support some form of dualism – in this case the view that the world includes two kinds of substance (or perhaps two kinds of property): the mental and the physical. In contrast to dualism, in physicalism, material facts determine all other facts. Since any fact other than that of consciousness may be held to be the same for a p-zombie and for a normal conscious human, it follows that physicalism must hold that p-zombies are either not possible or are the same as normal humans. The zombie argument is a version of general modal arguments against physicalism such as that of Saul Kripke. Further such arguments were notably advanced in the 1970s by Thomas Nagel (1970; 1974) and Robert Kirk (1974) but the general argument was most famously developed in detail by David Chalmers in The Conscious Mind (1996). According to Chalmers one can coherently conceive of an entire zombie world, a world physically indistinguishable from this world but entirely lacking conscious experience. The counterpart of every conscious being in our world would be a p-zombie. Since such a world is conceivable, Chalmers claims, it is metaphysically possible, which is all the argument requires. Chalmers states: "Zombies are probably not naturally possible: they probably cannot exist in our world, with its laws of nature." The outline structure of Chalmers' version of the zombie argument is as follows; According to physicalism, all that exists in our world (including consciousness) is physical. Thus, if physicalism is true, a metaphysically possible world in which all physical facts are the same as those of the actual world must contain everything that exists in our actual world. In particular, conscious experience must exist in such a possible world. Chalmers argues that we can conceive being outside of a world physically indistinguishable from our world but in which there is no consciousness (a zombie world). From this (so Chalmers argues) it follows that such a world is metaphysically possible. Therefore, physicalism is false. (The conclusion follows from 2. and 3. by modus tollens.) The above is a strong formulation of the zombie argument. There are other formulations of the zombies-type argument which follow the same general form. The premises of the general zombies argument are implied by the premises of all the specific zombie arguments. A general zombies argument is in part motivated by potential disagreements between various anti-physicalist views. For example, an anti-physicalist view can