Online research in philosophy

Phenomenal knowledge usually comes from experience. But it need not. For example, one could know what it’s like to see red without seeing red—indeed, without having any color experiences. Daniel Dennett (2007) and Pete Mandik (forthcoming) argue that this and related considerations undermine the knowledge argument against physicalism. If they are right, then this is not only a problem for anti‐physicalists. Their argument threatens to undermine any version of phenomenal realism—the view that there are phenomenal properties, or qualia, that are not conceptually reducible to physical or functional properties. I will argue that this threat is illusory. Explaining why will clarify what is and is not at issue in discussions of the knowledge argument and phenomenal realism. This will strengthen the case for physically and functionally irreducible qualia.

A prevailing view in contemporary philosophy of mind is that zombies are logically possible. I argue, via a thought experiment, that if this prevailing view is correct, then I could be transformed into a zombie. If I could be transformed into a zombie, then surprisingly, I am not certain that I am conscious. Regrettably, this is not just an idiosyncratic fact about my psychology; I think you are in the same position. This means that we must revise or replace some important positions in the philosophy of mind. We could embrace radical skepticism about our own consciousness, or maintain the complete and total infallibility of our beliefs about our own phenomenal experiences. I argue that we should actually reject the logical possibility of zombies.

Certain recent philosophical theories offer the prospect that zombies are possible. These theories argue that experiential contents, or qualia, are nonphysical properties. The arguments are based on the conceivability of alternate worlds in which physical laws and properties remain the same, but in which qualia either differ or are absent altogether. This article maintains that qualia are, on the contrary, physical properties in the world. It is shown how, under the burden of the a posteriori identification of qualia with physical properties, a reasoned choice can be made between the two types of theories which ultimately favors materialism and rejects zombies.

According to the zombie conceivability argument, phenomenal zombies are conceivable, and hence possible, and hence physicalism is false. Critics of the conceivability argument have responded by denying either that zombies are conceivable or that they are possible. Much of the controversy hinges on how to establish and understand what is conceivable, what is possible, and the link between the two—matters that are at least as obscure and controversial as whether consciousness is physical. Because of this, the debate over physicalism is unlikely to be resolved by thinking about zombies—or at least, zombies as discussed by philosophers to date.



In this paper, I explore an alternative strategy against the zombie conceivability argument. I accept the possibility of zombies and ask whether that possibility is accessible (in the sense of ‘accessible’ used in possible world semantics) to our world. It turns out that the question of whether zombie worlds are accessible to our world is equivalent to the question of whether physicalism is true. By assuming that zombie worlds are accessible to our world, supporters of the zombie conceivability argument beg the question against physicalists. I will then consider what happens if a supporter of the zombie conceivability argument should insist that zombie worlds are accessible to our world. I will argue that the same ingredients used in the zombie conceivability argument—whatever they might be—can be used to construct an argument to the opposite conclusion. If that is correct, we reach a stalemate between physicalism and property dualism: while the possibility of some zombies entails property dualism, the possibility of other creatures entails physicalism. Since these two possibilities are inconsistent, one of them is not genuine. To resolve this stalemate, we need more than thought experiments.

Zombies, as conceived by philosophers these days, are supposed to be creatures that are physically indistinguishable from normal people that nevertheless completely lack phenomenal consciousness. The kind of zombie I want to focus on is one that is molecule- by-molecule identical to a healthy, normal, adult human being living in a world physically like ours — indeed this might be our own actual world. To make things more concrete, pick any such person that you actually know. Let this be John. John is not a zombie. Now consider an exact, perfect, physical replica of John, call him Zhon. Note that because John and Zhon are physically alike, they are also behaviorally and functionally alike. So if you were to encounter Zhon, you could not distinguish him from John. Under the imagined circumstances so far, you would normally expect Zhon to be conscious as well. But let’s stipulate that Zhon has no conscious experiences whatsoever — he’s never had them, nor will he ever have them. So Zhon, according to this stipulation, doesn’t know — indeed cannot know — what it is like to have conscious experiences of any kind. There is nothing it is like to be Zhon. Zhon lacks conscious phenomenology altogether. If Zhon were to be a metaphysically possible creature, he would be a zombie.1 So this is the notion of zombie I would like to focus on. According to many philosophers, Zhon is a possible creature, and that is because Zhon is a conceivable creature. This gives us the argument from zombies against physicalism. Physicalism is the doctrine that says: all that exist is physical through and through, including conscious minds and their conscious experiences. The zombie argument, as we might call it, is a species of conceivability arguments: 1. If Zhon is conceivable, then Zhon is possible. 2. Zhon is conceivable. 3. Hence, Zhon is possible. Now since the choice of Zhon was arbitrary, we can, of course, generalize the argument to all zombies like Zhon — that is, to zombies that are physically indistinguishable, in relevant respects, to healthy, normal, adult human beings..

A zombie is a creature just like a conscious being in certain respects, but wholly lacking in consciousness. In this paper, I look at zombies from the perspective of basic ontology (“from below”), taking as my starting point a trope ontology I have defended elsewhere. The consequences of this ontology for zombies are mixed. Viewed from below, one sort of zombie—the exact dispositional zombie—is impossible. A similar argument can be wielded against another sort—the exact physical zombie—but here supplementary principles are needed to get to the impossibility result. Finally, at least two sorts of zombie—the behavioural and functional zombies—escape these arguments from below.

This book covers a vast amount of material in the philosophy of mind, which makes it difficult to do justice to its tightly argued and nuanced details. It does, however, have two overarching goals that are visible, so to speak, from space. In the first half of the book Kirk aims to show that, contra his former self, philosophical zombies are not conceivable. By this he means that the zombie scenario as usually constructed contains an unnoticed contradiction, and explaining the contradiction reveals a radical misconception about the nature of phenomenal <span class='Hi'>consciousness</span>. His second aim of the book is to construct a theory of perceptual-phenomenal <span class='Hi'>consciousness</span> that avoids this contradiction.            The anti-zombie argument can be stated rather easily. According to the ‘zombist’ there can be a creature that is a molecule-for-molecule-duplicate of me and yet lacks phenomenal <span class='Hi'>consciousness</span>. At the same time they want to hold that we have ‘epistemic access’ to our phenomenal <span class='Hi'>consciousness</span>. These two claims are not consistent with each other. To see why, imagine a zombie world that is identical to ours except in respect of phenomenal <span class='Hi'>consciousness</span>. Since that world is just like ours we can assume that it is causally closed under the physical. Now, continues Kirk, it should be possible to add to that world whatever it is that the zombist thinks will transform it into a world that does have phenomenal <span class='Hi'>consciousness</span>. But since whatever we added would have to be nonphysical, since their world is identical to ours (excepting <span class='Hi'>consciousness</span>), and so could not interact causally with the physical world (which is closed under the physical), it follows that we could not know anything about these ‘e-qualia’. Therefore, we could not have ‘epistemic access’ to them.            To make this vivid he offers what he calls the ‘sole-pictures’ argument. Again, consider our zombie world..

We imagine Zombies as beings identical to us with respect to all physical and behavioural facts but different with respect to phenomenal facts. For example, zombies might say, just like us, ‘this grapefruit is really sour’ or ‘my left knee hurts’, but, unlike us, they have no phenomenal experiences corresponding to these utterances or to the relevant physical states. The idea of zombies has been used to construct the following argument against the physicalist approach to consciousness.

Case 1: Perhaps the phenomenal facts—facts about what it’s like to see red, or to taste freshly made pesto—do not supervene with metaphysical necessity on the physical facts and physical laws. This might be because the connections between the physical and the phenomenal are entirely unprincipled. Alternatively, it might be because whatever psychophysical laws do govern those connections are contingent. Either way, the claim is that there are metaphysically possible worlds that are just like the actual world in terms of what physical laws hold, and in terms of the distribution of physical properties, but which are phenomenally different from the actual world. In some such worlds, different phenomenal facts obtain. In other such worlds, no phenomenal properties are instantiated at all. Call the latter sort of world a ‘phenomenal zombie world’, or, for short, just a ‘zombie world’.

Introduction -- Phenomenal consciousness -- Phenomenal consciousness and self-representation -- The connection between phenomenal consciousness and creature consciousness -- Consciousness of things -- Real world puzzle cases -- Why consciousness cannot be physical and why it must be -- What is the thesis of physicalism? -- Why consciousness cannot be physical -- Why consciousness must be physical -- Physicalism and the appeal to phenomenal concepts -- Some terminological points -- Why physicalists appeal to phenomenal concepts -- Various accounts of phenomenal concepts -- My own earlier view on phenomenal concepts -- Are there any phenomenal concepts? -- Phenomenal concepts and burgean intuitions -- Consequences for a priori physicalism -- The admissible contents of visual experience : the existential thesis -- The singular (when filled) thesis -- Kaplanianism -- The multiple contents thesis -- The existential thesis revisited -- Still more on existential contents -- Consciousness, seeing and knowing -- Knowing things and knowing facts -- Nonconceptual content -- Why the phenomenal character of an experience is not one of its nonrepresentational properties -- Phenomenal character and representational content, part I -- Phenomenal character and representational content, part II -- Phenomenal character and our knowledge of it -- Solving the puzzles -- Mary, Mary, how does your knowledge grow? -- The explanatory gap -- The hard problem -- The possibility of zombies -- Change blindness and the refrigerator light illusion -- A closer look at the change blindness hypotheses -- The no-seeum view -- Sperling and the refrigerator light -- Phenomenology and cognitive accessibility -- A further change blindness experiment -- Another brick in the wall -- Privileged access, phenomenal character, and externalism -- The threat to privileged access -- A Burgean thought experiment -- Social externalism for phenomenal character? -- A closer look at privileged access and incorrigibility -- How do I know that I am not a zombie? -- Phenomenal externalism.