The capacity to represent things to ourselves as possible plays a crucial role both in everyday thinking and in philosophical reasoning; this volume offers much-needed philosophical illumination of conceivability, possibility, and the relations between them.

There is a long tradition in philosophy of using a priori methods to draw conclusions about what is possible and what is necessary, and often in turn to draw conclusions about matters of substantive metaphysics. Arguments like this typically have three steps: first an epistemic claim , from there to a modal claim , and from there to a metaphysical claim.

This paper was chosen by The Philosopher’s Annual as one of the ten best articles appearing in print in 2000. Reprinted in Volume XXIII of The Philosopher’s Annual. In his very influential book David Chalmers argues that if physicalism is true then every positive truth is a priori entailed by the full physical description – this is called “the a priori entailment thesis – but ascriptions of phenomenal consciousness are not so entailed and he concludes that Physicalism is false. As (...) he puts it, “zombies” are metaphysically possible. I attempt to show that this argument is refuted by considering an analogous argument in the mouth of a zombie. The conclusion of this argument is false so one of the premises is false. I argue at length that this shows that the original conceivability argument also has a false premise and so is invalid. (shrink)

The paper presents a dilemma for both epistemic and non-epistemic versions of conceivability-based accounts of modal knowledge. On the one horn, non-epistemic accounts do not elucidate the essentialist knowledge they would be committed to. On the other, epistemic accounts do not elucidate everyday life de re modal knowledge. In neither case, therefore, do conceivability accounts elucidate de re modal knowledge.

The Humean view that conceivability entails possibility can be criticized via input from cognitive psychology. A mainstream view here has it that there are two candidate codings for mental representations (one of them being, according to some, reducible to the other): the linguistic and the pictorial, the difference between the two consisting in the degree of arbitrariness of the representation relation. If the conceivability of P at issue for Humeans involves the having of a linguistic mental representation, then (...) it is easy to show that we can conceive the impossible, for impossibilities can be represented by meaningful bits of language. If the conceivability of P amounts to the pictorial imaginability of a situation verifying P, then the question is whether the imagination at issue works purely qualitatively, that is, only by phenomenological resemblance with the imagined scenario. If so, the range of situations imaginable in this way is too limited to have a significant role in modal epistemology. If not, imagination will involve some arbitrary labeling component, which turns out to be sufficient for imagining the impossible. And if the relevant imagination is neither linguistic nor pictorial, Humeans will appear to resort to some representational magic, until they come up with a theory of a ‘third code’ for mental representations. (shrink)

The conceivability argument against physicalism1 starts from the prem- ises that: It is conceivable that I have a zombie-twin, i.e., that there is someone who is physically identical to me and yet who lacks phenomenal con- sciousness; and If it is conceivable that I have a zombie-twin, then it is possible that I have a zombie-twin. These premises entail that physicalism is false, for physicalism is the claim—or can be assumed for our purposes to be the claim2—that.

The notion of conceivability has traditionally been regarded as crucial to an account of modal knowledge. Despite its importance to modal epistemology, there is no received explication of conceivability. One purpose of this paper is to argue that the notion is not fruitfully explicated in terms of the imagination. The most natural way of presenting a notion of conceivability qua imaginability is open to cogent criticism. In order to avoid such criticism, an advocate of the modal insightfulness (...) of the imagination must broaden the idea of what it is to be imaginable. I argue that this required broadening renders the imagination idle . Consequently, I distinguish two different accounts of the evidential basis of modal knowledge and present a more general argument that concludes that the very notion of conceivability should be eschewed in modal epistemology. (shrink)

This paper advances the thesis that we can justifiably believe philosophically interesting possibility statements. The first part of the paper critically discusses van Inwagens skeptical arguments while at the same time laying some of the foundation for a positive view. The second part of the paper advances a view of conceivability in terms of imaginability, where imaginging can be propositional, pictorial, or a combination of the two, and argues that conceivability can, and often does, provide us with justified (...) beliefs of what is metaphysically possible. The notion of scenarios is developed, as is an account of how filling out scenarios can uncover a defeater or, in many cases, strengthen the justification for the relevant possibility statement. (shrink)

Materialism in the philosophy of mind is the thesis that the ultimate nature of the mind is physical; there is no sharp discontinuity in nature between the mental and the non-mental. Anti-materialists asser t that, on the contrary, mental phenomena are different in kind from physical phenomena. Among the weapons in the arsenal of anti-materialists, one of the most potent has been the conceivability argument. When I conceive of the mental, it seems utterly unlike the physical. Anti-materialists insist that (...) from this intuitive difference we can infer a genuine meta-physical difference. Materialists retor t that the nature of reality, including the ultimate natures of its constituents, is a matter for discovery; an objective fact that cannot be discerned a priori. In this paper I under take to provide an explicit analysis of the dialectic that surrounds the conceivability argument. My principal conclusion is that the materialist is right in resisting the reasoning that star ts from considerations of what is conceivable and ends with genuine metaphysical conclusions. However my approach is much more sympathetic to the anti-materialist position than is the standard materialist line, and I will provide a limited defense of some crucial aspects of the anti-materialist position. Materialism will emerge from this fight intact, but shaken. (shrink)

According to the ‘conceivability argument’ [1] it’s conceivable that a conscious human being H may have a perfect physical duplicate H* who isn’t conscious, [2] whatever is conceivable is possible, therefore [3] H* may possibly exist. This paper argues that the conceivability argument can’t help in discussion of the ‘mind–body problem’ even if [2] is allowed to be true. This is not because [1] is false, but because we don’t and can’t know enough about the nature of the (...) physical to know whether or not [1] is true. This follows from ‘the silence of physics’—the fact that physics neither does nor can tell us about the intrinsic non-structural nature of the physical, and the consequences of this fact for any adequate account of the meaning of the word ‘physical’. (shrink)

According to haecceitism, some maximal possibilities differ even while they are qualitatively indiscernible. Since haecceitism is a modal thesis, it is typically defended by appeal to conceivability arguments. These arguments require us to conceive of qualitatively indiscernible possibilities that differ only with respect to the identity of the individuals involved. This paper examines a series of conceivability arguments for haecceitism and a variety of anti-haecceitist responses. It concludes that there is no irresistible conceivability argument for haecceitism even (...) while anti-haecceitist responses do come with certain notable commitments. (shrink)

In this paper, we argue that ‘Weak Modal Rationalism’, which is the view that ideal primary positive conceivability entails primary metaphysical possibility, is self-defeating. To this end, we outline two reductio arguments against ‘Weak Modal Rationalism’. The first reductio shows that, from supposing that ‘Weak Modal Rationalism’ is true, it follows that conceivability both is and is not conclusive evidence for possibility. The second reductio shows that, from supposing that ‘Weak Modal Rationalism’ is true, it follows that it (...) is possible that ‘Weak Modal Rationalism’ is necessarily false, and hence that ‘Weak Modal Rationalism’ is false. We then argue that adopting a weaker position according to which conceivability is merely prima facie evidence for possibility provides limited protection from our criticism of conceivability arguments. (shrink)

This paper compares and contrasts two conceivability arguments: the zombie argument (ZA) against physicalism, and the perfect actor argument (AA) against behaviourism. I start the paper by assuming that the arguments are of the same kind, and that AA is sound. On the basis of these two assumptions I criticize the most common philosophical suggestions in the literature today about what is wrong with ZA, and what is right in it. I end the paper by suggesting that the comparison (...) between the two arguments makes plausible an epistemic response to ZA according to which the conceivability of a zombie - that is, someone identical to me in all physical respects but different in some phenomenal respect - is being confused with the conceivability of something else, i.e. someone identical to me in physical respects that are epistemically available, but different in some phenomenal respect. (shrink)

David Chalmers' conceivability argument against physicalism relies on the entailment from a priori conceivability to metaphysical possibility. The a posteriori physicalist rejects this premise, but is consequently committed to psychophysical strong necessities. These don't fit into the Kripkean model of the necessary a posteriori, and they are therefore, according to Chalmers, problematic. But given semantic assumptions that are essential to the conceivability argument, there is reason to believe in microphysical strong necessities. This means that some of Chalmers' (...) criticism is unwarranted, and the rest equally afflicts the dualist. Moreover, given that these assumptions are independently plausible, there's a general case to be made for the existence of strong necessities outside the psychophysical domain. (shrink)

This paper examines the ramifications of Hume's view of the relation of conceivability to metaphysical possibility. It argues that the limitations Hume places of the representations involved in moves to conceivability to metaphysical possibility preclude any straightforward argument against full-blooded causal realism in Hume from conceivability. Furthermore, our finding certain states of affairs conceivable when they are not metaphysically possible is perfectly compatible with the thrust of the causal realist position.

To what extent and how is conceivability a guide to possibility? This essay explores general philosophical issues raised by this question, and critically surveys responses to it by Descartes, Hume, Kripke and "two-dimensionalists.".

Wright (In Gendler and Hawthorne (Eds.), Conceivability and possibility, 2002) rejects some dominant responses to Kripke’s modal argument against the mind-body identity theory, and instead he proposes a new response that draws on a certain understanding of counterpossibles. This paper offers some defensive remarks on behalf of Lewis’ objection to that argument, and it argues that Wright’s proposal fails to fully accommodate the conceivability intuitions, and that it is dialectically ineffective.

In The Conscious Mind, D. Chalmers appeals to his semantic framework in order to show that conceivability, as employed in his "zombie" argument for dualism , is sufficient for genuine possibility. I criticize this attempt.

Christopher Hill contends that the metaphysical modalities can be reductively explained in terms of the subjunctive conditional and that this reductive explanation yields two tests for determining the metaphysical modality of a proposition. He goes on to argue that his reductive account of the metaphysical modalities in conjunction with his account of modal knowledge underwrites the further conclusion that conceivability does not provide a reliable test for metaphysical possibility. I argue (1) that Hill’s reductive explanation of the metaphysical modalities (...) in terms of the subjunctive conditional does not yield a reductive explanation of knowledge of metaphysical modality in terms of knowledge of subjunctive conditionals, and (2) that his account of modal knowledge is at odds with his contention that conceivability does not provide epistemic access to metaphysical possibility. (shrink)

The Phenomenal Concept Strategy offers the physicalist perhaps the most promising means of explaining why the connection between mental facts and physical facts appears to be contingent even though it is not. In this article, we show that the large body of evidence suggesting that our concepts are often embodied and grounded in sensorimotor systems speaks against standard forms of the PCS. We argue, nevertheless, that it is possible to formulate a novel version of the PCS that is thoroughly in (...) keeping with embodied cognition, focuses on features of physical concepts, and succeeds in explaining the appearance of contingency. (shrink)

This paper offers a detailed criticism of different versions of modal scepticism proposed by Van Inwagen and Hawke, and, against these views, attempts to vindicate our reliance on thought experiments in philosophy. More than one different meaning of “ modal scepticism” will be distinguished. Focusing mainly on Hawke’s more detailed view I argue that none of these versions of modal scepticism is compelling, since sceptical conclusions depend on an untenable and, perhaps, incoherent modal epistemology. With a detailed account of modal (...) defeaters at hand I argue that Van Inwagen and Hawke’s scepticism is either groundless, or it leads to boundless and unacceptable modal scepticism. Additionally, I show that Hawke’s conception of analogical modal reasoning is problematic. Either his principle of similarity is arbitrary or it begs the question about modal scepticism. In contrast to Hawke’s restricted view of analogical modal reasoning, I present two examples of analogy-based modal justification of philosophically relevant possibility claims. My criticism of modal scepticism also shows that there is no good reason to insist on a sharp distinction between an unproblematic and a presumably dubious kind of modality. The upshot is that in absence of proper defeaters both Yablo-style conceivability and properly applied analogical reasoning are reliable guides to possibility, and also that modal justification comes in degrees. The proposed framework of defeaters of modal justification as well as the analysed examples of analogical modal reasoning trace out interesting new areas for further discussions. (shrink)

In the history of modern philosophy systematic connections were assumed to hold between the modal concepts of logical possibility and necessity and the concept of conceivability. However, in the eyes of many contemporary philosophers, insuperable objections face any attempt to analyze the modal concepts in terms of conceivability. It is important to keep in mind that a philosophical explanation of modality does not have to take the form of a reductive analysis. In this paper I attempt to provide (...) a response-dependent account of the modal concepts in terms of conceivability along the lines of a nonreductive model of explanation. (shrink)

The notion of conceivability has traditionally been regarded as crucial to an account of modal knowledge. Despite its importance to modal epistemology, there is no received explication of conceivability. In recent discussions, some have attempted to explicate the notion in terms of epistemic possibility. There are, however, two notions of epistemic possibility, a more familiar one and a novel one. I argue that these two notions are independent of one another. Both are irrelevant to an account of modal (...) knowledge on the predominant view of modal reality. Only the novel notion is relevant and apt on the competing view of modal reality; but this latter view is problematic in light of compelling counterexamples. Insufficient care regarding the independent notions of epistemic possibility can lead to two problems: a gross problem of conflation and a more subtle problem of obscuring a crucial fact of modal epistemology. Either problem needlessly hampers efforts to develop an adequate account of modal knowledge. I conclude that the familiar notion of epistemic possibility should be eschewed in the context of modal epistemology. (shrink)

It is widely believed that platonists face a formidable problem: that of providing an intelligible account of mathematical knowledge. The problem is that we seem unable, if the platonist is right, to have the causal relationships with the objects of mathematics without which knowledge of these objects seems unintelligible. The standard platonist response to this challenge is either to deny that knowledge without causation is unintelligible, or to make room for causal interactions by softening the platonism at issue. In this (...) essay I argue that the idea of causal relations with fully platonist objects is unproblematic. (shrink)

According to Williamson, our knowledge of metaphysical necessities and possibilities is just a “special case” of our knowledge of counterfactual conditionals. This subsumption of modal under counterfactual thinking mainly serves a methodological role: to sign the end of “philosophical exceptionalism” in modal epistemology, namely the view that our knowledge of metaphysical modalities is obtained by means of a special, dedicated, possibly a priori, capacity. In this paper, I show that a counterfactual approach to modal epistemology is structurally similar to more (...) traditional “conceivability-based” approaches. On this basis, I then show that the counterfactual approach suffers some of the same problems and I conclude that it is still based on a quite exceptional capacity to determine the truth of modal metaphysical claims. Given that, for Williamson, the epistemology of thought experiments should also be subsumed under the counterfactual approach, the problem I raise in this paper has consequences for his approach to thought experiments. (shrink)

The dissertation addresses the mind-body problem, and in particular, the problem of how to fit phenomenal consciousness into the rest of reality. Phenomenal consciousness - the what it’s like feature of experience - can appear to the scientifically inclined philosopher to be deeply mysterious. It is difficult to understand how the swirl of atoms in the void, the oscillation of field values, the firing of synapses, or anything physical can add up to the smells, tastes, feelings, moods, and so forth (...) that comprise our phenomenal experience. There is a series of arguments - the so-called “Conceivability Arguments” - that spells out this puzzlement. If this arguments are successful then there is no place for phenomenal consciousness in a completely physical reality. The main conclusion of this dissertation is that the Conceivability Arguments are all dependent on a flawed premiss, and that therefore these arguments - perhaps the most powerful among anti-physicalist arguments - all fail. Conceivability Arguments begin with the premiss that we can conceive of any physical or functional facts obtaining without there being any phenomenal experience at all. This is sometimes expressed by saying that zombies (i.e., beings that are our physical and functional duplicates, but possess no phenomenal experiences) are conceivable. The claim that zombies are conceivable does not have to do with our powers of imagination, or our psychological abilities, but rather with the nature of physical and phenomenal concepts. The reason that zombies are claimed to be conceivable is that each person’s thinking about phenomenal properties is completely dependent on her first person acquaintance with her own experience. From this assertion of conceivability it is inferred that zombies are genuinely possible. And this conclusion is incompatible with physicalism as that doctrine is usually understood. I argue that these arguments all fail; they are refuted by a master argument that I call “the Zombie Refutation.” The reason they fail has to do with the very nature of phenomenal concepts that gives rise to the conceivability of zombies. Because of the special nature of these concepts, the principle underlying the Conceivability Arguments - that principle that links conceivability and possibility - turns out to be self-refuting. Thus, the zombies that the Conceivability Arguments supposedly demonstrate to be possible, return to undermine those very arguments; a fitting revenge. (shrink)

David Chalmers’ ‘conceivability’ argument against physicalism is perhaps the most widely discussed and controversial argument in contemporary philosophy of mind. Recently, several thinkers have suggested a novel response to this argument, which employs the ‘powerful qualities’ ontology of properties. In this paper, I argue that this response fails because it presupposes an implausible account of the physical/phenomenal distinction. In the course of establishing this, I discuss the so-called ‘ultimate’ argument for the claim that dispositional properties form the subject matter (...) of physics. I argue that the ultimate argument can be interpreted in a strong or a weak way, and that the strong interpretation is implausible. I argue that this undermines the powerful qualities based response to the conceivability argument. I also argue for a general conclusion: that we should not define ‘the physical’ exclusively in terms of a distinction drawn from ontology. (shrink)

Hill and Levine offer alternative explanations of these conceivabilities, concluding that these conceivabilities are thereby defeated as evidence. However, this strategy fails because their explanations generalize to all conceivability judgments concerning phenomenal states. Consequently, one could defend absolutely any theory of phenomenal states against conceivability arguments in just this way. This result conflicts with too many of our common sense beliefs about the evidential value of conceivability with respect to phenomenal states. The general moral is that the (...) application of such principles of explanatory defeat is neither simple nor straightforward. (shrink)

One reason for the recent attention to conceivability claims is to be found in the extended use of conceivability in philosophy of mind, and then especially in connection with zombie thought experiments. The idea is that zombies are conceivable; beings that look like us and behave like us in all ways, but for which “all is dark inside;” that is, for a zombie, there is no “what it is like.” There is no “what it is like” to be (...) a zombie, there is no “what it is like” for a zombie to feel pain, there is no “what it is like” for a zombie to taste, or feel, or smell something. They are creatures without consciousness. I am skeptical about the conceivability of zombies. That is not to say that I believe that there is some inherent contradiction to be found in the idea of zombies. Instead, I do not think that I am justified in believing that zombies are conceivable. The focus on justification is not common in the literature on conceivability, or for that matter in the literature on the possibility of zombies. Instead, the focus tends to be on trying to find out whether or not the notion of a zombie is contradictory. It is widely accepted in the literature on conceivability that the absence of a contradiction when conceiving of X is both necessary and sufficient for X to be conceivable. That might be true of ideal conceivability, but as I will argue below, ideal conceivability is not relevant to our (human) pursuit of knowledge and understanding. Further, as I will argue, once we focus on non-ideal conceivability the notion of justification, and degrees of justification comes into play. (shrink)

Why do we tend to ascribe possibility to what we can imagine? One strategy for answering that question involves the thought that, just as sensory episodes often involve its seeming to us as though the world is certain ways, so imaginings involve its seeming to us that what we have imagined is possible. This chapter argues that while some imaginings do feature appearances of possibility, very many others do not; and it explores the broader relevance of its conclusions for modal (...) epistemology. (shrink)

Many well-known arguments against physicalism—e.g., Chalmers’s Zombie Argument and Kripke’s Modal Argument—contend that it is conceivable for there to be physical duplicates of ourselves that have no conscious experiences and also that what is conceivable is possible—and therefore, if phenomenal-physical identity statements are supposed to be necessary, then physicalism can’t be true. Physicalists typically respond to these arguments either by questioning whether such creatures can truly be conceived, or denying that the conceivability of such creatures provides good evidencefor their (...) ‘metaphysical’ possibility. An increasing number of physicalists, however, contest these arguments in a different way, namely, by suggesting that the conceivability premises in these arguments beg the question: one’s ability to conceive of the existence of zombies depends exclusively on what one antecedently believes to be the nature of conscious experience —and therefore cannot legitimately be used to draw conclusions about whether conscious experiences could be physical states or processes. My aim in this paper is to consider, and raise questions about, this response to the antiphysicalist arguments—and argue that physicalists have more promising ways to disarm them. (shrink)

In his 1998 postscript to ‘The Possibility of Resurrection’ Peter van Inwagen argues that the scenario he describes by which God might resurrect a human organism, even though probably not true, is still conceivable and, consequently, ‘serves to establish a possibility’, namely, the metaphysical possibility of the resurrection of material beings. Van Inwagen, however, has also argued in favour of ‘modal scepticism’ [van Inwagen in, God, knowledge and mystery: essays in philosophical theology, Cornell University Press, Ithaca 1995b, pp. 11–12; van (...) Inwagen in, Philos Stud 92:67–84, 1998a]. That is, he thinks that we should limit all our claims about what is possible to ‘ordinary propositions about everyday matters’, 1998a). In this paper I argue that van Inwagen’s modal argument as found in ‘The Possibility of Resurrection’ is inconsistent with his modal scepticism as found in ‘Modal Epistemology’. In consequence, I argue that, given his modal scepticism, the task van Inwagen set himself in ‘The Possibility of Resurrection’ has not been achieved. (shrink)

This paper examines Descartes' controversial theory of the creation of eternal truths and the views of modality attributed to Descartes in recent interpretations of it. It shows why attempts to make Descartes' view intelligible by distinctions of different kinds of modality fail to do justice to his theory, which is radical indeed without being incoherent or involving universal possibilism or irrationalism. Descartes' opposition to traditional rationalist views of modality, it suggests, can be seen instead as foreshadowing contemporary views prefixed, logical (...) structure of reality or of the divine intellect. (shrink)

This article is a discussion of Hume's maxim Nothing we imagine is absolutely impossible. First I explain this maxim and distinguish it from the principle Whatever cannot be imagined (conceived), is impossible. Next I argue that Thomas Reid's criticism of the maxim fails and that the arguments by Tamar Szábo Gendler and John Hawthorne for the claim that "it is uncontroversial that there are cases where we are misled" by the maxim are unconvincing. Finally I state the limited but real (...) value of the maxim: it does help us, in certain cases, reliably to make up our minds. Along the way I show that Reid, his criticism of the maxim notwithstanding, actually employs it, and I furthermore argue that the principle What is inconceivable, is impossible is spurious. (shrink)

Conceivability is an important source of our beliefs about what is possible; inconceivability is an important source of our beliefs about what is impossible. What are the connections between the reliability of these sources? If one is reliable, does it follow that the other is also reliable? The central contention of this paper is that suitably qualified the reliability of inconceivability implies the reliability of conceivability, but the reliability of conceivability fails to imply the reliability of inconceivability.

The central recommendation of this article is that philosophers trained in the analytic tradition ought to add the sensibilities and skills of the historian to their methodological toolkit. The value of an historical approach to strictly philosophical matters is illustrated by a case study focussing on the medieval origin of conceivability arguments and contemporary views of modality. It is shown that common metaphilosophical views about the nature of the philosophical enterprise as well as certain inference patterns found in thinkers (...) from Descartes to Chalmers have their origin in the theological concerns of the Scholastics. Since these assumptions and inference patterns are difficult to motivate when shorn of their original theological context, the upshot is that much post-Cartesian philosophy is cast in an altogether unfamiliar, and probably unwelcome, light. The methodological point, however, is that this philosophical gain is born of acquaintance with the history of ideas. (shrink)

Those who seek to defend a sceptical realist reading of Hume on causal necessity have a number of textual and philosophical hurdles to clear. This paper attempts to clear one and only one hurdle. So one should not look here for a complete case in favour of a sceptical realist reading: I merely attempt to dispose of what looks like a decisive objection to a conception of objective necessary connection which, I believe, Hume endorses.

Christopher Hill and Joseph Levine have argued that the conceivabilities involved in anti-materialist arguments are defeated as evidence of possibility. Their strategy assumes the following principle: the conceivability of a state of affairs S constitutes evidence for the possibility of S only if the possibility of S is the best explanation of the conceivability of S. So if there is a better explanation of the conceivability of S than its possibility, then the conceivability of S is (...) thereby defeated as evidence of possibility. Hill and Levine proceed to offer alternative explanations of these conceivabilities, concluding that these conceivabilities are thereby defeated as evidence. However, this strategy fails because their explanations generalize to all conceivability judgments concerning phenomenal states. Consequently, one could defend absolutely any theory of phenomenal states against conceivability arguments in just this way. This result conflicts with too many of our common sense beliefs about the evidential value of conceivability with respect to phenomenal states. The general moral is that the application of such principles of explanatory defeat is neither simple nor straightforward. (shrink)