The problem of mental causation is at the heart of the mind-body problem. And for physicalist or materialist views of mind, the key to solving the problem of mental causation is getting a satisfactory understanding of how the mental is realized in the physical. Recent discussions of physicalism have focused on the notion of supervenience; but I think that the focus should instead be on the notion of realization. Supervenience comes in a variety of forms – and the form we need to understand, in order to understand mental causation, is that in which the properties in the supervenience base can be said to realize the properties that supervene on them. Any physicalist theory, whether or not it is a functionalist theory, needs to maintain that the mental is realized in the physical, and so needs an account of realization. But my main focus will be on the realization of functional properties.

I take as my point of departure a recent paper by George Bealer that attempts to show that functionalist accounts of mind cannot give a satisfactory account of self-consciousness. Although Bealer's primary target is functionalism, he takes his arguments to establish a version of property dualism. They are supposed to show that mental properties are “first-order properties,” not the higher-order properties functionalists take them to be. And because Bealer thinks that there are decisive reasons for rejecting type physicalism, he thinks that the only way for mental properties to be first order is for them to be nonphysical.

One natural route to the view that intersubjective spectrum inversion is possible is via the plausible claim that we can imaging the occurrence of intrasubjective inversion – a change whereby the different colors systematically look different to a person than they did before, although she is able to make all the same color discriminations as she did before, and sees things as having the same color similarity and difference relationships as before. Whereas the existence of complete intersubjective inversion would be behaviorally undetectable and might seem unverifiable, the occurrence of intrasubjective inversion seems straightforwardly verifiable, both from the first-person and the third-person perspective. Yet if intersubjective inversion is at least a logical possibility, it seems that intersubjective inversion should also be at least a logical possibility.

This line of argument I will call the intra-inner argument. It is an argument I have advanced in several places. As might be expected, it has met with a variety of objections.

First, some maintain that insofar as intrasubjective spectrum inversion is conceivable, it would consist simply in its coming to be the case that the subject systematically misperceives the colors of things – sees red things as green, blue things as yellow, and so on. This sort of inversion is possible on the “intentionalist” view according to which the only introspectively accessible features of color experiences are their intentional or representational features, their being “as of” certain colors.

These lectures have been organized around the question of whether there is any good sense in which our introspective access to our own mental states is a kind of perception, something that can appropriately be called “inner sense.” In my first lecture I distinguished two versions of the perception model of introspection, based on two different stereotypes of sense-perception. One of these, based primarily on the case of vision, is what I called the object-perceptual model – it takes perception to be in the first instance a relation to objects and only secondarily a relation to facts. I argued in my first lecture that introspection does not have nonfactual objects of the sort required to make this model applicable. The other, which does not require perception to have nonfactual objects, I called the broad perceptual model; its key tenet is that the existence of the objects of perception, whether they be factual or nonfactual, is independent both of their being perceived and of there being the possibility of their being perceived. The view that introspection conforms to this was my target in my second lecture, where I argued that it is of the essence of various kinds of mental states that they are introspectively accessible.

But one important issue was left dangling. If we had only such intentional states as beliefs and desires to deal with, the view that introspective awareness is awareness of facts unmediated by awareness of objects would seem phenomenologically apt. My awareness of a belief just comes down to my awareness that I believe such and such.

Some would say that the philosophy of mind without the first-person perspective, or the first-person point of view, is like Hamlet without the Prince of Denmark. Others would say that it is like Hamlet without the King of Denmark, or like Othello without Iago. I say both. I think of myself as a friend of the first-person perspective. Some would say that I am too friendly to it, for I hold views about first-person access and first-person authority that many would regard as unacceptably “Cartesian.” I certainly think that it is essential to a philosophical understanding of the mental that we appreciate that there is a. first person perspective on it, a distinctive way mental states present themselves to the subjects whose states they are, and that an essential part of the philosophical task is to give an account of mind which makes intelligible the perspective mental subjects have on their own mental lives. And I do not think, as I think some do, that the right theory about all this will be primarily an “error theory.” But I also think that the first-person perspective is sometimes rightly cast as the villain in the piece. It is not only the denigrators of introspection that assign it this role. Kant did so in the Paralogisms, seeing our vantage on our selves as the source of transcendental illusions about the substantiality of the self. And Wittgenstein's “private language argument” can be seen as another attempt to show how the first-person perspective can mislead us about the nature of mind.

A distinctive feature of recent philosophy of mind has been the repudiation of “Cartesianism.” With one part of this repudiation, namely the rejection of mind-body dualism, I am in complete agreement. But my concern in the present essay is with a different part of it, namely the rejection of the Cartesian conception of the minds epistemic access to itself – as a first approximation, the view that each of us has a logically “privileged access” to his or her own mental states, and that it is of the essence of mind that his should be so.

Like the repudiation of Cartesian dualism, the repudiation of the Cartesian privileged access thesis is nothing new, and stems at least as much from scientific as from philosophical considerations. An extreme version of the privileged access thesis is the “transparency thesis” – the view, apparently held by Descartes, that nothing can occur in a mind of which that mind is not conscious. It is not easy to see, now, how this ever could have been plausible. In any case, it is widely seen as having been refuted by Freud, as well as by recent psychological research of a distinctly non-Freudian character which seems to show both that a vast amount of what goes on in a person's mind is completely inaccessible to that person's introspective consciousness, and, what is equally shocking to Cartesian preconceptions, that when people do report on their own mental operations, these reports are often wrong.

Let me begin by presenting two opposed conceptions of the relationship between the realm of the mental and our knowledge of this realm, neither of which is the conception I shall be supporting.

One I will call, with no pretension to scholarly accuracy, the Cartesian conception. According to this, the mind is transparent to itself. It is of the essence of mental entities, of whatever kind, to be conscious, where a mental entity's being conscious involves its revealing its existence and nature to its possessor in an immediate way. This conception involves a strong form of the doctrine that mental entities are “self-intimating,” and usually goes with a strong form of the view that judgments about one's own mental states are incorrigible or infallible, expressing a super-certain kind of knowledge which is suited for being the epistemological foundation for the rest of what we know.

The other is the view that the existence of mental entities and mental facts is, logically speaking, as independent of our knowing about them introspectively, and of there being whatever means or mechanisms enable us to know about them introspectively, as the existence of physical entities and physical facts is of our knowing about them perceptually, or of there being the means or mechanisms that enable us to have perceptual knowledge of them. This is the view that implies that our introspective self-knowledge should be construed in terms of what in my first lecture I called the broad perceptual model.

One of the views associated with Descartes is that it is of the essence of mind that each mind has a special, privileged access to its own contents. Recently, I think, this view has been very much out of favor. Those who have rejected it have not, in general, denied that there is something that might be called a “special access” to one's own mental states. Usually they have not denied that normally a person knows of his own beliefs, desires, sensations, thoughts, etc. in a way that is utterly different from that in which one person knows of such mental states in another person. And in the case of at least some mental phenomena, in particular sensations and occurrent thoughts, it would generally be allowed that a person's access to those phenomena in himself is both more comprehensive and less subject to error than his access to the same sorts of phenomena in other persons. What is denied, when this Cartesian doctrine is rejected, is, first, that the special access a person has to his own mental states is necessarily infallible or “incorrigible,” or at least yields knowledge having a kind of certainty which empirical knowledge about other matters cannot attain, and second, that it is in any way constitutive or definitive of mental states, or of minds, or of the concepts of these, that these states intimate their existence to their possessors in a special and direct way.