We are concerned here to understand the ultimate metaphysical nature of both sensations and qualitative characteristics. Apart from the behaviorist doctrine that sensations can be reduced to congeries of behavioral dispositions, and the eliminativist thesis that the existence of sensations is in some sense fictional, both of which seem to me to be wildly implausible, there are just four views that one can take of these matters – type materialism, dualism, the double-aspect theory, and functionalism. We have reached the conclusion that, under certain assumptions, type materialism is to be preferred to dualism and the double-aspect theory. It is time now to look at functionalism.

Functionalism is broadly relevant to most of the main concerns of the philosophy of mind. It gives us a unified perspective from which to view sensations, emotions, the will, the nature of the self, and propositional attitudes (belief, desire, intention, and the other mental states that seem to involve relations to propositions). Here I wish to focus on those aspects of functionalism that are concerned with the sensory realm. Because of this, my exposition of functionalist doctrines will sidestep some technical questions that would have to be faced if we were considering the functionalist account of propositional attitudes. Further, my criticisms of functionalism will be directed only against its claims about sensations. They are not intended to call other functionalist doctrines into question.