Why should there be a functionalist theory?

But before we look in more detail at some functionalist proposals, it will help if we consider why anyone should think that it ought to be possible to construct a functionalist theory.

In section 1.2 I raised two questions that a theory of the mind ought to answer: “What justifies our belief that other minds exist at all?” and “How are we to explain the relations of a mind and its body?” Functionalism answers the second question quite simply: a person's body is what has the states that function as his or her mind.

But consider now what functionalism implies in answer to the first question. To have a mind, functionalists claim, is to have inter­nal states that function in a certain way, a way that determines how a person will react to input—in the form of sensations and percep­tions. The answer to the other-minds problem must, therefore, be that we know about other minds because we have evidence that people have internal states that function in the right way. And, in fact, we do have such evidence, as the behaviorists pointed out. People with minds act in ways that are caused by what is going on in their minds, and what is going on in their minds is caused by things that happen around them. One reason for being a functionalist is, thus, that it allows you to deny the Cartesian claim that minds are essentially private, that only you can know what is going on in your mind. Wittgenstein's private-language argument gives us a reason for doubting that minds can be essentially private. We shall see in the next chapter why many philosophers have held that nothing that exists can be knowable by only one person. For the thesis that there are things that cannot, even in principle, be known by anyone appears inconsistent with some very basic facts about knowledge. To make these arguments now, I would have to step ahead of this chap­ter's topic. But when you have read what I say in the next chapter (2.6) about Verificationism, you might want to think again about whether functionalists are right in holding that it is an advantage of their theory that it denies that the mind is essentially private.

1.6