Conceivability, Possibility, and the Mind-Body Problem

In his very influential book, The Conscious Mind, David Chalmers argues that if physicalism is true then every positive truth is a priori entailed by the full physical description – this is called “the a priori entailment thesis – but ascriptions of phenomenal consciousness are not so entailed and he concludes that Physicalism is false. As he puts it, “zombies” are metaphysically possible. I show that his argument can be refuted by considering an analogous argument in the mouth of a zombie. The conclusion of this argument is false so one of the premises is false. I argue at length that this shows that the original conceivability argument also has a false premise and so is unsound.