Must Functionalists Be Aristotelians?

Functionalism in the theory of mind requires an account of function that has a normative component—mere conditional connection (whether indicative or sub-junctive) is not enough. For instance, a component of a computing system isn’t an adder just in case its output is always or would always be the sum of the inputs, since any computing system in a world with as much indeterminism as ours can err or malfunction. Two general reductions of normative language have been proposed that one might wish to apply to the problem of defining proper function: the evolutionary reduction (Wright, Millikan) and the agential reduction (Plantinga). We argue that whatever the merits of the reductions in other contexts, a functionalist theory of mind that defines proper function in either of these ways must fail. The argument proceeds by first showing the agential reduction is viciously circular in the context of a functionalist theory of agency. Second, if functionalism about mind is true and proper function is reducible evolutionarily, then it is possible to have a situation in which the presence or absence of mental properties depends in an implausibly spooky, acausal way on remote facts. It is plausible that the only currently avail-able way for the functionalist to meet these challenges is to accept irreducible end-directed causal powers of minds and/or their functional parts, in accordance with a broadly Aristotelian tradition.