cugini@NBS-VMS.ARPA ("CUGINI, JOHN") (11/18/86)
Can't resist a few more go-rounds with S. Harnad. Lest the size of these messages increase exponentially, I'll try to avoid re-hashing old issues and responding to side-issues... > Harnad: > I agree that scientific inference is grounded in observed correlations. > But the primary correlation in this special case is, I am arguing, between > mental states and performance. That's what both our inferences and our > intuitions are grounded in. The brain correlate is an additional cue, but only > inasmuch as it agrees with performance. > ...in ambiguous > cases, behavior was and is the only rational arbiter. Consider, for > example, which way you'd go if (1) an alien body persisted in behaving like a > clock-like automaton in every respect -- no affect, no social interaction, > just rote repetition -- but it DID have something that was indistinguishable > (on the minute and superficial information we have) from a biological-like > nervous system), versus (2) if a life-long close friend of yours had > to undergo his first operation, and when they opened him up, he turned > out to be all transistors on the inside. I don't set much store by > this hypothetical sci-fi stuff, especially because it's not clear > whether the "possibilities" we are contemplating are indeed possible. But > the exercise does remind us that, after all, performance capacity is > our primary criterion, both logically and intuitively, and its > black-box correlates have whatever predictive power they may have > only as a secondary, derivative matter. They depend for their > validation on the behavioral criterion, and in cases of conflict, > behavior continues to be the final arbiter. I think I may have been tactitly conceding the point above, which I now wish to un-concede. Roughly speaking, I think my (everyone's) epistemological position is as follows: I know I have a mind. In order to determine if X has a mind I've got to look for analogous external things about X which I know are causally connected with mind in *my own* case. I naively know (and *how* do I know this??) that large parts of my performance are an effect of my mind. I scientifically know that my mind depends on my brain. I can know this latter correlation even *without* performance correlates, eg, when the dentist puts me under, I can directly experience my own loss of mind which results from loss of whatever brain activity. (I hope it goes without saying that all this knowledge is just regular old reliable knowledge, but not necessarily certain - ie I am not trying to respond to radical skepticism about our everyday and scientific knowledge, the invocation of deceptive dentists, etc.) I'll assume that "mind" means, roughly, "conscious intelligence". Also, assume throughout of course that "brain" is short-hand for "brain activity known (through usual neuro-science techniques) to be necessary for consciousness". Now then, armed with the reasonably reliable knowledge that in my own case, my brain is a cause of my mind, and my mind is a cause of my performance, I can try to draw appropriate conclusions about others. Let's take 4 cases: 1. X1 has brains and performance - ie another normal human. Certainly I have good reason to assume X1 has a mind (else why should similar causes and effects be mediated by something so different from that which mediates in my own case?) 2. X2 has neither brains nor performance - and no mind. 3. X3 has brains, but little/no performance - eg a case of severe retardation. Well, there doesn't seem much reason to believe that X has intelligence, and so is disqualified from having mind, given our definition. However, it is still reasonable to believe that X3 might have consciousness, eg can feel pain, see colors, etc. 4. X4 has normal human cognitive performance, but no brains, eg the ultimate AI system. Well, no doubt X4 has intelligence, but the issue is whether X4 has consciousness. This seems far from obvious to me, since I know in my own case that brain causes consciousness causes performance. But I already know, in the case of X4, that the causal chain starts out at a different place (non-brain), even if it ends up in the same place (intelligent performance). So I can certainly question (rationally) whether it gets to performance "via consciousness" or not. If this seems too contentious, ask yourself: given a choice between destroying X3 or X4, is it really obvious that the more moral choice is to destroy X3? Finally, a gedanken experiment (if ever there was one) - suppose (a la sci-fi stories) they opened you up and showed you that you really didn't have a brain after all, that you really did have electronic circuits - and suppose it transpired that while most humans had brains, a few, like yourself, had electronics. Now, never doubting your own consciousness, if you *really* found that out, would you not then (rationally) be a lot more inclined to attribute consciousness to electronic entities (after all you know what it feels like to be one of them) than to brained entities (who knows what, if anything, it feels like to be one of them?)? Even given *no* difference in performance between the two sub-types? Showing that "similarity to one's own internal make-up" is always going to be a valid criterion for consciousness, independent of performance. I make this latter point to show that I am a brain-chauvinist *only insofar* as I know/believe that I *myself* am a brained entity (and that my brain is what causes my consciousness). This really doesn't depend on my own observation of my own performance at all - I'd still know I had a mind even if I never did any (external) thing clever. To summarize: brainedness is a criterion, not only via the indirect path of: others who have intelligent performance also have brains, ergo brains are a secondary correlate for mind; but also via the much more direct path (which *also* justifies performance as a criterion): I have a mind and in my very own case, my mind is closely causally connected with brains (and with performance). > As to CAUSATION -- well, I'm > sceptical that anyone will ever provide a completely satisfying account > of the objective causes of subjective effects. Remember that, except for > the special case of the mind, all other scientific inferences have > only had to account for objective/objective correlations (and [or, > more aptly, via) their subjective/subjective experiential counterparts). > The case under discussion is the first (and I think only) case of > objective/subjective correlation and causation. Hence all prior bets, > generalizations or analogies are off or moot. I agree that there are some additional epistemological problems, compared to the usual cases of causation. But these don't seem all that daunting, absent radical skepticism. We already know which parts of the brain correlate with visual experience, auditory experience, speech competence, etc. I hardly wish to understate the difficulty of getting a full understanding, but I can't see any problem in principle with finding out as much as we want. What may be mysterious is that at some level, some constellation of nerve firings may "just" cause visual experience, (even as electric currents "just" generate magnetic fields.) But we are always faced with brute-force correlation at the end of any scientific explanation, so this cannot count against brain-explanatory theory of mind. > Perhaps I should repeat that I take the context for this discussion to > be science rather than science fiction, exobiology or futurology. The problem > we are presumably concerned with is that of providing an explanatory > model of the mind along the lines of, say, physics's explanatory model > of the universe. Where we will need "cues" and "correlates" is in > determining whether the devices we build have succeeded in capturing > the relevant functional properties of minds. Here the (ill-understood) > properties of brains will, I suggest, be useless "correlates." (In > fact, I conjecture that theoretical neuroscience will be led by, rather > than itself leading, theoretical "mind-science" [= cognitive > science?].) In sci-fi contexts, where we are guessing about aliens' > minds or those of comatose creatures, having a blob of grey matter in > the right place may indeed be predictive, but in the cog-sci lab it is > not. Well, I plead guilty to diverting the discussion into philosophy, and as a practical matter, one's attitude in this dispute will hardly affect one's day-to-day work in the AI lab. One of my purposes is a kind of pre-emptive strike against a too-grandiose interpretation of the results of AI work, particularly with regard to claims about consciousness. Given a behavioral definition of intelligence, there seems no reason why a machine can't be intelligent. But if "mind" implies consciousness, it's a different ball-game, when claiming that the machine "has a mind". My as-yet-unarticulated intuition is that, at least for people, the grounding-of-symbols problem, to which you are acutely and laudably sensitive, inherently involves consciousness, ie at least for us, meaning requires consciousness. And so the problem of shoehorning "meaning" into a dumb machine at least raises the issue about how this can be done without making them conscious (or, alternatively, how to go ahead and make them conscious). Hence my interest in your program of research. John Cugini <Cugini@NBS-VMS> ------