Blocking Definitions of Materialism

It is often thought that materialism about themind can be clarified using the concept of supervenience. But there is a difficulty. Amaterialist should admit the possibility ofghosts and thus should allow that a world mightduplicate the physical character of our worldand enjoy, in addition, immaterial beings withmental properties. So materialists can't claimthat every world that is physicallyindistinguishable from our world is alsomentally indistinguishable; and this is wellknown. What is less understood are thedifferent ways that immaterial add-ons can maketrouble for supervenience-theoreticformulations of materialism. In this paper, Ishall present a problematic kind of add-on thathas been ignored and look at threesupervenience-theoretic attempts to formulatematerialism in that light.