SIFA 2006

The conceivability argument is one of the most discussed arguments against physicalism. The so-called phenomenal concept strategy has become one of the most attractive responses against it. However, Chalmers (2006b) has recently argued that no version of the phenomenal concept strategy can succeed. In my paper I intend to examine his main argument for that conclusion and argue that it is not sound.

The conceivability argument can be formulated simply thus: let P be a complete physical description of the actual world. Let Q be a complete phenomenal description of the world. It seems that we can imagine a scenario where P holds but Q does not. For example, we can imagine a possible world physically identical to our world that lacks consciousness. That is, P→Q is not a priori true.

Physicalism is committed to the claim that the conditional P→Q is necessary. But as we have seen, it is a posteriori, that is, it is conceivably false. From this, some argue that the conditional is not necessary. So physicalism is false. [1]

Advocates of the conceivability argument argue that the (alleged) epistemic gap between physical truths and phenomenal truths implies the existence of an ontological gap between physical truths and phenomenal truths. The phenomenal concept strategy attacks this argument by claiming that the epistemic gap is not due to any ontological gap, but rather to the special features of phenomenal concepts.

Chalmers poses a dilemma against the phenomenal concept strategy, claiming that any version of the strategy is doomed to fail. His argument is the following:

(3) Either C is not physically explicable, or C cannot explain our epistemic situation.[2]

The dilemma starts in the following way: for any account of phenomenal concepts C, either it is entailed a priori by physical truths (P) or it is not. That is, either P&~C is conceivable, or it is not.

The first premise explores what happens if P&~C is conceivable. The problem is that, in this case, P does not entail C a priori, and then, according to Chalmers’ characterization of explanation as a priori entailment, we cannot explain C in physical terms.

The second premise of the argument examines the possibility that P&~C is not conceivable, that is, that P does entail C a priori. In this case, even zombie-worlds satisfy C: every physical duplicate of the actual world satisfies C. Then, we would not have the problem of the previous case, but we would have another problem: now even zombies satisfy C. Our epistemic position (let’s call it E) is very different from zombies’ epistemic position. That is, we satisfy E, whereas zombies do not satisfy E. So zombies satisfy C (according to this horn of the dilemma), but not E. Then, C does not entail E a priori, because we can conceive of some beings (zombies) that satisfy C but not E. And therefore, C cannot explain E. But E is our global epistemic position, which includes the epistemic gap between P and Q. Then, C cannot explain the relevant epistemic gap, because having C does not suffice for being in the relevant epistemic position. So premise (2) is true.

Chalmers characterizes someone’s epistemic situation as including “the truth values of their beliefs and the epistemic status of their beliefs (as justified or unjustified)” (Chalmers 2006b: 9). Then, it seems clear enough that zombies do not share our epistemic situation, since zombies’ beliefs such as ‘I am phenomenally conscious’ do not seem to be true of them or at least are not as justified as our corresponding beliefs.

I do not think this poses a problem for the phenomenal concept strategy. What an account of phenomenal concepts C has to explain is why there is an epistemic gap between P and Q, not our whole epistemic situation. Even if having C does not rule out that one is a zombie, this is not a problem for C to explain why P does not entail Q a priori. Zombies do not pose any problem for this explanatory task, because zombies are not able to infer a priori Q from P either.

In my paper I develop this suggestion and I defend it from Chalmers’ objections. I offer two elucidations of epistemic gap, that which the phenomenal concept strategy is supposed to explain: a strong one according to which instantiating the epistemic gap as we do implies being conscious, and a weak one which does not imply that. I argue that Chalmers is wrong is assuming that C has to explain the epistemic gap in the strong sense. One of his motivations for this assumption is that, on his view, explaining satisfactorily the epistemic gap involves explaining the conditions that enable us to formulate conceivability arguments, and if we were not conscious, we could not formulate conceivability arguments, so in order to explain the epistemic gap, we have to offer an explanation that entails that we are conscious. In response, I argue that it is unjustified to demand that a good explanation of the explanatory gap must explain all the conditions for formulating conceivability arguments. Secondly, I argue that his assumption is problematic because it can be interpreted as begging the question against the advocate of the phenomenal concept strategy.

I conclude that the phenomenal concept strategy should aim to explain the explanatory gap in the weak sense, and that Chalmers has posed no problem against the ability of the strategy to meet this aim.

Chalmers, D. 2006a. The Two-Dimensional argument against materialism. In D. Chalmers (ed.) The Character of Consciousness, Oxford University Press, forthcoming.

Chalmers, D. 2006b. Phenomenal concepts and the explanatory gap. In T. Alter & S. Walter (eds.) Phenomenal Concepts and Phenomenal Knowledge: Essays on Consciousness and Physicalism, Oxford University Press, forthcoming. Available at: http://consc.net/papers/pceg.html

[1] See Chalmers 2006a for a very detailed presentation and defence of this argument.

[2] Chalmers 2006b, 7.