Schaffer distinguishes four materialist views, four views of what "thoughts, feelings, wishes, and the other so-called mental phenomena" (IP3 271b) are.

1. eliminative materialism: "Such terms have no real meaning at all ..." (IP3 271b) (He calls this "the unintelligibility thesis" (IP3 272a).)
2. the avowal theory: utterances that appear to speak of mental states are not statements at all. When I say "I believe that George W. Bush was re-elected," I am not really asserting anything about beliefs. I'm just behaving.
3. behaviorism: beliefs, desires and other apparent mental states, are merely dispositions to behave in certain ways.
4. the identity theory: beliefs, desires, and other apparent mental states simply are physical states of the central nervous system.