The zombie argument for dualism runs: (1) zombies are conceivable, (2) whatever is conceivable is metaphysically possible, (3) therefore zombies are possible, (4) therefore physicalism is false. The most contested step among philosophers is:
AStep 1 — most philosophers accept that zombies involve no logical contradiction, so conceivability is granted
BStep 2 — the inference from conceivability to metaphysical possibility is the central point of dispute
CStep 3 — it does not follow from mere conceivability that zombies are genuinely possible
DStep 4 — even if zombies are possible, identity theory could still hold in the actual world
Step 2 — the conceivability-to-possibility inference — is where the logical weight lies. Even if we accept that zombies are conceivable (no obvious contradiction), critics argue that conceivability is not a reliable guide to genuine metaphysical possibility. We may be able to 'imagine' something while lacking the cognitive insight to see that it is actually impossible. Step 1 is also contested (Dennett denies zombies are genuinely conceivable), but Step 2 is the deeper structural vulnerability of all modal arguments for dualism.
Question 2 Multiple Choice
Water was discovered to be necessarily H₂O — in every possible world where water exists, it is H₂O. Yet before chemistry, people could not derive 'water = H₂O' from their concept of water alone. A physicalist uses this example to argue:
AThat all necessary identities must eventually become knowable a priori as science advances
BThat our inability to see a priori how the brain generates consciousness doesn't mean there is a possible world where they come apart
CThat consciousness must be identical to a specific physical substance, just as water is identical to H₂O
DThat modal intuitions are always unreliable and modal arguments should be abandoned entirely
The water/H₂O case is the physicalist's key counterargument: it shows that something can be necessarily true without being knowable a priori. Before chemistry, people couldn't derive 'water = H₂O' from their concept of water — yet the identity is metaphysically necessary in all possible worlds. By analogy, consciousness may be necessarily identical to some physical state even though we cannot derive this a priori. The epistemic gap (we can't see how physics generates consciousness) does not entail a metaphysical gap (a possible world where they come apart) — which is exactly the inference the zombie argument needs.
Question 3 True / False
The zombie argument, if successful, would establish that consciousness is not identical to any physical brain state, thereby refuting physicalism about the mind.
TTrue
FFalse
Answer: True
This is the correct conclusion. If zombies are metaphysically possible — if there is a possible world with all the same physical states but no consciousness — then consciousness cannot be identical to any physical state. Physical identity claims are necessary: if A = B, then in every possible world A = B. So the existence of a possible world where the physics is present but consciousness is absent shows the identity fails. Since physicalism holds that mental states are identical to (or necessitated by) physical states, successful zombie arguments do refute it.
Question 4 True / False
An epistemic gap — our inability to explain a priori how physical processes generate conscious experience — is sufficient evidence that there is a genuine metaphysical gap between the physical and the mental.
TTrue
FFalse
Answer: False
This is the key inference that critics of modal arguments deny. The water/H₂O analogy makes this vivid: people couldn't derive 'water = H₂O' a priori, yet no metaphysical gap exists — water is necessarily H₂O in all possible worlds. Analogously, our inability to see how physical processes generate consciousness (the 'hard problem') does not entail there is any possible world where they come apart. Confusing epistemic inaccessibility with metaphysical contingency is the core error the modal argument may be committing.
Question 5 Short Answer
Explain the distinction between an epistemic gap and a metaphysical gap in philosophy of mind, and why this distinction is the fault line for evaluating modal arguments like the zombie argument.
Think about your answer, then reveal below.
Model answer: An epistemic gap is a failure of a priori knowledge: we cannot explain from first principles how physical processes give rise to subjective experience. A metaphysical gap is stronger: there is a genuinely possible world where the physical facts hold but the mental facts do not — the two can come apart. Modal arguments try to move from the epistemic gap (zombies are conceivable) to a metaphysical gap (zombies are possible, so physics and consciousness are not necessarily connected). Critics argue this inference fails because some necessary truths are not knowable a priori — as water = H₂O demonstrates.
The distinction matters because modal arguments need metaphysical possibility to establish anti-physicalist conclusions. Mere conceivability only shows an epistemic gap — we can't see how the connection works. Physicalists grant this gap but deny it entails metaphysical separability. The entire debate turns on whether our imaginative faculty reliably tracks genuine possibility or whether we can 'conceive' scenarios that are in fact impossible because we lack knowledge of hidden necessities.