Abstract

Functionalism is the doctrine that mental states, by their nature, just are certain causal-dispositional states: all that it is to be some arbitrary mental state is to be a state that is disposed to have certain causes and effects. In a series of papers, Nick Zangwill has argued that functionalism faces a problem accommodating the possibility of systematic irrationality – that is, the fact that thinkers can be disposed to be irrational. In brief: according to Zangwill, the functionalist theory of the mind implies that thinkers, by their nature, are necessarily disposed to be rational. But this result is flatly inconsistent with the possibility of systematic irrationality. Here I show how the functionalist can reconcile the possibility of systematic irrationality with the ultimately causal-dispositional nature of mental states by endorsing the doctrine that the mind admits of divisions within itself. If I am correct, the functionalist can accommodate the possibility of systematic irrationality by holding that mental states are defined by the causal relations that they would be disposed to have if they ever ‘came into direct causal contact’ with one another.