admits only of the causation of one event by one or more antecedent events belonging to one or more chains of causation which stretch back indefinitely far in time. Since this is the only sort of causation recognized by the physical sciences, intentional causation on the NCSD model is bound to be invisible from the perspective of such a science (compare Lowe 2003b). To a physicalist, this invisibility will seem like a reason to dismiss the notion of intentional causation as spurious, because “non-scientific.” To more broadminded philosophers, I hope, it will seem like a reason to discern no conflict between explanation in the physical sciences and another more humanistic way of explaining our intentional actions.

BIBLIOGRAPHY Baker, L.R. 2000. Persons and Bodies: A Constitution View. Cambridge: Cambridge University Press. Bennett, J. 1988. Events and their Names. Oxford: Clarendon Press. Chisholm, R.M. 1976. Person and Object: A Metaphysical Study. London: George Allen and Unwin. Corcoran, K., ed. 2001. Soul, Body, and Survival: Essays on the Metaphysics of Human Persons. Ithaca: Cornell University Press. Crane, T., and Mellor, D.H. 1990. “There is No Question of Physicalism.” Mind 99: 185–206.

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Descartes, R. 1984. Meditations on First Philosophy. In The Philosophical Writings of Descartes, edited by J. Cottingham, R. Stoothoof and D. Murdoch. Cambridge: Cambridge University Press. Foster, J. 1991. The Immaterial Self: A Defence of the Cartesian Dualist Conception of the Mind. London and New York: Routledge. Gendler, T.S., and Hawthorne, J., eds. 2002. Conceivability and Possibility. Oxford: Clarendon Press. Kim, J. 1980. “Events as Property Exemplifications.” In Action Theory, edited by M. Brand and D. Walton, 159–77. Dordrecht: D. Reidel. ———. 1993. “The Non-Reductivist’s Troubles with Mental Causation.” In Mental Causation, edited by J. Heil and A. Mele, 189–210. Oxford: Clarendon Press. ———. 2001. “Lonely Souls: Causality and Substance Dualism.” In Corcoran, ed., 30–43. 2001. Libet, B. 1985. “Unconscious Cerebral Initiative and the Role of Conscious Will in Voluntary Action.” Behavioral and Brain Sciences 8: 529–66. Lowe, E.J. 1989. Kinds of Being: A Study of Individuation, Identity and the Logic of Sortal Terms. Oxford: Blackwell. ———. 1996. Subjects of Experience. Cambridge: Cambridge University Press. ———. 1999. “Self, Agency, and Mental Causation.” Journal of Consciousness Studies 6: 225–39. ———. 2000a. An Introduction to the Philosophy of Mind. Cambridge: Cambridge University Press. ———. 2000b. “Causal Closure Principles and Emergentism.” Philosophy 75: 571–85. ———. 2001. “Identity, Composition, and the Simplicity of the Self.” In Corcoran, ed., 139–58. 2001. ———. 2003a. “Personal Agency.” In Minds and Persons, edited by A. O’Hear, 211–27. Cambridge: Cambridge University Press. ———. 2003b. “Physical Causal Closure and the Invisibility of Mental Causation.” In Physicalism and Mental Causation: The Metaphysics of Mind and Action, edited by S. Walter and H.-D. Heckmann, 137–54. Exeter: Imprint Academic. ———. forthcoming. “Could Volitions be Epiphenomenal?” Meixner, U. 2004. The Two Sides of Being: A Reassessment of Psycho-Physical Dualism. Paderborn: mentis. Olson, E.T. 2001. “A Compound of Two Substances.” In Corcoran, ed., 73–88. 2001. Robinson, W.S. 2004. Understanding Phenomenal Consciousness. Cambridge: Cambridge University Press. Scruton, R. 1989. “Corporate Persons.” Proceedings of the Aristotelian Society Supplementary Volume 63: 239–66. Strawson, P.F. 1959. Individuals: An Essay in Descriptive Metaphysics. London: Methuen. Swinburne, R. 1986. The Evolution of the Soul. Oxford: Clarendon Press. van Inwagen, P. 1981. “The Doctrine of Arbitrary Undetached Parts.” Pacific Philosophical Quarterly 62: 123–37.

8 Emergent Dualism Antonella Corradini

In this chapter I shall seek to show that emergentism in the philosophy of mind should be understood as a dualistic position. This claim will no doubt be surprising to many readers, since British Emergentists are known to have been in favour of ontological monism. Thus, my first step consists in examining what the British Emergentists’ monism amounts to.

1. MONISM IN BRITISH EMERGENTISM Emergentism is a philosophical movement that was initiated in Great Britain in the first quarter of the twentieth century by thinkers such as S. Alexander (1920), C. Lloyd Morgan (1923), C.D. Broad (1925) and others.1 It has been a multifarious current of thought from its very origins. Some of the differences in the concept of emergence that we can detect in contemporary debates were mostly already present in the philosophical discussion at the beginning of the twentieth century. Among the distinctions which are relevant to the topic under scrutiny, perhaps the most important to mention is the distinction between emergence as an epistemological and as an ontological concept. Such a difference can be traced back to the difference between the non-predictability and the non-deducibility of properties in emergent systems. By saying that a property of an emergent system, for example liquidity, is non-deducible, we mean that the belonging of that property to the emergent system cannot be logically deduced from the laws governing lowerlevel components, that is to say, the atomic microstructure. This implies that the theory which describes the properties at the lower level is incomplete as 185

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regards the properties occurring at the higher level. This definition of nondeducibility allows us to understand the relationship between nondeducibility and non-predictability. The fact that lower-level laws are insufficient for explaining the existence of emergent properties implies that even the complete knowledge of such laws, together with knowledge of the initial conditions, is not sufficient for predicting the occurrence of higher-level properties. As a consequence, non-deducibility is a sufficient condition of non-predictability. However, non-predictability is not in principle a sufficient condition of non-deducibility. In fact, the non-predictability of the alleged emergent property might depend on the fact that the theory from which this property is deducible exists, but is unknown. In this case nonpredictability goes together with deducibility. Predictability is therefore deducibility from a theory which is known, whereas deducibility is such from any existing theory, either known or unknown. This means that an unpredictable property is only epistemically emergent, while an undeducible property is ontologically emergent (and also epistemically as a consequence of its ontological emergence). On the contemporary philosophical scene, both epistemological and ontological emergence has been championed, and this is a sign of the different strenghts of commitment that philosophers demonstrate to the emergentistic doctrine.2 In an analogous way, some of the British Emergentists (such as Alexander 1920) seem to have leant towards epistemological emergence, while others (like Broad 1925) seem likely to have favoured its ontological variant. I shall try to underpin my interpretation of the mentioned authors and to show how their conception of emergence is related to their stance towards monism.3 A common feature of all British Emergentists is the attribution of novelty to emergent phenomena. Speaking of the “emergent evolution,” for example, Lloyd Morgan affirms that “stress is laid on this incoming of the new. Salient examples are afforded in the advent of life, in the advent of mind, and in the advent of reflective thought. But in the physical world emergence is no less exemplified in the advent of each new kind of atom, and of each new kind of molecule. It is beyond the wit of man to number the instances of emergence. But if nothing new emerge—if there be only regrouping of pre-existing events and nothing more—then there is no emergent evolution” (1923, 1–2). Novelty pertains therefore to every domain of reality and consists in the occurring of a qualitative change which causes new properties of things to arise. Alexander is as eager as Lloyd Morgan to emphasize the character of novelty possessed by emergent phenomena. “The emergence of a new quality from any level of existence means that at that level there comes into being a certain constellation or collocation of the motions belonging to that level, and possessing the quality appropriate to it, and this collocation possesses a new quality distinctive of the higher complex”

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(1920, Bk iii, ch. ii B, 45). It may then be surprising to read what Alexander writes some pages after: “Each new type of existence when it emerges is expressible completely or without residue in terms of the lower stage, and therefore indirectly in terms of all lower stages; mind in terms of living process, life in terms of matter with its movements, matter itself in terms of motion” (Bk iii, ch. ii. B, 67).4 It seems almost an oxymoron to speak of the same entity at the same time and in the same respect both in terms of emergence and of reduction. But this paradoxicality is going to disappear as soon as we interpret Alexander’s allegiance to emergence in terms of epistemological emergence. This move is not just an ad hoc strategy to avoid detecting contradiction in Alexander’s thought. The fact that it is not so can be inferred from this quotation: “It is thus a certain constellation . . . of physico-chemical processes which behaves vitally, and the presence of such constellations which makes the structure to which they belong an organism. To call it organism is but to mark the fact that its behaviour . . . is, owing to the constellation, of a character different from those which physics and chemistry are ordinarily concerned with. . . . At the same time, this new method of behaviour is also physico-chemical and may be exhibited without remainder in physico-chemical terms, provided only the nature of the constellation is known. . . . Until that constellation is known, what is especially vital may elude the piecemal application of the methods of physics and chemistry” (Bk iii, ch. ii. B, 62, my italics). From this passage it should be apparent that on Alexander’s construal life phenomena can be reduced to physico-chemical ones under the condition that the laws ruling their behaviour are known. Thus, the non-reducibility of life phenomena to the physico-chemical ones is not due to their ontological emergence, but rather to the lack of knowledge of the “constellations” which characterize them. As, according to Alexander, this holds not just for life, but for all emergent levels, his thesis seems to me a crystal-clear instance of epistemological emergence. If my interpretation is right, then it is no wonder that Alexander was a monist. He was so because in his view emergent phenomena do not affect the structure of reality, which is ultimately ruled by the fundamental laws of physics and mathematics. However, what can be said about monism combined with ontological emergence? To go deeper into this question I shall pay attention to Broad’s emergentism, as a putative representative of the ontological kind of emergence. Broad’s main theoretical concern was the epistemological status of “special sciences” such as chemistry, biology, psychology, and their relations to physics. Two main answers to this question were offered at his time: mechanism and vitalism. However, in Broad’s view they were both unsatisfactory. As far as mechanism is concerned, one of its advantages was its introducing “a unity and tidiness into the world which appeals very strongly to our aesthetic interests . . .” (Broad 1925, 76). Such advantages, however, were ob-

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tained at the price of ignoring many aspects of the external world, which cannot be explained through mechanistic categories. The mechanistic ideal “cannot be the whole truth about the external world, since it cannot deal with the existence or the appearance of “secondary qualities” (76–77). The only way to account for secondary qualities is to resort to emergent laws and, what’s more, to a particular sort of emergent laws, the “trans-physical” ones (52). These are emergent laws which attest the ultimate character of secondary qualities, as irreducible to physical properties. Besides the transphysical laws Broad also aknowledges “intra-physical laws,” which are further subdivided into “trans-ordinal laws” and “intra-ordinal laws.” While the former connect phenomena belonging to different levels of complexity, the latter deal with phenomena belonging to the same level of complexity. Since trans-ordinal laws are also emergent laws, the question arises what is the difference between emergent laws which are trans-physical and emergent laws which are intra-physical but trans-ordinal. Broad traces back the difference to the dissimilar epistemological status of the two kinds of laws. Trans-physical laws, in fact, are necessarily emergent laws. Also a mathematical archangel who knows everything about the microstructure underlying the qualitative aspects of the macrostructure would be unable to predict the latter. Trans-ordinal laws, on the contrary, are empirical hypotheses, whose truth or falsity can be stated only a posteriori, after the emergent phenomena have or have not manifested themselves. In this case, the emergence of the properties occurring in the trans-ordinal laws is only presumptive, for emergence could depend on the limits of our knowledge. “Within the physical realm it always remains logically possible that the appearance of emergent laws is due to our imperfect knowledge of microscopic structure or to our mathematical incompetence. But this method of avoiding emergent laws is not logically possible for trans-physical processes” (81). While the phenomena described by the trans-physical laws are emergent in an absolute way, Broad allows that sometimes emergence in the physical realm can be attributed to our epistemic limits. This admission, however, does not entitle us to classify Broad among the supporters of epistemological emergentism. Indeed, if the attempts to find an explanation of emergent phenomena through a lower-level theory fail systematically, this represents a very strong reason for asserting that such phenomena are really emergent. Broad seems therefore to be an ontological emergentist, who furthermore makes a distinction between an absolute, a priori emergence and a hypothetical, a posteriori emergence. I shall come back to this distinction soon, but before doing that I need to say something about Broad’s monism. Broad is no doubt a monist. We can infer it, for example, from a concession he makes to mechanism: “We might, if we liked, keep the view that there is only one fundamental kind of stuff” (77). As a matter of fact, the qualitative changes that occur at the emergent

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levels are not due to a change of stuff, but to a change of the correlations among the particles which dynamically constitute the one fundamental stuff. At the emergent levels a structural change takes place, as we can see from this quotation: “Put in abstract terms the emergent theory asserts that there are certain wholes, composed (say) of constituents A, B, and C in a relation R to each other; that all wholes composed of constituents of the same kind as A, B, and C in relations of the same kind as R have certain characteristic properties; that A, B, and C are capable of occurring in other kinds of complex where the relation is not of the same kind as R; and that the characteristic properties of the whole R(A,B,C) cannot, even in theory, be deduced from the most complete knowledge of the properties of A, B, and C in isolation or in other wholes which are not of the form R(A,B,C). The mechanistic theory rejects the last clause of this assertion” (61). Thus, emergentism and mechanism are not divided on whether to accept monism or not, but on whether to understand it in reductionistic or anti-reductionistic terms. Broad himself names his view “Emergent Materialism.” As the best among seventeen competing views in the philosophy of mind, emergent materialism is characterized by considering materiality as a differentiating attribute and mentality as an emergent characteristic (610). Broad explains what he means by “differentiating attribute” in the Introduction to his book. While the “Substantial Attributes” are the essential attributes of every substance (such as duration and capability of standing in causal relations), the “Differentiating Attributes” are the special attributes that every substance must have besides the essential ones and that make it a substance of a certain kind, for example a material or a mental substance (22). Still different from the just mentioned attributes are the non-differentiating attributes, some of which are “Emergent Attributes” and others “Reducible Attributes” (607). Differentiating attributes express basic features of substances, whereas non-differentiating emergent or reducible attributes describe properties of substances that somehow depend on the former. The seventeen positions discussed by Broad in Chapter XIV of his 1925 work derive from diverse combinations among differentiating attributes and emergent or reducible non-differentiating attributes. Lack of space and fear of wearing the reader advise me to limit my examination to emergent materialism in its relations to reductive materialism and to dualism. The compendium on page 623 of Broad (1925) helps us to understand what divides Broad’s emergent materialism from reductive materialism, according to which materiality is a differentiating attribute and mentality is a reducible characteristic. For the reductive materialist or behaviourist “being a mind” is nothing but being a body “making certain overt movements or undergoing certain internal physical changes” (612), which is too radical a thesis in Broad’s view.5 Emergent materialism, instead, limits itself to only denying that the mental characteristic and the physical characteristic belong

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to different events or substances. “He (the emergent materialist) may wish to maintain only that there is one event which has the two characteristics of being an awareness of a red patch and of being a molecular movement of a certain kind.” What makes emergentism a form of materialism, however, Broad enlarges on some lines below, that is to say, that the mental properties of the material events are “completely determined by the material properties which these events also have.” The conviction that mentality is rooted in materiality is at the origins of Broad’s rejection of dualism, which considers mentality and materiality both as differentiating attributes. Broad’s criticism is first levelled at the “Dualism of Incompatibles”—roughly Descartes’ position—according to which mentality and materiality cannot both belong to the same substance (610).6 After dismissing it as “really quite groundless” (642), he devotes himself to criticism of some versions of the “Dualism of Compatibles,” that, contrary to the first kind of dualism, admits that both differentiating attributes can belong to the same substance (609). But this more modest form of dualism does not avoid the common error of all kinds of dualism, that is to say, to consider mentality as a differentiating attribute, e.g., a basic feature of reality. Broad reminds us that only living organisms exhibit mentality and that the more complex the organisms are the higher their mental faculties are. As this suggests that mentality is an emergent or reducible attribute, Broad thus concludes that empirical evidence is against dualism (646). Against Broad’s rejection of dualism it could be objected that mentality’s being rooted in materiality is not per se an argument against dualism toutcourt. The empirical evidence Broad appeals to in order to confute dualism is perfectly compatible at least with property dualism, provided that in addition to materiality the role of an autonomous mental dimension also finds acknowledgment. As we know, this latter point is denied by Broad, who maintains that mentality is completely determined by materiality. However, his thesis is not grounded on empirical evidence, but on a metaphysical presupposition, which is no more justified than the competing dualistic interpretation of the empirical facts. Moreover, it is far from obvious that the claim of the complete determination of mentality by materiality is compatible with an ontological understanding of emergence. Rather, it appears very similar to a strong supervenience thesis, to the effect of neglecting the distinctive features of emergence, i.e. novelty. Finally, a last word about trans-physical laws and monism. As we have seen above, the emergent laws on whose emergence doubt cannot be cast are the trans-physical laws, which connect the micro-structure of an object to the secondary qualities of its macro-level. As there are many irreducible kinds of secondary qualities, there must also be many corresponding irreducible laws (80). Although they are not the only emergent laws, they are the most significative, since the “method of avoiding emergent laws is not

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logically possible for trans-physical processes” (81). Broad’s claim is close to contemporary arguments which aim at showing the irreducibility of the qualia of experience to neurophysiological events. These arguments, in fact, do not merely affirm that hitherto the qualia of experience are proved nonreducible to their material basis; rather, they point at the impossibility in principle of such a reduction, stressing in this way the explanatory gap existing between physical processes and conscious subjectivity. Many philosophers consider the irreducibility of qualia as a sign of the validity of some form of dualism, but Broad does not seem to believe that the asserted irreducibility of secondary qualities must lead to any breach of materialism. Broad thinks that the nature of trans-physical laws also depends on the view one adopts on secondary qualities (52).7 As far as he himself is concerned, he seems to privilege the point of view that secondary qualities do not exist in reality, but just seem to exist, as they do not inhere in the physical objects, but only in sensa (204 ss). “A Secondary Quality is a determinable characteristic which certainly inheres or seems to inhere . . . in the objective constituents of some perceptual situations in some determinate form or other, but which there is no reason to believe inheres . . . in any physical object” (206). On Broad’s construal, physical events and mental factors cooperate in causing an external object to seem to an observer to have a certain quality, which the object does not really have (50). This circumstance is sufficient to exclude both the validity of pure mechanism and of dualism: the former cannot ignore the existence or at least the appearance of secondary qualities, the latter cannot maintain that they constitute an autonomous domain of reality. Nevertheless, I don’t believe that Broad’s anti-realistic conception of secondary qualities is able to exclude a dualistic interpretation of trans-physical laws. Against Broad, in fact, it must be objected that secondary qualities— whatever their ontological status may be—have the characteristic to appear to a subject who, as such, belongs to a dimension of reality which is completely other than materiality. Thus, it is precisely the irreducibly subjective nature of secondary qualities which represents, pace Broad, a powerful argument in favour of dualism.

2. EMERGENCE AND NON-REDUCTIVE PHYSICALISM IN CONTEMPORARY DEBATE The preceding short historical survey of British Emergentism allows the reader to better understand why in the present-day debate emergentism in philosophy of mind has often been assimilated to non-reductive physicalism. Both positions are supposed to have in common a commitment to a monistic materialistic ontology, though combined with the claim that higher-level properties, such as the psychological ones, are not reducible to the physical basic

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properties. Jaegwon Kim, one of the most resolute advocates of the similarities between emergentism and non-reductive physicalism,8 goes so far as to declare the latter as a form of emergentism, and to see in the recent success of non-reductive physicalism a renewal of the emergentistic atmosphere of the 1920s and 1930s of the past century (Kim 1992, 121). In particular, emergentism and non-reductive physicalism would share four main principles: besides the previously mentioned principles of physical monism and of the irreducibility of higher-level properties, the “Physical Realization Thesis” and “Mental Realism” are also to be added. Setting aside for the moment the fourth thesis, the third principle says that “all mental properties are physically realized; that is, whenever an organism or system instantiates a mental property M, it has some physical property P such that P realizes M in organisms of its kind” (1993, 344). Kim does not maintain that the relation of physical realization is always to be preferred to others such as strong supervenience; rather, mutual relations obtain between them, so that the claim that mental states are physically realized implies the claim that they are physically supervenient (1993, 342). However, it is hardly possible even only after brief reflection to believe that there are no dissimilarities between emergentism and non-reductive physicalism. I shall now draw attention to two differences, although I will discuss some further distinctions in the final remarks of this paragraph. The first difference regards the source of the irreducibility claim made both by emergentists and non-reductive physicalists. As Kim himself notes, the idea of “physical realization” is based upon the “multiple realization argument,” whose acceptance by the philosophical community in the late 1960s of the twentieth century marked the passage from reductive to non-reductive physicalism. Emergentism, obviously, does not share the multiple realization argument.9 However, the reason why it does not must be traced back not merely to the different historical context but also to the fundamentals of both doctrines. What makes physicalism non-reductive is the fact that the same mental state can be implemented by different physical bases. This implies that the higher-level, mental properties retain their formal structure and that the variation takes place at the lower, physical level of the implementation basis. In the case of emergentism, instead, the irreducibility of higher-level properties is grounded in the qualitative novelty that arises from the new kind of “relatedness” occurring among them. The variation refers here to the higher levels, thus making plausible the claim that the new and more complex properties are not reducible to those of the lower levels. At least in the strong variants of emergence, therefore, the irreducibility of higher-level properties is based on a much more robust ontological commitment than in non-reductive physicalism. As far as the second dissimilarity between emergentism and non-reductive physicalism is con-

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cerned, it must be stressed that the physical realization thesis may require that the connection between physical and mental properties be not only physically necessary but also explanatory (LePore and Loewer 1989, 179). It cannot escape our notice that, though not required by all supporters of non-reductive physicalism, an explanatory relation between mental and physical properties is fully compatible with the spirit of this view, while the claim of the non-deducibility and of the non-explainability of the higherlevel properties from the lower-level ones is—as we know—the hallmark of emergentism. It is perhaps not too surprising for the reader to discover that Kim tends to underestimate this fundamental difference, confining to a footnote the admission that “emergentists will deny that the ‘basal conditions’ can ever constitute an explanatory basis for any property emergent from them” (1993, 347, footnote 21). In his opinion, such a divergence is more apparent than real, as it is partly due to the different conceptions of explanation and reduction involved. In any case, it does not affect the application of the argument he develops against both emergentism and nonreductive physicalism. As a matter of fact, Kim’s fervour in assimilating the two views mainly aims at making a trenchant criticism of both of them. Let us thus turn to a short analysis of Kim’s argument against emergentism and non-reductive physicalism. First, we have to say something about “Mental Realism,” the fourth thesis which in Kim’s eyes both positions share. It says that “mental properties are real properties of objects and events . . . not fictitious manners of speech” (1993, 344). The main consequence of the reality of mental properties is, according to “Alexander’s dictum,” that they have their own causal powers. This idea fits perfectly in the emergentistic frame. Emergentists, in fact, typically maintain that each emergent level of reality is endowed with specific causal powers that can be exerted at the same level of complexity, but also from the higher levels towards the lower ones (for this reason the epistemologist David Campbell later dubbed this form of causation “downward causation”). As Lloyd Morgan puts it, when a new kind of correlation appears (for example, at the level of life), “the way in which physical events which are involved run their course is different in virtue of its presence— different from what it would have been if life had been absent” (1923, 16). Kim’s claim, however, is that both emergentism and non-reductive physicalism are committed to downward causation, as this is entailed by the basic tenets of both views (1993, 350). According to the Causal Realization Principle, “if a given instance of S occurs by being realized by Q, then any cause of this instance of S must be a cause of this instance of Q (and of course any cause of this instance of Q is a cause of this instance of S)” (1993, 352). This principle implies that same-level causation is possible only if a causal action is exerted upon the physical realization basis of the

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property to be instantiated and this sort of causation is downward causation. However, does this combination of downward causation with “upward determination” make downward causation plausible? Or, alternatively, does downward causation make sense within the conceptual frame of physicalism? In his influential 1999 essay on emergence, Kim employs powerful argumentative tools to give a negative answer, that downward causation does not make sense in a physicalistic context. After making a distinction between reflexive and non-reflexive downward causation,10 Kim scrutinizes the structure of reflexive downward causation which—as just mentioned—is combined with upward determination. Kim’s argument goes as follows. Let W be a whole having a certain emergent property M; let W be constituted by parts a1 . . . an, which have properties P1 . . . Pn, with a certain relation R holding for the parts of the whole. Then we have 1. Downward-causation: W’s having M in t causes some aj having Pj in t. 2. Upward determination: Each ai’s having Pi at t and R holding for the ais at t together determine W to have M (or W’s having M depends wholly on the ais having Pis and on the relation R holding among them) The fundamental question that Kim puts at this point is whether (1) is compatible with (2), that is to say, if it is possible “for the whole to causally affect its constituent parts on which its very existence and nature depend” (1999, 28). To answer this question, Kim distinguishes between two cases: synchronic reflexive downward causation and diachronic reflexive downward causation. In the first case, which is equivalent to the combination of (1) and (2), the wholly dependence of M from W’s microstructure implies that M would not take place at t if Paj did not hold at t, which means that Paj is a necessary condition of M. It is then clear that here an unacceptable causal circularity takes place. As a matter of fact, as long as the microstructure is not characterized by aj having Pj, M cannot emerge and, as a consequence, it cannot be the cause of aj’s having Pj. On the other hand, if M has already emerged from the microstructure, this can be explained only by the fact that the underlying microstructure realizes all the conditions necessary for M’s emergence, to which also Paj belongs. But, then, it does not make any sense to say that M has an influence on aj’s acquiring Pj. Kim’s conclusion is that synchronic reflexive downward causation must be rejected, since it is a fully incoherent concept. This conclusion is neutral between competing metaphysical positions on the relationship between the mental and the physical. Moreover, it holds even if the emergent property is understood as dependent on physical conditions which are necessary but insufficient for its emerging. Not even in this case can M exert a causal action on the microstructure because, though this latter is only one of the components from which M emerges, it is nevertheless a necessary condition in the causal relation.

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In the second model, diachronic reflexive downward causation, W has M at t and aj has Pj at t as before. W’s having M at t, however, can exert a causal influence on aj’s acquiring the new property Q at t + Dt. This is a form of reflexive causation, since M causally influences the underlying microstructure. However, such a causation does not display the antinomic and circular character of synchronic causation. In fact, emergent property M causes at t aj’s acquiring Q at t + Dt, but aj’s having Q is not part of W’s microstructure at t. Downward causation in its diachronic version is thus a coherent notion. Still, in the light of Kim’s conception of emergence, it is void of significance. The principle of upward determination, in fact, claims that an emergent property wholly depends on, or is wholly constituted by, its realization basis. Let M be the emergent property (at level n) and M_ its realization basis (at level n-1). Moreover, let us suppose that M causes (according to diachronic downward causation) event P_ (at level n-1). Things being so, there is no reason at all to exclude that P_’s cause is M_ and not M. Since the causal relation is understood as a relation of nomological sufficiency, the following obtains: M_ is a sufficient condition of M and M is a sufficient condition of P_; thus, by transitivity, M_ is a sufficient condition of P_. In other words, an event at level n-1 which is caused by an emergent property at level n is also caused at level n-1 by the realization basis M_ of M. Moreover, since the initial cause of the causal chain holding between both levels is represented by M_, M’s influence becomes wholly redundant, and M turns out to be an epiphenomenal property.11 Kim’s verdict, therefore, is that downward causation, even in its most plausible version, is incompatible with physicalism. This derives not only from Kim’s argument just outlined, but also from downward causation’s implying the violation of the principle of causal closure of the physical world and, as a consequence, the rejection of the completeness of physics, both of which are among the pillars of physicalism. Kim’s remedy for the loss of causal power of the mental states is to reduce them to physical states, thus borrowing from these their causal efficacy. As far as downward causation is concerned, it can still have a place in science and in philosophy, provided we are ready to give it up as an ontological category and to consider it as a way of describing the world, which, yet, is a purely physical world (Kim 1993, 1999). Neither emergentism nor non-reductive physicalism can accept these conclusions, which underline the plausibility of both positions. But are these conclusions unavoidable? They are so only if the mental level is determined by the physical one, that is to say, if the underlying basis is not only a necessary but also a sufficient condition of the emergent property. However, the thesis of upward determination is not a part of any scientific discipline, but is a mere assumption, which turns out not to be true if the emergent quality is such in virtue of its not being wholly dependent on its realization basis. Indeed, it is plausible to maintain that higher-level mental

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functions, even if they presuppose the activation of the neurophysiological level—for there is no thought without brain—cannot be produced by their neurophysiological basis alone. If this is the case, then higher-level mental functions are able to influence the brain’s activity, that is to say, they are sufficient conditions for it (according to downward causation), while their neurophysiological basis is insufficient for generating higher-level mental functions, although it represents the necessary condition of them. Against this view of the micro-macro relationship can be objected that it leans towards dualism, whereas both emergentists and non-reductive physicalists are as reluctant to embrace dualism as they are to endorse reductive physicalism. “Traditional dualists and neo-vitalists”—Kim reminds us— maintain that to the physical basis must be added “a pinch of mental substance or a dash of entelechy to make the recipe work.” But not for the emergentists, since for them “an appropriate physical basis is all that is necessary to generate higher-level phenomena” (1992, 124). Kim’s thesis is confirmed by Lloyd Morgan’s words: “if vitalism connote anything of the nature of Entelechy or Elan—any insertion into physico-chemical evolution of an alien influence which must be invoked to explain the phenomena of life—then, so far from this being implied, it is explicitly rejected under the concept of emergent evolution . . . we seek to indicate purely naturalistic lines of advance” (12). How to counter Kim’s and Lloyd Morgan’s joint objection? First, it must be stressed that dualism does not necessarily consist in inserting strange entities into the course of nature. Second, it must be emphasized that the emergentistic view, though not non-reductive physicalism, finds its most natural collocation in a dualistic framework. In the remainder of this paragraph I shall try to substantiate this claim. In non-reductive physicalism downward causation is a derivative concept. In fact, Kim obtains it by showing that it is implied by same-level causation, which, in its turn, is implied by upward causation. But the implication from same-level causation to downward causation holds only under the condition that upward determination holds. Therefore, non-reductive physicalism is committed to downward causation insofar as it is a form of physicalism. Kim applies the same scheme to emergentism, but in this case his strategy is not justified, since for emergentists downward causation is not a derivative notion, but a primitive one, which lies at the very heart of their view. It is the utmost expression of the emergentistic thesis of the irreducibility of higherlevel properties, thus it cannot be thought as disjointed from the nonexplainability thesis. The fact that the explainability of the mental by the physical does not hold for emergentism undermines any project—like Kim’s— to give a physicalistic interpretation of downward causation. While nonreductive physicalism is tied to upward determination and is compatible with the explainability of the mental by the physical and with Kim’s idea of downward causation, in the case of emergentism the non-explainability of

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the mental by the physical and the correlated concept of downward causation are hardly compatible with upward determination. In general, Kim tends to trivialise downward causation by characterizing it independently of its emergent character. Both in the example of Kim’s typewriter, which if dropped causes myriads of molecules to fly away (non-reflexive downward causation) and in Sperry’s example of the bird who flies into the blue yonder also moving all its parts (diachronic reflexive downward causation), we are presented with cases of downward causation which involve resultant and not emergent properties. Such cases—states Kim—“seem legion” (1999, 25), are neither strange nor mysterious, and are of no special interest, either for science or for philosophy. But the “interesting” cases, such as the emergent causal powers of consciousness upon the neurophysiological processes, do not seem to be much less trivial than the previous examples, if we follow Kim’s interpretation of downward causation. Actually, since the alleged emergent properties do not exert a real causal power on their own (they are epiphenomenal), they should be better labelled as “resultant” properties. However, this is certainly not the idea that emergentists have of downward causation. The kind of downward causation they deal with is neither trivial nor ubiquitous but concerns those particular cases where emergent, irreducible properties exert a novel and genuine causal power, in virtue of which—as Lloyd Morgan would say—the lower-level events which are involved run their course in a way different from what it would have been in their absence. Still, two differences between emergentism and non-reductive physicalism in respect of dualism should be mentioned. First, as Kim himself is ready to admit, most emergentists have no problem with abandoning the causal closure of the physical world and, as a consequence, the completeness of physics. But, in Kim’s words, “no contemporary non-reductive physicalist can afford to be so cavalier about the problem of causal closure.” A physicalist can in fact wisely share Kim’s worry: if you give up the completeness of physics, why call yourself a “physicalist”? (1993, 356). As regards the second dissimilarity, emergentism and non-reductive physicalism exhibit a difference in the structure of their respective theories. Both views are often said to imply a property dualism in virtue of their claim of the irreducibility of higher-level properties. However, the sort of property dualism implied by non-reductive physicalism is profoundly different from the emergentistic one. The former, in fact, views mental properties as situated at two different levels, the abstract and the concrete ones. At the abstract level, properties are exclusively defined by their formal role in producing the behavioural output and are not committed to any ontological position, being thus in principle also compatible with dualism. But, at the concrete level, mental properties are implemented by physical states and, as we know, they are determined by them. Mental properties, therefore, are

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distinct from the physical ones only at the abstract level but, once implemented, they are token-identical with them. Property dualism in emergentism does not involve in principle abstract mental states and considers mental properties, as far as they exist, as concrete properties token-different from their physical bases. This idea generates some tension within emergentism understood as a form of monism, but it can become wholly coherent by disavowing monism itself and by putting emergentism into a dualistic framework.

3. EMERGENTISM AS DUALISM In recent years some attempts have been made to develop emergentistic models which repudiate the original monistic tenets of British Emergentism and display more or less marked “dualistic” features. In this paragraph I shall address the main theses put forward in these models and discuss them critically in the light of the results achieved in the previous parts of the chapter. Aiming at laying out a strong ontological concept of emergence, in several essays12 Timothy O’Connor characterizes emergent properties as “nonstructural” properties. He defines structurality as follows: “A property, S, is structural if and only if proper parts of particulars having S have properties not identical with S and jointly stand in relation R, and this state of affairs is the particular’s having S” (O’Connor-Wong 2005, 663).13 An emergent property is defined by contrast as the property of a composite system that is wholly non-structural, and emergentism is defined as the view according to which there are basic, non-structural properties had by composite individuals (664). The view supported, at least in this essay,14 is property-dualism, according to which mental properties are token-distinct from the microphysical ones (664). But, how to figure out the relationship between these two different sorts of properties? O’Connor complains that the relationship is often conceived as synchronic, static and formal, due to the contemporary tendency to assimilate emergentism to non-reductive physicalism and, as a consequence, emergence to the concept of synchronical supervenience. Rather, the relationship of micro-level structures and macro-level emergent properties should be viewed as dynamic and causal. In fact, the causal action of the underlying properties is needed to explain the occurrence of emergent properties at a given level of complexity.15 Yet, emergent properties have causal powers which are irreducible to those of the micro-level structure and which exert at their turn an influence on lower-level and/or same-level entities (665). O’Connor’s claims about the causal relationship between macro- and micro-level are in my opinion the most critical aspects of his proposal. On the one hand he defends the typical emergentistic doctrine of the existence of a

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downward causation. Given the non-structurality of emergent properties, “their causal influence does not occur via the activity of the micro-properties which constitute (them)”; rather they bear their influence “in a direct ‘downward’ fashion on the object’s microstructure” (O’Connor 2003, 5). On the other hand, however, O’Connor also maintains that emergent properties, as everything that occurs, depend on the causal dispositions of the fundamental physical properties (7). The tension existing in O’Connor’s thought on this matter can be well illustrated by the passage where he examines the criticism of epiphenomenalism levelled at emergent properties (2005, 668). He emphasizes that an emergent system is not causally closed as regards its purely physical aspects and that emergent properties are thus not epiphenomenal. But, immediately after making this claim, he writes: “Consistent with this, it is true in an emergentistic scenario that everything that occurs rests on the complete dispositional profile of the physical properties prior to the onset of emergent features. For the later occurrence of any emergent properties are contained (to some probabilistic measure) within that profile, and so the effects of the emergent features are indirectly a consequence of the physical properties, too.” It is hard to agree with O’Connor about the consistency of downward causation with the just mentioned “Causal Unity of Nature Thesis” (2003, 7).16 Moreover, supporting the latter causes him more difficulties than it does for the British Emergentists. While these maintained that the macro-properties are constituted by new kinds of “relatedness” among already existing elements, O’Connor, due to his thesis of non-structurality of emergent properties, must argue that they are basic properties of composite objects, token-distinct from the physical ones, which has the consequence of widening the chiasmus between the physical and the emergent dimension. A way out of this difficulty can perhaps be found in O’Connor’s response to Kim’s criticism of downward causation. Though conceding that “the distinctive potentialities of emergent properties do stem indirectly from the total potentialities of the basic physical properties,” he adds that “they do not determine the emergent effects (or fix the emergent probabilities) independently of the causal activity of those emergents” (2005, 670). What does this sentence precisely amount to? The only coherent meaning I can give to it is that the potentialities of the basic physical properties are necessary but not sufficient conditions of the causal powers of emergent properties. But this has two consequences which are not compatible with O’Connor’s picture of emergence. First, the “Causal Unity of Nature Thesis” is no more valid; second, the fundamental question arises about where the special causal powers had by emergent properties stem from. As they do not entirely derive from the potentialities of the basic physical properties, they must be rooted in a different dimension of reality. This implies that an unambiguous reading of O’Connor’s previous sentence brings us to a more explicit form of dualism than that allowed by the author himself.

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Paul Humphreys takes a standpoint on emergence that in many respects has affinity with O’Connor’s.17 He provides a thorough treatment of the ontological assumptions underlying emergence, that I shall sum up as follows. According to Humphreys, there are i-level properties P(i,m) and entities x(i,r). Phenomena or processes occurring at a certain level are complex states of affairs related to each other. Such relations are, for example, of a causal kind: P(i,m)[x(i,r)](t) causes P(i,n)[x(i,s)](t’). This means that the instance of P(i,m)[x(i,r)] at t produces the instance P(i,n)[x(i,s)] at t’. Emergent phenomena occur when a fusion operation * acts on certain property instances. Humphreys expounds the process of fusion as follows. If, for example, P(i,m)[x(i,r)](t) and P(i,n)[x(i,s)](t) are i-level property instances, then P(i,m) x(i,r)](t)*P(i,n) x(i,s)](t) is an i+1-level property instance, the result of fusing P(i,m)[x(i,r)](t) and P(i,n)[x(i,s)](t). Since fusion is usually not instantaneous, this fact must be represented by the following formula: P(i,m)[x(i,r)](t)*P(i,n)[x(i,s)](t)⇒P(i,m)*P(i,n)[x(i,r) +) (x(i,s)](t’), where [x(i,r)+ x(i,s)] is the concatenation of the objects x(i,r) and x(i,s). However, the fusion operation acting on objects does not result in a simple concatenation of the objects here represented by x(i,r) and x(i,s), but in a new i+1level object x(i+1,c). Thus, the result of fusing can eventually be formalized in the following way: P(i,m)[x(i,r)](t)*P(i,n)[x(i,s)](t)⇒P(i,m)*P(i,n) [x(i,r) + x(i,s)](t’) = P(i,m)*P(i,n) [x(i+1,c)](t’) = P(i+1,k) [x(i+1,c)](t’) (Humphreys 1997a, 8–9). As regards the nature and the meaning of the fusion operation, Humphreys makes some points which are worth mentioning. First, he emphasizes that fusion is not a formal operation. “By a fusion operation, I mean a real physical operation, and not a mathematical or logical operation on predicative representations of properties. That is, * is neither a logical operation such as conjunction or disjunction nor a mathematical operation such as set formation.”(10). Another important aspect of P(i,m)*P(i,n) [x(i+1,c)](t’) is its holistic character, according to which its causal effects cannot be correctly represented in terms of the separate causal effects of P(i,m)[x(i,r)](t) and P(i,n)[x(i,s)](t).18 Moreover, such instances do not exist separately after their fusion. This is the reason why in this new context it does not make any sense to speak of a subvenient basis from which new properties, understood as supervenient properties, emerge. Emergent properties are not supervenient properties. Rather, they are caused by lower-level properties which give rise to them through fusion and do not exist any more after fusion. This also allows Humphreys to show that Kim’s criticism against downward causation is groundless. As Humphreys puts it, “it is false to say that the i-level property instances co-occur with the (i+1)st level property instances. The former no longer exist when they fuse to form the latter” (13). In this way, Kim’s argument is defeated already at its first step, where Kim claims that upward- and same-level causation imply downward causation.

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However, also Humpreys’ fusion model is subject to criticism. Humpreys maintains that the cause of the emergent property, i.e the property resulting from fusion, lies in the underlying basis. But what does he really mean by that? Fusion cannot be merely produced by the separate action of the particles and their properties, that is to say, by x(i,r)’s having P(i,m) and x(i,s)’s having P(i,n). Fusion takes place because the particles x(i,r) and x(i,s) with their properties enter a new relation able to trigger the process of fusion. Yet, such a new relation cannot simply amount to a new organization of the particles, since, then, it would be a formal relation, which—as Humpreys says— cannot give rise to an emergent property. But neither can it be a new relation of a non-formal kind, for it would be an emergent property (of a relational kind) without underlying basis, which would start an infinite regress. This property, in fact, should be itself the result of a fusion among properties belonging to a lower level and so on ad infinitum. There only remains, then, the possibility of conceiving fusion as a process triggered by the fact that the new organization of the particles takes place in a field of possibilities that is independent from the particles’ physical properties and is able to give rise, together with them, to the fusion process. In other words, the cause of fusion and, as a consequence, the sufficient reason of the emergent property, is the micro-structure with its formal complexity plus a field of forces independent from the physical forces of the micro-structure. This conclusion violates, once again, the “Unity of Nature Thesis,” but—I contend—this is the price we must pay if we want to have a fusion operation that is neither formal nor physicalistic. William Hasker (1999) aknowledges the existence of various degrees of emergence, according to the different phenomena and domains of reality under scrutiny. His weakest concept of emergence is emergence0 or logical emergence. It consists, in Hasker’s favourite example, in the complex and beautiful properties showed by fractal patterns, despite their being a mere logical consequence of the equations that generate the patterns (173). The second form of emergence, in ascending order, is emergence1a, and occurs when causal interactions among lower-level elements are able to explain higher-level features, like, for example, solidity or liquidity (173-4). For Searle, whose position is critically discussed by Hasker, this is the only possible notion of emergence, since the “much more adventurous” conception involving downward causation is rejected as it violates “even the weakest principle of the transitivity of causation” (Searle 1992, 112). But, for most emergentists and for Hasker himself, this latter is instead a distinctive concept of emergence, labelled by the author “emergence1b.” If a process is emergent1b, it is still explained by the causal interactions of its elements, but it is also endowed with its own causal powers whose operations are described by emergent laws (Hasker, 174). On Hasker’s view, mind and consciousness are emergent1b, but they also exhibit an even stronger form of

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emergence, called by Hasker emergence2. This form of emergence is possessed only by consciousness and consists in its power of exercising libertarian free will (177). We could wonder why Hasker thinks it necessary to ascribe to the conscious mind two forms of emergence, a weaker one, emergence1b, and a stronger one, emergence2. A tentative explanation is this. According to the emergentistic doctrine, the mind shares the characteristic of being emergent1b with other natural phenomena such as life. This means that mind has its own emergent powers, such as rationality and decision-making, and that its behaviour is ruled by specific emergent laws pertaining to the mental level. But, while emergent1b mental features are natural features that at a lower degree may be also present in other living beings possessing mentality, emergent2 features, like free will, are characteristics of the human being alone and belong to a dimension different from the natural one. Mental causation is in this case free causation, which is not ruled by laws, though emergent, but by teleological rules. Categories like value, teleology, agency, intentionality, acquire their proper meaning only if understood as emergents2. Moreover, in order to account for the peculiarity of the mind—so argues Hasker—property emergence is necessary, but not sufficient. As we know from the unity-of-consciousness argument,19 a conscious experience is a unity which cannot be decomposed into separate parts. From this Hasker draws the conclusion that what is needed here is not only property emergence, but the emergence of the mind as a new individual entity, whose nature is immaterial (Hasker 2008, 12–13). Hasker’s emergent dualism resembles traditional substance dualism insofar as mind is conceived as an immaterial substance, but differs from it in the convinction that the immaterial soul depends on material processes both for its origin and for its continuance (13). To sum up, although Hasker keeps the term “dualism” only for substance dualism as related to emergence2, he admits two sorts of dualism: propertydualism (combined with substance monism), which is sufficient to account for emergents1b, and substance dualism, which is necessary to account for emergents2, that is to say, for the most peculiar characteristics of the human being such as free will. Yet, however significant the difference between emergence1b and emergence2 may be, I believe that both forms of emergence face the same challenge, i.e. whether they find any justification within Hasker’s emergentistic framework. The author seems to scrupulously adhere to the emergentistic doctrine, according to which higher-level features emerge from purely physical processes. As evidence of this fact, I shall quote some places from Hasker (1999). Against the misleading “thinking of the different levels as concrete and capable of exerting . . . distinct kinds of causal influence,” Hasker objects that “the only concrete existents involved are the ultimate constituents and combinations thereof; the only causal

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influences are those of the ultimate constituents in their interaction with each other, and the only way the ‘higher levels’ can make a difference is by altering or superseding the laws according to which the elements interact” (175–76). Some pages after, Hasker concedes that emergent dualism has one major cost, i.e. that “the theory requires us to maintain, along with the materialists, that the potentiality for conscious life and experience really does exist in the nature of the matter itself” (194). Even the soul, which represents the highest level of emergence, “comes into existence as a result of a certain functional configuration of the material constituents of the brain and nervous system” (190). Keeping this in mind, let us turn back to Searle’s criticism of emergence (both 1b and 2). On the one hand, if the neurons, by their causal interactions, generate consciousness, then, by the transitivity of causality, they also generate all its causal powers. But, then, consciousness would not have any distinctive causal powers, least of all powers that are supposed to transcend the natural domain. On the other hand, “if consciousness were emergent2, then consciousness could cause things that could not be explained by the causal behavior of the neurons” (Searle 1992, 112). Indeed, speaking of the emergence of the mental substance, Hasker claims that the soul “is able, in Searle’s words, to ‘cause things that could not be explained by the causal behavior of the neurons’” (1999, 190). Since this claim is not compatible with the dependence of consciousness on purely material processes, Hasker seems to be faced with a dilemma. The first way out of the dilemma is to abandon emergentism outright, and to embrace traditional property and/or substance dualism. If for Hasker this solution is not feasible—as I suspect—the only possibility he is left with is to admit that the physical processes leading to emergence are only a necessary condition within a global sufficient condition which also involves nonphysical causal powers. An analogous criticism has been made of O’Connor’s and Humphreys’ property emergentism, but, I submit, it is still more valid if made of Hasker’s substance dualism.

4. EMERGENT DUALISM AS I VIEW IT The previous paragraph has been devoted to the exposition and the critical analysis of some dualistic versions of emergentism. It has surely not gone unobserved that the three emergentistic views we have examined so far demonstrate different degrees of commitment to dualism. A question of central importance is whether emergent dualism is likely to be a variant of property dualism or if it also aknowledges the emergence of whole individuals. Besides Hasker, who is a professed substance dualist, Humphreys, as is apparent from his formal treatment of fusion, is also in principle in favour of the hypothesis of the emergence of whole objects.20 However, he

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has seemingly no interest in investigating this matter further. O’Connor, instead, devotes one of his essays (O’Connor-Jacobs 2003) to the examination of this controversial issue. He moves from the consideration that human beings are endowed with mental states which confer on them a unity as thinking biological substances. This functional unity of persons as wholes implies their particularity, which does not derive from the particularity of their parts, but is primitive. In the same way, the essential properties of a person are also primitive, since they cannot be reduced to those of her fundamental parts. Thus, O’Connor accepts emergent individuals, but by “individual” he means the composite system itself, with its distinctive particularity and its distinctive holistic features. He does not allow, instead, the emergence of a mental substance, whose acceptance would lead to a kind of substance dualism. O’Connor’s rejection of substance dualism holds both for the case where, after having emerged, the emergent individual is ontologically independent from the physical substrate and for the alternative case where it continues to depend on it. In the first case, “a radical kind of creation ex nihilo” is required, for which there are “no remotely plausible candidate instances.” As far as the second case is concerned, O’Connor objects that the natural emergence of an individual wholly distinct from the body is implausible and runs against the best empirical evidence (548–49). However, is the “emergent composite view of human persons” (553) able to account for emergence understood in a strong ontological sense? To ask this question, we must recall what we have pointed out in the previous paragraph about the origin of emergent properties and their causal powers. The problem with substance monism lies in the fact that the origin of emergent properties cannot be merely physical, because a physical structure is not sufficient for justifying the emergence of non-physical, mental properties. As I am not a Platonist, I believe—as O’Connor does—that emergent properties exist and can exert their causal powers only as instantiated properties. But, differently from O’Connor, I think that they cannot be instantiated in a mere physical substrate. Hence, they must be instantiated in a substrate which is ontologically independent from the body. It must be stressed that only an entity endowed with ontological independence is able to guarantee that its inherent forces can really exert their causal powers. If the mental substance were ontologically dependent on the body, in fact, it would have to borrow its causal powers from the body itself, so that a substance dualism with ontological dependence of the mental substance on the body would not be a much better option in this respect than a substance monism. The fact that the non-material mental substance is ontologically independent from the body, however, does not imply that it is wholly independent from it. Unlike Descartes, and similarly to Aquinas, emergent dual-

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ism does require a sort of dependence of the mental substance on the body, that is to say, a functional dependence. The mind needs an external structure, the body, in order to perform its own functions, such as perceiving, thinking, reasoning, or deliberating21. By postulating a non-material, mental substance ontologically independent but functionally dependent on the body, am I subject to the first objection raised by O’Connor against substance dualism, according to which this theory requires a creatio ex nihilo? I take this objection to be a strong one, because, if valid, two unwelcome consequences would follow from it. First, emergent dualism would cease to be emergent, since an act of creation would render the process leading to emergence simply redundant. Emergent dualism would lose its distinctiveness from traditional dualisms “which postulate a special divine act of creation as the origin of the soul” (Hasker 2008, 13). But, still worse, while in traditional dualisms the notion of a creatio ex nihilo by God is perfectly coherent, the same does not hold for emergent dualism. What is in fact a creatio ex nihilo? It amounts to put into existence a particular endowed with ontological independence. But, under the supposition that an emergent individual is “an individual that comes into existence as the result of a certain configuration of the brain and nervous system, but which is not composed of the matter which makes up that physical system” (13), a creatio ex nihilo in an emergentistic scenario is simply impossible. The emergence of a mental individual, in fact, cannot be a creation of the material basis, because empirical causes are able to modify the properties of an already existing substance, but they are not able to bring a new substance into existence! Yet, however strong O’Connor’s objection may be, it does not affect my own position. Substance dualism with ontological independence of the mind implies an impossible creatio ex nihilo only under the condition that the processes from which the mind emerges are merely material processes. Thus, this criticism can be countered if the development of the mental substance is traced back not only to material components, but also to a distinctive, non-material dimension of reality, endowed with ontological independence and existing from the very beginning of the emergent process. Such a dimension is the origin of the potentiality of development of the mental substance, which becomes actualized at the moment in which the biological structure reaches the necessary degree of complexity. Emergent dualism champions the idea of a co-evolution of mind and body, at the ontogenetic as well as at the phylogenetic level, on whose basis the realisation of nonbiological potentialities is induced by the development of the biological structure, which, in its turn, is afterwards affected by the causal activity of the conscious mind.22 Moreover, it is worth mentioning that the process of actualization of the mental substance also implies its particularization, its

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being the mind of a specific human individual. As we have just seen, the actualization of the mind is induced by a biological process of high complexity, but increasing complexity is also a sign of increasing individualization, so that my position does not face the problem of having to explain why a certain mental substance exerts its causal powers exclusively on its brain and not on somebody’s else brain.23 The point of view I am here sketching out could, however, be subject to the second objection that O’Connor makes against substance dualism, that is to say, that it forces us to contemplate “a composite physical system’s giving rise, all in one go, to a whole, self-contained, organized system of properties bound up with a distinct individual.” The implausible consequences of this idea, as applied to human beings, would lie in the fact that “at an early stage of physical development, a self emerges having all the capacities of an adult human self, but most of which lie dormant owing to immaturity in the physical system from which it emerges” (O’Connor-Jacobs 2003, 549). I confess that this objection puzzles me, in particular as regards the alleged lack of accordance of emergent substance dualism with empirical evidence. What a developmental psychologist observes concerning the developmental history of a child is the appearance at a certain stage of her development of mental capabilities, whose complexity and sophistication gradually increase, together with the concomitant maturing of the physical structure. This empirical state of affairs—it seems to me—may be interpreted equally well both by an “emergent composite view” and by an emergent substance dualistic view of the human being. In other words, accordance with empirical evidence is not the benchmark on whose basis a confrontation among both positions has to take place. The merits of my variant of emergent dualism are to be found first of all at the conceptual level. My proposal explains the emergence of the mental substance without resorting to any creatio ex nihilo, and also accounts for its ontological independence from the biological structure. In so doing, it guarantees that the mental substance has autonomous emergent powers that it can exert in a downward fashion on the body. Moreover, due to the mind’s functional dependence on the body, my proposal, unlike Cartesian dualism, accounts for the existence of correlations of all mental states with brain states. As we know, neuroscientific research attests the detailed dependence of mental functions on brain functions and the existence of a systematic network of mind-brain correlations, so that at this stage of neuroscientific advancement no dualistic theory can afford to be ill at ease with such empirical data. Other forms of emergent substance dualism meet the criterion of accounting for mind-body correlations.24 I submit that, together with these, my proposal deserves a closer look.

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NOTES 1. For general presentations of the British Emergentists’ movement see McLaughlin (1992), Stephan (1992) and (20052), part II. 2. Some proposals which are close to epistemological emergence are, for example, Nagel (1961), Bedau (1997), Clark (2001). 3. I am aware of the fact that other interpretations of Alexander’s philosophy are possible (see Kim 1993, 347; O’Connor-Wong, 2002, 4–6). I would be content if my own interpretation would be judged as showing some degree of plausibility. 4. Actually, the quotation on page 45 continues as follows: “The quality and the constellation to which it (the higher complex) belongs are at once new and expressible without residue in terms of the processes proper to the level from which they emerge.” 5. Broad critically examines reductive materialism or behaviourism on pages 612–24. 6. Broad’s criticism of the Dualism of Incompatibles is developed on pages 625–30. 7. A discussion about the different views on secondary qualities can be found on pages 46–52 in the context of the criticism made by Broad of the ideal of pure mechanism. 8. Others are, for example, van Cleve (1990) and Mc Laughlin (1997). 9. We should not forget that the main argument brought forward by Broad against dualism consists in showing that mentality is exclusively “implemented” in living bodies! 10. Kim defines reflexive downward causation thus: “Some activity or event involving a whole W is a cause of, or has a causal influence on, the events involving its own microconstituents.” It is to be distinguished from non-reflexive downward causation, “in which an event involving a whole causes events involving lower-level entities that are not among its constituents” (1999, 26–27). 11. The objection that emergent properties are epiphenomenal was first put forward by Pepper (1926). 12. O’Connor (1994), (2000a), (2000b), (2003), O’Connor-Wong (2002), (2005), O’Connor-Jacobs (2003). 13. O’Connor applies to particulars David Armstrong’s definition of “structural universal.” 14. As we will see soon, in another essay O’Connor favours the thesis of the emergence of individuals, instead of properties. 15. Actually, it sounds very strange to emergentistic ears that the underlying micro-structure is supposed to “explain” the occurrence of emergent properties! 16. From the “Causal Unity of Nature Thesis” O’Connor distinguishes the stronger “Micro-Macro Constitution Thesis,” according to which “every (token) macro-level phenomenon is constituted by a nested structure of microphysical processes” (2003, 7). He accepts the first but rejects the second thesis, since on O’Connor’s view it does not apply to every natural phenomenon. 17. See Humphreys (1996) (1997a), (1997b), (2006). O’Connor discusses Humphreys’ standpoint in O’Connor-Wong (2005), footnote 10.

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18. The holistic character of fusion is very close to the property of non-additivity of emergent systems (see Mill 1973, ch. VI). 19. See Hasker (1999), ch. V. 20. See Humphreys (1997a), footnote 11, where he claims that even if it is historically true that British Emergentists were for property emergence, “it is as well to allow, at least notationally, that we might have new entities as well as properties.” 21. Thomas Aquinas on this point affirms: “In the present state of life in which the soul is united to a passible body, it is impossible for our intellect to understand anything actually except by turning to the phantasms. And of this there are two indications. First of all because the intellect, being a power that does not make use of a corporeal organ, would in no way be hindered in its act through the lesion of a corporeal organ if for its act there were not required the act of some power that does make use of a corporeal organ. Now sense, imagination, and the other powers belonging to the sensitive part make use of a corporeal organ. Therefore it is clear that for the intellect to understand actually, not only when it acquires fresh knowledge, but also when it uses knowledge already acquired, there is need for the act of the imagination and of the other powers. For when the act of the imagination is hindered by a lesion of the corporeal organ, for instance, in a case of frenzy, or when the act of the memory is hindered, as in the case of lethargy, we see that a man is hindered from actually understanding things of which he had a previous knowledge.” Summa Theologiae, I, q84, a7. 22. For the idea of a co-evolution of mind and body as implied by emergent dualism see Hasker (2008), 15. 23. I am referring to the pairing problem raised by Kim (2001), 35–39 against mind-body substance dualism. 24. On this see Hasker (1999), 153–57 and 197–200.

BIBLIOGRAPHY Alexander, S. 1920. Space, Time, and Deity. 2 vol. London: Macmillan. Beckermann, A., H. Flohr, and J. Kim, eds. 1992. Emergence or Reduction? Essays on the Prospects of Nonreductive Physicalism, Berlin-New York: de Gruyter. Bedau, M. 1997. “Weak Emergence.” Philosophical Perspectives 11: Mind, Causation, and World: 375–99. Bedau, M., and P. Humphreys, eds. 2006. Emergence: Contemporary Readings in Science and Philosophy. Cambridge, Mass: MIT Press. Broad, C.D. 1925. The Mind and its Place in Nature. London: Routledge and Kegan Paul. Klark, A. 2001. Mindware. An Introduction to the Philosophy of Cognitive Science. New York, Oxford: Oxford University Press. Hasker, W. 1999. The Emergent Self. Ithaca and London: Cornell University Press. ———. 2008. “Emergent Dualism: A Mediating View of the Nature of Human Beings,” manuscript; Italian translation: “Dualismo emergente: una prospettiva di mediazione sulla natura degli esseri umani,” In L’uomo a due dimensioni, edited by A. Lavazza, 240–55. Milano: Bruno Mondadori.

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Humphreys, P. 1996. “Aspects of Emergence.” Philosophical Topics 24: 53–70. ———. 1997a. “How Properties Emerge.” Philosophy of Science 64: 1–17. ———. 1997b. “Emergence, Not Supervenience.” Philosophy of Science 64 (Proceedings): S337–S345. ———. 2006. “Emergence.” The Encyclopedia of Philosophy, edited by D. Borchert. 2nd ed. New-York: MacMillan. Kim, J. 1992. “ ‘Downward Causation’ in Emergentism and Nonreductive Physicalism.” In Beckerman, Flohr, and Kim, eds., 119–38. ———. 1993. “The Nonreductivists’s Troubles with Mental Causation.” In J. Kim. Supervenience and the Mind: Selected Philosophical Essays, 336–57. Cambridge: Cambridge University Press. ———. 1999. “Making Sense of Emergence.” Philosophical Studies 95: 3–36. ———. 2001. “Lonely Souls: Causality and Substance Dualism,” In Soul, Body, and Survival, edited by K. Corcoran, 30–43. Ithaca and London: Cornell University Press. LePore, E., and B. Loewer. 1989. “More on Making Mind Matter.” Philosophical Topics 17: 175–91. Morgan, C. Lloyd. 1923. Emergent Evolution. London: Williams and Norgate. McLaughlin, B.P. 1992. “The Rise and Fall of British Emergentism.” In Beckerman, Flohr, and Kim, eds., 49–93. ———. 1997. “Emergence and Supervenience.” Intellectica 2: 25–43. Mill, J. S. 1973. A System of Logic. In Collected Works of John Stuart Mill, vol. VII, Toronto: Toronto University Press. Nagel, E. 1961. The Structure of Science. New York: Harcourt Brace and World. O’Connor, T. 1994. “Emergent Properties.” American Philosophical Quarterly 31: 91–104. ———. 2000a. Persons and Causes. New York-Oxford: Oxford University Press. ———. 2000b. “Causality, Mind, and Free Will.” Philosophical Perspectives 14: 105–17. ———. 2003. “Groundwork for an Emergentist Account of the Mental.” Progress in Complexity, Information, and Design 2.3.1: 1–14. O’Connor, T., and H.Y. Wong. 2002. “Emergent Properties,” , edited by E. N. Zalta, Winter 2002 edition. plato.stanford.edu/archives/win202/entries/Propertiesemergent/. ———. 2005. “The Metaphysics of Emergence.” Nous 39: 658–78. O’Connor, T., and J.D. Jacobs. 2003. “Emergent Individuals.” Philosophical Quarterly 53: 540–55. Pepper, S. 1926. “Emergence.” Journal of Philosophy 23: 241–45. Searle, J. 1992. The Rediscovery of the Mind. Cambridge, Mass: MIT Press. Stephan, A. 1992. “Emergence. A Systematic View on its Historical Facets.” In Beckerman, Flohr, and Kim, eds., 25–48. ———. 2005. Emergenz. Von der Unvorhersagbarkeit zur Selbstorganisation. Paderborn: mentis. Thomas Aquinas. 1952. The Summa Theologica. Chicago-London-Toronto-Geneva: Encyclopedia Britannica, Inc. Van Cleve, J. 1990. “Mind-Dust or Magic? Panpsychism Versus Emergence.” Philosophical Perspectives 4: 215–26.

9 Concepts, Dualism, and The Human Intellect David S. Oderberg

1. INTRODUCTION There are various ways in which dualists have defended, and continue to defend, the idea that the human mind, or some aspect of it, resists wholesale explanation in material terms. They appeal to such things as: the phenomenal character of experience; the irreducibility of the first-person perspective; the simplicity of the self as against the mutable complexity of the physical body; the existence of free will; the nature of intentionality; the existence of morality and moral responsibility; as well as other phenomena that appear to defy any kind of materialist reduction. At least some of these approaches are, in my view, correct. Others, however, are at least questionable. For instance, an appeal to the survival of the self despite total replacement of bodily parts might lead one to wonder whether we should be dualists about some non-human animals, perhaps the primates. But then we might wonder whether, if dualism about, say, chimpanzees were true, they also had free will and moral responsibility. It is, to say the least, highly doubtful whether this is so. Even more pointedly, the appeal to phenomenology raises the question of whether we should be dualists about all animals. Framing the issue in terms of conscious experience, there is good reason for thinking that even humble protozoans are conscious, unlike any plants (Oderberg 2007, chapter 8). That is to say, even the lower animals have sensory receptors that take in information, interpret it, amplify it where necessary, filter out noise, and communicate it to conspecifics. These are all actions of conscious beings; yet we should not be dualists about microbes. It might be thought that microbes are not conscious because there is nothing it is like—to use the standard way of putting 211

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things made popular by Thomas Nagel (1974)—for them to feel what they feel. Yet it is a mistake to think that for a being to feel something it is necessary that there be something it is like for it to feel that thing. A being may be merely conscious in the sense of having no phenomenology associated with its conscious states, at least in the Nagelian sense. A protozoan might sense a noxious environment, and take consequent action to avoid it, without that sensation’s feeling like anything. A higher animal such as a mammal might feel the pain of a pin-prick without that pain’s having any phenomenological character, such as feeling tingly or sharp. It might feel painful, of course: how else should a pain feel? To that extent there is something phenomenal in the animal’s experience. But it would be wrong to assume we had, on conceptual grounds, to say anything more about the character of its sensation. The point of these examples is to suggest that arguments for dualism can sometimes be blunt instruments; or, to vary the metaphor, they can be a net with too coarse a mesh. I do not propose here to show definitively why we should not bite the bullet of certain dualist arguments and attribute something immaterial to the constitution of non-human animals. All that need be said is that to do so looks like a case of the dualist tail wagging the metaphysical dog. To be a dualist is, first and foremost, to recognize there is something about us human beings that precludes materialistic reduction. Is there something about human beings that requires a dualist explanation such that, whilst that feature may also on investigation turn out to be shared by, say, higher mammals, it is highly unlikely to be possessed by microbes or spiny anteaters? Perhaps appeal to a certain kind of phenomenology can ground an argument against materialism, but what kind it must be is more complicated than the common style of argumentation usually acknowledges. By contrast, an older way of arguing for dualism, based on the Aristotelian tradition, does not invoke anything subjective, first-personal, or phenomenological. Instead, it identifies a feature of human beings more amenable to third-personal investigation—the activity of reason. According to this kind of argument, human beings engage in a kind of activity that resists materialistic reduction, a position that can be established without appeal to anything necessarily subjective or perspectival in what each person knows about themselves. To be sure, investigation and analysis of our subjective states gives access to data about what we do and how we do it that impress the traditional dualist, but the data themselves are not essentially subjective. I have called the kind of dualism representative of the Aristotelian (and Thomistic) tradition “hylemorphic dualism” (Oderberg 2005), but what follows is compatible not only with that kind of dualism. I will discuss it at various points, but the central argument to be presented should be congenial also to substance dualists of Cartesian or other stripes, and perhaps

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also to certain kinds of event or property dualists. It is meant as a general argument to the effect that there is something constitutive of the human being, amenable both to third- and first-personal investigation, that requires the postulation of an immaterial element.

2. WHAT CONCEPTS MUST BE The argument favoured by the hylemorphic dualist in favour of an immaterial element in the human being takes its cue from Aristotle’s remark that the intellect has no bodily organ (Loeb 1943, 171).1 The idea is that intellectual activity—the formation of concepts, the making of judgments, and logical reasoning—is an essentially immaterial process. By essentially immaterial is meant that intellectual processes, in the sense just mentioned, are intrinsically independent of matter, this being consistent with their being extrinsically dependent on matter for their normal operation in the human being. Extrinsic dependence, then, is a kind of non-essential dependence. For example, certain kinds of plant depend extrinsically, and so non-essentially, on the presence of soil for their nutrition, since they can also be grown hydroponically. But they depend intrinsically, hence essentially, on the presence of certain nutrients that they normally receive from soil but can receive via other routes. Something similar is true of the human intellect. To engage in concept formation, judgment, and reasoning is to engage in a process not essentially dependent on matter. Nevertheless, the normal operation of the process in the human being—that is, operation in an unattenuated way—extrinsically requires the presence of matter, whereby the intellect operates on sensory information delivered through material channels. I will not discuss extrinsic dependence on matter here, only the essential character of intellectual operation. The dualist argument under consideration depends on a certain view of concepts, namely that they have an entitative character. The term “entitative” is here introduced with a specific sense distinct from that connoting mere being. In traditional ontology, anything thinkable is a being. Nothing distinguishes concepts in this broad sense from any other thing. On the more restricted reading I am proposing, concepts are entitative in the sense that they are not to be identified with capacities, powers, practices, activities, or any kind of behaviour whether actual or possible. A number of powerful arguments along these lines have been provided by Jerry Fodor (1995; 1998) and I do not intend to rehearse them all here.2 Several issues, however, should be discussed. In response to the claim that concepts can be reduced to sorting capacities, Fodor rightly points out that all co-extensive concepts would then be identical, unless the capacity included the disposition or ability to sort possible as

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well as actual instances of the concept. But even in this case, necessarily coextensive concepts such as triangle and trilateral would be identical (Fodor 1995, 8). Hence a standard move is to supplement sorting capacities with dispositions to make certain inferences. Fodor takes the inferences to be ones the concept possessor is disposed to make “from the sorting he performs” (1995, 9), but this cannot be right. The person who sorts the triangles from the non-triangles and the trilaterals from the non-trilaterals will find that all and only the triangles fall into the same “mental basket,” as it were, as the trilaterals. He will not, as Fodor supposes, then be disposed to think of triangles as having three angles, and trilaterals as having three sides, without also being disposed to think of triangles as having three sides and trilaterals as having three angles. Indeed, one would expect that it is only the latter that he would be disposed to infer from the sorting: for the sorting would not reveal that triangles had angles and trilaterals had sides, rather the reverse. It would be of no avail to strengthen the causal connection between the sorting and the inference-making by holding that a triangle collector is disposed to make certain inferences about the objects in his collection precisely because he thinks of the triangles qua triangles. For anyone who thinks of triangles qua triangles is ipso facto disposed to think of them as having sides. Now Fodor supposes, on behalf of the concept reductionist, that the person who collects triangles must accept that the objects in his collection have angles “whether or not he has noticed that they have sides”; mutatis mutandis for the collector of trilaterals (1995, 9). Yet this is a wholly unrealistic scenario, at least as far as triangles and trilaterals are concerned: no one, not even a child, who collects triangles can fail to notice that they have sides, and no one who collects trilaterals can fail to notice that they have angles, whether the collector knows the word for angles (viz., “angle”) or not. The scenario would be more plausible for necessarily co-extensive properties of more complex geometrical structures, but we can see that mere sorting capacity, tied to the contingencies of what the sorter might or might not notice, cannot be sufficient for a general account of concept possession. More important is that one should expect that the ability to think of triangles as having angles and trilaterals as having sides should exist prior to any sorting or capacity to sort. In other words, having the capacity to sort triangles must depend causally upon a prior ability to draw certain inferences about triangles, in particular that they have angles. To sort Fs is to be able to place Fs in a category of their own based on at least some of their characteristics. But then one must already be able to recognize those characteristics before one can place the Fs into the category. And to be able to recognize those characteristics is precisely to be able to think of the Fs as possessing them. Of course, one might be able to recognize angles without being able to think of a given kind of figure as possessing them; but then one would not be able to sort that very kind of figure into a category of its own, whether generically or specifically, on the assumption that having angles was essen-

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tial to that kind of figure. So having the concept of a triangle cannot consist in an ability to sort and an ability to draw certain inferences based on the sorting, given that the sorting requires the ability to draw certain inferences in the first place. Nor is there any reason to think it consists in the ability to sort and the ability to draw certain inferences not based on the sorting, for what else could the inferences be based on? The obvious answer is propositions understood in virtue of prior possession of the concept of a triangle— yet this is precisely the answer not open to a concept reductionist. Leaving aside the ability to sort, the reductionist might still insist that possession of the concept of an F consists in the ability to draw inferences that define F-ness. It is not that such a capacity presupposes possession of the concept, but that possession of the concept just is the capacity. Fodor’s objection to this position, which he labels “definitional pragmatism,” is that most concepts do not have definitions. “At a minimum,” he tells us, “to define a concept is to provide necessary and sufficient conditions for something to be in its extension” (1995, 12), but such a requirement cannot be met for most concepts. He goes on to contrast the capacity to define a bachelor with the capacity to define a dog, which latter is not possessed by anyone, at least not if definitions are to be non-circular. Fodor’s main objection to the definitional approach is that, circularity aside, “being a necessary and sufficient condition for the application of a concept is not a sufficient condition for being a definition of the concept” (1995, 12). One could, for instance, list all and only the dogs and say that this provides necessary and sufficient conditions for being a dog. But we need a list that includes all actual and possible dogs in order to have the right kind of necessary and sufficient conditions, lest we fall into the old problem of co-extensiveness. Yet he fails to note that the equally old problem of necessary co-extensiveness will still be present: we can claim that triangles are defined by being on the list of actual and possible triangles, but they are also on the list of actual and possible trilaterals, so modalized necessary and sufficient conditions will not do. Fodor’s objection, then, reduces to the earlier one against sorting: our conceptual capacities are more finegrained than capacities to list or to sort by modalized necessary and sufficient conditions. At a more basic level, Fodor goes wrong in two ways when he discusses definitional pragmatism. His explicit claim is: 1. Being able to define a concept is being able (at least) to provide necessary and sufficient conditions for its application. His implicit claim is: 2. Most concepts do not have definitions because they do not have necessary and sufficient conditions for their application.

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At first glance, it is tempting to charge Fodor with confusing these distinct claims. Since (1), even if true, is a claim about our epistemic capacities, nothing follows concerning the metaphysical truth of whether concepts have definitions. Yet he could respond that the general lack of the second capacity in (1) is at least good evidence for the truth of the first half of (2). More significantly, it would be cold comfort for the definitional pragmatist to be told that we might be in a situation in which (2) is false but (1) is true, since if Fodor is right that we cannot provide necessary and conditions of application for most concepts, it follows that we cannot define most concepts, and for the definitional pragmatist this means that we fail to possess most of the concepts we think we have. The proper response to Fodor’s claims is simply to deny both of them. To take (2) first, on what grounds can we say that most concepts do not have necessary and sufficient conditions for their application? To take the ageold Aristotelian definition of man, “man is a rational animal” does give necessary and sufficient conditions for being human. (For various issues and complications surrounding this definition, see my 2007, especially chapter 5.) The definition of gold as a metal composed of the element with atomic number 79 also provides necessary and sufficient conditions for being gold. The definition of fish as aquatic verterbrates possessing gills in the mature case, as far as ichthyology goes, also gives the requisite necessary and sufficient conditions, as does the definition of water as a kind of stuff capable of existing in solid, liquid, and gaseous states and whose molecular composition is given by the formula H2O. There is nothing circular about any of these definitions, so it is not clear why Fodor levels the objection he does, since these sorts of example make the case for very many concepts. What about most concepts? That depends on whether there are good arguments for essentialism as an overall metaphysical position, and I submit that there are, though I cannot rehearse them here (see Oderberg 2007). They are based on ontology, taxonomy, scientific method, on the poverty of anti-essentialist arguments, responses to the problem of vagueness, among other considerations. The possibility of defining objects—of real definition—and hence of defining the concepts that apply to them cannot be dismissed by a simplistic appeal to the supposed lack of necessary and sufficient conditions. More germane to the present discussion is Fodor’s first claim. If (1) is taken at face value, it might well turn out to be false. Most if not all concepts might have definitions in the sense of, at a minimum, necessary and sufficient conditions of application, but can we be so sure we are able to provide them? Without adjudicating the issue here, suppose we cannot. It does not follow that we are unable to provide partial definitions, e.g., by giving necessary but not sufficient conditions, or sufficient but not necessary conditions, or some but not all of the jointly necessary or jointly sufficient

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conditions. Or we might be able to give only probable necessary and sufficient conditions, or defeasible conditions. Or we might only have necessary and sufficient conditions containing a certain amount of vagueness or approximation. If any of this is true, as it seems to be for many categories of object, it does not imply we cannot give definitions. A probable, vague, incomplete, or approximate definition is not a rubber duck, but something that requires supplementation by degrees, not a change of kind, in order to be a correct definition in the sense of being exhaustive, precise, and certain. Moreover, this account of our definitional capacities is just what we should expect—on the assumption that having concepts equates to being able to give definitions—in light of the fact that our possession of concepts, for most concepts, looks similarly to be a matter of degree. An ichthyologist has a fuller grasp of the concept fish than I do. A metallurgist has a more complete grasp of the concept aluminium than you likely do. But I do possess the concept fish and you almost certainly possess the concept aluminium. One can know what a thing is without being able to say everything there is that is true of that thing; and concept possession is compatible with, in some cases, quite meagre knowledge. Of equal if not greater cause for concern is Fodor’s insistence that “[d]efinitions turn out to contribute vanishingly little to explaining what subjects do in tasks that involve applying concepts to things that fall under them” (1995, 13). They do not, he thinks, play a predictive or explanatory role in cognitive science. Here he is talking not just about necessary and sufficient conditions, but about the very role of essentialism in our cognitive practices. He asserts: “natural kind concepts . . . [are] self-conscious and cultivated intellectual achievements.” We should not use natural kind concepts as “the paradigms on which we should model our accounts of concept acquisition and concept possession.” Moreover: “[I]n the history of science, and in ontogeny, and, for all I know, in phylogeny too, concepts of natural kinds as such only come late. Homer, and children, and animals, have few of them or none.” (All quotations from Fodor 1998, 154, 155.) Yet these assertions contradict copious empirical evidence, of the kind gathered by Susan Gelman, supporting the role of essentialist thinking from the early stages of human psychological development (Gelman 2003). Gelman asserts (at 297): [T]he available data strongly suggest that by four years of age children treat certain categories as having rich inductive potential; privilege causes over other sorts of properties in determining category membership; invoke nonobvious, internal, or invisible qualities, and consider them more tightly linked to identity than outward properties; treat membership in a kind as stable over outward transformations; appeal to innate potential; and so forth.

That children do not essentialize is, according to Gelman, a misconception; that they do so cannot be explained by any appeal to historical accident

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or late developments in scientific method and our increasing familiarity with it. Notwithstanding that an essentialist might dispute some of the wording in the above quotation,3 it is clear from cognitive psychology that one cannot simply dismiss, as Fodor does, the explanatory role of essentialist thinking, and the definitional practices that go hand in hand with it. The problem with definitional pragmatism—the reduction of concepts to capacities to give definitions—is that it makes a mystery of how it is that we even have such capacities in the first place. The worry is a particular case of the general concern over trying to account for concepts in terms of conditions of concept possession (as in Peacocke 1992). Being able to think about Fs in a certain way, to recognize them, classify them, make generalizations about them, and the like, might all be consequences of possessing the concept of an F; but they cannot, singly or jointly, constitute what it is to have that concept. They manifest possession of the concept, but possession of the concept must itself involve some kind of mental operation bearing a relation to the objects to which the concept applies. Does not being able to think of Fs in a certain way, and draw inferences about them, involve a kind of mental operation and not mere capacities? To acquire and possess a concept is actually to do or have done something using one’s intellect, not merely to be able to do something. For Fred to have the concept of gold, he must have performed some kind of operation with his mind, an operation that gives rise to various sorts of recognitional, discriminatory, and inferential—not to mention linguistic—capacities. Yet doesn’t this approach to concepts involve an unacceptable mentalism? Concepts are supposed to be objective, public, shareable things, however they are ultimately construed. As Peacocke puts it, when speaking of concepts as mental representations, “[i]t is possible for one and the same concept to receive different mental representations in different individuals” (1992, 3). Three interpretations of this claim need to be considered, however, and although none of them undermine the approach to concepts I am defending, Peacocke’s remark does suggest a problem with concepts as understood by representationalists such as Fodor. The first interpretation conflates concepts and conceptions. Different individuals might have, say, different conceptions of space or time, while sharing the same concept of space or time. They might both know what space or time is, at least partially, but attach different connotations to the same thing, attribute different characteristics to it, and so on. It does not imply that concepts cannot be mental entities. (For more on the distinction between concepts and conceptions, see Ezcurdia 1998; Macià 1998.) On the second interpretation, one person might have a more precise or complete grasp of a concept than another, though they both share the concept. Fred might have the concept of gold, and know its atomic composition, whilst Frieda has the concept of gold yet lacks this particular bit of knowledge. Again, nothing here militates against concepts’ being mental entities.

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On the third interpretation—not one to which Peacocke himself would subscribe—the claim amounts to no more than holding that different people can define the same thing in different ways. Bob might define an echidna as a mammal whereas Barbara does not. Only one of them will be correct if they really are thinking or talking about one and the same thing, yet it is at least plausible to say that the concept echidna is possessed by both Bob and Barbara, especially if both have been sufficiently exposed to echidnas to be able to do most of the recognitional and discriminatory work that manifests grasp of the concept. It would be even more plausible if, say, Barbara—who is wrong about echidnas not being mammals—based her misdefinition on a more general, and arguable, theory of biological taxonomy. The third interpretation is consistent with Bob’s and Barbara’s both having performed the same, or a sufficiently similar, mental operation in virtue of which they can be truly said to have the concept echidna. Peacocke’s assertion does, nevertheless, highlight something of the utmost importance about concepts. It must be a non-negotiable feature of any theory of concepts that concepts be public and shareable, a fact long insisted upon by Fregeans. Frege himself, as is well known, identified concepts with the referents of predicates (Frege 1951). The view seems strange, but in one sense Frege is right: thinking purely etymologically, a concept is precisely what is conceived; and what is conceived are things in the world. If I have the concept of redness, I must conceive of redness. Yet what happens, on such a view, to concepts as mental entities? Neo-Fregeans such as Peacocke, who identify concepts with senses or modes of presentation, retain the idea that senses are objective and public, but on this view what we take hold of mentally when we have a concept are abstract objects, not concrete ones. A concrete object presents itself in a certain way, but the conceiver does not take hold of the object, only of the way in which the object presents itself. Representationalists, by contrast, hold that the publicity of concepts is wholly accounted for within their theory by the fact that mental tokens instantiate types. Thus if Charles and Carol both have the concept of redness, the mental particulars each has within their minds/brains instantiate the single representation-type redness. Margolis and Laurence go as far as to say that whether we call concepts particulars or universals is a matter of mere terminology; since the representation tokens and their types both exist, we can focus on the tokens in constructing our theory of concept acquisition and possession (Margolis and Laurence 1999, 7, 76–77). If anything, though, the idea that the publicity of concepts as mental particulars is underwritten by their instantiating the same types fares less well than the neo-Fregean insistence that concepts are abstract entities that concept possessors grasp. In the latter case, the problem is that concept possession does not involve laying hold of the thing to which the concept applies; rather, it involves a mediated grasp of something abstract to which the thing is related in an appropriate way (e.g., via a mode of presentation). Even if

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we say, as plausibly we should, that the things to which the concepts are related are themselves abstract—kinds and properties (and their combinations), which in the terminology of Lowe (2006) are called substantial and non-substantial universals—grasp of these things is still mediated, on the neo-Fregean view, by the grasp of something else abstract but not identical to them. At least the neo-Fregean might have a story to tell concerning the indirect grasp of things in the world by means of senses. But to say that concepts as particulars are shareable merely in virtue of their instantiating types is to do away with the notion of grasping a concept altogether. It is wrong to say, for instance, that we grasp feelings or sensations. Yet particular feelings or sensations also instantiate types, and so we correctly say that two people can have the same pain or the same colour experience. Moreover, those particulars are caused by things or events in the world. So too the concept dog is a type whose tokens are particulars, in individuals possessing the concept, such that the particulars are caused by things in the world, namely dogs. However complicated the causal story, the basic structure is the same. Yet why then do we not grasp feelings or sensations in the way that we grasp concepts? It seems that the type-token distinction does not do the work required to show both what it is about concepts that makes them graspable, and what it is that we do when we grasp concepts. We need, I submit, a different approach to concept acquisition and possession. The approach must respect the idea that when we grasp a concept we lay hold directly of the thing to which it applies. In other words, concept acquisition and possession must involve direct engagement with the world, and it must require some kind of action on our part with respect to the world with which we engage. But concepts must also be the matter of reason: they must be the things upon which our rational faculty operates in judgment and inference. The details of such an approach must await another occasion, but in outline it invokes the idea of abstraction from the extra-mental world. In order to acquire the concept of triangularity, say, a person must either lay hold directly of a universal present in particular instances or else, by means little understood at present, receive that universal by communication from a person who has already done so. In either case, the universal—a real thing in the world existing as multiplied in its instances—must literally enter the mind of a person for them to acquire and possess the concept. In more traditional parlance, what is so abstracted is a form, be it substantial or characterizing, or some combination of these. Forms are essentially common, hence there can be no concept of individuals as such. I have the concept tiger because I have, say, been exposed to sufficiently many instances of individual tigers (the picture is of course more complex than this). But I can have no concept of Tigger the tiger. I can have the concept of a human being, but no concept of Socrates. It is not that the concept of Socrates, or Socrateity if you will, is forever beyond my grasp; rather, there is no concept of Socrates.

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3. NO INDIVIDUAL CONCEPTS What about individual essences? Suppose Socrates has a haecceity, a primitive thisness true of him. Would this not be the matter of an individual concept of Socrates? I do not see how it would. If there are haecceities (itself doubtful), then I can have the concept of haecceity as a generic property whose instances are unshareable, and hence conceive of it as applying generically to Socrates; but it does not follow that I have a concept of Socrates. In this sense, an individual concept would not be the concept of an individual. I could think of Socrates as being this individual, or as being identical to Socrates; but this does not mean I have a concept of him. Concepts are tied to understanding: to have a concept is to understand something. But I do not understand Socrates (except in certain figurative or otherwise irrelevant psychological contexts). Again, I understand what a human being is, and so understand that Socrates is a human being. Hence I have the concept of a human being, and apply it to Socrates. Part of what it is to have such a concept is to see how it does or might apply to certain individuals. But it does not follow that I thereby understand the individual except inasmuch as I understand what the individual is; but no individual concepts are involved in that. Similarly, I understand and can evaluate various propositions in which Socrates figures—that he is short, or snub-nosed. But again all I am doing is applying various concepts to an individual, and thinking of him as falling under those concepts; but thinking of an individual and having a concept of that individual are not the same, just as acquaintance with an individual and being able to reidentify an individual do not imply having a concept of the individual. Again, suppose there were individual essences in a thicker sense, involving bundles of properties. Could I not then have a concept of an individual (as opposed to the concept individuality, which we all have and which does not depend on there being individual essences)? Well, if Socrates possessed a unique bundle of tropes (modes in traditional terminology or property instances in modern parlance) then the question would merely be pushed one stage back: could I have the concept of this particular trope, or of this unique trope bundle? Similar considerations to those just raised would reemerge. Or else, if Socrates were identical to a trope bundle then I could know that Socrates is this trope bundle; but then I would simply know that a certain singular identity statement was true, and this would no more involve my having the concept either of Socrates or of the particular bundle than my knowing that Hesperus is Phosphorus involves my having the concept of Hesperus or the concept of Phosphorus (as opposed to knowing that Hesperus/Phosphorus falls under the (schematic) concept being a planet with such-and-such characteristics). Suppose Socrates possessed a unique set of properties (rather than tropes); then I would have the concept of those properties and of Socrates’s falling under them, but would not

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thereby have the concept of Socrates. And if he were identical to a bundle of properties, I would again merely know the truth of a singular identity statement. If, on the other hand, some or all of the properties were unshareable, the case for an individual concept would look stronger: for Socrates would not be identical with, or possess, a bundle of individual properties. The properties would not be individual since they would not be tropes. But they would not be shareable either. The sorts of property one might appeal to are likely to be relational, in particular spatiotemporally relational: having such-and-such an origin, being born at such-and-such a time and place, and so on. Would properties answering in the right way to such schematic descriptions be unshareable? Yes, but not in the sense required for me to have an individual concept of Socrates. Properties concerning origin might not be shareable in this world: for example, if Socrates came into existence at particular time t1and place s1, then no other person in this world can have that property.4 But such a property is shareable across worlds: Socrates has it in the actual world, but it is logically possible for another person to have it. Since the property is shareable in this modal sense, what I conceive when I conceive that Socrates is or possesses the relevant property bundle is that Socrates falls under the concepts defining the bundle (in the case of possession) or I simply conceive of the bundle, and think of it as Socrates (in the case of identity). In neither case do I have an individual concept. Rather, I have a concept or concepts of wholly shareable entities. The moral of the story concerning individual concepts is that since there are none, we have no reason to depart from the view that concepts concern entities shareable by the things that fall under them. They are, then, doubly shareable, since they can also be shared by the individuals who acquire and possess them. They are not senses or modes of presentation, since objects fall under concepts but they do not fall under senses or modes of presentation. Objects present themselves in various ways, and from these we derive conceptions of them; this is what modes of presentation most plausibly involve. If senses are just modes of presentation, the same consideration applies to them. If they are something distinct—a purely semantic entity of some sort—then a similar consideration applies, namely that objects do not literally fall under purely semantic entities. Objects fall under extra-mental entities that in some way correspond to semantic entities; but what could “correspond” mean? If it means only correlation, suitably fleshed out, then we are left with the position that if concepts are purely semantic entities that merely correspond to non-semantic entities outside the mind, then there is a conceptual veil between us and the world: we can have our concepts, but no objects literally fall under them. Concepts end up as Lockean ideas in a contemporary guise, forever mediating between us and extramental reality.5 We can never lay hold of an object, only of a sense to which the object in some way corresponds. But doesn’t this simply mean that

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Frege was right to regard concepts as universals? Not quite, since concepts as universals cannot be in the objects that are characterized by them, whereas for Frege they are: they are the denotata of predicate terms, and those denotata are the properties that characterize individuals. Yet universals, to be conceivable, must in some way be in the mind. This is no mere metaphor: concepts are the matter of judgment and reasoning, and though we can make judgments and reason about universals in rebus, we cannot perform acts of judgment and reasoning upon universals in rebus. We make judgments and inferences upon the things within our mind. So if we are to be able to lay hold of extra-mental reality directly, and at the same time be capable of acting mentally upon extra-mental reality, that reality has in some way to get into our minds. What gets into our minds, I submit, are precisely the universals—the forms—that obtain in reality, but only those universals as abstracted from the reality in which they obtain. These, then, are the concepts. They are best thought of not as abstract entities, but as abstracted entities (“extracted” has a nice connotation here as well)—entities the mind lays hold of directly and immediately.6

4. THE STORAGE PROBLEM A problem arises for the view that the mind, considered just as the brain (or some other physical entity or system), acts in a purely material way. For if the abstracted forms—the concepts—are literally in the mind so conceived, we should be able to find them, just as we are able to find universals in rebus by finding the things that instantiate them or the things of which they are true. We can find triangularity by finding the triangles, and redness by finding the red things. But we cannot find the concepts of either of these by looking inside the brain. Nothing in the brain instantiates redness or triangularity; when Fred acquires the concept of either, nothing in his brain becomes red or triangular. Yet these concepts must be in his mind, and if the mind just is the brain they should be in his brain; yet they are not. It seems that concepts are not located anywhere in the brain. But they must be in the mind since concepts are precisely what the mind acts upon in order to make judgments and inferences. Concepts are the matter of intellectual operation, but they do not seem to be materially located, whether in the brain or any other part of the person. This is what I call the “storage problem.” Moreover, it does not appear that all we need is a more sophisticated neuroscience or neuropsychology in order to find the concepts in our brains. For there is what might be called an ontological mismatch between concepts and any putative material locus for them, in other words between the proper objects of intellectual activity and any kind of potential

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physical embodiment of them. For a start, concepts and what they constitute—propositions and arguments—are abstract, whereas potential material loci for them are concrete. This is not a point about instantiation. The instantiation of the abstract by the concrete is a commonplace (however difficult it is to understand) and reveals nothing special about the human mind. Human beings, as said earlier, do not instantiate the concepts that get into their minds; they acquire, possess, and store them. It is no mere façon de parler to speak of a person’s stock of concepts, for such entities are indeed stored, in some way, in the mind. The problem of ontological mismatch, by contrast, is the problem of how an abstract thing such as a concept, with all its sui generis properties, could ever be stored or located in a concrete object such as a brain. Again, concepts are unextended; brains are extended. Here the idea is that concepts are not even categorially capable of location in a brain due to lack of extension. The lack on the part of concepts is not a mere privation, such as when a concept happens not to have a possessor, but an intrinsic incapability of possessing something—material location—by analogy with, say, the case of a number’s not being red. Looked at this way, it might be thought straight nonsense to claim that a concept is either extended or unextended. But this supports my point equally well, since it does make sense—and is true—to say that a brain is extended, thus preserving the idea of ontological mismatch. Further, concepts are universal, whereas material loci are particular. So the problem is how anything that is abstract, unextended, and universal could be embodied, located, or stored in anything concrete, extended, and particular. Concepts have an ontological profile that reveals them not to be the kind of thing that could be stored in anything physical. But they are stored in the mind. Therefore, the mind cannot be anything physical, whatever dependence it may have on physical things such as parts of bodies for certain sorts of non-intellectual operation such as sensation. (I will return to sensation later.) To complicate matters for the materialist a little more, consider just those concepts that are not only abstract, unextended, and universal, but also semantically simple, that is to say, incapable of further analysis into conceptual constituents. Suppose, per impossibile as I have argued, that the materialist could overcome the problem concerning ontological mismatch between the features of concepts just mentioned and those of potential material loci. Suppose she held that a semantically complex concept, like black dog (to use a typical Fodorean example) had its locus in the brain spatially distributed in a way that was isomorphic to its complexity. In this case, the concept black had location A, the concept dog had location B, and some kind of structural relation between A and B constituted the relation between the concepts as elements of the unified concept black dog. Now what could

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she say about simple concepts? We need not enter into debate about which ones they are, but that there are some is highly plausible: take the concept being, or the concept unity, or identity. Many non-naturalists in ethics would say good was unanalyzable. Let us assume these concepts cannot be broken down into constituents, though it be possible to give a contextual explication of them, illustrate them, and so on. Assuming all the other difficulties could be overcome, there would still not be any prospect of finding a material locus for these simple concepts unless the putative locus was itself materially simple, in the sense of being material but metaphysically indivisible.7 Speaking generally, the very idea of a material simple seems not to make any sense. If a material object were simple it would be unextended; but then it what sense would it be material? To countenance extended metaphysical indivisibles would be only to countenance objects that could not—perhaps according to metaphysically necessary laws of nature—be physically separated into parts. Such objects would still have geometrical parts, that is to say sub-regions defined by the spatial (or spatiotemporal) boundaries enclosing them. Yet simple concepts are in no sense complex: there is no sense of “part” according to which a simple concept has parts that are either separable or else inseparable according to some law but nevertheless definable in a way akin to the definition of geometrical parts of putative extended but metaphysically indivisible simples. Another approach might be to understand materially simple loci as idealizations or limits, like spacetime points. But there is no way of similarly understanding simple concepts such that the latter could be mapped onto the former: the simplicity of simple concepts just is not like any kind of simplicity that could be attributed to material loci. Going back to the idea of treating materially simple loci for simple concepts as extensionless points, it must be emphasized that an extensionless point is not a something but a nothing, and so could not be a locus for simple concepts, which are something. Further, extensionless points cannot have any constitutive relation to the extended, which is why Aristotle was adamant that the infinite divisibility of space and matter is only potential, not actual (Ross 1930, III.5–8, 204a7–208a25). But simple concepts do have a constitutive relation to complex ones, as good, for instance, does to good person. Yet suppose, despite all the difficulties, we could make sense of the idea of a material simple: could it be a candidate locus for simple concepts? Well, are we to postulate a simple located in the brain? If so, is it the same simple in which all simple concepts are stored? If the answer is yes, it is hard to make sense of the idea of multiple simple concepts in one materially simple location—about as hard as making sense of many dimensionless points located at one dimensionless point. If the answer is no, and the materialist proposes multiple material loci, he has to account for the mental unity by which one mind has many such concepts. Perhaps he could give

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an account in terms of geometrically defined structures linking any simple concepts to all the other ones, but no such account is currently available. And there are still the complex concepts, like black dog, to deal with. They could not be located in material simples; at least, it is hard to see how any kind of complexity could be embodied in something simple. Even on the interpretation of material simples as extended but metaphysically indivisible, the problem of separability rears its head: for the simple so understood is not divisible, but the complex concept is. Fred can have the concept black without the concept dog, and vice versa. He can have the concept black and then acquire the concept dog, or have both concepts and then lose one of them. But the extended yet indivisible material locus is by definition never separated, let alone put back together or increased. The other option is for the materialist to hold that complex concepts have materially complex locations, such as extended brain regions. Then he has to account for mental unity given that the simple concepts have simple locations. How are the simple locations related to the complex ones—in the way that lines are related to points, or areas to lines, or volumes to edges? I do not claim to have proved that no such structural account could be given, only to have shown that the existence of simple concepts merely aggravates the already immense difficulty of smoothing over the fundamental mismatch between concepts and their putative material storage.

5. FINITENESS, INFINITY, AND THE INTELLECT One of the fundamental problems of cognitive science, in its ubiquitously materialistic guise, has been to explain the storage of concepts. Most of the research, however, is either beside the point insofar as it attempts to solve the storage problem, or else yields precious little knowledge. In a recent paper, Martin and Chao (2001, 195) note: “A common feature of all concrete objects is their physical form.8 Evidence is accumulating that suggests that all object categories elicit distinct patterns of neural activity in regions that mediate perception of object form (the ventral occipitotemporal cortex).” The authors go on to describe how functional brain-imaging techniques show that representations of different object categories are located in discrete cortical regions that are “distributed and overlapping,” embedded in a “lumpy feature-space”(2001, 196). To be sure, functional imaging may well reveal correlations between certain intellectual activities and certain cortical activities: if, as the dualist should hold, persons are essentially embodied beings,9 such correlations are only to be expected since persons require corporeal activity in order to interact with the world both physically and mentally. But correlation and co-location are not the same thing.

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Martin and Chao go on, prudently, to say (2001, 196): “Clearly, it would be difficult, as well as unwise, to argue that there is a ‘chair area’ in the brain. There are simply too many categories, and too little neural space to accommodate discrete, category-specific modules for every category. In fact, there is no limit on the number of object categories.” In a later paper, Martin reviews the evidence for regions of neural activity associated with the learning and recall of “object concepts” (Martin 2007). What object concepts are supposed to be is not clearly explained, though he talks about the “representation of the meaning of concrete objects and their properties” (26), itself a somewhat vague and loose formulation. What he concludes is that information about the sensory and motor properties of objects is “stored in [the] corresponding sensory and motor systems” of the brain (38), and that objects in different categories, such as faces and animals on the one hand and tools on the other, are “represented in” distinct but overlapping regions. Yet he holds that “object concepts are not explicitly represented, but rather emerge from weighted activity within property-based brain regions” (25). Again the formulation is rather vague, but the idea seems to be that knowledge of what kinds of object are and what they do is spread throughout the brain, engaging a number of predictable regions associated with sensory and motor knowledge, as well as category-specific regions that themselves overlap the former. All of this is consistent with Martin and Chao’s considered view that there cannot be a region for each category. That distinct neural regions are associated with broad categories of object (e.g., animals versus tools), and that every representation of an object concept engages numerous distinct but overlapping areas, does nothing to undermine the idea of a fundamental ontological mismatch between concepts and their putative material embodiment. The intellect is capable of grasping a potential infinity of concepts, but no corporeal organ can harbour a potential infinity of anything. Looked at purely quantitatively, the problem can be put in terms of a dilemma. Either the more complex the concept, the larger the brain region in which it is stored; or the more complex the concept, the smaller the region. If we take the former, then the materialist is faced with the evident finite size of the brain: at some point there simply will not be enough brain space for new and more complex concepts than any that have so far been stored. If we take the latter, then we have to believe that more and more complex concepts can somehow be stored in smaller and smaller regions: yet how can this be? Are we to believe that, say, the concept black, furry, friendly, small, loyal, hungry dog is stored in a smaller region than the concept dog? How can less neural matter perform a greater storage function? Looked at qualitatively, the intellect is distinguished by the feature that it can grasp a potentially infinite number of categories of concept, and within

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each category a potentially infinite number of exemplars. In other words, there is no limit to the number of kinds of thing the intellect can grasp, and no limit to the number of examples of each kind that it can recognize. By contrast, organs such as the eyes or ears can only receive categorially limited kinds of stimulus, such as colours and sounds respectively (inter alia); and within each kind of sensory stimulus they can only receive a limited number of examples; hence we cannot naturally see certain colours or hear certain sounds. The very physical finiteness of the organs of sight and hearing means they are bounded with respect to what kinds of information they can take in. This is patently not so for the intellect; but it does not exclude the fact that the intellect, being finite in its own way, cannot discover certain things. There is a difference between the intellect’s not being able to reach certain truths by its own operation, and its suffering an intrinsic material limitation on the kind of information it can take in. The absence of such a material limitation, again, is consistent with the intellect’s being extrinsically limited in respect of the physical information it can take in—for example, not having the concept of a colour that is beyond the visible spectrum available to the eye.10 But if the sort of limitation just mentioned applies to the eyes and ears, it must apply to any proposed organ for storing concepts. The features of the eye and ear that make them singularly unsuitable for intellectual operation apply equally to the brain, the nervous system, or any other proposed material locus. It is the very materiality of such a locus that prevents it from storing the proper objects of intellectual activity.

6. ANIMALS AND LOWER MENTAL FUNCTIONS It might be wondered why the analysis I have given of the ontological mismatch between concepts and potential material loci does not apply equally to lower mental functions such as sensations and feelings. Should not the dualist equally argue that sensations, for instance, are unextended, abstract, and universal? And if so, since many animals have them, shouldn’t we be dualists about those animals? A dualist could, of course, bite the bullet and draw the same conclusion as she draws concerning human beings. But there is no obvious reason to do so. The only sense in which a sensation such as pain is an abstract entity is that it is a type of sensation that has particular tokens. It is not an abstracted entity in the sense we should give to concepts as explained earlier. In order to have a pain, a creature does not need to abstract anything from anything, whether in the extra-mental or the mental world. In order to have a pain, nothing universal—no form, to use the traditional terminology—needs to enter into the mind of the creature that possesses a pain. Pain is itself a uni-

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versal—a kind of modification or characteristic of a thing. Its instances are the particular pains that individual pain sufferers have. Being in pain is also a universal, and its instances are the particular states of being in pain of individual sufferers. Nevertheless, for an individual to be in pain, no universal needs to enter into the mind of the sufferer; what happens when a creature is in pain is, as far as universals go, perfectly well accounted for, in contemporary terms, by the type/token distinction. A token of a certain sensation type gets into the mind of the sufferer. How does it do so? By the usual causal processes by which pains are brought about. Now there might be a further question about the qualitative aspect of pain, whether it is reducible to anything physical, and so on. To discuss this would take us into the classic issues surrounding reductionism and the identity theory that I have sought to avoid. There is no need to canvass them here because they both play no role in my argument and raise questions about the very terms in which the current debate is framed, some of which I have already discussed elsewhere (Oderberg 2005). As far as the argument presented here is concerned, all that needs to be said is that the storage problem has no evident analogue in the case of a lower mental function such as sensation in general or pain in particular. Since, in the case of sensation, nothing abstract needs to enter into the mind of the creature that has it, so nothing unextended or universal needs to enter into its mind. What enters its mind will be wholly particular, and as such there should be no metaphysical barrier to investigating where such a particular might be located in a physical object such as the brain or a physical system such as the nervous system. By contrast, in order to have the concept of pain something abstract, that is to say abstracted, would need to enter into the mind of the possessor of that concept. The possessor would need to abstract from particular pains the universal or form pain, a real universal existing as multiplied in its various instances. The ontological mismatch problem, hence the storage problem, would again arise. But we have no reason to think that non-human animals that are capable of having pain are also capable of having the concept of pain. So again the dualist is in no way forced to countenance the existence of anything immaterial in the animals.

7. CONCLUSION The idea that certain mental functions require an immaterial element in the human mind raises, of course, all the usual questions about what that element could be, and whether countenancing it is simply a case of explaining the obscure by means of the more obscure. I have discussed some of the issues related to these worries in another place (Oderberg 2005). Speaking generally here, I want to end with two observations.

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First, there is much that can and should be said about the immaterial element in the human intellect, especially how it is related to the body. Hylemorphic dualism has a metaphysical story to tell about that relation and about the operations of the mind in both its material and immaterial aspects. In many ways it is a superior account to other kinds of dualism. It sees the human person as a compound of immaterial soul and material body, united in a complex way that is in some ways like, and in others unlike, the hylemorphic composition of material substances. So hylemorphic dualism is embedded within a broader metaphysic and is only comprehensible within the terms of that metaphysic. The broader account is, however, evaluable on its own merits, and itself has much to commend it (see further my 2007). Perhaps what distances hylemorphic dualism most from Cartesian dualism is precisely that it does not treat the mind as an add-on to an otherwise materialistic and mechanistic universe, but embeds it in a general ontology. True, for the hylemorphic as for other kinds of dualist, there is a radical discontinuity between mind and matter. But for the hylemorphist there is also a continuity according to which higher mental functions such as concept acquisition and possession are placed in an overall hierarchy of functions possessed by the various kinds of thing that exist. The human being himself is placed within such a hierarchy. He is not a Cartesian ego or centre of consciousness placed within a sea of materiality. The human being is himself essentially material in part, and so not wholly explicable in immaterial terms. There is a tension here, but it is a healthy tension the understanding of which enables us to comprehend the place of the human being in the cosmos. Secondly, and on a more modest note, there is nothing wrong in itself with negative ontology any more than negative theology. To establish the basic claim of dualism, at least along the lines presented here, nothing needs to be said about what the immaterial element of the mind is, whether the mind is wholly immaterial, whether it has location, how it interacts with the body, how it could support the existence of concepts within it, and so on. All that needs to be established is that whatever the acquisition and possession of concepts really involves, it cannot be purely material. Matter simply is not sufficient to support or explain the phenomenon of human conceptual thought. To say that conceptual thought cannot be like that does not imply an obligation to explain just what it is like. To some extent, though, I have said what it must be like. There is still a lot more to be said— drawing on a story that in all its essentials goes back to Aristotle.11

NOTES 1. On the Generation of Animals II.3, 736b28: “for bodily activity [somatiké energeia] has nothing in common with the activity of reason [nous]” (my translation);

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see also De Anima II.1, Ross (1931), 413a6 and De Anima III.4, Ross (1931), 429a25. 2. I also do not intend to discuss the prototype theory of concepts, according to which concepts are representations encoding information about statistical relations between things that fall under the concept and features the things possess. The theory, at least on some interpretations, takes concepts to have an entitative character in the sense I propose, but prototype theory is also wildly implausible and has been refuted by Fodor; see (1998), chapter 5. 3. Talk of “internal” and “invisible” qualities invites the thought that children are “hidden structure” essentialists of a Putnamian or even Lockean kind, but such essentialism is in itself questionable as a general theory of essence (Oderberg 2007, chapters 1 and 2) and does not seem necessary in accounting for children’s essentialist practices. 4. In fact it is more complicated than that. Even Socrates’s property of having come into the world at a particular spatiotemporal location is shareable in this world, being actually shared by his head; or if this can be evaded by precisifying the respective locations, then it is shared by his body; or for those who believe Socrates just is his body, then it is shared by the mereologically essential lump of matter constituting him at the very time and place at which he and it came into existence. 5. A word about “extra-mental.” It might be thought that concepts of mental states, for instance, are not concepts of anything extra-mental. But “extra-mental” in the present context means “outside the mind of the person having the concept.” To have a concept of pain, for instance, involves having the concept of something that exists outside the mind of the possessor, even if the possessor happens to be in pain. Their particular pain instance is in their mind; but pain itself is not. 6. I have argued that there are no concepts of individuals. What about the concept of God? (I am grateful to Philip Stratton-Lake for posing this question.) On the theory of what concepts are that I propose, there is no concept of God either, appearances notwithstanding. Although there is no room to go into all the details here, the basic idea is that it is no more the case that God has instances than that Socrates or Fido have instances. God is not identical to any universal or combination of universals than are other individuals. Hence God is no more to be identified with anything the mind can abstract than are other individuals. Indeed, it is plausible that there is even more reason for denying that there is a concept of God than that there is a concept of Socrates. For Socrates has a definition inasmuch as he, like all other human beings, is a rational animal. So we at least have the concept of Socrates qua rational animal. This is not the concept of Socrates qua Socrates, i.e. qua individual distinct from other individuals of the same (or another) kind. Such concepts are what I deny in the present section: it is Socrates’s very individuality that prevents there being a concept of him in this sense. If we want to say that there is a concept of Socrates in the sense that we have the concept of a human being and can define it, well and good. But it is arguable that God does not even have this. God does not have a definition in the sense in which Socrates has one, since He does not fit into the genus/species taxonomy whereas Socrates does. (For more on taxonomy, see my (2007).) He is not an instance any more than He has instances. We sometimes think of God as a kind of deity or divinity, but on reflection we can see that such a way of thinking is at best merely analogous to the way we think of Socrates

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as a kind of human, at worst incoherent. For what might the kind deity even be? It is not the mere necessary uniqueness of God that makes such a question seem absurd (though I suspect this to be relevant) but the fact that there are no available criteria for what even counts as being in the putative kind deity. It follows that the typical textbook examples of the definition of God (a being that is omnipotent, omniscient, etc.) are not strictly definitions at all but ways of thinking of God: to use the Kripkean terminology, such property designations help to fix the reference of “God,” just as “was the teacher of Plato” helps to fix the reference of “Socrates.” That I can think of Socrates as the teacher of Plato does not imply that I have a concept of Socrates. The Anselmian account of God as a being greater than which none can be conceived should be treated similarly. 7. Why couldn’t the locus be materially complex? But then it would have parts, whereas simple concepts have none. Suppose, however, that there was a law of nature such that the proposed materially complex locus for a simple concept was a physical minimum; any locus smaller than that could not be the locus of a concept. If this were the case, then although the complex locus would be divisible, its parts could not themselves be loci for concepts, thus matching the property of simple concepts that they have no parts that are concepts. The problem is that the complex locus would still be divisible, even though not into parts that could themselves house concepts. Simple concepts, by contrast, have no parts whatsoever (ex hypothesi), whether semantic, syntactic, or of any other kind. Hence they would have nothing to correspond to the putative materially complex locus, and the mismatch between them would stand. (I am grateful to Andy Taylor for raising the point that prompted this note.) 8. Note the use of the term “form,” which in the context of the paper means something more than shape. The Aristotelian air is suggestive. 9. To say that persons (by which I mean human persons) are essentially embodied is not to say that they must have a body at every moment of their existence; see further Oderberg (2005). 10. Similarly, what I argue is consistent with our being limited by memory and other physical constraints on what concepts we can retain. That we can and do forget what we have learned does not undermine the storage problem. The process of forgetting is little understood, but whatever it involves it is not an excess of concepts physically stored in the brain, i.e. a simple lack of brain space. The physical mechanisms of memory do not help us to resolve what is a metaphysical problem. 11. I am grateful to colleagues and students at the University of Reading Work in Progress seminar for comments on a draft of this paper.

BIBLIOGRAPHY Ezcurdia, M. 1998. “The Concept-Conception Distinction.” Philosophical Issues 9: 187–92. Fodor, J. 1995. “Concepts: A Potboiler.” Philosophical Issues 6: 1–24. ———. 1998. Concepts: Where Cognitive Science Went Wrong. Oxford: Clarendon Press.

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Frege, G. 1951. “On Concept and Object”. Mind 60: 168–80. (Orig. pub. 1892; translated by P. Geach and M. Black. Reprinted in Translations from the Philosophical Writings of Gottlob Frege, edited by P. Geach and M. Black. Oxford: Blackwell, 1952, and in The Frege Reader, edited by M. Beaney. Oxford: Blackwell, 1997). Gelman, S.A. 2003. The Essential Child: Origins of Essentialism in Everyday Thought. New York: Oxford University Press. Margolis, E. and Laurence, S., eds., 1999. Concepts: Core Readings. Cambridge, Mass: Bradford Books/MIT Press. Martin, A. 2007. “The Representation of Object Concepts in the Brain.” Annual Review of Psychology 58: 25–45. Martin, A., and Chao, L.L. 2001. “Semantic Memory and the Brain: Structure and Processes.” Current Opinion in Neurobiology 11: 194–201. Loeb, 1943. Aristotle: Generation of Animals, translated by A.L. Peck, Loeb Classical Library. Cambridge, MA: Harvard University Press. Lowe, E.J. 2006. The Four-Category Ontology: A Metaphysical Foundation for Natural Science. Oxford: Clarendon Press. Macià, J. 1998. “On Concepts and Conceptions.” Philosophical Issues 9: 175–85. Nagel, T. 1974. “What is it Like to be a Bat?.” The Philosophical Review 83: 435–50. Oderberg, D.S. 2005. “Hylemorphic Dualism.” In Personal Identity, edited by E.F. Paul, F.D. Miller, and J. Paul, 70–99. Cambridge: Cambridge University Press, (Orig. pub. as Social Philosophy and Policy 22, 2005, 70–99.) ———. 2007. Real Essentialism. London: Routledge. Peacocke, C. 1992. A Study of Concepts. Cambridge, Mass: MIT Press. Ross, W.D., ed. 1930. Aristotle: Physics. Oxford: Clarendon Press. (Vol. II of The Works of Aristotle.) ———. 1931. Aristotle: De Anima. Oxford: Clarendon Press. (Vol. III of The Works of Aristotle.)

Index

action, ix, 163 action potential, 85 Alexander, S. 185–87, 193, 207–08 animal, 162–63, 165n12 Aquinas, 205, 208–09 argument from dimension, 130–31 Aristotle, 102; on immateriality of intellect, 213; on infinite divisibility, 225 Baker, L. R., 42, 151, 164n4, 165n12, 166, 169, 172, 174 Bawden, H. H., 118 beliefs, 11–12, 14, 17, 19 Bennett, J., 181 binding problem, 85 bodies, 168–69, 170, 171, 172–77, 180 body-mind problem, 127–29, 132–34 Bohr, N., 105 brain, 18, 20–21, 30, 118, 168, 175–76 Brightwell, 107 British Emergentists, xiv, 185–86, 199, 207–08 Broad, C. D., 108, 185–91, 207 calculational device, 104, 114 capacity. See dispositions Cartesian doubt, 170

Cartwright, N., 104 category, xv causal: closure, xii, xiv, 120, 147–48, 159, 177–82, 195, 197; correlate, 159; equivalence, 159; explanation, 180–82; overdetermination, 160; parallelism, 160; powers, viii, 193, 197–99, 201, 203–04, 206; realization principle, 193; set, 107 causality, 74, 92,n1; strong , 74, 92n1; weak, 92n1 causation, 147–48, 159–60; mental causation, ix–x; conditional forward, 113 cause: conditional forward, 113; levels, 108; principal, instrumental and occasional, 111; top-down, 116. See also dispositions Cerebral cortex, 49, 54, 56, 58–59, 61 Chalmers, D. J., 65, 149 Chisholm, R. M., 176 choice, 180–82 co-evolution of mind and body, 205, 208 cognitive processes, xv, 59–60, 61–62; development, 4–30; stages, 108 common sense psychology, 49, 57 Commons, M. L. 109

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complementarity, 72, 76–77, 90–91 composition, 172–73 conceivability argument, 170–71 concepts, 168, 211–33; as abstracted objects, 223; no concepts of individuals, 221–23; entitative character, 213; of God, 231n6; and infinite capacity of intellect, 226–28; ontological profile of, 224; as public and shareable, 218–20; as senses or modes of presentation, 219–20; simple and complex, 224–26; and the storage problem, 223–26; and type/token distinction, 219–20 conscious experience. See consciousness consciousness, ix, xiii, 87, 70, 81, 90–91, 157, 160, 162–63; in animals, 211–12, 228–29 conservation laws, 120 constitution, 172–73 contrastives, 9–10 correspondences, 115 Crane, T., 148, 150–51, 166, 168 cross-cultural comparisons, 12–13, 19, 22, 24–25, 28 cultural information. See cross-cultural comparisons culture, role of the, 50 Damasio, A. R., 50 Davidson, D., 148, 150, 166 death, 23–25 decision, 180–82 decision-making, 48–49, 56–57 decoherent history, 105, 114 definition, essentialist, 216–17 dendron, 79, 82, 85–87 Dennett, D. C., 149–50, 164, 164n2, 164n3, 166 dependence of the mental on the physical, 152 derivative dispositions, 103 Descartes, R., 99, 149, 152–54, 165n6, 169, 172, 190, 204 desires, 8–9, 14, 17, 19 determinism, 182

differentiating vs non-differentiating attributes, 189 discrete degrees, 99–123 dispositions, 101–10; categorical irreducibility, 102; derivative, 103; ontology, 114 downward causation, 193–97, 199–201; reflexive vs. non reflexive 194, 207; synchronic vs. diachronic 194, 207 dualism, 69, 75, 89, 90, 145, 152–54, 156, 189, 190–91, 198–99; aspect, 44–45; Cartesian, 69, 70–71, 75–76, 132–36, 206; emergent, 185–209; epistemological, 45-46; hylemorphic, 211–33; hylemorphic versus Cartesian dualism, 230; interactive,177–9; mental, 90; methodological, 45–46, 157–58 ; mind-brain, 69; naïve, 3–4, 10, 17, 30; of incompatibles vs of compatibles, 190, 207; particle-wave, 72–73, 76, 90, 92n2, 92n5; polar, xiii, 136–40; property, 45, 167–68, 197–98; quantum, 76; substance, 45, 167–82; weak, 129–31 Eccles, J. C., 100 eliminativism. See materialism eliminative emergent: laws, 188, 190–91, 201–02; materialism, 189–90; vs. resultant properties, 197; substance dualism, 202–06 emergentism, xiv, 52–53, 185–209; vs non-reductive physicalism, 191–98; epistemic vs ontological, 186; and creatio ex nihilo, 205 Emmet, D., 112 emotions, 9, 14, 17, 19, 49, 53–54, 56, 63 energy,103; conservation, 120 epiphenomenalism, 148, 159, 195, 197, 199 epistemic possibility, 171 EPR-Gedankenexperiment, 77

Index event: causation, 181–82; selection, 105 evolution, 160–63; emergent, 186, 196, 209 evolutionary advantage. See evolution exocytosis, 80, 81, 82, 89, 84–86, 91, 95; experiences, 168, 175. See also consciousness, intentionality and intentional experience explanation, 60–61 fact-causation, 181 false beliefs. See beliefs field: of propensity, 102; quantum field, 105 first-person perspective, 41–42 fMRI, 54 Fodor, J.: on concept reductionism, 213–15; on definitional pragmatism, 215–18 force, 103 Foster, J., 169 Frege, G., 219, 223 freedom of choice, 181 Freeman, W. J., 50 free will, ix, 89, 202, 209, 211 functionalism, 148 Gelman, S., 217 generative sequence, 111–15 goals. See intentions God, 19, 28–29 Gowan, J. C., 109 Hamiltonian, 104 harmony of the body, 99 Hasker, W. 201–03, 205, 208 Heisenberg: Gedankenexperiment, 76; uncertainty relation, 77, 83, 92n8 hidden parameters, 77 Horgan, T., 150–51, 166 human being, 162, 165n12, 165n13 Humphreys, P. 200, 203, 207–09 Husserl, E., 149 Idealism, xii, 128–30 identity-conditions, 173–74

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identity theory, 143–46, 150, 154 illusion, 43–44, 50 independence of the mental from the physical, 152–55 indeterminism, 163 indivisibility argument, xiv, 171, 174 information, 161–62 inner experience, 42 instrumental cause, 111 insula, 54, 56 intellect: intellectual activity, xv intellectual justice, 156 intentional causation, 181 intentionality, viii, x, xiii, 4, 8, 17–18, 30, 42, 46, 57, 63, 65, 136, 140; intentional experience, 158, 161 intentions, 5–6, 7, 19 intersubjectivity, 42 intuitive ideas, 4, 17, 18–19, 22, 27–30 intuitive psychology. See theory of mind Kim, J., 167, 172, 177, 192–200, 207–09 Kripke, S., 52 Kuhn, T., 156 language, 137–38 laws of nature, 160–61 Leibniz, G. W., 149 Lewis, D. K., 148, 157, 166 Libet-experiment, 89,180 limbic system, 59, 61 Lloyd Morgan, C. 185–86, 193, 197, 209 localisation, 59, 64 Lowe, E. J, 165n15, 166,168, 169, 172, 173, 174, 175, 177, 179, 180, 181, 182 Margolis, E. and Laurence, S., 219 Martin, A. and Chao, L. L., 226–27 Mary, thought experiment of, 47–48 materialism, 127–28, 130–31, 143–44, 149, 151–53, 155–58; eliminative, vii, 50, 51–52, 145–46, 150; honest,

238

Index

154; mysterious, 151n5; non-reductive, 144, 150–56; reductive, 144–46, 148, 150–55 matter, 102 McGinn, C., 164n5, 165–66 measurement problem, 101 mechanism, 188–89, 191, 207 Meixner, U., 170, 178 Mellor, D. H., 168 memory, 115 mental, 128–29; space, 119; states, 4, 7, 14–16; substance, 119. Meschini, D., 107 metaphysical possibility, 171 metaphysics, 157 mind, 18, 20–21, 23, 25–27, 30 mind-brain duality, 69, 70, 71–72, 90 mirror neurons, 64 modularism, 64 Molnar G., 102 monism, 152; neutral, 164n5; reductive vs. non-reductive, 189; and transphysical laws, 190–91 multiple realization argument 192 multiple generative levels, 103, 113 Mumford, S., 114 mysterianism, 164n5, 165 Nagel, T., 52, 212 naturalism, 118, 158 naturalization, viii, xiii non-algorithmic binding, 87 non-Cartesian substance dualism,168–82 nonlocality, 120 non-predictability vs. non-deducibility of properties, 185–86 novelty, 186–87, 190, 192 occasional cause, 111 O’Connor, T. 198–200, 203–07, 209 Oderberg, D. S., 211, 229 Olson, E. T., 172 ontology: of dispositions, 102, 114 pain, 52, 53; and other sensations, 228–29

parallelism, 55, 60, 62, 178–79 Peacocke, C., 218–19 Penrose, R., 106 perception, 115 persistence-conditions, 174 persons, 168, 180 PET, 58 phenomenal seeming, 158 phenomenology, 158, 165n13 philosophy, 143, 149, 156; analytic, 157 physical correlate, 158–59 physical realization thesis, 192–93 physicalism, vii, ix, xiii, 143, 150, 178–79 Piaget, J. R., 4–5, 15, 18–19, 108; childhood animism, 5; childhood realism, 5, 15 potential barrier, 84, 92n8, 95 potential energy, 103 potential. See dispositions power. See dispositions pregeometry, 106 principal cause, 111 probability, xi, xiii propensity. See dispositions properties, 167–68 psychoanalysis, 59 psychological states. See mental states psychology, 107–10, 115–18, 146, 158 psychon, 87 psychophysics 158–59 qualia of experience, 191 quality, secondary, 131, 139, 188, 191, 207 quantum: field theory, 105; mechanics, xi; physics, xiii quasiparticle, 83–84, 95–96; mass of, 83, 97 Quine, W. v. O., 150, 157, 164n3 readiness-potential, 89 reality of the mental, 43–44 reasons for action, 181 reducibility, 164n1 reduction of the wave packet, 104, 111

Index reductionism, xiii, xiv, 114 reflection. See reflective ideas reflective ideas, 4, 17–19, 21–22, 27–30 religion, 156 replacement argument, 174 representation, 11–12, 14, 17, 161, 165n10, 165n11 Robinson, W. S., 177 Rovelli, C., 106 Ryle, G., 150, 164n3 Schroedinger equation, 101, 112 science, 143, 148–49, 156–58 scientific world-view, 157 Scruton, R., 173 Searle, J., 41, 165n11, 166 selection event, 105 self, xiv, 172, 173, 175, 180 self-consciousness, viii, xiii, 162 sensation, xv, 61 short time spectroscopy, 84 simplicity of the self, 171–73 soul, x–xi, xv, 18, 23, 25–27, 30, 172 space: mental, 119 special sciences, 187 Sperry, R. W., 52–53 stochastic resonance, 87–88 Strawson, P. F., 175 subject of action, 163 subject of experience, 161–64, 165n13, 165n15, 166, 191

239

subjectivity, 41–42, 52 subjects, 175–77 substance, ix, xiv, 163–64, 165n15, 166, 167; mental, 119 supernatural beings, 4, 27–29 supervenience, 129, 190, 192, 198, 225; global, 129, 129n2 Swinburne, R., 169 temporal continuant, 163 theory of mind, 4, 8–18, 30 Thompson, I. J., 102, 109 thoughts, 176–77 three-world-classification, 71 token-identity theory. See identity theory transcendental ideas, 17, 22–29 tunnel effect, 84 type-identity theory. See identity theory ultimatum game, 54, 57 unity argument, 175–77 universals, xv upward determination, 194–97 van Inwagen, P., 176 vesicle, 78–81 vitalism, 188, 196 Walker, E.H., 100 wave function. 104 Wittgenstein, L., 150, 157, 164n3

About the Editors

Alessandro Antonietti is full professor of cognitive psychology and head of the department of psychology at the Catholic University of the Sacred Heart in Milano. He carried out experimental studies about creativity, mental imagery, analogical thinking, and multimedia learning. He was also interested in theoretical issues concerning the epistemological foundations of psychology and the mind-body problem. Antonella Corradini is professor of philosophy of the human sciences at the Catholic University of Milan, Italy. She studied philosophy of science, logic and ethics at the Universities of Padua, Würzburg, and Regensburg and obtained her PhD degree at the University of Genua with a dissertation on the logical and epistemological aspects connected to the foundations of ethics. Her main research concerns regard the philosophy of mind and action. the philosophy of psychology, the philosophy of biology, and the human sciences and the foundations of ethics. With S. Galvan and E. J. Lowe, she is coeditor of Analytic Philosophy Without Naturalism, Routledge 2006. E. Jonathan Lowe has been educated at the Universities of Cambridge (1968–1972) and Oxford (1972–1975). He has been a member of the Philosophy Department at Durham University since 1980 (and professor since 1995), specializing in metaphysics, the philosophy of mind and action, the philosophy of logic and language, and the philosophy of John Locke. He is the author of Kinds of Being (1989), Locke on Human Understanding (1995), Subjects of Experience (1996), The Possibility of Metaphysics (1998), An Introduction to the Philosophy of Mind (2000), A Survey of Metaphysics (2002), Locke (2005), The Four-Category Ontology (2006), and Personal Agency (2008). 241