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)

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)

According to the conceivability argument, physicalism is false since it is conceivable and hence possible that the physical truth do not entail the phenomenal truth. The influential way of responding to the conceivability argument is to claim that our conceivability intuitions can be accounted for in purely psychological terms, by appealing to some cognitive and functional differences between phenomenal and physical concepts, and that therefore what is conceivable does not entail what is possible. On this account, the entailment from the (...) physical to the phenomenal that physicalism is committed to can be necessary and a posteriori. I argue that this way of responding to the conceivability argument cannot work. The conceivability argument depends on an assumption which implies that the psychophysical entailment cannot be necessary and a posteriori and appealing to the differences between phenomenal and physical concepts has no force against that assumption. (shrink)

Brian Loar argues that we can account for the conceptual independence of coextensive terms purely psychologically, by appealing to conceptual rather than semantic differences between concepts, and that this leaves room for assuming that phenomenal and physical concepts can be coextensive on a posteriori grounds despite the fact that both sorts of concepts refer directly . I argue that Loar does not remove the mystery of the coextensiveness of those concepts because he does not offer any explanation of why they (...) should be coextensive. Secondly, I argue that even if we grant that phenomenal and physical concepts can be coextensive on a posteriori grounds, we are committed to holding that there are two different and essential modes of presentation of phenomenal properties, the physical and the phenomenal, and that this precludes us from seeing phenomenal properties as essentially physical in an unrelativized sense. (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)

The question whether perceptual experiences justify perceptual beliefs is ambiguous. One problem is the well familiar skeptical one. How can perceptual experiences justify beliefs if those experiences may systematically deceive us? Our experiences might be just as they are and yet the world might be radically different. But there is also another problem about the justification of perceptual beliefs which arises independently of the above skeptical worry. This other problem has to do with our understanding of the very notion of (...) justification. It seems natural to think that justification can exist only in so far as what is justified is inferentially linked to the justifier. The question, then, is whether perceptual experiences can serve as an inferential basis for perceptual beliefs. The content of experiences does not seem to be the same sort of content that is possessed by beliefs. So the nature of the relation between experiences and beliefs is far from obvious. In this paper I survey various attempts of justifying the view that there is an inferential relation between experiences and beliefs so that the latter can be justified by the former and I argue that none of those attempts is satisfactory. I also suggest that the problem which those attempts address may be illusory. Even though it seems true that experiences and beliefs possess different kinds of contents, there may be no logical gap between those contents that needs to be bridged by some philosophical reflection. (shrink)

According to an influential physicalist view, the intuition of distinctness is a cognitive illusion in the sense that it results from fallacious reasoning: we erroneously infer that the referents of phenomenal and physical concepts are different, from the fact that there is a certain difference between our uses of those concepts. (Kammerer, Review of Philosophy and Psychology 10:649–667, 2019) has recently argued, however, that it is psychologically implausible that the intuition of distinctness results from a fallacy: the reasoning process leading (...) to this intuition is, in several psychological respects, similar to valid reasoning and dissimilar to typical fallacies, which gives us a reason to think that this process is a case of valid reasoning. I argue that there are no psychological reasons to think that the process underlying the intuition of distinctness (or at least the crucial part of this process) is a case of valid reasoning. There is, in fact, only one crucial psychological respect in which this process resembles valid reasoning, and although the two processes are similar in one crucial respect, this does not rule out that the intuition of distinctness results from a fallacy, namely, the sort of fallacious reasoning that physicalists have in mind. Furthermore, since the process underlying the intuition of distinctness resembles typical fallacies in one crucial respect, there is a reason to think that the intuition of distinctness does result from a fallacy. (shrink)

According to some philosophical views, parts of objects (either three-dimen¬sional or four-dimensional) and whole objects are distinct entities. This raises the question of how to identify objects and their parts across possible worlds. By the principle of the necessity of diversity, the distinctness of objects and their parts must be preserved across possible worlds and this, paradoxically, seems to imply that in other possible worlds objects cannot be temporally or spatially different from what they actually are. For example, it seems (...) that if Descartes and his temporal part are two distinct objects, Descartes could not have lived any shorter than he actually did. I argue that we can avoid this paradoxical conclusion once we realize that no temporal part of Descartes can be identified in other possible worlds with an independently existing person. In general, the view I defend is that parts of objects are not identical with independently existing objects across possible worlds. (shrink)

Brain bisection raises the intriguing question about how many minds the split-brain patients have. Thomas Nagel and Derek Parfit, who have brought this question into consideration, come to similar conclusions in response to it. They both argue that the question has no answer, that there simply isn’t any countable number of minds that the split-brain patients have. In addition, Parfit argues that the split-brain cases can be adequately described only if we adopt a certain particular view about the metaphysical nature (...) of a person. The goal of this paper is to clarify both of those views and, in particular, to explain why Parfit’s preference for one model of personhood does not determine how many persons survive brain bisection. (shrink)

Kripke’s antimaterialist argument, under David Papineau’s new interpretation, is not based on assuming that the conceivability of zombies entails possibility and does not lead to the conclusion that materialism is false but rather to the conclusion that we are all in the grip of the intuitive feeling that materialism is false. Leaving it open whether or not Papineau’s interpretation of Kripke’s argument is correct, I argue here that by appealing to the intuition of dualism we can see that the conceivability (...) of zombies is not a reliable guide to possibility. (shrink)

David Chalmers argues that zombies are possible because they are ideally conceivable and that therefore consciousness does not supervene on the physical. In this paper I discuss the most influential criticism of the conceivability-possibility principle in the current literature. According to that criticism, the conceivability-possibility principle is unjustified because it depends on a certain unjustified assumption concerning the semantic conditions under which necessary statements can be true a posteriori, namely that a posteriority is due to contingency at the reference-fixing level, (...) so that a necessary statement can be true a posteriori only if at least one of the concepts flanking the identity sign refers contingently. (shrink)