The materialistic theory of mind is inadequate in at least four respects.
First, this theory does not provide a believable account of what is happening when we are thinking, feeling, perceiving, remembering, desiring, willing, and the like. Let us consider “thinking,” since this is the example that Materialist has briefly discussed. It seems evident that
(a) whether or not a neural process of some unique sort is occurring whenever a person is thinking of some particular thing, this certainly has never been shown to be the case and
(b) even if it should be the case that thinking of a determinate sort is always accompanied by some corresponding neural process, it does not follow that thinking simply consists in this neural process. The question of what neural processes are correlated with what mental state is, surely, an empirical question. It can scarcely be claimed that the investigation of this matter has proceeded to the point where anyone can with any assurance claim a one-to-one correspondence between the two. Even if this were to be established, it is extremely implausible to hold that thinking is the same thing as the neural process that accompanies it. A well-designed and properly programmed computer, for example, is capable of solving certain sorts of problems far more quickly and efficiently than even the brightest of mathematicians; yet, we should not (except in metaphor) describe the process by which it does so as one of “thinking.” What is the difference? The difference is that to say that something is an instance of “thinking” is to posit a mind, a consciousness, as the subject of the thinking; nothing other than metaphysical prejudice could ever induce something to give a different answer.
…The materialistic theory of mind implies that men never act in terms of conscious purposes freely chosen by them, but only in the ways resultant from the mechanical causes operative upon them. In our own experience, at least, we know that this is not true. Despite Materialist’s disavowal of the older mechanism, his position involves a mechanistic view of human behavior; and mechanism, old or new, is a bitter pill to swallow. We surely believe ourselves to act freely and purposively a good deal of the time–indeed, I should say that we know ourselves to do so. Unless we are to regard this knowledge as no knowledge–as illusory, in other words–we must reject the materialistic account of mind. If we do adopt that account, we must not hesitate to accept its mechanistic consequences.
(Halverson, A Concise Introduction to Philosophy, 224-25)