Abstract

We often do metaphysics by intuitions about possible cases. An example is the argument for functionalism about belief and desire. The argument starts from the premise that, intuitively, it is not possible for belief and desire to vary independently of functional nature —functional duplicates are necessarily belief-desire duplicates—and concludes that belief and desire are functional states. An equally famous example is the argument against functionalism for sensory qualities. The argument starts from the premise that, intuitively, it is possible for sensory nature to vary independently of functional nature—functional duplicates might be sensory inverts—and concludes that sensory states are not functional states.