Zombies and Consciousness

Kirk, Robert

Oxford, UK: Clarendon Press, 2005
280 pp., ISBN: 0199285489 (hbk), $65.00


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 consciousness. His second aim of the book is to construct a theory of perceptual-phenomenal consciousness 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 consciousness. At the same time they want to hold that we have ‘epistemic access’ to our phenomenal consciousness. 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 consciousness. 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 consciousness. But since whatever we added would have to be nonphysical, since their world is identical to ours (excepting consciousness), 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. Let’s add whatever it is that the zombist thinks will transform it into a world like ours. Now let’s ima  gine that by a “strange shift in the natural laws” of the zombie world the visual processes that in me cause e-qualia instead cause


sequences of constantly changing pictures to appear on the soles of [the zombie twin’s] feet. The changing colored patterns on his soles are isomorphic to those neural process in the same way as my e-qualia are isomorphic…to similar process in my brain. (p. 45)


Is there any reason to think that the zombies will have any access to these sole-pictures? Kirk’s answer is ‘NO!’ If not then zombies are not conceivable. The zombist commits what he calls the ‘jacket fallacy’: They treat qualia as something that can be stripped off a world without changing anything in the way that I can remove a jacket and remain the same. In the second half of the book Kirk tries to construct a theory of perceptual-phenomenal consciousness that does not commit the jacket fallacy.

            Central to his attempt is the notion of a decider, i.e. a creature that has a certain ‘basic package’ of capacities. These are the capacities to initiate and control its own behavior, acquire and retain information about its environment, interpret information, assess its situation, choose between alternative courses of action, and have goals (p. 89). These capacities allow an organism to make decisions and control its behavior, and so allow the creature to perceive the world. However, having the basic package—though necessary—is not sufficient for perceptual-phenomenal consciousness. To show this he asks us to consider a rabbitoid; rabbitoids are creatures similar to a rabbit, i.e., a decider; but whereas the rabbit “perceives things that potentially help it or harm it without having to perform any act of summoning up its memories,” the rabbitoid stores all of its information and cannot use it unless it is “called up, or unless it just popped up (whatever that means), or had some other indirect effect” (p. 142). The rabbitoid differs from the rabbit because, in the rabbit, perceptual information “forces itself upon [it] as it comes in” (p. 143). Kirk then speculates that from an evolutionary standpoint it looks like the rabbit has a real advantage over the rabbitoid. These considerations lead him to think that to be sufficient for perceptual-phenomenal consciousness the information that the basic package allows the creature to use must be ‘directly active’.

            There are two aspects to direct activity which Kirk calls ‘instantaneity’ and ‘priority’. Information that allows the creature to instantaneously and “spontaneously produce appropriate non-verbal behavior” (p151) has instantaneity while perceptual information has priority if 


the events constituting the system’s acquisition of the information…act on the organism’s central processes…regardless of the information’s relevance to whatever goals the organism may currently have.  (p. 153)


These two characteristics are not two separate properties but rather aspects of the same property that he calls direct activity. He can now state his view: For there to be something that it is like for an organism to have a perceptual experience is for the organism to be a decider-plus; that is to have the basic package plus direct activity.  This means that it is not conceivable for there to be a creature which had the basic package-plus and yet lacked phenomenal consciousness. His argument is that since the basic package-plus meets all the functional requirements for phenomenal consciousness it meets the requirements for phenomenal consciousness tout suite.

            Let me briefly raise an objection. This is hard for me because, as an identity theorist, I am tempted to take issue with his discussion of the rivalry between functionalism and the identity theory, but there is a more pressing concern for Kirk’s account, so I reluctantly leave this issue aside. Let me just note that it is unclear the extent to which what he calls functionalism actually competes with the identity theory, even though he clearly indicates that he thinks it does. Here is the more pressing issue: it is arguable that the basic package-plus is not sufficient for phenomenal-perceptual consciousness if any kind of higher-order theory of consciousness is correct (though it may well be necessary). I gather that he is aware of this kind of objection from Carruthers’ work:


Higher-order theorists are likely to object that … it’s quite easy to conceive of something being a decider-plus without perceptual-phenomenal consciousness. They might say perceptual information could be acquired ‘transparently’: without the content’s including a ‘dimension of seeming or appearance’ (Carruthers 2000: 184). They might add that this additional feature can be provided only if the subject is capable of higher-order thought. The trouble is that this extra feature seems necessary only if you conflate two distinct conceptions of perceptual-phenomenal consciousness. On one conception…it is sufficient for perceptual-phenomenal consciousness that there is something it is like to perceive this or that thing. The other conception requires in addition something on the following lines: that the subject be aware of having the experience… appealing to the second conception of perceptual-phenomenal consciousness, which obviously entails a capacity for higher-order thought, comes too close to begging the question. (p. 171)


For someone familiar with David Rosenthal’s version of higher-order theory this accusation is nothing short of stunning. What Kirk calls ‘too close’ to question begging is none other than what Rosenthal calls the ‘transitivity principle,’ which says that a state’s being conscious or not consists in the subject being suitably aware of it or not.

            The higher-order theorist is not conflating two kinds of consciousness but rather trying to explain one in terms of the other. They explain a state’s being conscious in terms of our being conscious of it. The reason that Kirk fails to notice this is because, like most who use the ‘what-it-is-like rubric’, he is lead to believe that all mental states must occur consciously. He therefore fails to respect the distinction between conscious and unconscious mental states. Since there are common-sense and experimental reasons for thinking that perceptual states occur unconsciously, we need to explain what the difference is between them and conscious ones. The transitivity principle answers this question. On Rosenthal’s version of higher-order theory (Rosenthal, 2005) it is possible for any mental state to occur unconsciously; it does so just in case it is not accompanied by a HOT. This requires that he specify what qualitative states are in a way that does not mention consciousness, which is difficult but not inconceivable (he develops homomorphism theory to fill this need). So it is conceivable that there could be a creature which had all of my first-order states and none of my higher-order states. This creature would, according to the theory, lack phenomenal consciousness, yet would arguably be a decider-plus; incoming perceptual information would endow it with the necessary instantaneous capacities. This is not to say that I endorse Rosenthal’s view, though I do respect the transitivity principle. The point is that Rosenthal’s view is conceivable and so being a decider-plus is not sufficient for phenomenal consciousness.

            Objections notwithstanding, this is an outstanding addition to the literature that is well worth reading for anyone seriously interested in consciousness.




Rosenthal, D. (2005). Consciousness and Mind, Oxford: Clarendon Press.


Richard Brown

Department of Philosophy

Brooklyn College, CUNY

2900 Bedford Ave.

New York, NY 11210 USA

E-mail: onemorebrown@yahoo.com