Physicalist theories of mind

Physicalism and the varieties of physicalism#

FoundationAQA 7172 3.4 Metaphysics of mind — PhysicalismDfE GCE Philosophy subject content

The varieties of physicalism

Fig. 1Behaviourism (dispositions), identity theory (brain states) and eliminativism (folk psychology is false).

Physicalism (or materialism) is the thesis that everything that exists is physical, or is wholly determined by (supervenes on) the physical. Applied to the mind, it denies dualism: there is no immaterial soul and no irreducible non-physical property; the mind is either identical to, or nothing over and above, the physical states and processes of the brain and body. Physicalism's attractions are considerable: it fits the scientific worldview and the manifest dependence of the mind on the brain (brain damage alters the mind); it avoids the interaction problem (no non-physical mind to interact); it respects causal closure and conservation; and it is ontologically economical (one kind of thing, not two).

The GENERAL argument for physicalism is an inference to the best explanation from the intimate dependence of the mental on the physical. Everything we discover about the mind — that specific experiences correlate with specific brain activity, that drugs and injuries alter consciousness, that mental capacities develop with the brain and decline with its decay — is best explained by supposing the mind IS the brain (or is realised by it), not by supposing there is an additional non-physical substance or set of properties mysteriously correlated with it. Causal closure adds force: since every physical event has a sufficient physical cause, and the mind evidently causes physical events (behaviour), the mental must itself be physical (else it is epiphenomenal). Physicalism is thus the default view of most contemporary philosophers of mind, and the burden is often placed on the dualist to show something is left out.

Physicalism is not a single theory but a family, differing over WHAT mental states are and HOW they relate to the physical. LOGICAL/ANALYTICAL behaviourism analyses mental-state TALK as talk about behavioural dispositions (to be in pain is to be disposed to wince, cry out, avoid the cause). Mind-brain type IDENTITY theory holds that mental states ARE (are identical to) brain states (pain = C-fibre firing), as water = H2O. ELIMINATIVE materialism holds that our common-sense mental categories (belief, desire, pain) are the posits of a false theory ('folk psychology') and should be ELIMINATED, replaced by the categories of a mature neuroscience. These differ over whether mental states exist (eliminativism says the folk ones do not), and if so what they are (dispositions, or brain states).

A key distinction organises the varieties: REDUCTIVE versus NON-REDUCTIVE, and whether the theory concerns MEANING or ONTOLOGY. Logical behaviourism is a claim about the MEANING of mental terms (a priori, conceptual analysis: 'pain' MEANS a behavioural disposition). Identity theory is a claim about ONTOLOGY (a posteriori, empirical: pain turns out to BE a brain state, discovered by science, as water turned out to be H2O). Eliminativism is a claim that the entities do not exist at all. Functionalism (next topic) is a further variety, defining mental states by functional role rather than by behaviour or brain state, and is compatible with physicalism (roles realised by brains). Locating a theory as a claim about meaning, ontology, or existence, and as reductive or eliminative, is the key to assessing it — and to seeing that the objections differ for each: behaviourism faces the category-mistake and circularity objections, identity theory faces multiple realisability, and eliminativism faces the self-refutation charge.

Worked example

Meaning, ontology, or existence?

For each physicalist theory, say whether it is a claim about the meaning of mental terms, the ontology of mental states, or their existence.

Behaviourism
A claim about MEANING: 'pain' means a disposition to pain-behaviour — an a priori conceptual analysis.
Identity theory
A claim about ONTOLOGY: pain IS a brain state (C-fibre firing) — an a posteriori empirical identity, like water = H2O.
Eliminativism
A claim about EXISTENCE: the folk-psychological states (belief, desire) do not exist, being posits of a false theory.
The upshot
The objections differ accordingly: behaviourism faces the category-mistake/circularity, identity theory multiple realisability, eliminativism self-refutation.

Result: Behaviourism is about meaning, identity theory about ontology, and eliminativism about existence — a division that determines which objection each faces and how it must be evaluated.

Typical mistakes

Treating physicalism as one theory; behaviourism (meaning), identity theory (ontology) and eliminativism (non-existence) make importantly different claims and face different objections.
Confusing identity theory (an empirical, a posteriori ontological identity) with behaviourism (an a priori conceptual analysis of mental TALK).

Active revision

Explain the difference between logical behaviourism, type identity theory and eliminative materialism. (5-mark AO1 response)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for philosophy (Department for Education)

Logical behaviourism: Ryle and the category mistake#

StandardAQA 7172 3.4 Metaphysics of mind — PhysicalismDfE GCE Philosophy subject content

Ryle's category mistake

Fig. 2Seeking the mind as an inner thing behind behaviour is like seeking 'the University' as a building beside the colleges.

Logical (or analytical) behaviourism holds that statements about mental states can be ANALYSED into (translated into) statements about behaviour and dispositions to behave. To be in pain is not to be in a private inner state but to be disposed to certain behaviour — wincing, crying out, avoiding the cause; to believe it will rain is to be disposed to take an umbrella, say 'it will rain', and so on. Carl Hempel gave a strict, verificationist version (mental statements mean the same as the physical/behavioural statements that would verify them). The view is a claim about the MEANING of mental terms: 'pain' just MEANS a behavioural disposition, so there is no hidden inner referent for dualism to worry about.

Gilbert Ryle (The Concept of Mind, 1949) gives the most influential version, attacking what he calls the 'dogma of the Ghost in the Machine' — the Cartesian picture of the mind as a private inner theatre lying behind behaviour. Ryle argues this rests on a CATEGORY MISTAKE: it mis-assigns mental concepts to the wrong logical category. His famous illustration: a visitor is shown the colleges, libraries and departments of a university and then asks 'but where is the University?' — as if the University were a further building alongside the colleges, when in fact the University just IS the organised whole of those institutions. Likewise, Descartes looked for the mind as a further, inner THING behind behaviour, when 'mind' is not the name of a private object but a way of describing the organised patterns and capacities of intelligent behaviour. To have a mind is to be able to do certain things intelligently, not to possess a ghostly inner substance.

Ryle applies this especially to 'knowing how' and dispositions: intelligence is not a matter of inner mental acts accompanying behaviour, but of behaving intelligently — the clever chess player's cleverness is IN the skilful play, not in hidden inner operations that cause it. Mental terms, on this view, are largely DISPOSITIONAL: to say glass is brittle is not to name a hidden inner quality but to say it WOULD shatter if struck; likewise to say someone is vain is to say they are disposed to behave in certain ways. This dissolves the mind-body problem: there is no ghostly mind to relate to the body, only the behaving, capable person. Behaviourism thereby avoids dualism's interaction problem and other-minds problem (other minds are not hidden — we observe intelligence directly in behaviour) and fits an empirical, scientific approach to the mind.

Behaviourism faces decisive objections. First, it seems to leave out the INNER, QUALITATIVE aspect of mental states — the FELT pain, not just the disposition to wince. The 'super-Spartan' (or perfect actor) objection: a super-Spartan could be in agony yet, by iron self-control, exhibit NO pain-behaviour and no disposition to it — so pain cannot BE the behavioural disposition, since one can have the pain without the disposition (and, conversely, a perfect actor can exhibit pain-behaviour with no pain). Second, the CIRCULARITY objection (Chisholm): mental states cannot be analysed into behaviour without reference to OTHER mental states — whether I take an umbrella depends not just on believing it will rain but on WANTING to stay dry AND believing the umbrella will help; so any behavioural analysis of a belief must mention desires, and vice versa, so the analysis is circular and cannot eliminate the mental. Third, behaviourism seems to get the DIRECTION of explanation wrong: my pain CAUSES my wincing, but if pain just IS the disposition to wince, it cannot be its cause. Fourth, it struggles with the ASYMMETRY of self-knowledge (I know my own pain directly, not by observing my behaviour). Evaluation is that logical behaviourism rightly attacks the Cartesian inner theatre and captures the behavioural connections of mental concepts, but that the super-Spartan and circularity objections are widely regarded as fatal: mental states are not simply behavioural dispositions, because they have an inner, qualitative and causal reality that dispositions omit — which motivates the move to identity theory (mental states are inner BRAIN states) and functionalism (inner states defined by causal role).

Worked example

The super-Spartan objection

Explain how the super-Spartan objection challenges logical behaviourism.

The theory
To be in pain IS to have a disposition to pain-behaviour (wincing, crying out, avoidance).
The counterexample
A super-Spartan, trained to total self-control, is in agony but exhibits NO pain-behaviour and no disposition to it.
The other side
Conversely, a perfect actor exhibits full pain-behaviour with no pain at all.
The conclusion
So pain is neither necessary nor sufficient for the disposition: one can have the pain without the disposition and the disposition without the pain — pain is not the disposition.

Result: The super-Spartan and perfect-actor cases show pain cannot BE a behavioural disposition, because the felt state and the disposition come apart — a widely accepted refutation of logical behaviourism that motivates inner-state theories (identity, functionalism).

Typical mistakes

Confusing logical behaviourism (a philosophical thesis about the MEANING of mental terms) with methodological behaviourism in psychology (a research programme); the specification concerns the former.
Presenting behaviourism as denying that we have inner lives crudely; Ryle's subtle point is that 'mind' is not a further inner OBJECT — the objection is that this still leaves out felt qualia.

Active revision

'Mental states are nothing more than dispositions to behave.' Assess this claim. (25-mark essay)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for philosophy (Department for Education)

Mind-brain type identity theory#

StandardAQA 7172 3.4 Metaphysics of mind — PhysicalismDfE GCE Philosophy subject content

Identity theory: mental states are brain states

Fig. 3Modelled on scientific identities like water = H2O, pain is identified with a brain state.

Mind-brain type identity theory (U. T. Place, 'Is Consciousness a Brain Process?', 1956; J. J. C. Smart, 'Sensations and Brain Processes', 1959) holds that mental states are IDENTICAL to brain states: types of mental state ARE types of brain state (pain = C-fibre firing, the experience of red = such-and-such neural process). Unlike behaviourism, it locates mental states in INNER states (the brain), so it can accommodate the felt, causal reality of pain that behaviourism omitted. Unlike dualism, these inner states are wholly physical. The identity is claimed to be a CONTINGENT, A POSTERIORI, empirical identity, discovered by science — exactly like 'water = H2O', 'lightning = electrical discharge', 'heat = molecular motion'. Just as science discovered that water IS H2O (not by conceptual analysis but by empirical investigation), so neuroscience will discover that pain IS a certain brain state.

The theory's central strategy is to model the mind-brain identity on the theoretical identities of science. 'Water = H2O' is not a synonymy ('water' does not MEAN 'H2O' — one can understand 'water' without knowing chemistry) but a discovered identity of REFERENCE: the term 'water' and the term 'H2O' pick out the same stuff. Likewise 'pain' and 'C-fibre firing' are not synonymous, but pick out the same state. This answers the immediate objection that 'pain' does not MEAN 'brain state': the identity is a posteriori and about reference, not meaning, so the failure of synonymy is expected and harmless (as with water/H2O). Smart also defended the theory on grounds of PARSIMONY (Ockham's razor): if brain states can do all the explanatory work, positing additional non-physical mental states or properties is an unnecessary multiplication of entities.

The identity theory has real advantages. It keeps mental states as inner, causally efficacious, felt states (unlike behaviourism), while making them physical (unlike dualism), so it avoids both the super-Spartan objection and the interaction problem. It fits the neuroscientific correlation of mental states with brain states, treating those correlations as identities rather than mere correlations (which is more economical than dualist correlation). And it makes mental causation unproblematic: since the mental state IS a physical brain state, it causes behaviour in the ordinary physical way.

The theory faces the classic anti-identity objections and, decisively, MULTIPLE REALISABILITY (next section). Smart himself addressed several early objections. The 'phenomenal properties' objection (from Leibniz's Law): mental states have properties (they are private, felt, seem non-spatial) that brain states lack (they are public, spatial), so by Leibniz's Law they cannot be identical. Smart's reply is the 'topic-neutral' analysis: reports of experience ('I have a yellowish-orange after-image') can be paraphrased in a way NEUTRAL between physical and non-physical ('something is going on like what goes on when I see an orange') so that they ascribe no non-physical property that a brain state must lack — the felt qualities are 'topic-neutral' descriptions of what is in fact a brain process. The knowledge and zombie arguments (previous topic) press the qualia objection harder: if Mary learns something new, or zombies are possible, then experiences have phenomenal features not captured by their physical description, refuting the identity. Identity theorists reply with the phenomenal-concepts strategy. But the objection widely regarded as decisive against TYPE identity is multiple realisability: the same mental TYPE (pain) can be realised by different physical types in different creatures (human C-fibres, octopus neurons, perhaps silicon), so pain cannot be IDENTICAL to any one brain-state type — which motivates the move to functionalism. Evaluation is that type identity theory is a strong improvement on behaviourism (inner, causal, felt states that are physical) and rightly models the mind-brain relation on scientific identities, but that multiple realisability is a serious, arguably fatal, objection to the TYPE version, and the qualia arguments remain a challenge — so the theory survives, if at all, only as a token-identity or functionalist view.

Worked example

The topic-neutral reply to Leibniz's Law

Explain the objection that mental states have properties brain states lack, and Smart's topic-neutral reply.

The objection
Experiences seem private, felt and non-spatial; brain states are public and spatial; by Leibniz's Law, differing in properties, they are not identical.
Smart's move
Analyse experience-reports 'topic-neutrally': 'I have an orange after-image' means 'something is going on like what goes on when I really see an orange' — ascribing no explicitly non-physical property.
The effect
So the report does not attribute to the experience any property (privacy, non-spatiality) that a brain state must lack; the felt quality is a topic-neutral description of a physical process.
The residue
But the knowledge and zombie arguments press that the phenomenal character IS a further property, so the topic-neutral reply needs the phenomenal-concepts strategy to fully answer them.

Result: The topic-neutral analysis blunts the Leibniz's-Law objection by denying that experience-reports ascribe non-physical properties, but the deeper qualia arguments (Mary, zombies) keep the pressure on, so the reply is a strong but not final defence.

Typical mistakes

Saying identity theory claims 'pain' MEANS 'brain state'; it claims an a posteriori identity of REFERENCE (like water/H2O), so failure of synonymy is expected and not an objection.
Overlooking the topic-neutral reply to Leibniz's Law; Smart argues experience-reports ascribe no non-physical property a brain state must lack, so the argument does not go through.

Active revision

Explain mind-brain type identity theory and one advantage it has over logical behaviourism. (12-mark AO1 response)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for philosophy (Department for Education)

Multiple realisability#

AdvancedAQA 7172 3.4 Metaphysics of mind — PhysicalismDfE GCE Philosophy subject content

The multiple realisability argument

Fig. 4The same mental type is realised by different physical types across creatures, so it is not identical to any one.

The multiple realisability objection, due to Hilary Putnam ('The Nature of Mental States', 1967), is widely regarded as the decisive refutation of TYPE identity theory. The argument: the same TYPE of mental state (e.g. pain) can be REALISED by many different types of physical state in different kinds of creature. Humans feel pain via C-fibre firing; but octopuses, with very different nervous systems, also feel pain; so, plausibly, do reptiles, birds and mammals with diverse neural structures; and perhaps a silicon-based alien or an artificial intelligence could feel pain via yet another physical substrate. If pain can be realised by C-fibres in humans, by different neurons in octopuses, and (in principle) by silicon in a machine, then pain is NOT identical to any one physical type — for identity is one-to-one, and pain is one-to-MANY with respect to physical types.

The logic is Leibniz's Law again, but turned against the identity theorist: if pain = C-fibre firing, then anything in pain has C-fibres firing; but the octopus is in pain WITHOUT C-fibres firing; so pain is NOT identical to C-fibre firing. Generalising, pain is not identical to ANY specific physical type, because for any physical type you name, some possible creature could be in pain without being in THAT type. So the type identity theory — which identifies each mental TYPE with a single physical TYPE — is false; it 'chauvinistically' ties pain to human neurophysiology, wrongly excluding creatures that share the mental state but not the physical realisation.

The multiple realisability objection motivates FUNCTIONALISM (next topic) as the natural successor to identity theory. If what makes a state PAIN is not its physical make-up (which varies) but its FUNCTIONAL ROLE — its typical causes (bodily damage) and effects (avoidance behaviour, other mental states) — then pain can be MULTIPLY realised: any physical state that plays the pain-role, whatever its material, IS pain. Functionalism thus keeps physicalism's virtues (mental states are realised by physical states) while accommodating multiple realisability (the same role, different realisers), which is why it became the dominant theory. Multiple realisability is therefore not just an objection but a signpost to the successor theory.

Identity theorists have replies. First, TOKEN identity: retreat from TYPE identity (every pain-type = one brain-type) to TOKEN identity (each PARTICULAR instance of pain = some particular physical state, though different instances may be different physical types). Token identity preserves physicalism (every mental token is physical) while conceding multiple realisability (no type-type identity), and is compatible with functionalism. Second, SPECIES-SPECIFIC (local) identity: perhaps pain-in-humans = C-fibre firing, pain-in-octopuses = some other state — the identities are relativised to species, so there are many narrow type-identities rather than one universal one. Critics reply that species-specific identity concedes the main point (there is no single physical type for pain as such) and looks ad hoc, and that it multiplies identities implausibly. Evaluation is that multiple realisability decisively refutes the strong, universal TYPE identity theory (pain is not identical to any one physical type across all creatures), and that the identity theorist's best options (token identity, species-specific identity) either collapse into or lead towards functionalism. So the objection succeeds against type identity but does NOT refute physicalism as such: token identity and functionalism remain physicalist, holding that every mental state is realised by (though not type-identical to) some physical state. The lesson is that the mental is physical but at the level of FUNCTION, not of specific physical type — which is precisely functionalism's thesis, and why the metaphysics-of-mind dialectic moves from identity theory to functionalism at this point.

Worked example

From multiple realisability to functionalism

Explain how multiple realisability leads from identity theory to functionalism.

The problem
Pain is realised by different physical types in humans, octopuses and (possibly) machines, so it is not identical to any single physical type — type identity fails.
The question
What do all these physical realisers have in common that makes them PAIN, if not their physical make-up?
The functionalist answer
They share a FUNCTIONAL ROLE: caused by bodily damage, causing avoidance behaviour and distress. Pain IS that role, whatever realises it.
The pay-off
Functionalism keeps physicalism (roles are physically realised) while accommodating multiple realisability (same role, different realisers) — so it succeeds identity theory.

Result: Multiple realisability refutes type identity but points to functionalism: mental states are individuated by functional role, not physical type, so the same state can have many physical realisers — the dominant post-identity view.

Typical mistakes

Thinking multiple realisability refutes physicalism itself; it refutes TYPE identity, but token identity and functionalism remain physicalist (every mental state is still physically realised).
Confusing type and token identity; type identity ties each mental TYPE to one physical TYPE (refuted), while token identity ties each mental INSTANCE to some physical instance (survives).

Active revision

'Multiple realisability shows that mental states are not brain states.' Discuss. (25-mark essay)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for philosophy (Department for Education)

Eliminative materialism#

AdvancedAQA 7172 3.4 Metaphysics of mind — PhysicalismDfE GCE Philosophy subject content

The self-refutation objection

Fig. 5Asserting eliminativism expresses a belief, but eliminativism denies beliefs exist, so the assertion undermines itself.

Eliminative materialism (Paul and Patricia Churchland) is the most radical physicalism: it holds that our common-sense conception of the mind — 'folk psychology', the framework of beliefs, desires, hopes, fears and other propositional attitudes we use to explain and predict behaviour — is a FALSE and misleading THEORY, and that its posits (beliefs, desires) do not really exist. Just as we eliminated phlogiston, caloric fluid, witches and the crystalline spheres when better theories came along, so a mature neuroscience will REPLACE folk psychology, and we will stop talking of 'beliefs' and 'desires' as we stopped talking of phlogiston. There are no beliefs or desires; there are only brain states, to be described in the categories of a completed neuroscience.

The argument treats folk psychology as an EMPIRICAL THEORY and judges it by scientific standards, on which the Churchlands argue it fails. First, folk psychology is STAGNANT and has not progressed for millennia (we explain behaviour much as the ancient Greeks did), unlike successful sciences. Second, it is EXPLANATORILY INADEQUATE: it cannot explain many phenomena (mental illness, memory, sleep, learning, the workings of perception). Third, it does not INTEGRATE with the rest of science — its categories (belief, desire) do not map onto the categories of neuroscience, suggesting they carve nature wrongly. A theory that is stagnant, explanatorily weak, and fails to reduce to or integrate with the maturing science below it is, by the ordinary standards of science, a candidate for ELIMINATION, not preservation. So beliefs and desires will go the way of phlogiston.

Eliminativism is distinguished from the other physicalisms by its treatment of the mental. Behaviourism ANALYSES mental states (into behaviour); identity theory REDUCES/IDENTIFIES them (with brain states); eliminativism ELIMINATES them (there are no such things). Where identity theory says 'beliefs turn out to be brain states', eliminativism says 'there are no beliefs, only brain states' — the difference being that identity theory VINDICATES folk psychology (its posits are real, and physical), whereas eliminativism CONVICTS it of error. The two are rival predictions about how neuroscience will relate to common sense: will it identify folk categories with neural ones (identity/reduction) or replace them (elimination)?

The most discussed objection is that eliminativism is SELF-REFUTING (self-defeating). To ASSERT eliminativism is to express a BELIEF (that eliminativism is true) and to intend to convince others of it; but eliminativism says there are no beliefs; so in asserting it, the eliminativist presupposes exactly what the theory denies — the assertion undermines itself. If there are no beliefs, then the eliminativist does not BELIEVE eliminativism, and is not ASSERTING anything (assertion involves expressing a belief), so the theory cannot even be coherently stated. The Churchlands reply that this objection begs the question: it ASSUMES the folk-psychological framework (that meaningful assertion requires beliefs) to attack a theory that challenges that very framework — just as a defender of 'vital spirit' might have said 'you cannot claim to be ALIVE while denying vital spirit', wrongly assuming the framework under dispute. A future theory might reconstruct 'assertion' and 'meaning' without beliefs. Critics find this unconvincing — it is hard to see what asserting COULD be without something like belief — and add a second objection: the INTUITIVE CERTAINTY that we DO have beliefs, desires and (especially) conscious experiences is greater than our confidence in any argument that we do not; introspection seems to reveal our mental states directly, and denying pain or belief outright is a reductio. Evaluation is that eliminativism is a bold and clarifying position — it rightly warns that folk psychology is not sacrosanct and could in principle be revised by science — but that the self-refutation worry and the intuitive certainty of our mental lives make its wholesale elimination of belief and experience deeply implausible; most philosophers accept that folk psychology may be REVISED but not wholly ELIMINATED, and that eliminativism about CONSCIOUSNESS (qualia) is even harder to credit than eliminativism about the propositional attitudes.

Worked example

The self-refutation objection and its reply

Set out the self-refutation objection to eliminativism and the Churchlands' response.

The objection
To assert eliminativism is to express the BELIEF that it is true; but eliminativism says there are no beliefs; so the assertion presupposes what it denies.
The consequence
If there are no beliefs, the eliminativist does not believe or genuinely assert anything, so the theory cannot even be coherently stated.
The Churchlands' reply
This begs the question: it assumes the folk framework (assertion requires belief) to attack a theory challenging that framework — like 'you cannot be alive while denying vital spirit'.
Assess
The reply is ingenious but strained: it is hard to see what assertion could be without something belief-like, and the intuitive certainty of our mental lives tells against wholesale elimination.

Result: The self-refutation objection is powerful; the Churchlands' question-begging reply shows it is not strictly demonstrative, but the difficulty of reconceiving assertion without belief, plus the certainty of our conscious lives, makes eliminativism about belief and experience deeply implausible.

Typical mistakes

Confusing eliminativism with identity theory; identity theory says beliefs ARE brain states (vindicated), eliminativism says there ARE no beliefs (eliminated) — opposite verdicts on folk psychology.
Stating the self-refutation objection as decisive without the Churchlands' reply (that it begs the question by assuming the folk framework); a fair evaluation engages the reply.

Active revision

'Eliminative materialism is self-refuting.' Is this claim true? Defend your answer. (25-mark essay)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for philosophy (Department for Education)

Objections and the standing of physicalism#

AdvancedAQA 7172 3.4 Metaphysics of mind — PhysicalismDfE GCE Philosophy subject content

How the physicalist theories fare

Fig. 6Behaviourism and type identity are refuted, eliminativism is implausible; token identity and functionalism survive, facing the qualia problem.

A final assessment tracks how the three physicalist theories fare against their objections and against the qualia problem that unites the unit. Logical behaviourism is generally regarded as refuted: the super-Spartan and circularity objections show mental states are not merely behavioural dispositions, and it omits the inner, felt reality of experience. Type identity theory is a genuine advance (inner, causal, physical states) but is refuted as a UNIVERSAL type theory by multiple realisability, surviving only as token identity or being absorbed into functionalism. Eliminative materialism is a bold clarification but is rendered deeply implausible by the self-refutation worry and by the intuitive certainty of our mental lives, especially our conscious experiences. So none of the three is fully satisfactory as it stands, though token identity and functionalism (the successor) remain live physicalist options.

The deepest and most persistent objection to physicalism AS SUCH is the problem of QUALIA — the knowledge and zombie arguments of the dualism topic, which press that no physical account captures the felt, phenomenal character of experience (the hard problem). This is the thread that runs through the whole unit: behaviourism omits qualia (super-Spartan), identity theory must explain them away (topic-neutral analysis, phenomenal concepts), eliminativism must deny they exist (illusionism), and functionalism will face the absent/inverted qualia objections. Physicalism's fate turns on whether the explanatory gap between physical and phenomenal is merely EPISTEMIC (a limit on our concepts, compatible with physicalism — the phenomenal-concepts strategy) or ONTOLOGICAL (a real gap, refuting physicalism — the dualist reading). This is the single unresolved question on which the assessment of physicalism ultimately rests.

Physicalism's positive case remains powerful, and a fair judgement weighs it against the qualia problem. The dependence of the mind on the brain, the success of neuroscience, causal closure and conservation, and ontological parsimony all support physicalism, and dualism's alternatives (interaction, epiphenomenalism) have grave costs. So physicalism is the default view, and the burden on it is specifically to account for consciousness. The physicalist's best strategy is the phenomenal-concepts strategy (we grasp physical brain states via special phenomenal concepts that make them SEEM non-physical, generating the explanatory gap as an artefact of our concepts, not of the world) — which, if successful, dissolves the knowledge and zombie arguments and vindicates physicalism about qualia. Whether it succeeds is exactly the open question.

A defensible A-Level judgement is nuanced and names its standard. Among the three physicalist theories, token identity (or its functionalist development) is the strongest, since behaviourism and eliminativism are refuted and type identity founders on multiple realisability. On physicalism AS SUCH, the honest verdict is that it has the stronger positive case (mind-brain dependence, causal closure, parsimony) but has not conclusively solved the qualia problem — the explanatory gap is real, and whether it is epistemic or ontological is unresolved. A candidate might reasonably conclude that physicalism is the most probable view, on the strength of its positive case and the costs of dualism, but that it owes an account of consciousness (via the phenomenal-concepts strategy) that it has not yet delivered — so its truth is likely but not established. What earns the marks is distinguishing the three theories, tracking the qualia thread through all of them, and defending a judgement that acknowledges both physicalism's strengths and the unresolved hard problem.

The topic sets up functionalism (next) as the natural successor: it keeps physicalism's virtues (physically realised mental states, no interaction problem, mind-brain dependence) while accommodating multiple realisability (states individuated by role, not physical type), thereby answering the objection that felled type identity. But functionalism inherits the qualia problem in a new form — the absent-qualia (China brain) and inverted-qualia objections are the knowledge and zombie arguments applied to functional states — so the hard problem, unresolved by any physicalist theory here, carries forward as the central challenge to functionalism too. The metaphysics of mind is thus a single sustained dialectic, with the reality of qualia as its recurring, unresolved pressure point.

Worked example

Model 25-mark plan: can physicalism account for consciousness?

Plan an essay defending a judgement on whether physicalism can account for consciousness.

Thesis
Physicalism has the stronger positive case and its best theories survive, but it has not conclusively solved the qualia problem; its truth is probable but not established.
AO1
Behaviourism, type identity, eliminativism; the qualia arguments (Mary, zombies) as the challenge.
For physicalism
Mind-brain dependence, causal closure, parsimony; behaviourism/eliminativism refuted, but token identity/functionalism survive.
The challenge
The knowledge and zombie arguments show an explanatory gap; the phenomenal-concepts strategy tries to make it merely epistemic.
Judgement
Conclude physicalism is the most probable view (strong positive case, costly dualist rivals) but owes an account of consciousness (via phenomenal concepts) not yet delivered — so likely, not proven.

Result: A defensible judgement: physicalism's positive case makes it the most probable view and its surviving theories (token identity, functionalism) are strong, but the unresolved qualia problem means it has not conclusively accounted for consciousness — the epistemic/ontological status of the explanatory gap is the decisive open question.

Typical mistakes

Concluding physicalism is refuted because behaviourism, type identity and eliminativism each face objections; token identity and functionalism remain, and the real issue is the qualia/explanatory-gap question.
Ignoring the phenomenal-concepts strategy; it is the physicalist's central reply to the knowledge and zombie arguments, and any judgement on physicalism must engage it.

Active revision

'Physicalism cannot account for consciousness.' Is this claim true? Defend your answer. (25-mark essay)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for philosophy (Department for Education)

Key points

Meaning, ontology, or existence?

Key points

The super-Spartan objection

Key points

The topic-neutral reply to Leibniz's Law

Key points

From multiple realisability to functionalism

Key points

The self-refutation objection and its reply

Key points

Model 25-mark plan: can physicalism account for consciousness?

Sources

Physicalist theories of mind

Key points

Meaning, ontology, or existence?

Key points

The super-Spartan objection

Key points

The topic-neutral reply to Leibniz's Law

Key points

From multiple realisability to functionalism

Key points

The self-refutation objection and its reply

Key points

Model 25-mark plan: can physicalism account for consciousness?

Sources