 Functionalists argue that the irreducibilty of mental kinds is nevertheless compatible with a token-token identity theory (Fodor 1974, 1997). Mental kinds are not type-identical with neurophysiological kinds (i.e. there is not one type of neurophysiological correlate for each type of mental state, so we cannot make general identity statements such as “pain = C-fibres firing”). A Martian and I, both in a state of fear at a time t, may be in different physiological states. Nevertheless, my token instance of the kind fear at time t will be identical with the token physical state in my brain at that time. Likewise, the token instance of the Martian’s fear at time t1 is identical with his token physical state.