Monism and physicalism: the mind as the brain

What this dot point is asking

This dot point belongs to Unit 2 of the TASC Philosophy course, the mind/body problem. Where Descartes posited two substances and then struggled to connect them, the physicalist dissolves the interaction problem by denying the second substance altogether. If everything is physical, there is no mysterious immaterial mind that needs to make contact with matter.

Physicalism as a monism

Monism holds there is ultimately one kind of thing. Physicalism is the monism which says that thing is physical: matter, energy and their arrangements as described by science. On this view the mind is not a separate substance but a feature of the physical brain, and what we call mental events are, in the end, physical processes of the brain. The chief argument is its fit with science. Neuroscience steadily correlates mental states with brain activity, and physicalism explains this neatly by saying the mental state simply is the brain activity, not a separate item that happens to accompany it.

The mind-brain identity theory

The sharpest form of physicalism is the identity theory, developed by Ullin Place and J. J. C. Smart in the 1950s. They proposed that mental states are identical to brain states in the same way scientific identities are discovered: just as we learned that water is H2O and lightning is an electrical discharge, we can learn that pain is, say, a particular pattern of neural firing. This is an identity, not a correlation. Pain does not merely accompany the brain state; it is that brain state, described in everyday language rather than the language of neuroscience.

Type identity and token identity

The identity theory comes in two strengths. Type identity says every type of mental state is identical to a single type of brain state, so pain everywhere is the very same kind of neural event. Token identity is weaker, saying each particular instance, or token, of a mental state is some physical state or other, without requiring that all instances of a given mental type share one physical type. The distinction matters because the strongest objection targets type identity directly.

The multiple realisability objection

Hilary Putnam raised the decisive challenge. The same mental state, such as pain, seems realisable in very different physical systems: a human brain, a very differently structured animal nervous system, perhaps an artificial system. If creatures with no shared brain-state type can all be in pain, then pain cannot be identical to one type of brain state, and type identity fails. This objection pushed many philosophers toward functionalism, which identifies mental states by their causal role rather than their physical make-up, and toward token identity as a fallback. For the TASC course, show that you grasp the appeal of physicalism as a scientific, economical theory, and that you can deploy multiple realisability as the standard objection while noting the token identity reply.