The China Brain

One characterization of functionalism that is probably vague enough to be acceptable to most functionalists is: each type of mental state is a state consisting of a disposition to act in certain ways and to have certain mental states, given certain sensory inputs and certain mental states. ... Functionalists want to individuate mental states causally, and since mental states have mental causes and effects as well as sensory causes and behavioral effects, functionalists individuate mental states partly in terms of causal relations to other mental states. ...