 The appeal of meaning-preserving functional characterizations, therefore, is that in providing topic-neutral equivalents of our mental state terms and concepts, they blunt the anti-materialistic force of the Distinct Property Argument. True enough, analytic functionalists can acknowledge, terms like ‘pain’, ‘thought’, and ‘desire’ are not equivalent to any descriptions expressed in the language of physics, chemistry, or neurophysiology. But if there are functional descriptions that preserve the meanings of these terms, then a creature's mental states can be identified simply by determining which of that creature's internal states and processes play the relevant functional roles (see Lewis 1966). And since the capacity to play these roles is merely a matter of having certain causal relations to stimulations, behavior, and one another, the possession of these properties is compatible with a materialistic theory of the mind.