Physicalism

Abstract

Physicalism is a view about the relationship between people’s mental properties and their physical properties. It claims that people’s mental properties are nothing over and above – nothing additional to – their physical properties. People’s mental properties would certainly be nothing over and above their physical properties if their mental properties turned out to form a proper subset of their physical properties, so that every mental property turned out to be identical with – to be literally one and the same thing as – some physical property (e.g. the physical property of having one’s brain be in such and such neurophysiological state). People’s mental properties might also be nothing over and above their physical properties if mental properties turned out to be identical with functional properties that were physically realised. A functional property is the property of having some or other physical property that plays a particular functional role (e.g. that has certain typical causes and typical effects). For example, suppose the mental property of being in pain turns out to be the property of being in some or other internal state that is typically caused by bodily damage and that typically causes wincing and groaning. In that case, if the internal state playing that functional role is always in fact some physical state of the brain, even if it is not always the same type of physical brain state, then being in pain is nothing over and above a physical property. The claim that a particular mental property is identical with a particular physical or functional property is not advanced as any kind of a priori claim, e.g. as a conceptual or analytic truth. It must be supported by empirical evidence. For example, it is argued that the identification of mental property M with physical property P would provide the best explanation of an observed correlation between instances of M and instances of P. Physicalism is claimed to be analogous to such a posteriori scientific hypotheses as that genes are segments of DNA or that chemical elements are systems of physical particles. The two features of mental states that are most often argued to present a problem for physicalism are the phenomenal character of sensations (e.g. the introspectible nature of a severe toothache) and the intentionality of beliefs and desires (e.g. the fact that believing that Bhutan is in India is about Bhutan and India). Physicalists have offered physicalism-friendly accounts of both features.