John Perry’s Knowledge, Possibility, and Consciousness is based on the Jean Nicod Lectures, which he gave in Paris in 1999. The main goal of this book is to defend what he calls ‘antecedent physicalism’ from various common objections to physicalism. The book is organised as follows. In Chapter 1 Perry reviews a number of antiphysicalist arguments, which have been intensively discussed in the last few years among philosophers of mind. In Chapters 2 and 3 he formulates antecedent physicalism. Unlike eliminativism, antecedent physicalism grants the subjective character of phenomenal experiences. It then tries to construct the best possible account of them on the assumption that they are physical (p. 27). However, according to Perry, it is a mistake to think that the antecedent physicalist is ‘a complete dogmatist for whom physicalism is a religious principle’. The antecedent physicalist is rather one ‘who is committed to physicalism in the sense that she or he sees some compelling reasons for it and will not give it up without seeing some clear reason to do so’ (p. 27). In the rest of the book Perry attempts to show how his antecedent physicalism can block existing antiphysicalist arguments. In Chapter 4 he discusses the zombie argument, according to which physicalism is false because the existence of a zombie—someone physically identical to a human being but lacking conscious experience altogether—is a logical possibility. In Chapters 5, 6 and 7 Perry discusses the knowledge argument, according to which physicalism is false because there could be a scientist—call her Mary—who knows all the physical facts but does not know what it is like to see colour. In Chapter 8 Perry discusses the modal argument, according to which physicalism, the identity theory in particular, is false because psycho-physical identity statements such as ‘pain=c-fibre stimulation’ cannot be true, even if we regard them as necessary and a posteriori. In what follows I briefly explain my objection to Perry’s analysis of the knowledge argument, which occupies a substantial part of the book.
According to Perry, proponents of the knowledge argument assume that physical facts can be grasped only objectively. That is why, Perry says, they think that Mary in a black-and-white environment can acquire complete physical knowledge merely through black-and-white textbooks and black-and-white television. Perry contends that the knowledge argument is unsuccessful precisely because this assumption is false. There are physical facts, he says, the subjective character of which can be apprehended only when one has relevant experiences. He remarks:
The antecedent physicalist is committed to subjective ways of knowing physical facts in the following pretty clear and perfectly reasonable sense. There is a way of knowing what an experience is like that is available to a person who is having the experience that is not available to others. A sighted person can know what it is like to see objects in a way that a person who has never seen cannot. (p. 166)
Perry puts a lot of effort into explaining why some facts are known only by having a relevant experience. However, even if his explanation is cogent that does not immediately save physicalism from the force of the knowledge argument. For physicalists like Perry are required to explain further why those facts are rightly labelled as physical. Perry seems to respond to this problem by appealing to his assumption that physicalism is antecedently true. However, this response is untenable.
Perry formulates antecedent physicalism as a position which (i) accepts the truth of physicalism, the strong plausibility of which has derived from the successful history of the physical sciences and (ii) purports to construct ‘the best account, or at least a reasonably natural account, of subjective characters on the assumption that they are physical’ (p. 27). However, at least in response to the knowledge argument, physicalists are not allowed to assume antecedently that those facts that are known only by having relevant experiences are physical. For that begs the question against proponents of the knowledge argument. Proponents of the knowledge argument claim that certain facts about colour are non-physical because they are not known through ordinary way of acquiring physical knowledge -- i.e., reading black-and-white textbooks, watching black-and-white television and so on -- but only through relevant colour experiences. Physicalists like Perry are not allowed to dismiss this claim by simply stipulating that those facts are physical. (This is why some proponents of similar empiricist responses to the knowledge argument remain ontologically neutral. See, for example, (Conee, 1994). In sum: Perry’s objection to the knowledge argument is unsuccessful because he fails to respond to the most crucial question: what makes it the case that those facts that are known only through relevant experiences are physical?
As I have explained, I do not agree with Perry’s approach to the problem of phenomenal consciousness; in particular, I disagree with his approach to the knowledge argument. Nevertheless, I found his book extremely helpful in understanding complex issues in the recent debate on the topic. Dualism had been regarded as a dead philosophical doctrine for a long time, but has regained a number of supporters in the last couple of years. Perry’s book provides one of the clearest and most systematic defences of physicalism against this neo-dualist force.
References
Conee, E. 1994 Phenomenal Knowledge, Australasian Journal of Philosophy 72: 136-150.
