The ABC of Modal Epistemology - A Further Attempt to Meet the Epistemic Challenge

The (a)(b)(c) of Modal Epistemology: A Further Attempt to Meet the Epistemic Challenge. Sonia Roca

Abstract: This paper is about the epistemic challenge for mind-independence approaches of modality. The challenge is to elucidate the possibility conditions for modal knowledge, and arises from acceptance of the following three premises: (a) We have modal knowledge (which, for a mind-independence theorist is knowledge of the extra-mental world); (b) Any knowledge of the extra-mental world is grounded on causal affection; and (c) Any knowledge grounded on causal affection cannot outrun knowledge of mere truths (as opposed to modal truths). Most attempts to solve the challenge (Peacocke’s, Yablo’s and Chalmers’ among them), try to do so by denying premise (b). Here, reasons are given to doubt about the adequacy of such a strategy, and it is suggested that a better way of solving the challenge is by qualifying the acceptance of (b) as well as by denying (c).

1.

Mind-Independence and Epistemic Access.

Mind-independence accounts of modality have in common the claim that modal truth is independent on what is true about the subjects that think with modal concepts. In other words, that the truth makers for modal claims are out there, where ‘out there’ should be understood as out of the mind. Under the unquestioned assumption that we have modal knowledge, an epistemic problem is raised against mind-independence theories; according to the objector, those theories do not explain the possibility conditions for modal knowledge. As the problem has been traditionally presented in the literature, mind-independence theorists would be committed to a necessity-sensitive faculty that allows us to recognize modal facts. If we work under the assumption that there is such a faculty, it seems, the objector says, that the only plausible way of articulating the possibility conditions for modal knowledge requires us to be committed to the claim that this faculty enables us to be causally affected by modal facts. In E.Craig’s terms: How are we to know of necessity in reality unless it affects us, and in some way differently from mere truth? […] Think of the analogy: what affects my senses is the fact of the tree’s being there; it wouldn’t affect them any differently if its being there were necessary. [Craig, 104]

The diagnosis of the problem, as S. Blackburn states it, is that “we do not understand our own must-detecting faculty.” [Blackburn, 52]

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The problem can be formulated as follows: (a)

We have modal knowledge (which, for a mind-independence theorist is knowledge of the extra-mental world).

(b)

Any knowledge of the extra-mental world is grounded on causal affection.

(c)

Any knowledge grounded on causal affection cannot outrun knowledge of mere truths (as opposed to modal truths).

When endorsed from a mind-independence treatment, claims (a)-(c) are inconsistent, since (b)(c) imply not-(a). Thus, a mind-independence account must deny at least one of these claims. The (a)(b)(c) argument does a lot against mind-independence approaches. It may be seen as not really demanding an explanation of the possibility conditions for modal knowledge, but arguing instead for the impossibility of modal knowledge when the modal realm is seen as mindindependent. When the claim that we have modal knowledge is something we are not ready to cast doubts on, we must provide an explanation of how we can get modal knowledge. This is the starting point for most philosophers attempting to meet the epistemic challenge, and it makes the denial of either (b) or (c) mandatory, since they jointly deny (a). 2.

Shortcomings of Different (a)¬(b)(c) approaches.

In this section, I will survey and critically examine Peacocke’s, Yablo’s and Chalmers’ different ways of addressing the epistemic challenge. They all have in common the view that modal knowledge is fundamentally an a priori matter, and thus, their approaches constitute positive contributions to what G.Bealer has named ‘Rationalist Renaissance’ in Modal Epistemology.1 2.1

Peacocke’s Principle-Based Account.

Peacocke [(1997) and (1999)] has contributed to the current debate with the proposal of his Principle-Based Account; a mind-independence account which is claimed to meet the epistemic challenge. Since he shares, with his mind-dependence opponents, assumptions (a) and (c), his strategy is the denial of (b); see [Peacocke (1999): 170]. Roughly, his way of doing so is by identifying a set of Principles of Possibility, claimed to be implicitly known by any competent possessor of the concept possibly. I am not going to present 1

It may be thought that modal rationalism is precisely motivated by the belief that the modal realm is mind-dependent, and in particular that modal truth has its source in meanings and conventions. This would be mistaken if intended to be generally true. As for the approaches examined here, Peacocke could not be more explicit about his approach being a mind-independence one with a rationalist epistemology (see [Peacocke (1999): ch.4]); Yablo is also quite explicit about his mind-independence preferences in [Yablo (1993)], especially in §XV, and in [Yablo (1996)], especially in §XV. Chalmers is less explicit about this, but we can intuit a mind-independence flavour in how seriously he takes the threat posed to modal rationalism by strong necessities if there were any, and, although he is less explicit, it appears obvious to some that Chalmers intends conceivability as giving us access to modal facts out there (see, for instance, Della Rocca’s objection to Chalmers’ presupposition that “the modal properties of a thing are independent of the way that thing is referred to, or described or thought of” [Della Rocca (2002): 225].

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Peacocke’s account in detail here; for present purposes, it suffices to say that those principles encode constitutive/essential relations among concepts, and constitutive/essential relations among entities at the level of reference. Modal knowledge is analyzed in Peacocke’s account as consequential upon our knowledge of the Principles of Possibility (argued to be non-modal)2. That is, our way of coming to know modal truths is by reasoning from the Principles of Possibility, such that the epistemic status of our modal beliefs is inherited by the epistemic status of the Principles of Possibility. This elucidation of the possibility conditions for modal knowledge relies on the plausible assumption that from known premises [Principles of Possibility], whether implicit or not, and valid reasoning, we get known conclusions [Modal Knowledge]. Any commitment to a necessitysensitive faculty is here denied because, in his approach, the way of getting modal knowledge is simply by reasoning from the Principles of Possibility which any competent possessor of the concept implicitly knows. And this “coming to know by reasoning” is intended to oppose to “coming to know by discovering (or recognizing)”. However, Peacocke’s way of making (b) false does not meet the epistemic challenge. It only moves it from the domain of explicit modal knowledge to the domain of implicit knowledge about the Principles. For, the claim that modal beliefs reached by reasoning constitute modal knowledge presupposes as much as that we know the Principles of Possibility. Given that modal knowledge is so dependent upon the Principles of Possibility, and given the claimed mindindependence of modal truth, also those Principles should be mind-independently true. And, if this is so, the epistemic challenge arises now for them, since knowledge about constitutive issues is no less problematic than modal knowledge. Suppose that biological origins are essential to humans. And suppose further that a originates from b&c. In Peacocke’s account, my knowledge that a necessarily originates from b&c derives from reasoning and my implicit knowledge of the Principles of Possibility, which somehow include knowledge of a essentially originates from b&c. That this later piece of knowledge is not modal knowledge strongly depends on accepting K.Fine’s criticism to the modal account of the notion of essence, according to which, constitutive/essential issues are, first, non-modal, and second, ontologically prior to modality. However, it is hard to see how this divorce between the modal and the constitutive may make any difference with respect to epistemological worries. Rather, it seems 2

The non-modal character of the Principles of Possibility is motivated in [Peacocke (1999): 148] relying on Kit Fine’s views on the notion of essence. Fine [(1994)] has charged several objections to the “modal account” of the notion of essence and he has also developed an alternative account that takes constitutive issues as ontologically prior to modal ones. With respect to the criticisms to the modal account, he argues for the claim that, whenever an object essentially/constitutively has a property, it is necessary that it has it, but the converse is not true. From here, modal truth is ontologically consequential upon constitutive truth. This analysis is used by Peacocke to make a correlated epistemic analysis, to the effect that modal knowledge is consequential upon constitutive knowledge.

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that for an advocate of the modal account of the notion of essence, the epistemic challenge this paper is about could rightly be stated as a challenge concerning modal knowledge, whereas for someone like Peacocke and Fine, the same challenge is a challenge concerning both, modal and constitutive knowledge. Peacocke [(2001)] addresses this objection when addressing A. Heathcote’s similar worry. There he gives two different answers to how we can know those principles: “we still have to answer Heathcote’s question of why and how the Principles of Possibility are included in our a priori knowledge” [Peacocke (2001); 112]. In what follows, I will argue against both answers that they explain how we can implicitly and explicitly grasp their content, but that they both fail as an answer to how we can know them. I will conclude that the challenge has not yet been met. As to ‘how we can explicitly know the principles’ Peacocke describes a two-step process that would result in explicit a priori knowledge of the Principles. In the first step of the process we identify of a set of a priori (allegedly) known modal propositions; after that: At the second step, we go on to ask ‘What is the best explanation of the meaning of necessity that would accord with the truth of these modal propositions that are known a priori?’. I contend that the best explanation is that necessity conforms to the Principles of Possibility. This is an a priori abduction, from a priori data about the truth of certain modal propositions, to a conclusion about the best a priori explanation of why they are true. [Peacocke (2001), 112; my emphasis]

As an answer to how we can make explicit the content of the Principles, this seems compelling enough. But, as an answer to how we can come to (explicitly) know the principles, the answer is unsatisfactory. By abductive reasoning we arrive at an explicit formulation of what is the content that we (implicitly) use in reaching modal judgments. If we grant that abductive reasoning is knowledge-yielding, we can even grant that we know that the content we have just made explicit is the content we implicitly use in modal reasoning. But this is independent on the question about the truth of such content and, by extension, also independent on whether this content constitutes knowledge. If we had false beliefs about the constitutive, coming to know what the content of those principles is, would by no means be coming to know the content. As to how we can implicitly know the principles, Peacocke’s answers the following: The ordinary understander’s tacit knowledge may be acquired in the same way in which any other tacit knowledge that influences judgments, such as tacit knowledge of the definition of ‘chair’, or of the recursion for addition, may be acquired. Immersion of the learner in sufficiently many examples can generate an underlying state whose content explains the thinker’s classification of new examples. When this underlying state has the content of the Principles of Possibility, and has been acquired in ways that rule out the other ‘nearby’ hypotheses about what ‘necessarily’ means, it will amount to tacit knowledge of the Principles pf Possibility. [Peacocke (2001), 112; my emphasis]

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The idea here is that the meaning of ‘necessity’ is reflected in use and that this reflection is enough for a beginner to become a competent user of the concept; that is, to implicitly grasp its meaning. When this idea is combined with the claim that the meaning of ‘necessity’ is partially constituted by the content of the Principles of Possibility, what is implied by the combination is that immersion in sufficiently many examples is enough for the beginner to grasp the content of the Principles. However, can we freely jump from the “tacit grasp of the content” to the “tacit knowledge of the content”, especially when this knowledge is about a mind-independent realm? A positive answer to this question assumes that our concept of necessity is “epistemically felicitous”, so to call it (i.e., that the concept perfectly tracks external truth), but no reason is provided by Peacocke to this effect. Peacocke’s answer focuses here more on ‘tacit’ than on ‘knowledge’. And, although it may sound plausible as an answer of how the implicit conception associated to ‘necessity’ gets into our heads, it is not satisfactory as an answer to the question of why we should take it that this implicit conception constitutes implicit knowledge (mindindependently understood). To meet the epistemic challenge this paper is about, one has to offer a satisfactory explanation about how we get modal knowledge. I take it that Peacocke’s account, even in the case that it gets the truth of the matter with respect the metaphysics of modality, cannot, as it stands, be thought of as a mind-independence account that has met the epistemic challenge. To be clear, the strength of the criticism here is not devastating at all. The criticism does not establish that the Principle-Based Account cannot meet the epistemic challenge; only that, to meet it, a different route has to be inaugurated. 2.2

Conceivability Approaches.

Conceivability approaches also address the epistemic challenge by denying premise (b) in the argument from §1. Like in Peacocke’s case, modal knowledge is fundamentally a priori according to them. If we can help ourselves of the claim that whether or not we conceive that p is something transparent to us, and if we have available a motivation for the claim that conceivability is a good epistemic guide to possibility, we would have a rationalist elucidation of the possibility conditions for modal knowledge that would amount to its fundamental aprioricity. As we will see, however, there are two different ways in which the different conceivability notions used by conceivability approaches may fail to be transparent. The first kind of failure of transparency (to be addressed in §2.2.2) demands further development of the accounts but is still compatible with conceivability being a guide to possibility. The second kind of failure of transparency (this will be addressed in §2.3) is, however, more pressing; it requires a substantially different epistemology for essential/constitutive facts, and it reduces the adequacy of conceivability as a guide to possibility to only conceptual necessities. 5

2.2.1.

Yablo’s and Chalmers’ Accounts.

Yablo [1993] and Chalmers [2002] are prominent proponents of conceivability approaches. The common-ground idea between them is that conceivability is a good guide to possibility. But, whereas Yablo advocates an epistemic account of conceivability, Chalmers’ account is a nonepistemic one. Following Geirsson [2005] and Worley [2003], we can distinguish the differential traits between an epistemic and a non-epistemic account in the following terms. According to an epistemic account, “whether or not something is conceivable depends on what resources the thinker has available to allow her to think about the situation” [Geirsson, (2005): 290]; whereas, according to a non-epistemic account, “to be conceivable is to be true in a possible world, where the class of possible worlds is coextensive with the class of conceivable worlds, and where the possibility is determined by conceptual coherence o incoherence, and thought in terms of an ideal conceiver” [Geirsson, (2005): 290]. We should distinguish the two notions of conceivability that are at work in each account. The epistemic notion is subject-relative, and depends on the state of knowledge and conceptual resources of the subject upon which it is relativized. Here is Yablo’s notion of conceivability: Something p is conceivable for a subject S if S can imagine a situation that S takes to verify p. Whether S takes a certain situation to verify ‘water is not H2O’ depends on whether S knows that water is H2O. Given this relativization, not only to S’s conceptual resources, but also to S’s state of knowledge, the Greeks, according to Yablo’s notion of conceivability, could conceive of water not being H2O, but this is not so for a contemporary subject knowing that water is H2O. The non-epistemic notion of conceivability is an idealization of the epistemic one. This needs to be disambiguated, though. In Yablo’s notion of conceivability there are two parameters upon which the notion is relativized: one, conceptual resources plus cognitive capacities of the subject, and the other, her state of knowledge. These two parameters somehow parallel Chalmers’ primary and secondary intensions of concepts. So, when we say that ideal conceivability idealizes the relative one, which parameter is it exactly the one we idealize? We can in fact idealize any of the two parameters, thereby obtaining different notions of (ideal) conceivability which will yield to correspondingly different conceivability/possibility thesis, and all of them are indeed covered and examined in Chalmers’ account. However, given that the main aim of Chalmers’ approach is the defence of modal rationalism (the claim that we have a priori access to modal facts), he is mainly interested in idealizing only the conceptual resources and in dismissing states of knowledge (at least, the a posteriori elements in them). This nonepistemic notion of conceivability will be called here ‘conceivabilityIC’, since it is defined in

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terms of an Ideal Conceiver (IC). Given the infallible powers of the ideal conceiver, two facts hold: (a) a possible world that IC takes to verify p is a possible world that verifies p; and (b) the class of situations that the IC can imagine is the class of possible worlds. Using these two facts, conceivabilityIC entails possibility: Something p is conceivableIC if and only if there is a possible world in which p is true.3 The following table schematizes Yablo’s and Chalmers’ conceivability notions, and advances a distinction between two sorts of modality: Prima Facie Conceivability Primary Intension Conceptual Resources Secondary Intension

Ideal Conceivability CHALMERS

1-Possibility

CHALMERS

2-Possibility

YABLO

State Of Knowledge

Corresponding to the primary intension (conceptual resources) and to the secondary intension (states of knowledge), there are two different sorts of modality (what we would intuitively call, respectively, ‘the epistemic’ and ‘the metaphysical’ ones, although this terminology is here inexact for reasons to be made clear in short when commenting on Chalmers’ thesis): We can then say that S is primarily possible (or 1-possible) if its primary intension is true in some possible world (i.e. if S is true in some world considered as actual). S is secondarily possible (or 2-possible) if its secondary intension is true in some possible world (i.e. if S is true in some world considered as counterfactual).

[Chalmers (2002): 164]

Primary modality will turn out to be that part of metaphysical modality which is accessible a priori, whereas “secondary possibility and necessity correspond to the standard conception of what it is

for a statement to be metaphysically possible or necessary” [Chalmers (2002):164], and, in certain cases, depends on what is actually the case and therefore accessible a posteriori. Having said this, we can distinguish between Yablo’s and Chalmers’ conceivability thesis, attending to what notion of conceivability they are working with: (YABLO):

Conceivability is a guide to 2-Possibility.

(CHALMERS):

ConceivabilityIC is a guide to 1-Possibility.4

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Given what conceivabilityIC is, this thesis has to be understood with the following rough restriction: p has to be a thought, rather than a proposition, since it has to be something exclusively constituted by primary intensions. It will be clear in short that, from here, the possible worlds mentioned in this thesis are 1-possible worlds, rather than 2-possible worlds.

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According to Yablo, conceivability is a guide to metaphysical necessity (as ordinarily understood). According to Chalmers, conceivabilityIC is a guide 1-possibility, and it would be fallacious to infer 2-possibility from conceivabilityIC. However, and to qualify this, given that primarily possible worlds are “first class metaphysical possibilities” [Chalmers (2002): 165], it is still true that conceivabilityIC is a guide to metaphysical possibility; it is only that this will remain true as long as we keep the description of those worlds at the 1-intensional level. It is none of the aims of this paper to evaluate the extensional adequacy of these accounts; we are rather interested in evaluating the extent to which they can meet the epistemic challenge. We start with this in the next subsection. 2.2.2.

The First Failure of Transparency.

Let us first see what has been called ‘The Standard Objection’ for epistemic accounts5. From an account like Yablo’s, which works with an epistemic notion of conceivability, modal judgements based on conceivability (in this sense) are too fallible for conceivability to be a good enough guide to 2-possibility. One only needs to ignore that Hesperus is Phosphorus for she to be able to conceive that Hesperus is not Phosphorus and, from this act of conceiving, to believe the (illusion of) 2-possibility that Hesperus could fail to be Phosphorus. Given that we know how unreliable conceivability is in some cases, this gives us reason to doubt about any modal judgement on the basis that, for each case, we can’t tell whether our judgement is errant as in the illustrative case of Hesperus and Phosphorus. I seem to be able to imagine that I originate from different origins from my actual ones. On the basis of the current considerations, my inference from conceivability to 2-possibility would be objectionable. In Yablo’s account, there is room for different explanations of why I can conceive such a thing; it may be that I can conceive it because it is possible, but it may also be that it is impossible and I can conceive it because of my cognitive limits, or my lacking of some relevant piece of empirical knowledge. Epistemic accounts are therefore not in a good position to claim that conceivability methods are a good way to achieve 2-modal knowledge, since we know that epistemic conceivability does not entail possibility. Thus, the possibility conditions for modal knowledge (the phenomenon to be explained) cannot be elucidated by an epistemic account as something different from prima facie justified belief. To claim that we know by conceiving cannot be all what is needed to elucidate the possibility conditions for modal knowledge, because sometimes we falsely believe 4

Chalmers would also be sympathetic to claim that secondary conceivability entails secondary possibility: “One might then try to save a conceivability/possibility link by suggesting that ideal secondary conceivability entails possibility. This thesis is not implausible, but it is not helpful for our purposes here.” [162]. However, this is not the conceivability thesis relevant for a defence of modal rationalism: “If we are interested in modal rationalism, we should instead focus on ways in which primary conceivability might still be a guide to possibility [162]. 5 [References to Worley and Brueckner]

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by the same method. And to say that we know (when we do) by conceiving plus by being lucky does not seem to be a satisfactory way of meeting the epistemic challenge. On the face of this “standard objection” to epistemic accounts, it seems that we need a stronger notion of conceivability; strong enough to entail possibility, and such that to say that we know by conceiving is a complete enough elucidation of how we get modal knowledge. So suppose that we now idealize the two parameters from Yablo’s notion. We get then an IC knowing also any piece of knowledge there is to know about the actual world. Let us call ‘Secondary Ideal Conceiver’ (SIC) the so supplemented IC. Although not being the one that Chalmers is mostly interested, he considers the thesis that secondary ideal conceivability (let us call it ‘conceivabilitySIC’) entails secondary possibility, and believes it to be highly plausible. So let’s assume, for the sake of discussion, that it is true. The objection in this case is that it is misleading to take conceivabilitySIC as an epistemic guide to possibility if it is intended to mean epistemic guide for us. The reason is that conceivabilitySIC is not transparent to us. Whenever we manage to conceive that p, we do it with our conceptual resources and our current state of knowledge, and the fact that we are trapped in it explains why it is impossible for us to know whether p is also conceivable for the SIC (i.e., whether p is also conceivableSIC). Unfortunately, any attempt to establish such a thing would only establish whether p is conceivable for the (best) secondary ideal conceiver we can conceive, and this falls short in establishing that p is conceivableSIC. So, maybe conceivabilitySIC is too strong altogether. It is indeed stronger than conceivabilityIC in that the former but not the latter incorporates all empirical knowledge there is to know. But does this difference in strength prevent conceivabilityIC to be susceptible of the same criticism? No. Chalmers’ conceivabilityIC is working with conceptual idealization, and the charge of lack of transparency applies in this case as well. We want to know how we can come to know whether the zombie hypothesis is 1-possible, or whether the negation of Goldbach’s conjecture is 1-possible. It is no explanation of the phenomenon to say that the IC knows it by conceiving because we don’t have access to what the IC can conceive. The most we can tell is that we fail to see any conceptual incoherence in such hypothesis, but, given our awareness of our own limitations, this unwarrants the inference from: us failing to see a conceptual incoherence, to: there not being any.6 Similarly to what we saw for epistemic accounts, it seems now that we have reasons to doubt about any of our modal judgements. This is no surprise; we are not IC’s, and when the infallibility missing in epistemic accounts is achieved in the nonepistemic ones by means of idealization, it is hard to see how this non-human conceivability can help to explain the possibility conditions of human modal knowledge.

6 To see a much more detailed elaboration of this point in the frame of a discussion about Chalmers’ hypothesis about zombies, see [Worley, (2003)].

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Where does this leave us in relation to the epistemic challenge? The previous considerations may suggest that for conceivability approaches to satisfactorily meet the challenge, they have to have the following two virtues; not just one: (1)

Its notion of conceivability must entail possibility; and

(2)

It has to be transparent conceivability.

And the dilemma any conceivability account will face is that, the more virtuous it is with respect to one of them, the less virtuous it will be with respect to the other. As we have roughly illustrated, Yablo’s is an example of account that accommodates (2) but not (1), whereas it is the other way around in Chalmers’ case. This dilemma is to be taken seriously, and demands further development to both accounts, but it is not, per se, a devastating objection. Maybe for some local cases of conceivability we can know that our conceptual and cognitive powers are not less that the IC’s. In other words, maybe it can be made plausible that in certain cases, we, as we are, are (local) IC’s. Arguing for this claim will be sufficient for Chalmers to escape the dilemma, and it would be a way of blocking the step, present in both cases, going from: we know about cases where conceivability goes wrong, to: therefore, we can’t trust conceivability at all. Also Yablo has to motivate the claim that we are local IC’s, but, in his case, this is not sufficient. Since he also includes states of knowledge in his conceivability notion, he has also to motivate that we are local SIC’s. Assume it doable.7 Now, if the pieces of knowledge that a subject uses in judging modal claims divide into either: (i)

Empirical and non-modal; or

(ii)

A priori, and, if also modal, known by conceivability methods, once available the claim that their conceivability requirements do not exceed our conceivability powers,

then, conceivability approaches would have solved the current dilemma. For, taking into account empirically known non-modal truths (assuming that a satisfactory epistemology is available for them) does not undermine the epistemology of modal knowledge. And, taking into account the a priori known modal truths that we can know by matching the IC’s powers does 7

As for the non-epistemic account, Chalmers’ notion of secunda facie conceivability is, I guess, making efforts in this direction. [See Chalmers (2002) §2]. As for epistemic accounts, Geirsson [2005] has offered an account based on Yablo, but extending it precisely in that he elucidates a way of distinguishing degrees of justification for our modal judgements. His way of doing so may also be taken as an attempt to elucidate when modal judgement can be given the epistemic status of knowledge. The claim that we are local SIC’s, in Yablo’s case, may require that when we judge something to be conceivable in his sense, lack of knowledge play no role. To illustrate this: The Greeks could find it conceivable (as non-SIC’s) that H is not P because of his lack of knowledge that H is P. A Greek that would have behave as a local SIC would have required knowledge that H is not P, for him to judge it conceivable that H is not P. Given that such piece of knowledge is not available, that H is not P will never be conceivable for a local SIC.

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not undermine it either. The solution to the dilemma requires then to show that human conceivability matches ideal conceivability (at least) in some cases. This solution is compatible with epistemic inaccessibility of some part of the modal realm; at least, inaccessible by human conceivability methods. But, essential to conceivability thesis is the claim that, the only two sources of unknowability would be: –

A priori unknowable truths (a priori knowable by an IC), whose conceivability requirements exceed our conceivability and cognitive powers.

–

A posteriori unknowable truths, coming from the unknowability of empirical nonmodal truths.

How bad is this for a given conceivability approach depends on how ambitious such an approach is. If the rationalist intuition that motivates those accounts is that there is no part of the modal realm inaccessible to us, cases where the IC’s powers exceed ours would be bad news. It is not clear to me, however, why this should be bad news in itself for modal epistemology. Given that the source of inaccessibility would be cognitive and conceptual limitations, or unknowable non-modal truths, this problem will not be specific of modal epistemology and so, if the sort of modal epistemology that is offered by conceivability approaches is worse placed than the epistemologies for other domains, it will not be for this reason. There is, however, a different sort of lack of transparency of conceivability notions that cast serious doubts on the adequacy of conceivability as a guide to possibility. As we will see, it is hard to see how conceivability methods (even when idealized) can establish or refute substantial essentialist principles, like those of constitution or origins. To put it in terms of the solution to the dilemma of this section, the worry is that, contrary to what is assumed by conceivability approaches, there seems to be a third potential source of modal unknowability; namely, unknown essential truths. The next section elaborates on this. I will first identify common traits among the (a)¬(b)(c) strategies considered here, and then identify an explanatory deficit in conceivability approaches that strikingly resembles the one we saw in Peacocke’s case. 2.3.

The Second Failure of Transparency: The Explanatory Deficit.

Let’s take stock to see what conceivability approaches have in common with the PrincipleBased Account. The identification of common aspects, plus the identification of the essential divergence, will be useful to identify the source of their shortcomings. It is a recurrent thought in conceivability approaches that something being conceivable depends to some extent on there being no conceptual contradiction in the conceived content. For the IC, absence of conceptual contradiction will be necessary and sufficient for conceivabilityIC. For Yablo’s non-ideal conceivers, awareness of conceptual contradiction will be sufficient for 11

inconceivability and so will be awareness of non-conceptual contradiction (for instance, when we are aware of the contradiction in ‘Hesperus is not Phosphorus’). The underlying idea is the thought that our imaginative skills are only constrained by the rule of non-contradiction. In A.Sidelle’s terms: “We do not grant that contradictions can properly describe imaginations, but that is the only constrained upon what we can imagine”. [Sidelle (1989): 89] The same is true in Peacocke’s account. One of his Principles of Possibility, the Modal Extension Principle (MEP), requires that for something to be a genuine possibility, it must be free of any conceptual contradiction. Under the (plausible) assumption that we fail to be able to imagine an object with logically contradictory properties, and appealing to MEP, the unimaginability of a married bachelor is explained in Peacocke’s account by the unimaginability of a non-married married. Similarly, and again appealing to MEP, we can also explain why we cannot imagine that everyone in the room is English, John is in the room, and John is not English.8 In Peacocke’s account, MEP covers just conceptual necessities. It is precisely the belief that there are conceptual possibilities that are not metaphysical possibilities what leads Peacocke to the claim that satisfaction of MEP is necessary, but not sufficient, for metaphysical possibility. In order to see a connection here between Peacocke’s account and conceivability approaches, note that the standard cases in which conceivability approaches fall short as a proof for possibility are the cases in which satisfaction of MEP falls short as a sufficient condition for possibility. To illustrate this, that water is not H2O is conceivable9, and it also satisfies MEP; the reason being, in both cases, that there is no conceptual/logical contradiction in those thoughts. Its conceivability is a standard case (though solvable, as we saw in the last subsection) against the adequacy of conceivability approaches; and the absence of conceptual contradiction shows that satisfaction of MEP is not sufficient for possibility. The necessary and sufficient conditions for genuine possibility are given in Peacocke’s account by MEP in conjunction with a battery of Constitutive Principles encoding the essences of the entities in our ontology. It is clear from here that Peacocke acknowledges that the essences of things are not encoded in the concepts we use to think about them. This is also true of 8

For further reading on Peacocke’s discussion on the explanatory role that MEP plays in explaining the link between unimaginability and judgements of necessity see [Peacocke (1999): 179]. 9 N.B.: Primarily conceivable (in Chalmers’ account) and conceivable for S as long as S ignores that water is H2O (in Yablo’s account). The only thing needed to show that there is no conceptual contradiction according to Yablo is that, someone ignoring that water is H2O but possessing the corresponding concepts will find it conceivable that water is not H2O. In Chalmers case, there would be secondary conceptual contradiction, but no primary conceptual contradiction. What happens if we claim that it is not conceivable (like Chalmers does with respect to secondary conceivability) is addressed below in this section.

12

conceivability approaches. That we can conceive of water not being H2O is because water being (essentially) H2O is not encoded in our concept of water.10 Similarly, suppose that it is essential that human a originates from b&c (sperm and egg cell, respectively). That we can conceive of a originating from d&e (different from b&c) is explained by the fact that the essence of a is not encoded in our individual concept for a. Under the assumption that a originates from b&c,11 knowledge of it will be empirical, and it being an essentialist truth would be reflected in Peacocke’s account by its inclusion into the set of Constitutive Principles. We saw in §2.1 that Peacocke does not meet the epistemic challenge at the constitutive level, but at least it is explicit in his account that they are essentialist truths not reducible to conceptual ones. Peacocke identifies as potential sources of modal error the following three: (i)

We are wrong-about/unaware-of constitutive relations among concepts (which means being unaware of conceptual incoherence).

(ii)

We are wrong-about/unaware-of empirical non-modal claims.

(iii)

We are wrong-about/unaware-of essential/constitutive relations among the entities in our ontology.

If, knowing that aOb&c, I mistakenly judge it to be possible that aOd&e, this is explained in Peacocke’s account by my unawareness or denial that aOb&c is a constitutive truth. What can be said of conceivability approaches? They identify as sources of modal error only (i) and (ii) above.12 If I mistakenly judge it to be possible that aOd&e, this is explained in conceivability approaches by my unawareness or denial that aOb&c is true or by my unawareness or denial of some a priori modal principle such that, my awareness of it, in conjunction with my awareness of the truth that aOb&c would amount to my awareness of contradiction in aOd&e. From here, if knowing that aOb&c I still seem to be able to conceive that aOd&e, this is explained in conceivability approaches by my unawareness of some a priori principle. In every case of modal error, the relevant a priori principle and the relevant empirical knowledge needed to explain away a modal error are called by Yablo ‘defeaters’. We know what an empirical defeater for the (let us suppose) illusion of possibility that aOd&e would be (namely, knowledge that aOb&c). But which a priori principle could be a defeater for the (let us assume) illusion of possibility that aOd&e? The most natural candidate is this: 10 Again, at least not in the primary intension of concepts, in Chalmers’ case, and not in concepts tout court, in Yablo’s case. 11 To abbreviate, I will use ‘xOy&z’ to mean that x originates from y&z. 12 For a detailed discussion on this, see Peacocke on sources of modal error [Peacocke (1999): §163166]; Yablo on models of modal error, [Yablo (1993): §XIII]; and Chalmers on (a) how prima facie conceivability is an imperfect guide to possibility, and on (b) how ideal primary conceivability is a bad guide to secondary possibility [Chalmers (2002): §4].

13

(Nec-O)

xOy&z →

xOy&z

If (Nec-O) is true, and if conceivability approaches are to explain the possibility conditions for our knowledge of it, this modal principle has to be a priori, and grounded on conceivability methods. But what role conceivability methods can play here? How do we arrive at such (alleged) a priori principle? Following Kripke, we first focus on a particular instance of the antecedent and see what can we imagine assuming that particular case to be true. From here, we arrive at a formulation of what he calls (in his note 56) the general “principle suggested by these examples” that accommodates the outcomes of our conceivability experiments.13 How exactly do we proceed? Here is Yablo’s suggestion, following Kripke: How do I test the credibility of the conditional claim that if q then p is impossible? […] Suppose I want to decide whether, if salt = sodium, it is impossible for the ocean to contain more sodium than salt. Pretending that salt = sodium, I find it inconceivable that the ocean should contain these in different amounts; abandoning the pretense, I endorse the conditional. [Yablo (1993): footnote 66]

Although this quotation involves a principle with an identity statement in the antecedent, it is to be expected that the procedure would be the same in the case of (Nec-O), and this is in fact the method that Kripke less explicitly suggests in Naming and Necessity. In order to establish (a priori) whether the general principle xOy&z →

xOy&z is true, we first focus on a particular

case, for instance, aOb&c, suppose it, and see whether, under that supposition, we can imagine, for instance, aOd&e (from which we would derive ¬ aOb&c). If we cannot, we endorse aOb&c →

aOb&c. And, b abstracting, we endorse the general principle (Nec-O).

However, if this is the method to establish the a priori principle, a first methodological worry presents itself. The general principle was supposed to act as a defeater for someone claiming to be able to conceive that aOd&e, even when aware the aOb&c; that is, for someone under the (let us assume) illusion of possibility that aOd&e. But no one under such an illusion would accept the principle as a defeater, since acceptance of the general principle requires her being convinced of the negation of the illusion she is under. What this illusion will generate in any one under it is rather the belief that the principle is false. For, given what the methodology is, one’s reasons for believing in the possibility of aOd&e are the same as one’s reasons for believing in the falsity of the principle; namely, the apparent conceivability of aOd&e. The way the worry has been stated may suggest that it is a worry about how effective conceivability methods are in order to convince the easily deceived ones about their modal errors. And surely, it is a worry about this. It is worrying enough that those methods are inert to

13 This is in fact Kripke’s use of conceivability experiments; see [Kripke (1980) footnote 56 and its corresponding text].

14

ensure collective philosophical progress. But it is not only a worry about this. A more pressing worry concerns the knowability conditions of principles like (Nec-O). We saw that, according to conceivability approaches, awareness of contradiction is sufficient for inconceivability, and awareness of lack contradiction is sufficient for conceivability. To establish (Nec-O), we need the following to be the case: that, under the supposition that aOb&c is true, we are aware that aOd&e is unconceivable. But is the task available to us? Unlike the conceptual contradiction in ‘John is a married bachelor’, if there is a conceptual contradiction in aOd&e, it is not a transparent one, but a hidden one. So, without any supposition, we are not aware of any contradiction in aOd&e. The only way of arguing for the claim that this proposition is conceptually contradictory (under the assumption that aOb&c) seems to require two things: First, a commitment to the claim that a essentially originates from b&c (which is to say that aOd&e is metaphysically contradictory), and second, that this essence is (partially?) constitutive of our individual concept for a. If these two things are in place, given that a’s essence would logically exclude a from originating from d&e, it would follow that aOd&e would be, not only metaphysically contradictory, but also conceptually contradictory. But this means that, in the process of establishing (Nec-O), and in particular, in order to establish the hidden conceptual contradiction in (equivalently, the inconceivability of) aOd&e, merely supposing that aOb&c is true is not sufficient; we need to suppose that it is essentially true (plus assuming a view of concepts that would render them epistemically opaque). Now, if assuming that aOb&c is essentially true is required to establish (Nec-O), then, (Nec-O) cannot be established without begging the question. The situation seems to be the following. Either the essences of things are partially constitutive of our individual concepts of them, or they are not. If they are, merely assuming that aOb&c is true is not sufficient for, under that supposition, establishing the metaphysical contradiction in aOd&e, and thus, under only that (weak) supposition, it cannot be established that aOd&e is also conceptually contradictory; if it is indeed contradictory, it will be something we would not be aware of, and thus, we would still seem to be able to imagine that aOd&e; that is, we would not yet have reasons to endorse (Nec-O). If, on the other hand, the essences are not constitutive of concepts, then, independently on whether we assume that aOb&c is true or not, aOd&e is not conceptually contradictory (even if metaphysically so), and thus, we can conceive of it; thereby lacking any reason to endorse (Nec-O). We have seen that the view that essences are constitutive of concepts is neither Peacocke’s view, nor Yablo’s, nor Chalmers’ (as for what primary intensions is concerned). The explanatory deficit identified right below, however, does not depend on what our view on this 15

issue is. For, it seems to me that, whatever our option is about what is constitutive of concepts, anyone would agree that the contradictions in ‘a is a married bachelor’ and in ‘a originates from d&e’ (if any) are not of the same kind. Whether both of them are conceptual contradictions, or whether only the first one is, just by looking at the transparent/accessible parts of concepts (whether those parts exhaust them or not) we can detect the first contradiction, but not the second. In other terms, the first contradiction is epistemically transparent, but not the second. And this is all what is required for the explanatory deficit to arise. No matter then what our view on concepts is, the essences of things are not encoded in the transparent bit of our concepts for them; there is no transparent contradiction in ‘aOd&e’. If this is all it takes for something to be conceivable, then, aOd&e is conceivable; from here, conceivability approaches appealing only to the transparent notion of conceivability will be committed to the falsity of (Nec-O). If the non-transparent constituents of the concepts (whenever claimed to exist) are also relevant for conceivability, then, if a’s essence really excludes the possibility that a originates from d&e, then, aOd&e is not conceivable. But in this case, the epistemic challenge has not yet been met. Here is the old question, in the new terms: How do we know whether something is or not conceivable in this sense? This question, here, is exactly the same as the one we asked Peacocke an answer for: how do we know what the essences of the entities in our ontology are? The only way we can know p’s possibility by conceiving that p, is by knowing that we are conceiving that p. Transparent notions of conceivability do not need further epistemology, but will always yield non-essentialist results; non-transparent notions do need further epistemology. In this case, an epistemology of conceiving needs to be offered, on pain of explanatory deficit. Like in Peacocke’s case, the missing explanation is as to how we can get knowledge of constitutive/essential facts. And by the very nature of the problem here (how do we know whether something is non-transparently conceivable), conceivability methods appear to be useless. For, for them to be useful, in each case, we should ultimately establish or refute any general principle by means of transparent conceivability (on pain of opening an explanatory regress). But transparent conceivability will always yield non-essentialist results, establishing the negation of any essentialist principle in the same way as it establishes the negation of (NecO). Therefore, trying to establish whether something is non-transparently conceivable by means of transparent conceivability would render co-extensive the transparent and the non-transparent notions of conceivability, which would amount to the theoretical collapse of the two notions. Is sum, whether something is non-transparently conceivable or not is not expected to be answerable by means of conceivability methods.

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2.3.1. Conceivability Approaches: Anti-Essentialists, or Incomplete?

Where does this leave us? There are basically two options, and which one to take will depend on how strong one’s essentialist intuitions are: (1)

If we have strong essentialist intuitions, it must be acknowledged that conceivability approaches fall short as a defence of modal rationalism, at least until they are supplemented with a different rationalist elucidation of how we know essential constitutive facts. Conceivability methods do not explain how we can (if we can) know those allegedly a priori known principles, because it has been shown that conceivability methods do not establish them. This will generate an explanatory deficit of the same sort we saw in Peacocke’s case. As in there, the strength of this complaint is not that they cannot meet the epistemic challenge, rather, that something else than a conceivability thesis is needed to fully meet it; a different epistemology is needed for the alleged a priori principles like (Nec-O).

(2)

If, on the other hand, we have anti-essentialist intuitions, then, conceivability approaches may still have all the explanatory power the rationalist was hoping for. Conceivability approaches would explain how we can know the falsity of principles like (Nec-O). In this case, and on the basis of what has emerged above, it will be transparent conceivability the one doing all the explanatory work; that we can transparently conceive of a originating from d&e (plus extrapolation) would a priori establish the falsity of (Nec-O). This is an open theoretical option. But it is, first, an option that conflicts with Kripke’s intuitions and intentions, and, second, the conceivability/possibility thesis that such an account can provide will be compelling only to those with previous anti-essentialist intuitions. And this diminishes a lot the attractiveness of the thesis; only anti-essentialists can enjoy themselves with it, but it lacks any conviction power for the rest.

In sum, Peacocke seems to be one step further than Yablo and Chalmers when he explicitly acknowledges the need of the Constitutive Principles. He certainly makes it clear that knowledge of the truth that a originates from b&c plus conceptual resources and reasoning is not all what is required to get modal knowledge about a’s possibilities. Rather, we must also know whether this is an essential/constitutive truth (as opposed to mere truth). This is exactly the place where the (a)¬(b)(c) strategies considered here face again the same challenge they were trying to meet. 2.4.

The Missing Explanation Worry, Extended.

Suppose we take option (1) above. To how many cases of conceptual possibilities must we extend the “missing explanation worry”? In other terms, how many inferences from: p is free of conceptual contradiction, to: p is metaphysically possible, are now under suspicion? The answer

17

is that lots of them, if not all. Probably, the only modal claims that are epistemologically explained by conceivability methods are the (transparent) conceptual necessities; not surprisingly, the only ones covered by Peacocke’s MEP. Conceptual possibilities that are not conceptual necessities are all under suspicion now. For suppose that you have strong intuitions about the truth of (Nec-O). In this case, the transparent conceivability of aOd&e would be reason enough for you to mistrust transparent conceivability; you would rather be inclined to judge it as an example of conceptual possibility that is not a metaphysical possibility. Now consider any other conceptual possibility, like, for instance, that I break my left femur. To infer from here the corresponding metaphysical possibility may match our intuitions in this case; but, given that we have reasons to mistrust conceptual possibility as implying metaphysical possibility in other cases, this seems to be sufficient to mistrust it in general. After all, how can we know, by conceiving, that my essential properties allow for the breaking of my left femur, if we do not know, by conceiving, what my essential properties are? These considerations put in the same bag the following claims: (i)

It is possible for a to originate from d&e

(ii)

It is possible for this table to be made from different matter from the matter it is actually made from.

(iii) It is possible that John F. Kennedy dies from heart attack. (iv) It is possible that this table breaks. The first two (unlike the two last ones) have typical essentialist flavour. a’s possibility stated in (i) depends on it not being essential to a that it originates from b&c (and similarly for the table mentioned in (ii)). But also the two last claims are essentialist in the same way. The truth of (iii) depends on it not being essential to Kennedy that he dies shouted (and similarly for the table mentioned in (iv)). As for what conceivability approaches is concerned, our justifications for (i) to (iv) fall together until further epistemological considerations, aside from conceivability methods, are offered as to how, or as to whether, we can know those claims. There seems to be, though, a difference between (i)-(ii) and (iii)-(iv); namely, a difference in what our responses are when asked about their knowability. While we tend to think that we can know (iii) and (iv), we are more reluctant to say so for (i) and (ii). This difference is one of the main reasons to be unhappy with the epistemology provided by conceivability approaches. They do not explain the possibility conditions for some modal claims that we may regard as knowable. If we claim that (iii) and (iv) are examples of knowable modal claims, a satisfactory modal epistemology should account for them. And, if we are reluctant to claim that (i) and (ii) are knowable modal truths (or falsities), it is desirable that their disanalogy with (iii) and (iv) be spell out. 18

In the following section, I will first comment on the (a)(b)(c) premises. After that, in §3.2.1, I programmatically sketch the first steps towards a modal epistemology that elucidate the possibility conditions for modal knowledge of claims like (iii) and (iv). Later (in §3.2.2 and in §3.2.3) I show why the methodology used in §3.2.1 does not succeed in establishing or refuting claims like (i) and (ii).

3.

A Non-Uniform Modal Epistemology.

Before sketching the kind of modal epistemology that I think will best account for our modal knowledge, let me make explicit the aim of what follows. The aim is to put modal epistemology in its right place; neither in a better position than it deserves, but nor in a worse one. Arguably, knowledge of any actual law already comprises modal knowledge. This will be used, as an overall strategy, to illustrate how we can get modal knowledge of unrealized possibilities partially grounded on empirical observations. It may be objected to this strategy that rather than solving the epistemic challenge in the modal case, it extends it to most of our scientific knowledge about laws and causal powers. Granted, but I think that this is the worst that can happen to the present account. And if this is the worst that can happen, it is already a good result for modal-epistemologists. Mind-independence theorists of modality should not tolerate an unfair treatment with respect to their epistemology, and I suspect that more often than not, the epistemic challenge for mind-independence theories of modality is thought as something exclusive of modality. I hope that what follows will make it plausible that it is not. 3.1

Back to the (a)(b)(c) premises.

Let’s comment on premise (a); in particular, on our reasons for accepting it. Premise (a) of the epistemic challenge (as stated in §1) says that we have modal knowledge. This, I am going to take it for granted; but I want to stress that I take it to be true in a way compatible with partial epistemic inaccessibility. My motivations for this are that, while I do think we know claims like (iii) and (iv) above, I am agnostic, for reasons to be made clear below, about the knowability of claims like (i) and (ii). We should then distinguish (a) from (a’), whose truth I am not ready to be committed to: (a’)

For any kind of modal fact, we can know it.

Where should we start from in order to elucidate the possibility conditions of modal knowledge? I guess we should start by renouncing the aim of a uniform modal epistemology. Given the heterogeneity of the class of modal claims, and on the face of the failure of approaches that attempted to provide a unique and uniform modal epistemology (as conceivability approaches seemed to aim) we may start suspecting that a uniform epistemology

19

is not available. The suspicion is that the modal domain may be parcelled out in different subdomains such that, maybe (but only maybe) for any of them there is a satisfactory epistemological story to be told, whereas there is no single satisfactory epistemology to cover them all. So, premise (a) is accepted here, because it is believed that some sub-domains are epistemically accessible. But it is not universally accepted, because it is believed that, as for now, agnosticism is the right option for other sub-domains. The non-uniformity of the present account comes from the following beliefs. The (a)¬(b)(c) strategies provide a good enough explanation of how we can know metaphysical necessities derived from conceptual necessities; but there is a range of metaphysical possibilities that are taken to be knowable by the present account and that, as we saw in §2.4, have not yet been explained by (a)¬(b)(c) strategies. Premises (b) and (c) need to be qualified before we accept them or deny them. Let’s start with (b). What does exactly it mean that: (b)

Any knowledge of the extra-mental world is grounded on causal affection.

For any piece of knowledge, p, we should distinguish between: p’s being grounded only on causal affection, and p’s being partially grounded on causal affection. My knowledge that the telephone is ringing may be taken to be grounded only on causal affection. My knowledge that all ravens are black is grounded on causal affection, but not only on it; it is also grounded on induction. Yet, that all ravens are black is still knowledge of the extra-mental world. For the case of modal knowledge, modal rationalism denies premise (b) in both readings distinguished here. Let us be clear on this. Modal rationalism allows indeed for (knowledge of) a posteriori necessities, but they deny that this modal knowledge is grounded on causal affection. Causal affection will ground, for instance, that aOb&c; it will never ground that aOb&c. On the contrary, the ‘modal rationalism’ label suggests that our knowledge of them is fundamentally a priori. This seems to assume that, whenever a piece of modal knowledge is both partially a priori and partially a posteriori, there is also an asymmetry between the a priori and the a posteriori methods as for what the “grounding powers” is concerned, and that it is always the a priori method that has the grounding power. I am not sure that this asymmetry assumption truly generalizes to any piece of knowledge that is hybrid in this sense. It is clear however the reason why, from (a)¬(b)(c) approaches, one may want to say that the knowledge that aOb&c is fundamentally a priori: (Nec-O), the general principle in an argument for that necessity a posteriori, is the only modal premise, and it is a priori. If that had been successfully established, the case would have been made against the truth of (b). However, we have seen in §2.3 that principles like (Nec-O) have not yet been established a priori. From here, the assumption of an asymmetry in grounding powers, and in favour of the fundamental aprioricity of a posteriori modal knowledge, is still unmotivated, and so is thereby modal rationalism; in other terms, that (b) is false has not been sufficiently motivated yet. From here, my lack of 20

denial of premise (b) comes from the following. First, I take it to be intuitively plausible, and, second, until compelling reasons are given to the effect, I take it also that, if some piece of knowledge is partially known a posteriori, then, it is grounded on a posteriori methods.14 If we read premise (b) as meaning that any knowledge of the extra-mental world must be exclusively grounded on causal affection, then, a modal epistemology is no less needed than a revision of scientific knowledge in general. I think we have independent reasons to deny this “exclusivity” claim. Scientific knowledge seems to be partially grounded on causal affection but partially grounded on methods like abduction, induction and extrapolation. Any such knowledge will be, in some sense or other, immanence-transcendent. Modal knowledge is immanence-transcendent in the sense of being actuality-transcendent. So, if the door is open for immanence-transcendent knowledge partially grounded on causal affection, the door is open, at least in principle, for modal knowledge partially grounded on causal affection. This leads us to comment on premise (c); the one I deny, and whose negation I think that must be exploited in elucidating the possibility conditions for modal knowledge: (c)

Any knowledge grounded on causal affection cannot outrun knowledge of mere truths (as opposed to modal truths).

There are two issues to be distinguished here: first, whether possibility-knowledge can be partially grounded on causal affection, and, second, whether necessity-knowledge can. I will briefly address them in turn. Here is one motivation (more interestingly exploited in §3.2.1) for the claim that we can get possibility-knowledge partially grounded on causal affection. Deduction, induction, abduction and extrapolation methods are all highly used in scientific research. When combined with empirical observations, they yield, for instance, to formulations of actual laws. If those methods are knowledge-yielding, and if so are observational methods, then we probably know quite a lot of the actual laws. Whatever is determined by physical laws is physically necessary and thereby physically possible. And whatever is physically possible, is metaphysically possible. Thereby, by knowing physical laws, we already know a bit of the metaphysical realm.15 14

Given that I agree with (a)¬(b)(c) strategies as for what conceptual necessities is concerned, there is a non-interesting sense in which I would deny (b); namely, to the extent that it can be maintained that knowledge that all bachelors are unmarried is knowledge of the extra-mental world. If this is to be hold, then, the present strategy is a (a)¬(b)(¬c) strategy. 15 This argument could be strengthen by saying that, whatever is not excluded by knowable physical laws is physically possible; and from here we could jump to metaphysical possibility. Since there are more physical possibilities than there are physical necessities, this would yield much more knowledge of the metaphysical realm. However, this argument has implicit the presupposition that all physical laws are knowable, and I am not ready to assume such a thing. The argument that goes from physical necessity to physical possibility seems not objectionable in this way, and this is the reason why I have chosen it. I think, however, that without assuming knowability of all the laws, we can also know physical possibilities not derived from the physical necessities, which would make the class of knowledge of metaphysical possibility bigger than argued for here. This is the project of the next subsection.

21

Here is another, more straightforward, though maybe less interesting, way of getting possibilityknowledge: We derive possibility from actuality. For any actual truth we know, p, we derive p. In deriving possibility from actuality, we assume of course the principle that p→ p. Admitted, justification for such a principle is required, but for now, let us just assume that this is a priori. As Yablo [1993] and Hale [2002] say, however, the interesting cases of possibility-knowledge are cases in which we know that p is true even when p is not known to be true. This is the puzzling phenomenon we should give an explanation of. What about knowledge that something is necessary? If knowledge partially grounded on causal affection were sufficient for us to know all metaphysical possibilities, and also sufficient for us to know that they are all, then, given that something is necessary if and only if its negation is impossible, this would be sufficient for knowledge that something is necessary partially grounded on causal affection. However, since I am agnostic about the antecedent, I am not ready to be committed to such a strong claim. Indeed, I will give reasons below to think that we are not (yet) justified in the truth of such antecedent, which amounts to saying that agnosticism is the position to be taken (at least, at the moment). Again, let us be clear about the disagreement with modal rationalism. I do not mean to imply that modal rationalists deny (c) for those cases in which we derive p from the empirical knowledge that p; Yablo himself is explicit in that we can derive p from p. And I do not mean to imply either that modal rationalists would accept that no knowledge grounded on causal affection can be immanence-transcendent, or equivalently, that they would be committed to rationalism also for the case of knowledge of actual physical laws. In emphasizing the need of an (a)(b)¬(c) strategy, my claim is rather that: if modal rationalists have reasons to believe that knowledge of physical laws is partially grounded on causal affection, then, as we will see in §3.2.1, they already have reasons to believe that also modal knowledge is grounded on causal affection; i.e., they have reasons to deny (c). And at this point, my disagreement with modal rationalism is as follows: while modal rationalism seems to assume that the epistemic challenge in the modal case can be solved without exploiting the denial of premise (c), whenever indeed denied, I think that its denial must be exploited in elucidating the possibility conditions for those merely possible facts that we take to be knowable (like (iii) and (iv)). 3.2

A Partially Agnostic (a)(b)¬(c) Solution.

The core idea of the present account is that, if for some domain of knowledge, the use of induction, abduction, and extrapolation methods are not objectionable, then, if they are for some other domain of knowledge, the objector must give us reasons why it is so. Those methods are not objectionable in science in general, and, in particular, they are not in many areas of philosophy. Thus, unless positive reasons are given against the legitimacy of our use of them in 22

modal epistemology, we can feel free of using them as well, and also, and most importantly, we can feel free of using the knowledge that other disciplines arrive at by using them, as long as some rationale is provided to motivate the adequacy of particular uses of them. The easy cases: Elucidations for known merely possible facts.

3.2.1

The following claims are taken to be known here: -

It is possible that John Kennedy dies from heart attack

-

It is possible that this table breaks.

How can we know that? Briefly: For some a, we have empirically known that -

a has died from heart attack.

From here, and appealing to (p→ p), we infer: -

It is possible that a dies from heart attack

We abstract a away, and get the open sentence with no singular term φ(x): -

It is possible that x dies from heart attack.

And now, by appealing to a modal counterpart principle (on which I comment right below), we get φ(John Kennedy): -

It is possible that John Kennedy dies from heart attack.

For this to work as an epistemic explanation, we need a rationale to get the class of modal counterparts that the open-sentence

φ(x) determines. Intensionally, the class of modal

counterparts determined by this open sentence is the class of individuals that are modally analogous to a regarding a’s possibility of dying from heart attack. I suggest that it is the class of all individuals (possibly) with heart. How can we know that? Here is a suggestion: If we know that the direct cause of a’s death is that her heart broke down, and if we know that, given their similarity in intrinsic properties, all hearts are analogous in their causal powers (at least, as for functions and malfunctions is concerned), then, we know that the counterpart class determined by φ(x) includes all individuals with heart16. Knowing that John Kennedy is one of them (by knowing that he has heart), we thereby know about John Kennedy’s possibility of dying from heart attack.17 Now, either the two conjuncts of the antecedent are true, or they are not. If they both are true, the knowledge mentioned there grounds our knowledge that John Kennedy could die from heart 16

In fact, the intension of this class is slightly different: It includes all individuals possibly with heart; but, so far, we know which ones actually have heart, not which ones possibly have; or even worse: which possible individuals possibly have. So, we know some elements in that class, although we do not know whether there are more than them in that class. 17 To go a bit deeper in our epistemological investigations, we may ask: how do we know that all hearts can break down? The idea here is that by similar reasoning and the same methodology, we can establish it.

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attack (in conjunction with empirical knowledge that John Kennedy has heart). If it is objected that we lack the knowledge mentioned there, then, the epistemic challenge of this paper is unfairly stated if it is stated as an epistemic challenge challenging only modal knowledge, as if it were something disconnected from knowledge of causal laws and causal powers. The hope of the project is that this generalizes to almost any other possibility fact involving just one individual; and whose corresponding open sentence (free of singular terms) is of the form φ(x), like for instance, ‘it is possible that x breaks’18. I intend this as an elucidation of how we can know merely possible facts like (iii) and (iv); something missing in conceivability approaches. Complications arise when we inquire into possibility facts involving more than one individual, and we will deal with them in the next subsection. The aim of what follows is to spell out the disanalogy between (iii) and (iv), on the one hand, and (i) and (ii) on the other. And this disanalogy is intended to explain our different attitudes with respect to their knowability; also missing in conceivability approaches. 3.2.2.

The Hard Cases (I): At the moment, Agnosticism.

The current account puts a lot of weight on empirical observations in order to get modal knowledge. As for the easy cases, the lemma of our methodology can be metaphorically stated by saying that, most of the times, we learn from others’ experiences. What happens to a tells us about what may happen to its modal analogous. In a very important sense, experience is no less essential to our modal knowledge than reasoning with our (experiential) knowledge. So, suppose now that a originates from b&c. Are our conceptual resources, cognitive capacities, and empirical knowledge of what happens to other entities sufficient for us to know whether aOd&e? My answer to this question is that, at the moment, we don’t know, but that we have reasons to think that the methods we used in establishing conceptual necessities and the ones we used in establishing the easy cases from the previous subsection are not helpful here; or, at least, no so immediately so. The easy cases we dealt with in §3.2.1 had in common that the modal claims we were inquiring into involved only one individual in each case. When looking for a rationale that would inform us about the class of modal counterparts of a given sentence φ(x) without singular terms, we found that intrinsic similarity was a good criterion, to the extent that we had previous reasons for thinking that intrinsic properties determine causal powers (as well as “effect susceptibility”, so to call it). To continue with the example about origins, assume that: -

a originates from b&c.

By extrapolating any individual mentioned there, we get: 18

We will deal with exceptions of this general claim in section 3.2.3.

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-

x originates from y&z

For simplicity, let us take this as a binary relation (rather than ternary) among individuals and origins, of the form <x, >. The class of modal counterparts that this sentence determines is a class of pairs: of individuals in the first place, and pairs of sperms and egg cells in the second. If we could know what the extension of this relation is, we would know the truth or falsity of both, necessity of origins and sufficiency of origin: only if it is a function, necessity of origins as stated in (Nec-O) is true; only if its converse is a function, sufficiency of origins is true. Does the rationale about intrinsic similarity help here? I contend that it is insufficient. Let us grant that all human beings are intrinsically similar in the relevant sense (what ever the sense is); that all human sperms are intrinsically similar, and that also all human egg cells are. These are three different claims about intrinsic similarity. Let a be a human being (originated from b&c), d be a human sperm, and e a human egg cell. Those three claims individually justify the following partial knowledge of the relation, as well as the possibility knowledge that that partial knowledge of the relation imply. By appealing to those three claims, we know that there are pairs looking like this: -

>: a can originate from a human sperm and a human egg cell.

-

<x, >: d can, in conjunction with a human egg cell, give rise to a human being.

-

<x, >: e can, in conjunction with a human sperm, give rise to a human being.

However, we face here a question we did not face in the easy cases: Can we infer from these three possibilities, the possibility that >? The dilemma is that, on the one hand, to infer from those three possibilities, and without further rationale, that > seems to beg the question against origin essentialism. Even in the case that we were to adopt the most natural criterion of intrinsic similarity among n-tuples (in terms of intrinsic similarity of their elements), a further rationale is needed to defend the claim that any two intrinsically similar n-tuples are modal counterparts. On the other hand, to object the inference without further rationale seems to beg the question in favour origin essentialism. Even if we knew that b&c is the biological cause of a, this, by itself, does not establish that it is also its metaphysical cause. In any case, it is at the moment hard to see how the intrinsic similarities among human beings, among sperms, and among egg cells may help us to discover the existence or inexistence of ontological dependence relations among them; if intrinsic similarities are relevant here, and if the existence or inexistence of ontological dependence relations can indeed be discovered, the model needs further elaboration. In sum, whenever we are inquiring into modal facts involving more than one individual, intrinsic similarity of individuals seems to be insufficient as a rationale to decide the question. I am not claiming that no further rationale is ever obtainable; what seems clear though is that the 25

methods that seemed to work in the easy cases, or in the case of conceptual necessities, are not straightforwardly helpful here. This is, I hope, sufficient to explain why, while there seems to be agreement about the knowability (and truth) of claims like (iii) and (iv), there is no such agreement about the knowability (or truth) of claims like (i) and (ii). 3.2.3.

The Hard Cases (II):

Agnosticism as well, for slightly different reasons.

The focus of the previous subsection turned out to be relational essential properties (the ones that, if existent, imply ontological dependence relations between different existences). As in the easy cases, the hope of the project is that the conclusions drawn there generalize to any kind of relational essential property. What about non-relational essential properties like being human? They do not involve more than one individual. Therefore, that the knowability model of §3.2.1 does not apply for relational essential properties, does not explain why it would not apply to the non-relational ones. Let us see why, also in this case, agnosticism is, as for now, the best option. Consider again the sentence: -

It is possible that John Kennedy dies from heart attack.

And compare it with: -

It is possible that John Kennedy is a dog.

In §3.2.1, we derive the first one from knowledge of what intrinsic properties Kennedy has, plus knowledge that individuals with relevantly similar intrinsic properties have died from heart attack, plus knowledge that intrinsic properties determine causal powers. In other terms, empirical observations may inform us about which possible courses of events supervene on which intrinsic properties, and this helps us to know which possible course of events John Kennedy is susceptible of given what his intrinsic properties are. The question whether John Kennedy may be a dog is different from the one about his possible heart attack. The former is not asking about what may happen to him, given what his intrinsic properties are, but rather, asking whether his intrinsic properties could have been radically different (throughout all his history). It should be no surprise that intrinsic similarity is of no help here. Let o be a dog. By (p→ p) and extrapolation, we have: -

It is possible that x is a dog.

Given that dog is the only salient concept involved, the (relevant) intrinsic similarity here seems to be the definitory traits of dogs (presumably in terms of genetic code). What can we know about the class of counterparts determined by this open sentence? At the intensional level, we know that all individuals that are possibly dogs belong there. At the extensional level, we can certainly know that all actual dogs belong there, which informs us that all actual dogs are possibly dogs. But can we know whether John Kennedy belongs there? I don’t know. But it seems that we cannot know it by appealing to his relevant intrinsic similarity with dogs

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because, given that he is not actually a dog, he is relevantly dissimilar to any of them. The knowability model we used in the easy cases does not apply here either, which also helps to spell out the disanalogy that would make us accept the easy cases as known, but not the current ones. Conclusions VanInwagen is an example of philosopher who thinks that the modal realm is partially inaccessible.19 In Modal Epistemology he defends a sort of modal scepticism compatible with partial epistemic access for claims like (iii) and (iv), but committed to unknowability of claims like (i), (ii), and other claims like ‘it is possible there is a perfect being’, or that ‘it is possible that exist and nothing material exist’: My own view is that we often do know modal propositions, ones that are of use to us in everyday life, and in science, and even in philosophy, but do not and cannot know (at least by the exercise of our own unaided powers) modal propositions like the crucial modal premises of our three possibility arguments. […] The world contains a great deal of institutionalized pretense to knowledge of remote matters concerning which knowledge is in fact not possible. [vanInwagen (1998): 69]

Whenever this is the option, however, an explanation of how we can know “everyday life modal claims” is needed, as well as an explanation of why some part of the modal realm is inaccessible, and both things are missing in vanInwagen’s paper; the most he says with respect to this is that: I am convinced that whatever it is that enables us to determine the modal status of ordinary propositions about everyday matters, this method or mechanism or technique or device or system of intuitions or whatever it should be called is of no use at all in determining the modal status of propositions remote from the concerns of everyday life. I am convinced, moreover, that there is other method or mechanism or technique or device or system of intuitions that enables us to do this. [vanInwagen (1998): 76]

My position with respect to the knowability of claims like (i) and (ii) is certainly weaker than vanInwagen’s in that, where he holds scepticism, I am at the moment agnostic. I share nonetheless vanInwagen’s intuitions that the knowability conditions for (i) and (ii) are different from the knowability conditions for (iii) and (iv). Here, I have tried to elucidate the knowability conditions for the claims I take to be knowable, and also explain why those methods are not by

19

A less clear example is Peacocke [(1999): 166]. In those pages, he does not assess partial unknowability, but declines affirming total knowability.

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themselves sufficient to decide claims like (i) or (ii). However, I am not yet convinced that no other mechanism is available.20 Sònia Roca Royes [email protected] LOGOS-Grup de Recerca en Lògica, Llenguatge i Cognició Departament de Lògica, Història i Filosofia de la Ciència Universitat de Barcelona Baldiri reixac s/n, 08028 Barcelona, Spain. Visiting student at ARCHÉ-The AHRB Research Centre for the Philosophy of Logic, Language, Mathematics and Mind Department of Logic and Metaphysics University of St.Andrews St.Andrews, Fife KY16 9AL Scotland, U.K.

References Bealer, George (2002), "Modal Epistemology and the Rationalist Renaissance", in Gendler and Hawthorne Conceivability and Possibility (eds.), pp. 71-125. Blackburn, Simon (1986/1993), “Morals and Modals”, in Essays in Quasi-Realism, Oxford: OUP, 52-74. Brueckner, Anthony (2001), “Chalmers’s Conceivability Argument for Dualism”, Analysis, 61:187-193. Chalmers, David (2002), “Does Conceivability entail Possibility?”, in Gendler and Hawthorne Conceivability and Possibility (eds.), pp. 145-200. Craig, Edward (1985), “Arithmetic and Fact”, in I. Hacking (ed.) Essays in Analysis, Cambridge: CUP, 89-112 Della Rocca, (2002), “Essentialism vs. Essentialism”, in Gendler and Hawthorne Conceivability and Possibility (eds.), pp. 223-252. Fine, Kit (1994), “Essence and Modality”, Philosophical Perspectives, 8, Logic and Language, 1-16. Geirsson, Heimir (2005), “Conceivability and Defeasible Modal Justification”, Philosophical Studies, 122(3): 279-304.

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I would like to thank all members of both ARCHÉ (University of St.Andrews; http://www.standrews.ac.uk/~arche/) and LOGOS (Universitat de Barcelona; http://www.ub.es/grc_logos) for their helpful discussions on the topic, as well as for helpful comments and suggestions on previous drafts of this work.

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Gendler, Tamar S. and Hawthorne, John (2002), Conceivability and Possibility, (Oxford: Clarendon Press: 2002). Hale, Bob (2003), “Knowledge of Possibility and of Necessity”, Proceedings of the Aristotelian Society, CIII, pp. 1-20. Heathcote, Adrian (2001), “Yes, but what is the mother of Necessity?”; Philosophical Books, 42(2), 92-100 Kripke, Saul (1980), Naming and Necessity, Cambridge, Massachusetts, Harvard University Press. Peacocke, Christopher (1997), “Metaphysical Epistemology”, Mind, 106, 521-574.

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Truth

and

—— (1999), Being Known, Oxford, Oxford University Press. —— (2001), “The Past, Necessity, Externalism and Entitlement”, Philosophical Books, 42(2), 106-117. —— (2002a), “The Principle-Based Account of Modality: Elucidations and Resources”, Philosophy and Phenomenological Research, Vol.LXIV, Nº3, 663-679. —— (2002b), “Principles for Possibilia”, Noûs, 36:3, 486-508. Sidelle, Alan (1989), Necessity, Essence, and Individuation, Cornell University Press. vanInwagen, Peter (1998), “Modal Epistemology”, Philosophical Studies, 92: 67-84. Worley, Sara (2003), “Conceivability, Possibility and Physicalism”, Analysis, 63:15-23. Yablo, Stephen (1993), “Is Conceivability a Guide to Possibility” Philosophy and Phenomenological Research, 53:1-42. —— (1996), “How in the World?”, Philosophical Topics,

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