Conceiving the impossible and the mind-body problem

Abstract

I Intuitions based on the first-person perspective can easily mislead us about what is and is not conceivable.1 This point is usually made in support of familiar reductionist positions on the mind-body problem, but I believe it can be detached from that approach. It seems to me that the powerful appearance of contingency in the relation between the functioning of the physical organism and the conscious mind - an appearance that depends directly or indirectly on the firstperson perspective - must be an illusion. But the denial of this contingency should not take the form of a reductionist account of consciousness of the usual type, whereby the logical gap between the mental and the physical is closed by conceptual analysis - in effect, by analyzing the mental in terms of the physical (however elaborately this is done - and I count functionalism as such a theory, along with the topic-neutral causal role analyses of mental concepts from which it descends). In other words, I believe that there is a necessary connection in both directions between the physical and the mental, but that it cannot be discovered a priori. Opinion is strongly divided on the credibility of some kind of functionalist reductionism, and I wont go through my reasons for being on the antireductionist side of that debate. Despite significant attempts by a number of philosophers to describe the functional manifestations of conscious mental states, I continue to believe that no purely functionalist characterization of a system entails - simply in virtue of our mental concepts - that the system is conscious. So I want to propose an alternative. In our present situation, when no one has a plausible answer to the mind-body problem, all we can really do is to try to develop various alternatives one of which may prove in the long run to be an ancestor of a credible solution. This is a plea for the project of searching for a solution that takes conscious points of view as logically irreducible to, but nevertheless necessarily connected with, the physical properties of the organisms whose points of view they are. Consciousness should be recognized as a conceptually irreducible aspect of reality that is necessarily connected with other equally irreducible aspects - as electromagnetic fields are irreducible to but necessarily connected with the behavior of charged particles and gravitational fields with the behavior of masses, and vice versa. But the task of conceiving how a necessary connection might hold between the subjective and the physical cannot be accomplished by applying analogies from within physical science. This is a new ballgame. Yet I believe it is not irrational to hope that some day, long after we are all dead, people will be able to observe the operation of the brain and say, with true understanding, Thats what the experience of tasting chocolate looks like from the outside. Of course we already know what it looks like from far enough outside: the subject taking the first reverent mouthful of a hot fudge sundae, closing his eyes in rapture, and saying Yum. 2 My position is fairly close to that of Colin McGinn, but without his pessimism. See for example his essay Consciousness and the Natural Order, in The Problem of Consciousness (Blackwell, 1991). What I have to say here is also a development of a suggestion in The View From Nowhere (Oxford University Press, 1986), pp. 51-53. But I have in mind some view or representation of the squishy brain itself, which in light of our understanding we will be able to see as tasting chocolate. While that is at the moment inconceivable, I think that it is what we would have to have to grasp what must be the truth about these matters. My reading of the situation is that our inability to come up with an intelligible conception of the relation between mind and body is a sign of the inadequacy of our present concepts, and that some development is needed. At this point, however, all one can hope to do is to state some of the conditions that more adequate concepts would have to satisfy. One cant expect actually to come up with them.2 But I shall begin by describing the present impasse. II When we try to reason about the possible relations between things, we have to rely on our conceptual grasp of them. The more adequate the grasp, the more reliable our reasoning will be. Sometimes a familiar concept clearly allows for the possibility that what it designates should also have features not implied by the concept itself - often features very different in kind from those directly implied by the concept. Thus ordinary prescientific concepts of kinds of substances, such as water or gold or blood, are in themselves silent with regard to the microscopic composition of those substances but nevertheless open to the scientific discovery, often by very indirect means, of such facts about their true nature. If a concept refers to something that takes up room in the spatiotemporal world, it provides a handle for all kinds of empirical discoveries about the inner constitution of that thing. On the other hand, sometimes a familiar concept clearly excludes the possibility that what it designates has certain features: for example we do not need a scientific investigation to be certain that the number 379 does not have parents. There are various other things that we can come to know about the number 379 only by mathematical or empirical investigation, such as what its factors are, or whether it is greater than the population of Chugwater, Wyoming, but we know that it does not have parents just by knowing that it is a number. If someone rebuked us for being closed-minded, because we cant predict in advance what future scientific research might turn up about the biological origins of numbers, he would not be offering a serious ground for doubt. The case of mental processes and the brain is intermediate between these two. Descartes thought it was closer to the second category, and that we could tell just by thinking about it that the human mind was not an extended material thing and that no extended material thing could be a thinking subject. But this is, to put it mildly, not nearly as self-evident as that a number cannot have parents. What does seem true is that the concept of a mind, or of a mental event or process, fails to plainly leave space for the possibility that what it designates should turn out also to be a physical thing or event or process, as the result of closer scientific investigation - in the way that the concept of blood leaves space for discoveries about its composition. The trouble is that mental concepts dont obviously pick out things or processes that take up room in the spatiotemporal world to begin with. If they did, we could just get hold of some of those things and take them apart or look at them under a microscope or subject them to chemical analysis. But there is a prior problem about how those concepts might refer to anything that could be subjected to such investigation: They dont give us the comfortable initial handle on the 3 See Colin McGinn, Consciousness and Space, Journal of Consciousness Studies 2 (1995), pp. 220-30. 4 This is the objection that Arnauld made to Descartes, in the fourth set of objections to the Meditations. 5 Compare Donald Davidson, Mental Events, in his Essays on Actions and Events (Oxford University Press, 1980). occupants of the familiar spatiotemporal world that prescientific physical substance concepts do.3 Nevertheless it is overconfident to conclude, from ones inability to imagine how mental phenomena might turn out to have physical properties, that the possibility can be ruled out in advance. We have to ask ourselves whether there is more behind the Cartesian intuition than mere lack of knowledge, resulting in lack of imagination.4 Of course it is not enough just to say, You may be mistaking your own inability to imagine something for its inconceivability. One should be open to the possibility of withdrawing a judgment of inconceivability if offered a reason to think it might be mistaken; but there does have to be a reason, or at least some kind of story about how this illusion of inconceivability might have arisen. If mental events really have physical properties, an explanation is needed of why they seem to offer so little purchase for the attribution of those properties. Still, the kind of incomprehensibility here is completely different from that of numbers having parents. Mental events, unlike numbers, can be roughly located in space and time, and are causally related to physical events, in both directions. The causal facts are strong evidence that mental events have physical properties, if only we could make sense of the idea.5 Consider another case where the prescientific concept did not obviously allow for the possibility of physical composition or structure - the case of sound. Before the discovery that sounds are waves in air or another medium, the ordinary concept permitted sounds to be roughly located, and to have properties like loudness, pitch, and duration. The concept of a sound was that of an objective phenomenon that could be heard by different people, or that could exist unheard. But it would have been very obscure what could be meant by ascribing to a sound a precise spatial shape and size, or an internal, perhaps microscopic, physical structure. Someone who proposed that sounds have physical parts, without offering any theory to explain this, would not have said anything understandable. One might say that in advance of the development of a physical theory of sound, the hypothesis that sounds have a physical microstructure would not have a clear meaning. Nevertheless, at one remove, the possibility of such a development is evidently not excluded by the concept of sound. Sounds were known to have certain physical causes, to be blocked by certain kinds of obstacles, and to be perceptible by hearing. This was already a su