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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..

Certain conceivable situations figure as premises in arguments for the conclusion that conscious experiences have nonphysical properties or qualia. Frank Jackson's knowledge argument considers the hypothetical scientist Mary, who despite having complete scientific knowledge of colour vision, supposedly lacks knowledge of qualia. Both Saul Kripke's and David Chalmers' modal arguments involve zombies, conceivable creatures physically identical to us who lack qualia. Several physicalists have replied to all these objections by endorsing the phenomenal concept reply. Without trying to undermine this reply in general, I argue that recent versions of it proposed by John Perry and David Papineau are unsatisfactory.

A philosophical zombie is a being physically indistinguishable from an actual or possible human being, inhabiting a possible world where the _physical_ laws are identical to the laws of the actual world, but which completely lacks consciousness. For zombies, all is dark within, and hence they are, at the most fundamental level, utterly different from us. But, given their definition, this singular fact has no direct implications about the kind of motion, or other physical processes, the zombie will undergo within its own world. Under quite standard physicalist assumptions, such as certain assumptions about the 'initial conditions' of the zombie's world and that of the causal closure of the physical.

A philosophical zombie is a being physically indistinguishable from an actual or possible human being, inhabiting a possible world where the physical laws are identical to the laws of the actual world, but which completely lacks consciousness. For zombies, all is dark within, and hence they are, at the most fundamental level, utterly different from us. But, given their definition, this singular fact has no direct implications about the kind of motion, or other physical processes, the zombie will undergo within its own world. Under quite standard physicalist assumptions, such as certain assumptions about the 'initial conditions' of the zombie's world and that of the causal closure of the physical1, a zombie's behaviour, as well as its underlying physical state, should be indistinguishable from the behaviour and physical state of a genuine human being.

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.

Philosophical zombies are exactly as physicalists suppose we are, right down to the tiniest details, but they have no conscious experiences. (It is presupposed that all explicable physical events are explicable physically.) Are such things even logically possible? My aim is to contribute to showing not only that the answer is 'No', but why. (I concede that systems superficially like human beings might exist and lack consciousness.) My strategy has two prongs: a fairly brisk argument which demolishes the zombie idea; followed by an attempt to throw light on how something can qualify as a conscious perceiver. The argument to show that zombies are impossible exploits the point that in order to be able to detect our own 'qualia' we should have to be somehow sensitive to them; which the zombie idea rules out. The attempt to make clear why my zombie twin must be conscious exploits the idea that we have a reasonably clear grasp of a 'Basic Package' of psychological concepts.

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.

Many philosophers accept the conceivability of zombies: creatures that lack consciousness but are physically and functionally identical to conscious human beings. Many also believe that the conceivability of zombies supports their metaphysical possibility. And most agree that if zombies are metaphysically possible, then physicalism is false. So, the claim that zombies are conceivable may have considerable significance.¹.

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 are hypothetical creatures of the sort that philosophers have been known to cherish. A zombie is physically identical to a normal human being, but completely lacks conscious experience. Zombies look and behave like the conscious beings that we know and love, but "all is dark inside." There is nothing it is like to be a zombie.