Physicalism and the Identity Theory - TCE Philosophy (Tasmania)
“Monism and physicalism: the mind as the brain”
Monism is the view that mind and body are not fundamentally separate. Its leading form, physicalism, says there is only physical stuff, so the mind just is the brain and mental events are reducible to physical processes in it. The identity theory states that each type of mental state is identical to a type of brain state, much as water turned out to be H2O. You are asked to explain physicalism, present the identity theory and its appeal, and evaluate objections such as multiple realisability.
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 monist view that everything that exists is physical, so the mind is not a distinct non-physical substance but the brain, and mental states are nothing over and above states of the brain.
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.
If a mental event simply is a physical event in the brain, there are not two things needing to interact. The hard question of how an immaterial mind pushes on matter never arises, which is a major advantage physicalism claims over dualism.
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.
Ask whether the claim is that all pains are the same brain state, or only that each pain is some brain state. If pain in a human, an octopus and a hypothetical silicon machine must all be one identical neural type, that is type identity, and it faces multiple realisability. If only each individual pain need be physical in its own way, that is token identity, which survives the objection but explains less.
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.
Neuroscience showing that a feeling reliably accompanies brain activity establishes correlation, not identity. A dualist can accept the very same correlations and still claim two distinct things are merely linked. The identity theorist must argue the stronger claim that the mental state is the brain state, so do not treat brain scans alone as settling the debate.
Exam-style questions
Questions in the style of TASC exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Practice6 marksExplain the mind-brain identity theory and the difference between type and token identity.Show worked answer →
A 6 mark response needs the theory and the two strengths of identity.
Identity theory. Developed by Place and Smart, it holds mental states are identical to brain states in the way scientific identities are discovered, as water turned out to be H2O. Pain does not merely accompany a neural state; it is that neural state, described in everyday language. This dissolves the interaction problem, since there are not two things to interact.
Type vs token. Type identity says every type of mental state is identical to a single type of brain state, so all pains are the same neural kind. Token identity says only that each particular instance of a mental state is some physical state or other, without requiring a shared physical type.
Markers reward the identity (not correlation) point and an accurate type/token distinction, ideally noting type identity is what multiple realisability attacks.
Practice16 marks"Multiple realisability refutes physicalism." Critically evaluate this claim.Show worked answer →
A 16 mark extended argument essay should distinguish forms of physicalism and assess the objection.
Exposition. State physicalism (everything is physical; the mind is the brain) and the identity theory, distinguishing type and token identity.
The objection. Putnam: the same mental state, such as pain, seems realisable in very different physical systems (human brain, a differently structured animal nervous system, perhaps a machine). If creatures with no shared brain-state type can all be in pain, pain cannot be identical to one type of brain state, so type identity fails.
Assessment. The objection refutes type identity, not physicalism as such. Token identity survives (each pain is some physical state in its own way), and functionalism identifies mental states by causal role rather than physical make-up, preserving physicalism while accommodating multiple realisability. The cost is that token identity explains less than type identity.
Judgement. Conclude with a defended position, for example that multiple realisability refutes type identity but not physicalism, since token identity and functionalism remain available. Note correlation does not establish identity. Markers reward the type/token distinction, the functionalist escape, and a reasoned conclusion.