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.".
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 (about what can be known or conceived), from there to a modal claim (about what is possible or necessary), and from there to a metaphysical claim (about the nature of things in the world).
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 (I think successfully) 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 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.
My aim here is threefold: (a) to show that conceptual facts play a more significant role in justifying explanatory reductions than most of the contributors to the current debate realize; (b) to furnish an account of that role, and (c) to trace the consequences of this account for conceivability arguments about the mind.
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 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 (and the very term ‘epistemic possibility’) should be eschewed in the context of modal epistemology. (shrink)
We often decide whether a state of affairs is possible (impossible) by trying to mentally depict a scenario (using words, images, etc.) where the state in question obtains (or fails to obtain). These mental acts (broadly thought of as 'conceiving') seem to provide us with an epistemic route to the space of possibilities. The problem this raises is whether conceivability judgments provide justification-conferring grounds for the ensuing possibility-claims (call this the 'conceivability thesis'). Although the question has a long (...) history, contemporary interest in it was, to a large extent, prompted by Kripke's utilization of modal intuitions in the course of propounding certain influential theses in the philosophy of language and mind. The interest has been given a further boost by the recent two-dimensional approach to the Kripkean framework. In this paper, I begin by providing a detailed examination of a most recent attempt (due to Chalmers) to defend the thesis and argue that it is unsuccessful. This is followed by presenting my own gloss on Kripke's explanation of the illusions of contingency and I close by raising a general problem intended to undermine the prospects for a successful defense of the thesis. (shrink)
Chalmers argues that zombies are possible and that therefore consciousness does not supervene on physical facts, which shows the falsity of materialism. The crucial step in this argument – that zombies are possible – follows from their conceivability and hence depends on assuming that conceivability implies possibility. But while Chalmers’s defense of this assumption – call it the conceivability principle – is the key part of his argument, it has not been well understood. As I see it, (...) Chalmers’s defense of the conceivability principle comes in his response to the so-called objection from a posteriori necessity. The defense aims at showing that there is no gap between conceivability and possibility since no such gap can be generated by necessary a posteriori truths. I will argue that while Chalmers is right to the extent that there is no gap between conceivability and possibility within the standard Kripkean model of a posteriori necessity, his general conclusion is not justified. This is because the conceivability principle might be inconsistent with a posteriori necessity understood in some non-Kripkean way and Chalmers has not shown that no such alternative understanding of a posteriori necessity is available. (shrink)
The conceivability argument (CA) against physicalism1 starts from the prem- ises that: (1) 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 (2) 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. (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 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)
The superassertability theory of truth, inspired by Crispin Wright (1992, 2003), holds that a statement is true if and only if it is superassertable in the following sense: it possesses warrant that cannot be defeated by any improvement of our information. While initially promising, the superassertability theory of truth is vulnerable to a persistent difficulty highlighted by James Van Cleve (1996) and Terrence Horgan (1995) but not properly fleshed out: it is formally illegitimate in a similar sense that unsophisticated epistemic (...) theories of truth are widely acknowledged to be. Sustained analysis reveals that the unrestricted formal legitimacy argument is firmly grounded in first person conceivability evidence. (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)
The conditional analysis of phenomenal concepts, as proposed independently by Hawthorne (2002), Stalnaker (2002) and Braddon-Mitchell (2003), is used to undermine Chalmers’s (1996) conceivability argument in a way that is compatible with our having the zombie intuition. The aim of this paper is twofold: (1) To remove current misconceptions concerning how the analysis is to be applied. It will be explained how there are two distinct ways the analysis can be used to undermine the conceivability argument. (2) To (...) employ this exposition to defend the analysis from objections leveled against it by Chalmers (2005) and Alter (2007). (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.
In addition to conceiving of such imaginary scenarios as those involving philosophical zombies, we may conceive of such things being conceived. Call these higher order conceptions ‘meta-conceptions’. Sorensen (2006) holds that one can entertain a meta-conception without thereby conceiving of the embedded lower-order conception. So it seems that I can meta-conceive possibilities which I cannot conceive. If this is correct, then meta-conceptions provide a counter-example to the claim that possibility entails conceivability. Moreover, some of Sorensen’s discussion suggests the following (...) argument: if the conceivability of some proposition entails its possibility, then the meta-conceivability of some proposition entails its possibility; but we can meta-conceive impossibilities; so conceivability doesn’t entail possibility. In this paper, I’ll argue that one cannot entertain a meta-conception without thereby conceiving of the embedded lower-order conception. And so we can neither meta-conceive impossibilities nor meta-conceive possibilities of which we cannot thereby conceive. (shrink)
What can be inferred from the fact that something is, or is not, conceivable? In this paper I argue, contrary to some deflationary remarks in recent literature, that arguments which use such facts as their starting point may have significant philosophical import. I use Strawson's results from the first chapter of "Individuals" in order to show that Galileo's arguments in favor of the distinction between primary and secondary qualities, which are based on premises concerning conceivability, should not be dismissed: (...) they are the first step towards recognizing an important conceptual truth. (shrink)
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)
In his Essays on the Intellectual Powers of Man, Thomas Reid offers a barrage of objections to the view, held by David Hume, that conceivability implies possibility. In this paper, I present Reid's first two objections to the ‘maxim of conceivability’ and defend Hume from them. The first objection concerns our ability to understand impossible claims, while the second concerns thoughts about impossible claims (such as, for instance, the thought that they are impossible). Reid's objections have special force (...) against Hume because of his commitment to analyse all operations of the understanding in terms of conception. I argue that these objections fail, on the grounds that they presuppose substantive views about language which we are not warranted in attributing to Hume. Ultimately, Reid's objections help us draw out a set of intertwined issues about the language-mind relationship in Hume. (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.
A. Collins once argued that time travel is only imaginable if we relate the "event" out of context. John Hospers argues that it is logically possible for an iron bar to float in water even if it is actually (empirically) impossible. My point in this piece is that Hospers relies on viewing the floating out of context, in Walt Disney fashion; but that is no way to establish any kind of possibility. I also discuss "conceivability", a term frequently used (...) either to clarify logical possibility or to interchange for the same. I argue that it cannot do either. (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)
Hume's maxim consists of two principles which are logically independent of each other: (1) whatever is conceivable is possible; and (2) whatever is inconceivable is impossible. Thomas Reid offered several arguments against the former principle, while John Stuart mill argued against the latter. The primary concern of this paper is to examine whether Reid and mill were successful in calling Hume's maxim into question.
The purpose of this article is to defend Hume's claim that whatever is conceivable is possible from a criticism by William Kneale. Kneale argues that although a mathematician can conceive of the falsehood of the Goldbach conjecture, he does not conclude that it is not necessarily true. The author suggests that by taking into account Hume's distinction between intuitive and demonstrative knowledge, a revised version of his claim can be offered which is not open to Kneale's criticism.
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.
It is widely suspected that arguments from conceivability, at least in some of their more notorious instances, are unsound. However, the reasons for the failure of conceivability arguments are less well agreed upon, and it remains unclear how to distinguish between sound and unsound instances of the form. In this paper I provide an analysis of the form of arguments from conceivability, and use this analysis to diagnose a systematic weakness in the argument form which reveals all (...) its instances to be, roughly, either uninformative or unsound. I illustrate this conclusion through a consideration of David Chalmers. (shrink)
The conclusion of this argument (hereafter ZA) entails the falsity of physicalism because, technical details aside, physicalism is or entails the thesis that every psychological truth is entailed by some physical truth. If it is possible that I have a zombie duplicate however, then it is possible that the physical truths are as they are and some psychological truth is different. Hence 3 entails that physicalism is false. The second conceivability argument is one that is almost as famous, though (...) perhaps it is less famous for being a conceivability argument: the perfect actor argument against behaviorism (see, e.g., Putnam 1963, 1975). In a version that is both familiar and relatively clear, it goes like this. (shrink)
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.
Our limited a priori-reasoning skills open a gap between our finding a proposition conceivable and its metaphysical possibility. A prominent strategy for closing this gap is the postulation of ideal conceivers, who suffer from no such limitations. In this paper I argue that, under many, maybe all, plausible unpackings of the notion of ideal conceiver, it is false that ideal negative conceivability entails possibility.
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 (in this context). 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)
In this paper I argue that certain so-called conceivability arguments fail to show that a currently popular version of physicalism in the philosophy of mind is false. Concentrating on an argument due to David Chalmers, I first argue that Chalmers misrepresents the relation between conceivability and possibility. I then argue that the intuition behind the conceivability of so-called zombie worlds can be accounted for without having to suppose that such worlds are genuinely conceivable. I conclude with some (...) general remarks about the nature of conceivability. (shrink)
The conceivability argument against materialism, originally raised by Saul Kripke and then reformulated, among others, by David Chalmers holds that we can conceive of the distinctness of a phenomenal state and its neural realiser, or, in Chalmers’ variation of the argument, a zombie world. Here I argue that both phenomenal and natural kind terms are ambiguous between two senses, phenomenal and natural, and that the conceivability argument goes through only on one reading of a term. Thus, the antimaterialist (...) has to provide some reasons independent of anti-materialism itself to favour that reading of a term that supports his or her argument. Given that there are no such independent reasons, I conclude that we should put more weight on empirical considerations than on a priori discussion in resolving the question concerning the identity between a phenomenal state and its neural realiser. (shrink)
Functionalism, the philosophical theory that defines mental states in terms of their causal relations to stimuli, overt behaviour, and other inner mental states, has often been accused of being unable to account for the qualitative character of our experimential states. Many times such objections to functionalism take the form of conceivability arguments. One is asked to imagine situations where organisms who are in a functional state that is claimed to be a particular experience either have the qualitative character of (...) that experience altered or absent altogether. Many of these arguments are surprisingly advanced by materialist philosophers. I argue that if the conceivability arguments were successful against functionalism, then they would be successful against their alternative materialist views as well. So the conceivability arguments alone do not provide a good reason for materialists to abandon functionalism. I further argue that functionalism is best understood to be an empirical theory, and if it is so understood then the conceivability arguments have no force against it at all. A further consequence that emerges is that on an empirical functionalist view, qualia, if real, are properties in the domain of psychology. (shrink)
Explaining phenomenal consciousness may be the scientific and philosophical problem of our time, the last frontier of knowledge. This is not at all an easy task. For any serious attempt at finding a place for consciousness within the natural world was not successful so far. There is a conceptual tension here which makes this business of coming up with a unified (monist) explanation of mind and physical world one of the most intriguing mystery. The most predominant image of the natural (...) world is one of a physicalist type, whereas the mind, and especially the conscious subjective experience seem not to fit well within that physicalistexplanation. That explanatory failure may require a dualist metaphysical scheme (probably of a neo-Cartesian type). It may seem very well that we are caught in a dilemma, for we either embrace a physicalist explanation, but then it seems that we leave out consciousness from the big picture we are looking for, or else we face the huge task of conceiving a dramatic change of our scientific outlook about the natural world, and we don’t quite see how that would be possible or desirable. But then, should any attempt at understanding consciusness be a dead-end, something doomed to fail from a theoretical and explanatory point of view? In my paper I explore some philosophical underpinnings of contemporary dualism, focussing on the modal facets of the conceivability (neo-Cartesian) arguments. I will asses both the prospects and the moot points of this type of arguments. Of particular interest is the role that two-dimensional semantics plays in nowadays discussions of this topic. (shrink)
Certain cognitive and philosophical aspects of the concept of conceivability with intended or established diversion from (putative) reality are discussed. The “coherence gap problem” arises when certain fragments of the real world are replaced with imaginary situations while most details are (intentionally or not) ignored. Another issue, “the spectator problem”, concerns the participation of the conceiver himself in the world conceived. Three different examples of conceivability are used to illustrate our points, namely thought experiments in physics, a hypothetical (...) world devoid of consciousness (zombie world), and virtual reality. (shrink)
l examine the “omniscient interpreter” (OI) argument against scepticism that Donald Davidson published in 1977 only to retract it twenty-two years later. I argue that the argument’s persuasiveness has been underestimated. I defend it against the charges that Davidson assumes the actual existence of an OI and that Davidson’s other philosophical commitments are incompatible with the very conceivability of an OI. The argument’s surface implausibility derivesfrom Davidson’s suggestion that an OI would attribute beliefs using the same methods as afallible (...) human interpreter. But this problem can be remedied via the adoption of an ambiguity theory of belief.J’examine l’argument de “l’interprète omniscient” (IO) contre les objections sceptiques formulées par Donald Davidson en 1977, qu’il a rétractées vingt-deux ans plus tard. Je soutiens que la force de cet argument a été sous-estimée. Je m’inscris en faux contre les critiques voulant que Davidson ait supposé l’existence effective de l’IO, et que les autres croyances philosophiques de Davidson soientincompatibles avec la possibilité de concevoir l’idée d’un IO. Si l’argument semble peu plausible à prime abord, c’est que Davidson a suggéré qu’un IO attribuait les croyances en utilisant les mêmes méthodes qu’un interprète humain faillible. On peut remédier à ce problème en adoptant une théorie de l’ambiguïté des croyances. (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)
Descartes's view of modality is analyzed by contrast to two earlier models: the ancient realist one, defended by Boethius, where possibility and necessity are connected to natural potency, and the modern intensionalist one, which dissociates necessary and possible truths from any ontological foundation, treating them as conceptual, a priori given preconditions for any intellect. The emergence of this view is traced from Gilbert of Poitiers to duns Scotus, Ockham and Suarez. The Cartesian theory of the creation of eternal truths, it (...) is argued, involves a rejection of this idea of absolute conceivability and can be seen as a constructivist view of intelligibility and rationality. (shrink)
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)
Zalta's notion of encoding which lies at the core of his theory of abstract objects is refined so that it can capture cognitive dynamic phenomena such as multiple object-tracking in particular intentional contexts; namely hypothetical stipulation concerning abstract objects and counter-essential conceivability about ordinary ones. Zalta's Modal Axiom of Encoding is weakened and the notion of 'quasi-encoding' is spelt out.