Foundations of Philosophical Functionalism

Abstract

Philosophical functionalism, as distinct from the psychological school of functionalism that enjoyed popularity around the turn of the 20th century, is a theory about the nature of mental states. That is, functionalism offers an account of which conditions must be satisfied for something to count as a belief, or a desire, or a pain, or an itch, or a fear, or a memory. Functionalism is thus a metaphysical doctrine about mental states, that is, a doctrine concerning what makes something a mental state. “Metaphysical,” in this context, should not be taken to suggest anything mysterious. Chemistry is a metaphysical doctrine in just the same sense as functionalism: it is a theory that offers an account of which conditions must be satisfied for something to count as, say, a pure chemical substance rather than a mixture. As philosophical theories go, functionalism has been fantastically successful. Its contemporary form traces to seminal work that H. Putnam initiated in the 1960s, and it remains in early 21st century the most widely accepted theory of the nature of mental states among philosophers in the Anglo tradition. According to functionalism, the conditions necessary and sufficient for something to be a mental state are specified in terms of functional role. Functionalists have disagreed about the correct basis on which functional descriptions of mental states should rest, with the result that functionalism is better conceived as a family of closely related theories about the nature of mental states rather than a single uniform view. Briefly, the idea of functional role can be usefully illustrated by consideration of an artifact, such as a corkscrew, the nature of which is defined in terms of the function of removing corks. What it is to be a corkscrew is to perform this functional role. Likewise, the functionalist claims, what it is to be a mental state is to perform the functional role characteristic of a belief, or a desire, or a pain, and so on.