David Rosenthal

In Descartes's time the issue between materialists and their opponents was framed in terms of substances. Materialists such as Thomas Hobbes and Pierre Gassendi maintained that people are physical systems with abilities that no other physical systems have; people, therefore, are special kinds of physical substance. Descartes's DUALISM, by contrast, claimed that people consist of two distinct substances that interact causally: a physical body and a nonphysical, unextended substance. The traditional

Conscious mental states are states we are in some way aware of. I compare higher-order theories of consciousness, which explain consciousness by appeal to such higher-order awareness (HOA), and first-order theories, which do not, and I argue that higher-order theories have substantial explanatory advantages. The higher-order nature of our awareness of our conscious states suggests an analogy with the metacognition that figures in the regulation of psychological processes and behaviour. I argue that, although both consciousness and metacognition involve higher-order psychological states, they have little more in common. One thing they do share is the possibility of misrepresentation; just as metacognitive processing can misrepresent one’s cognitive states and abilities, so the HOA in virtue of which one’s mental states are conscious can, and sometimes does, misdescribe those states. A striking difference between the two, however, has to do with utility for psychological processing. Metacognition has considerable benefit for psychological processing; in contrast, it is unlikely that there is much, if any, utility to mental states’ being conscious over and above the utility those states have when they are not conscious.

Dualism is the view that mental phenomena are, in some respect, nonphysical. The best-known version is due to Descartes, and holds that the mind is a nonphysical substance. Descartes argued that, because minds have no spatial properties and physical reality is essentially extended in space, minds are wholly nonphysical. Every human being is accordingly a composite of two objects: a physical body, and a nonphysical object that is that human being's mind. On a weaker version of dualism, which contemporary thinkers find more acceptable, human beings are physical substances but have mental properties, and those properties aren't physical. This view is known as property dualism, or the dual-aspect theory

It’s often held that undetectable inversion of mental qualities is, if not possible, at least conceivable. It’s thought to be conceivable that the mental quality your visual states exhibit when you see something red in standard conditions is literally of the same type as the mental quality my visual states exhibit when I see something green in such circumstances. It’s thought, moreover, to be conceivable that such inversion of mental qualities could be wholly undetectable by any third-person means. And since first- person access is limited to a single individual, and so could not reveal a disparity in mental quality between us, third-person undetectability means undetectability tout court

At the level of our platitudinous background knowledge about things, speech is the expression of thought. And understanding what such expressing involves is central to understanding the relation between thinking and speaking. Part of what it is for a speech act to express a mental state is that the speech act accurately captures the mental state and can convey to others what mental state it is. And for this to occur, the speech act at least must have propositional content that somehow reflects that of the mental state, and perhaps must have other such properties as well.

Remarks such as ‘I am in pain’ and ‘I think that it’s raining’ are puzzling, since they seem to literally describe oneself as being in pain or having a particular thought, but their conditions of use tend to coincide with unequivocal expressions of pain or of that thought. This led Wittgenstein, among others, to treat such remarks as expressing, rather than as reporting, one’s mental states. Though such expressivism is widely recognized as untenable, Bar-On has recently advanced a neo-expressivist view, on which such remarks exhibit characteristics of both expressions of mental states and reports of those states. I argue against any attempt to see such remarks as both reporting and expressing the same mental states, and that a correct account rests on distinguishing the truth conditions of such remarks from their conditions of use.

Mind-body materialism is at its most inviting in the context of trying to give a unified treatment of the natural world. And the principle challenge it faces is to do justice to the distinguishing features of mental phenomena, which set them off from nonmental, physical reality. This challenge it not easy to meet. In 1971 I suggested that the difficulty in meeting it makes especially appealing the eliminative materialism of Feyerabend and Rorty. If adopting the materialist view that mental phenomena are physical in nature prevents us from giving a satisfactory account of what is distinctive about the mental, perhaps the trouble is not with materialism but with the mental. If we can describe and explain everything about the world in physical terms but cannot give a satisfactory account of the distinctively mental, why not conclude that there simply are no mental states and events? Physical terms would then suffice to describe and explain the phenomena we now classify as mental. Even if describing and explaining these things physically is not a practical option, the possibility of doing so would underwrite the eliminative materialist position