  Obviously then, types play an important role in philosophy of language, linguistics and, with its emphasis on expressions, logic. Especially noteworthy is the debate concerning the relation between the meaning of a sentence type and the speaker's meaning in using a token (a relation that figures prominently in Grice 1969). But the type-token distinction also functions significantly in other branches of philosophy as well. In philosophy of mind, it yields two versions of the identity theory of mind (each of which is criticized in Kripke 1972). The type version of the identity theory (defended by Smart (1959) and Place (1956) among others) identifies types of mental events/states/processes with types of physical events/states/processes. It says that just as lightning turned out to be electrical discharge, so pain might turn out to be c-fiber stimulation, and consciousness might turn out to be brain waves of 40 cycles per second. On this type view, thinking and feeling are certain types of neurological processes, so absent those processes, there can be no thinking. The token identity theory (defended by Kim (1966) and Davidson (1980) among others) maintains that every token mental event is some token physical event or other, but it denies that a type match-up must be expected. So for example, even if pain in humans turns out to be c-fiber stimulation, there may be other life forms that lack c-fibers but have pains too. And even if consciousness in humans turns out to be a brain waves that occur 40 times per second, perhaps androids have consciousness even if they lack such brain waves.