A Problem for Multiply Realizable Mental Tokens

Among physicalists about the mental, it is widely accepted that two mental states of the same type (e.g., two beliefs) can be realized by physical states of different types. Call this “mental type multiple realizability.” Some have defended a more radical multiple realizability view, however. The idea is that the very same mental state (or mental event) token, which is realized—in the actual world—by a certain physical realizer, could have been realized by another physical realizer. This is what we call “token-level multiple realizability.” If correct, this would challenge not only type-type identity, but also token-token identity, between mental and physical states. In this paper we present a problem for this view, in favor of token-token identity.