 Role functionalists identify pain with that higher-level relational property. Realizer functionalists, however, take a functional theory merely to provide definite descriptions of whichever lower-level properties satisfy the functional characterizations. On these views (also called “functional specification” theories), if the property that occupies the causal role of pain in human beings is C-fiber stimulation, then pain (or at least pain-in-humans) would be C-fiber stimulation, rather than the higher-level property of having some lower-level state that plays the relevant role. (This is not to suggest that there is a difference in kind between higher-level “role” properties and the lower-level “realizations” of those roles, since it may be that, relative to even lower-level descriptions, those realizations can be characterized as functional states themselves (Lycan 1987).