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)

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)

Materialism is the view according to which a zombie world is metaphysically impossible. Assuming that zombies are conceivable in the sense that we cannot rule out a priori that our world is a zombie world, materialists must hold that a zombie world is metaphysically impossible despite being conceivable. There are no good reasons to think that this view (type-B materialism) is false, since there are no good reasons to think that the corresponding phenomenal and physical/functional concepts cannot be distinct concepts (...) of the same thing. Nonetheless, we cannot understand how type-B materialism can be true. We cannot understand this, because we cannot in principle explain how a zombie world could be impossible despite being conceivable. (shrink)

Chalmers argues that ideal conceivability (conceivability on ideal rational reflection) entails possibility and on this basis assumes that zombies are possible and, therefore, that materialism is false. I argue that the paradigm cases of conceivability intuitions that Chalmers takes to be reliable guides to possibility are not only conceptually coherent, even on ideal rational reflection, but in addition have some rational explanation. The conceivability of zombies, however, has no rational explanation. So it is not ad hoc to deny (...) that the conceivability of zombies entails possibility. (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)

Jennifer Hornsby’s Simple Mindedness consists of twelve essays organized into sections focusing on three issues: the ontology of persons and mental events, how actions fit into a world of natural law, and the nature of intentional explanations. Most of the essays have been previously published but many of these are revised and include addenda. The collection is unified by its defending a position in the philosophy of mind Hornsby calls “naive naturalism.” She advertises naive naturalism as neither physicalist nor Cartesian. (...) Hornsby claims that the mind-body problem as currently discussed, that is, the question of how the mind fits into nature, arises because contemporary analytic philosophers have an overly scientistic view of nature restricting their concept of nature to whatever can be the proper subject matter of science. In her view, if naive naturalism were adopted, the mind-body problem, as it is currently discussed, would disappear. Hornsby is thus a member of that venerable tradition of English philosophers who see the mind-body problem as arising through an excessive fascination with science. (shrink)

Throughout her philosophical writing, Margaret Cavendish is clear in stating that colours are real; they are not mere mind-dependent qualities that exist only in the mind of perceivers. This puts her at odds with other seventeenthcentury thinkers such as Galileo and Descartes who endorsed what would come to be known as the ‘primary-secondary quality distinction’. Cavendish’s argument for this view is premised on two claims. First, that colourless objects are inconceivable. Second, that if an object is inconceivable then it could (...) not possibly exist in nature. My aim in this paper is to explain why Cavendish accepts both premises of this argument. However, the repercussions of this paper go much further than just explaining why she thinks colourless objects cannot exist in nature and the upshots are twofold. First, it provides new insights into the fundamental role that perception plays in Cavendish’s metaphysics. While Cavendish’s view that all of nature perceives is well-established, I show that Cavendish is also committed to the view that all of nature is perceivable. Second, it provides the first in-depth discussion of Cavendish’s modal epistemology and her reasons for thinking that inconceivability entails impossibility (in nature). (shrink)

Do conceivability arguments work against physicalism if properties are causal powers? By considering three different ways of understanding causal powers and the modality associated with them, I will argue that most, if not all, physicalist powers theorists should not be concerned about the conceivability argument because its conclusion that physicalism is false does not hold in their favoured ontology. I also defend specific powers theories against some recent objections to this strategy, arguing that the conception of properties as powerful blocks (...) conceivability arguments unless a rather implausible form of emergence is true. (shrink)

The development of highly humanoid sex robots is on the technological horizon. If sex robots are integrated into the legal community as “electronic persons”, the issue of sexual consent arises, which is essential for legally and morally permissible sexual relations between human persons. This paper explores whether it is conceivable, possible, and desirable that humanoid robots should be designed such that they are capable of consenting to sex. We consider reasons for giving both “no” and “yes” answers to these three (...) questions by examining the concept of consent in general, as well as critiques of its adequacy in the domain of sexual ethics; the relationship between consent and free will; and the relationship between consent and consciousness. Additionally we canvass the most influential existing literature on the ethics of sex with robots. (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.

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.

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)

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.".

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 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. Thirteen leading philosophers present specially-written essays, and a substantial introduction is provided by the volume editors, who demonstrate the importance of these topics to a wide range of issues in contemporary philosophy.

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)

If □ is conceived as an operator, i.e., an expression that gives applied to a formula another formula, the expressive power of the language is severely restricted when compared to a language where □ is conceived as a predicate, i.e., an expression that yields a formula if it is applied to a term. This consideration favours the predicate approach. The predicate view, however, is threatened mainly by two problems: Some obvious predicate systems are inconsistent, and possible-worlds semantics for predicates of (...) sentences has not been developed very far. By introducing possible-worlds semantics for the language of arithmetic plus the unary predicate □, we tackle both problems. Given a frame (W, R) consisting of a set W of worlds and a binary relation R on W, we investigate whether we can interpret □ at every world in such a way that □ $\ulcorner A \ulcorner$ holds at a world ᵆ ∊ W if and only if A holds at every world $\upsilon$ ∊ W such that ᵆR $\upsilon$ . The arithmetical vocabulary is interpreted by the standard model at every world. Several 'paradoxes' (like Montague's Theorem, Gödel's Second Incompleteness Theorem, McGee's Theorem on the ω-inconsistency of certain truth theories, etc.) show that many frames, e.g., reflexive frames, do not allow for such an interpretation. We present sufficient and necessary conditions for the existence of a suitable interpretation of □ at any world. Sound and complete semi-formal systems, corresponding to the modal systems K and K4, for the class of all possible-worlds models for predicates and all transitive possible-worlds models are presented. We apply our account also to nonstandard models of arithmetic and other languages than the language of arithmetic. (shrink)

Some people might be tempted by modal ontological arguments from the possibility that God exists to the conclusion that God in fact exists. They might also be tempted to support the claim that possibly God exists by appealing to the conceivability of God’s existence. In this chapter, I introduce three constraints on an adequate theory of philosophical conceivability. I then consider and develop both imagination-based accounts of conceivability and conceptual coherence-based accounts of conceivability. Finally, I return to the modal (...) ontological argument and consider whether the premise that possibly God exists can be supported by some conceiving. (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)

We often decide whether a state of affairs is possible by trying to mentally depict a scenario where the state in question obtains . These mental acts 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 . 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 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)

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)

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.

It is often supposed that in order to refute the view that laws of nature are necessary truths it is sufficient to appeal to Hume's argument from the conceivability of to the possibility of their being false. But while Hume's argument does present the necessitarian with insuperable difficulties it needs to be made clear just what these are. The mere appeal to Hume is quite insufficient for what he says can be interpreted in more than one way. And if (...) it constitutes an argument rather than a mere assertion Kneale has given reason to suppose that it is at least not obviously valid. The upshot of this article is that Hume's argument may be seen as a direct challenge to the notion that there could be propositions whose modal value is necessarily "opaque to the human intellect". (shrink)

The purpose of this article is to provide a case against certain claims made by modal skeptics with a specific application to the debate about whether conceivability is the right notion to employ in justifying the move from some state of affairs being conceivable to its being metaphysically possible. Does conceivability provide adequate, defeasible grounds for inferring metaphysical possibility? If not, is there a better approach that employs a replacement for conceivability? I argue that conceivability should be abandoned in (...) favor of rational intuitions understood in a way I hope to make clear and precise. To accomplish this purpose, I begin by examing the general way conceivability has been related to metaphysical possibility and opt for a replacement for conceivability. Next, I make clear and precise what I mean by that replacement—rational intuitions. Third, I present three representative accounts of modal knowledge offered by Timothy O’Connor, George Bealer, and Edmund Husserl. O’Connor’s account is externalist, Bealer’s is a hybrid between an internalist and externalist view, and Husserl’s is a purely internalist perspective. While all three are plausible perspectives, I will criticize and reject the first two accounts and argue that Husserl’s way out of modal skepticism is successful. I conclude that Husserl’s employment of rational intuition made precise by his notions of eidetic and categorial intuition, provides a rigorous, fruitful way to ground modal knowledge in general, and de re and de dicto possibility in particular. (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)

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)

This paper challenges the soundness of the two-dimensional conceivability argument against the derivation of phenomenal truths from physical truths in light of a hyperintensional, ground-theoretic regimentation of the ontology of consciousness. The regimentation demonstrates how ontological dependencies between truths about consciousness and about physics cannot be witnessed by epistemic constraints, when the latter are recorded by the conceivability—i.e., the epistemic possibility—thereof. Generalizations and other aspects of the philosophical significance of the hyperintensional regimentation are further examined.

I present an approach to our conceiving absolute impossibilities—things which obtain at no possible world—in terms of ceteris paribus intentional operators: variably restricted quantifiers on possible and impossible worlds based on world similarity. The explicit content of a representation plays a role similar in some respects to the one of a ceteris paribus conditional antecedent. I discuss how such operators invalidate logical closure for conceivability, and how similarity works when impossible worlds are around. Unlike what happens with ceteris paribus counterfactual (...) conditionals, the closest worlds are relevantly closest belief-worlds: closest to how things are believed to be, rather than to how they are. Also, closeness takes into account apriority and the opacity of intentional contexts. (shrink)

The paper articulates a novel strategy against external world skepticism. It shows that a modal assumption of the skeptical argument cannot be justified.

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 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 thesis that anything conceivable is possible plays a central role in philosophical debates about the self. Discussions about free will have focused, at least in the last hundred years, on whether a free yet determined action is conceivable. If it is, and if anything conceivable is possible, then a deterministic physics would by itself pose no obstacle to human freedom. Current debates about the nature and value of personal survival turn on whether it is conceivable for a person to (...) move from one body to another. Discussions about the topic of John Perry’s impressive book, the relation between a person’s mental and physical states, has recently centered on whether it is conceivable for physically identical beings to differ in their conscious experiences. Some claim that zombies, beings physically just like us but without any conscious experiences at all, are conceivable. If they are, and if anything conceivable is possible, then it would seem to follow that facts about conscious experience are not physical. In short, some form of mind-body dualism would have to be right after all. (shrink)