rjf@ukc.UUCP (11/20/86)
There has been some interesting discussion (a little while back now) on the possibility of 'truly' intelligent machines; in particular the name of Nagel has been mentioned, and his paper 'What is it like to be a bat?'. This paper is not, however, strictly relevant to a discussion of machine intelligence, because what Nagel is concerned with is not intelligence, but consciousness. That these are not the same, may be realised on a little contemplation. One may be most intensely conscious while doing little or no cogitation. To be intelligent - or, rather, to use intelligence - it seems necessary to be conscious, but the converse does not hold - that to be conscious it is necessary to be intelligent. I would suggest that the former relationship is not an necessary one either - it just so happens that we are both conscious and (usually) intelligent. Animals probably are conscious without being intelligent. Machines may perhaps be intelligent without being conscious. If these are defined seperately, the problem of the intelligent machine becomes relatively trivial (though that may seem too good to be true): an intelligent machine is capable of doing that which would require intelligence in a person, eg high level chess. On the other hand, it becomes obvious that what really exercises the philosophers and would-be philosophers (I include myself) is machine consciousness. As for that: Another article in the same collection by Nagel (Mortal Questions, 1978) takes his ideas on consciousness somewhat further. A summary of the arguments developed in 'Subjective and Objective' could not possibly do them justice (anyone interested is heartily recommended to obtain a copy), so only the conclusions will be mentioned here. Briefly, Nagel views subjectivity as irreducible to objectivity, indeed the latter derives from the former, being a corrected and generalised version of it. A maximally objective view of the world must admit the reality of subjectivity, in the minimal sense that individuals do hold differing views, and there is no better - or worse - judge of which view is more truly objective, than another individual. This view does not to any extent denigrate the practicality of objective methods (the hypothesis of objective reality is proven by the success of the scientific method), but nor is it possible to deny the necessity of subjectivity in some situations, notably those directly involving other people. It is surely safe to say that no new objective method will ever substitute for human relationships. And the reason that subjectivity works in this context is because of what Nagel terms 'intersubjectivity' - individuals identifying with each other - using their imaginations creatively and for the most part accurately to put themselves in another person's shoes. So what, really, is consciousness? According to Nagel, a thing is conscious if and only if it is like something to be that thing. In other words, when it may be the subject (not the object!) of intersubjectivity. This accords with Minsky (via Col. Sicherman): 'consciousness is an illusion to itself but a genuine and observable phenomenon to an outside observer...' Consciousness is not self-consciousness, not consiousness of being conscious, as some have thought, but is that with which others can identify. This opens the way to self-awareness through a hall of mirrors effect - I identify with you identifying with me... And in the negative mode - I am self-conscious when I feel that someone is watching me. It may perhaps be supposed that the concept of consciousness evolved as part of a social adaptation - that those individuals who were more socially integrated, were so at least in part because they identified more readily, more intelligently and more imaginatively with others, and that this was a successful strategy for survival. To identify with others would thus be an innate behavioural trait. So consciousness is at a high level (the top?) in software, and is, moreover, not supported by a single unit of hardware, but by a social network. In its development, at least. I, or anyone else, might suppose that I am still conscious when alone, but not without (the supposer, whether myself or another) having become conscious in a social context. When I suppose myself to be conscious, I am imagining myself outside myself - taking the point of view of an (hypothetical) other person. An individual - man or machine - which has never communicated through intersubjectivity might, in a sense, be conscious, but neither the individual nor anyone else could ever know it. A community of machines sufficiently sophisticated that they identify with each other in the same way as we do, may some day develop, but how could we decide whether they were really conscious or not? They might know it, but we never could - and that is neither pessimism not prejudice, but a matter of principle. Subjectively, we all know that consciousness is real. Objectively, we have no reason to believe in it. Because of the relationship between subjectivity and objectivity, that position can never be improved on. Pragmatism demands a compromise between the two extremes, and that is what we already do, every day, the proportion of each component varying from one context to another. But the high-flown theoretical issue of whether a machine can ever be conscious allows no mere pragmatism. All we can say is that we do not know, and, if we follow Nagel, that we cannot know - because the question is meaningless. (Technically, the concept of two different but equally valid ways of seeing, in this case subjectively and objectively, is a double aspect theory; the dichotomy lies not in the nature of reality, but in our perception. Previous double aspect theories, interestingly consistent with this one, have been propounded by Spinoza - regarding our perception of our place within nature - and Strawson - on the concept of a person. I do not have the full references to hand.) Any useful concepts among those foregoing probably derive from Nagel, any misleading ones from myself; none from my employers. Rob Faichney