A philosopher claims mental properties are real and causally efficacious, but cannot be defined in terms of or identified with physical properties. What is the strongest objection to this position?
AIt implicitly denies that brain states cause behavior, which is empirically false
BIf physical causation is closed, mental properties appear to do no additional causal work and become epiphenomenal
CIt commits to substance dualism, which has already been empirically refuted
DIt cannot explain why mental vocabulary is useful if it doesn't reduce to physics
This describes non-reductive physicalism, and the causal exclusion problem is its sharpest challenge. If every physical effect has a sufficient physical cause (causal closure of the physical), then a distinct mental property can't add further causal contribution without overdetermination. Mental properties appear epiphenomenal — present but causally idle. Option A misreads the position; option C confuses non-reductive physicalism with dualism (it accepts supervenience); option D is a weaker concern.
Question 2 Multiple Choice
Which of the following best distinguishes type identity theory from token identity theory?
AType identity allows multiple realizability; token identity does not
BToken identity identifies each particular mental event with some physical event, while type identity identifies entire mental categories with physical types
CType identity is a form of dualism; token identity is a form of physicalism
DToken identity requires mental descriptions to be eliminated in favor of neural ones; type identity does not
Token identity holds that each individual mental event (my specific pain right now) is identical to some physical event, but different instances of the same mental type may correspond to different physical types — permitting multiple realizability. Type identity makes the stronger claim: the mental type 'pain' as such is identical to a physical type like 'C-fiber firing,' so every instance of pain must be that neural state. Only token identity accommodates the fact that pain appears to occur in organisms with very different neural architectures.
Question 3 True / False
Supervenience alone — the claim that there can be no mental difference without a physical difference — commits a physicalist to the view that mental properties are identical to physical properties.
TTrue
FFalse
Answer: False
Supervenience is the weakest form of physicalism. It says mental facts track physical facts but is compatible with mental properties being genuinely distinct from physical properties — just dependent on them. Non-reductive physicalists accept supervenience while denying reduction or identity. Identity is a much stronger claim: two things that are identical are literally the same thing. Supervenience only requires dependence, not sameness.
Question 4 True / False
Type identity theory predicts that pain in a human and pain in an octopus must involve literally the same neural state.
TTrue
FFalse
Answer: True
Type identity theory holds that each mental type is numerically identical to a physical (neural) type — just as 'water' and 'H₂O' refer to the same substance. If pain = C-fiber firing, then any creature in pain must have C-fibers firing. But octopuses, humans, and hypothetical silicon systems have radically different substrates. This is precisely why multiple realizability is such a damaging objection to type identity: it seems implausible that all these realizations share a common neural type.
Question 5 Short Answer
What is the causal exclusion problem, and why does it specifically threaten non-reductive physicalism rather than physicalism in general?
Think about your answer, then reveal below.
Model answer: If physics is causally closed — every physical effect has a sufficient prior physical cause — then mental properties that are distinct from physical properties cannot do additional causal work without overdetermination. Non-reductive physicalism accepts supervenience (mental depends on physical) but denies identity (mental ≠ physical). This leaves mental properties causally redundant: everything the mental would cause is already fully caused by its physical base. Reductive physicalists dissolve the problem by identifying the mental with the physical; eliminativists dissolve it by denying mental properties exist.
The problem targets the specific combination of claims non-reductive physicalism holds: physical causal closure + irreducibility of mental properties. Either commitment alone is fine; holding both simultaneously creates the tension. The reductive physicalist and eliminativist each escape by abandoning one of the commitments the non-reductive physicalist insists on keeping.