Abstract:
A priori physicalism is the view that conscious states are a priori entailed by physical states. Cartesian doubt is a well known process whereby one doubts the existence of anything that it is epistemically possible to doubt. At the end of Cartesian doubt, the doubter finds herself coherently conceiveing of a state of affairs in which: (i) she is the only thing that exists, (ii) she exists as a thing whose nature is exhausted by conscious experience. In other words, she ends up conceiving of herself as a 'lonely ghost'. I will argue that the fact that we can coherently conceive of lonely ghosts is inconsistent with any of the forms of a priori physicalism on offer in the philosophy of mind literature. The two samples of a priori physicalism I will discuss are: David Lewis's brand of analytic functionalism and Fred Dretske's naturalistic representationalism. I will finish by outlining a respect in which this argument against a priori physicalism is dialectically stronger than the knowledge argument or the zombie conceivability argument.