From in%@vtcs1 Mon Dec 1 10:58:13 1986 Date: Mon, 1 Dec 86 10:57:57 est From: vtcs1::in% To: ailist@sri-stripe.arpa Subject: AIList Digest V4 #267 Status: RO AIList Digest Wednesday, 26 Nov 1986 Volume 4 : Issue 267 Today's Topics: Queries - Lisp or Smalltalk for Amiga & XLISP 1.8, Philosophy - Searle, Turing, Nagel ---------------------------------------------------------------------- Date: 24 Nov 86 11:21:33 PST (Monday) From: Tom.EdServices@Xerox.COM Subject: Lisp, Smalltalk for Amiga Does anyone know of Smalltalk or any Lisps (besides Xlisp and Cambridge Lisp) for the Commodore-Amiga? What I really want is a Common Lisp. Thanks for any help. ------------------------------ Date: 24 Nov 86 17:42:57 GMT From: mcvax!ukc!einode!tcdcs!omahony@seismo.css.gov (O'Mahony Donal) Subject: Looking for source of XLISP 1.8 I am looking for the source of Dave Betz's XLISP version 1.8. This is a version of LISP with object oriented extensions. I understand that it is available on the BIX bulletin board, but it is difficult to gain access from here. I would be grateful if sombody would post a copy Donal O'Mahony, Trinity College, Dublin, Ireland ------------------------------ Date: 22 Nov 86 21:46:13 GMT From: rutgers!princeton!mind!harnad@titan.arc.nasa.gov (Stevan Harnad) Subject: Re: Searle, Turing, Nagel On mod.ai, rjf@ukc.UUCP <8611071431.AA18436@mcvax.uucp> Rob Faichney (U of Kent at Canterbury, Canterbury, UK) made nonspecific reference to prior discussions of intelligence, consciousness and Nagel. I'm not altogther certain that his contribution was intended as a followup to the discussion that has been going on lately under the heading "Searle, Turing, Categories, Symbols," but since it concerns the issues of that discussion, I am responding on the assumption that it was. R. Faichney writes: > [T. Nagel's] paper [See Mortal Questions, Cambridge University Press > 1979, and The View From Nowhere, Oxford University Press 1986] > is not ... 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 a necessary one > either - it just so happens that we are both conscious and (usually) > intelligent. It would seem that if you believe that "to use intelligence...it seems necessary to be conscious" then that amounts to agreeing that Nagel's paper on consciousness is "relevant to a discussion of machine intelligence." It is indisputable that intelligence admits of degrees, both as a stable trait and as a fluctuating state. What is at issue in discussions of the turing test is not the proposition that consciousness is the same as intelligence. Rather, it is whether a candidate has intelligence at all. It seems that consciousness in man is a sufficient condition for being intelligent (i.e., for exhibiting performance that is validly described as "intelligent" in the same way we would apply that term to our own performance). Whether consciousness is a necessary condition for intelligence is probably undecidable, and goes to the heart of the mind/body problem and its attendant uncertainties. The converse proposition -- that intelligence is a necessary condition for consciousness is synonymous with the proposition that consciousness is a sufficient condition for intelligence, and this is indeed being claimed (e.g., by me). The argument runs like this: The issue in turing-testing is sorting out intelligent performance from its unintelligent look-alikes. As a completely representative example, consider my asking you how much 2 + 2 is, and your replying "4" -- as compared to my writing a computer program whose only function is to put out the symbol "4" whenever it encounters the string of symbols "How much is 2 + 2?" (this is basically Searle's point too). There you have it all in microcosm. If the word "intelligence" has any meaning at all, over and above displaying ANY arbitrary performance at all (including a rock sliding down a hill, or, for that matter, a rock NOT sliding down a hill), then we need a principled way of distinguishing these two cases. That's what the Total Turing Test I've proposed is meant to do; it amounts to equating intelligence with total performance capacities indistinguishable from our own. This also coincides with our only basis for inferring that anyone else but ourselves has a mind (i.e., is conscious). There is no contradiction between agreeing that intelligence admits of degrees and that mind is all-or-none. The Total Turing Test does not demand the performance capacity of Newton or Bach, only that of an (undistinguished) person indistinguishable from any other person one might know for a lifetime. Moreover, the Total Turing Test admits of variants for other species, although this involves problems of ecological knowledge and intuitions that humans may lack for any other species but their own. It even admits of pathological variants of our own species (retardation, schizophrenia, aphasia, paralysis, coma, etc. as discussed in other iterations of this discussion, e.g., with J. Cugini) although here too intuitions and validity probably break down. > 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. Not too good to be true: Too easy. And it would fail to capture almost all of our relevant pretheoretic generalizations or intuitions. Animals ARE intelligent (in addition to being conscious), although, as usual, their intelligence admits of degrees, and can only be validly assessed relative to their ecological or adaptive contexts (although even relative to our own ecology, many other species display some degree of intelligence). The machine intelligence problem -- which is the heart of the matter -- cannot be settled so quickly and easily. Moreover, the empirical question of what intelligence is cannot be settled by a definition (remember "2 + 2 = 4" and the rolling stone, above). Many intelligent people (with minds) can't play high-level chess, but no machine can currently do EVERYTHING that the least intelligent of these people can do. That's the burden of the Total Turing Test. > 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. Nagel is one of the few thinkers today who doesn't lapse into arbitrary hand-waving on the issue of consciousness and its "reducibility" to something else. Nagel's point is that there is something it's "like" to have experience, i.e., to be conscious, and that it's only open to the 1st person point of view. It's hence radically unlike all other "objective" or "intersubjective" phenomena in science (e.g., meter-readings), which anyone else can verify as being independent of one's "point of view" (although Nagel correctly reminds us that even objectivity is parasitic on subjectivity). The upshot of his analysis is that utopian scientific mind-science (cognitive science?) -- that future complete theory that will predict and explain it all -- will be essentially "incomplete" in a way that utopian physics will not be: Both will successfully predict and explain all their respective observable (objective) data, but mind-science will be left with something irreducible, hence unexplained. For me, this is not a great problem, since I regard the mission of devising a candidate that can pass the Total Turing Test to be an abundantly profound and challenging one, and I regard its potential results -- a functional explanation of the objective features of the mind -- as sufficiently desirable and useful, so that the part it will FAIL to explain does not bother me. That may well forever remain philosophy's province. But I do keep reminding the overzealous that that utopian mind science will be turing-indistinguishable from a mindless one. I keep doing this for two reasons: First, because I believe that this Nagelian point is correct, and worth keeping in mind. And second, because I believe that attempts to capture or incorporate consciousness in cognitive science more "directly" are utterly misguided, and lead in the direction of highly subjective over-interpretations, hermeneutics and self-delusion, instead of down the only objective scientific road to be traveled: modeling lifesize performance capacity (i.e., the Total Turing Test). It is for this reason that I recommend "methodological epiphenomenalism" as a research strategy in cognitive science. > 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. The Nagel part is right, but unfortunately all the rest (Minsky/Sicherman/hall-of-mirrors) has it all wrong, and is precisely the type of lapse into hermeneutics and euphoria I warned against earlier. The quote above (via the Colonel) is PRECISELY THE OPPOSITE of Nagel's point. The only aspect of conscious experience that involves direct observability is the subjective, 1st-person aspect (and the fact THAT I am having a conscious experience is certainly no illusion since Descartes at least, although what it tells me about the outside world may be, at least since Hume). Let's call this private terrain Nagel-land. The part others "can identify" is Turing-land: Objective, observable performance (and its structural and functional substrates). Nagel's point is that Nagel-land is not reducible to Turing-land. Consciousness is the capacity to have subjective experience (or perhaps the state of having subjective experience). The rest of the "mirrors" business is merely metaphor and word-play; such subject matter may make for entertaining and thought-provoking reading, as in Doug Hofstadter's books, but it hardly amounts to an objective contribution to cognitive science. > 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. Except that Nagel would no doubt suggest (and I would agree) that there's no reason to believe that the asocial or minimally social animals are not conscious too. But apart from that, there's a much deeper reason why it is probably futile to try to make evolutionary conjectures about the adaptive function of conscious experience: According to standard evolutionary theory, the only traits that are amenable to the kind of trial-and-error selection on the basis of their consequences for the survival of the organism and propogation of its genes are (what Nagel would call) OBJECTIVE traits: structure, function and behavior. Standard evolutionary conjectures about the putative adaptive function of consciousness are open to precisely the same objection as the utopian mind-science spoken of earlier: Evolution is blind to the difference between organisms that are actually conscious and organisms that merely behave as if they were conscious. Turing-indistinguishability again. On the other hand, recent variants of standard evolutionary theory would be compatible with a NON-selectional origin of consciousness, as an epiphenomenon. (In pointing out the futility of adaptive scenarios for the origin of consciousness, I am drawing on my own theoretical failures. I tried that route in an earlier paper and only later realized that such "Just-SO" stories suffer from even worse liabilities in speculations about the evolutionary origins of consciousness than they do in speculations about the evolutionary origins of behaviors; radically worse liabilities, for the reason given above. Caveat Emptor.) > ...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. I'm afraid you've either gravely misunderstood Nagel or left him far behind here. When I feel a pain -- when I am in the qualitative state of knowing what it's like to be feeling a pain -- I am not "supposing" anything at all. I'm simply feeling pain. If I were not conscious, I wouldn't be feeling pain, I'd just be acting as if I felt pain. The same is true of you and of animals. There's nothing social about this. Nor is "imagination" particularly involved (except perhaps in whatever external attributions are made to the pain, such as, "there must be something wrong with my tooth"). Even what is called clinically "imaginary" or psychosomatic pain -- such as phantom-limb pain or hysterical pain -- is subjectively real, and that's the point: When I'm really feeling pain, I'm not imagining I'm in pain; I AM in pain. This is referred to by philosophers as the "incorrigibility" of 1st-person experience. Although it's not without controversy, it's useful to keep in mind, because it's what's really at issue in the problem of artificial minds. We are asking whether candidates have THAT sort of qualitative, conscious experience. (Again, the "mirror" images about self-consciousness, etc., are mere icing or fine-tuning, compared to the more basic issue of whether or not, to put it bluntly, a machine can actually FEEL pain, or merely ACTS as if it did.) > 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. Some crucial corrections that may set the whole matter in a rather different light: Subjectively (and I would say objectively too), we all know that OUR OWN consciousness is real. Objectively, we have no way of knowing that anyone else's consciousness is real. Because of the relationship between subjectivity and objectivity, direct knowledge of the kind we have in our own case is impossible in any other. The pragmatic compromise we practice every day with one another is called the Total Turing Test: Ascertaining that others behave indistinguishably from our paradigmatic model for a creature with consciousness: ourselves. We were bound to come face-to-face with the "high-flown theoretical issue" of artificial consciousness as soon as we went beyond everyday naive pragmatic considerations and took on the burden of constructing a predictive and explanatory causal thoery of mind. We cannot know directly whether any other organism OR device has a mind, and, if we follow Nagel, our inferences are not meaningless, but in some respects incomplete and undecidable. -- Stevan Harnad (609) - 921 7771 {allegra, bellcore, seismo, rutgers, packard} !princeton!mind!harnad harnad%mind@princeton.csnet ------------------------------ End of AIList Digest ******************** From in%@vtcs1 Mon Dec 1 10:57:51 1986 Date: Mon, 1 Dec 86 10:57:32 est From: vtcs1::in% To: ailist@sri-stripe.arpa Subject: AIList Digest V4 #268 Status: RO AIList Digest Wednesday, 26 Nov 1986 Volume 4 : Issue 268 Today's Topics: Philosophy - Searle, Turing, Symbols, Categories ---------------------------------------------------------------------- Date: 22 Nov 86 12:13:02 GMT From: mcvax!lambert@seismo.css.gov (Lambert Meertens) Subject: Re: Searle, Turing, Symbols, Categories In article <229@mind.UUCP> harnad@mind.UUCP (Stevan Harnad) writes: > I know directly that my > performance is caused by my mind, and I infer that my > mind is caused by my brain. I'll go even further (now that we're > steeped in phenomenology): It is part of my EXPERIENCE of my behavior > that it is caused by my mind. [I happen to believe (inferentially) that > "free will" is an illusion, but I admit it's a phenomenological fact > that free will sure doesn't FEEL like an illusion.] We do not experience our > performance in the passive way that we experience sensory input. We > experience it AS something we (our minds) are CAUSING. (In fact, that's > probably the source of our intuitions about what causation IS. I'll > return to this later.) I hope I am not suffering from a terrible disease like incipient schizophrenia, but for me it is not the case that I perceive/experience/ am-directly-aware-of my performance being caused by anything. It just happens. I have some indirect evidence that there is some relation between the performance I can watch happening and some sensations (such as anxiety or happiness) that I can somehow experience directly whereas others have no such direct access and can only infer the presence or absence of these sensations within me by circumstantial evidence. How do I know I have a mind? This reminds me of the question put to a priest (teaching religion) by one of the pupils: "Father, how do we know that people have a soul?" "Well," said the priest, "here I have a card in memory of Klaas de Vries. Look, here it says: `Pray for the soul of Klaas de Vries.' They wouldn't put that there if people had no souls, would they?" There is something funny with this debate: it is hardly translatable into Dutch. The problem is that if you look up "mind" in an English-Dutch dictionary, some eight translations are suggested, none of which has "mind" as their primary meaning if translated back to English, except for idiomatic reasons (like in: "So many men, so many minds"). Instead, we find (1) memory; (2) meaning; (3) thoughts; (4) ghost; (5) soul; (6) understanding; (7) attention; (8) desire. Of these, I contend, "ghost" and "soul" are closest in meaning if someone says: "I know I have mind. But how can I know that other people have minds?" OK, if you substitute "consciousness" for "mind", then this does no essential harm to the debate and things become translatable to Dutch. What you gain, is that you loose the suggestion evoked (at least to me) by the word "mind" that it is something perhaps not quite, but almost, tangible, something that you could lock up in a box, or cut in three, or take a picture of with a camera using aura-sensitive film. "Consciousness" is more like "appetite": you can have it and you can loose it, but even though it is functionally related to bodily organs, you normally don't think of it as something located somewhere. Does our appetite cause our eating? ("My appetite made me eat too much.") How can we know for sure that other people have appetites as well? I propose to consider the question, "Can machines have an appetite?" Now why is consciousness "real", if free will is an illusion? Or, rather, why should the thesis that consciousness is "real" be more compelling than the analogous thesis for free will? In either case, the essential argument is: "Because I [the proponent of that thesis] have direct, immediate, evidence of it." Sometimes we are conscious of certain sensations. Do these sensations disappear if we are not conscious of them? Or do they go on on a subconscious level? That is like the question if a falling tree in the middle of a forest makes a sound in the absence of creatures capable of hearing. That is a matter of the most useful (convenient) definition. Let us agree that the sensations continue at least if it can be shown that the person involved keeps behaving as if the concomitant sensations continued, even though professing in retrospection not to have been aware of them. So people can be afraid without realizing it, say, or drive a car without being conscious of the traffic lights (and still halt for a red light). How can you know that you have been conscious of something that you reacted upon? You stopped in front of a red light (or so others tell you) while involved in a heated argument. You have no remembrance whatsoever of that light being red, or of your slowing down (or of having been at that intersection at all). Maybe your attention was so completely focussed on the argument that the reaction to the traffic light was fully automatic. Now someone tells you: No, it wasn't automatic. You muttered something unfriendly about that other car driver who made as if he was going to drive on and then suddenly braked. And now, zzzap!, the whole episode pops up in your mind. You remember that car, the intersection, the traffic light, its jumping to red, the slight annoyance at not making it, and the anger about that *@#$%!!! other driver whose car you almost crashed into. Maybe everything is conscious. Maybe stones are conscious of lying on the ground, being kicked against, being picked up. Their problem is, they can hardly tell us. The other problem is, they have no memory (lacking an appropriate substrate for storing a trace of these experiences). They are like us with that traffic light, if there hadn't been that other car with that idiot driver. Even if we experience something consciously, if we loose all remembrance of it, there is no way in which we can tell for sure that there was a conscious experience. Maybe we can infer consciousness by an indirect argument, but that doesn't count. Indirect evidence can be pretty strong, but it can never give certainty. Barring false memories, we can only be sure if we remember the experience itself. Now maybe everything we experience is stored in memory. It may be that we cannot recall it like that, but using special techniques (hypnosis, electro- stimulation, mnemonic drugs) it could be retrieved. On the other hand, it is more plausible that not quite everything is stored in memory, since that would require a tremendous channel width for storing things, which is not really functional, or, at least, there are presumably better trade-offs in terms of survival capability given a limited bran capacity. If some things we experience do not leave a recallable trace, then why should we say that they were experienced consciously? Or, why shouldn't we maintain the position that stones are conscious as well? That position is maintainable, but it is not very useful in the sense that the word "consciousness" looses its meaning; it becomes coextensive with "existence". We "loose" our bicameral minds, Freud, and all that jazz. More useful, then, to use "consciousness" only for experiences that are, somehow, recallable. It makes sense that not all, not most of, but some of the things that go on in our heads are stored away: in order to use for determining patterns, for better evaluation of the expected outcome of alternatives, for collecting material that is useful for the construction or refinement of the model we have of the outside world, and so on. Being the kind of animal homo is, it also makes sense to store material that is useful for the refinement of the model we have of our inside world, that which we think of as "ourselves". After all, we consult that model to pre-evaluate the outcome of certain alternatives. If we don't "know" ourselves, we are bound to do things (take on a responsibility, marry someone, etc., things with a long-term commitment) that will lead us unto suffering. (We do these things anyway, and one of the causes is that we don't know ourselves that well.) So a lot of the things that go on "in the front of our minds" are stored away, and are recallable. And it is only because of this recallability that we can say that these things were "in the front of our minds", or "in our minds" at all. Imagine now a machine programmed to "eat" and also to keep up some dinner conversation. It has some rules built-in about etiquette like that it is impolite to eat too much, but also some parameter varying in time to model "hunger", and a rule IF hunger THEN eat. It just happens that the machine is very, very hungry. There is a conflict here, but fortunately our machine is equipped with a conflict-resolution module (CRM) that uses fuzzy logic to get an outcome for conflicting rules. The outcome here is that the machine eats more than is polite. The dinner-conversation module (DCM) has no direct interface with the CRM, but it is supplied with the resultant behaviour as part of its input data and so it concludes (using the rule base) that it is not behaving too politely. Speaking anthropomorphically, we would say that the machine is feeling uneasy about it. Actually, a flag "uneasiness" is raised, and the DCM is programmed to do something about it. Using the rule base, the DCM finds a rule that tells it that uneasiness about being impolite can be reduced by apologizing about it. The apology submodule (ASM) is invoked, which discovers that a casual apology will do in this case, one form of which is just to state an appropriate cause for the inappropriate behaviour. The rule base tells ASM that PROBABLE CAUSE OF eat IS appetite, (next to tape-worms, but these are measured as less appropriate under the circumstances), so "<; >" is passed back to DCM, which, after invoking appropriate syntactic transformations, utters the unforgettable words: "Boy, do I have an appetite today." How different are we from that machine? If we keep wolfing down food at a dinner, knowing that we are misbehaving (or just substitute any behaviour that you are prone to and that you realize is just not quite right--come on, there must be something), is the choice made the result of a conscious process? I think it is not. I have no reason to think it is. Even if we ponder a question consciously ("Whether 'tis nobler in the mind to suffer ..."), I think the outcome is not the result of the conscious process, but, rather, that the consciousness is a side-effect of the conflict-resolution process going on. I think the same can be said about all "conscious" processes. The process is there, anyway; it could (in principle) take place without leaving a trace in memory, but for functional reasons it does leave such a trace. And the word we use for these cognitive processes that we can recall as having taken place is "conscious". We can as it were instantly focus our attention on things that we are not conscious of most of the time (the sensation of sitting on a chair, the colour of the sky). This means merely that we can influence which part of the processes going on all the time get the preferential treatment of being stored away for future reference. The ability to do so is clearly functional, notwithstanding the fact that we can make a non-functional use of it. This is not different from the fact that it is functional that I can raise my arm by "willing" it to raise, although I can use that ability to raise it gratuitously. If the free will here is an illusion (which I think is primarily a matter of how you choose to define something as elusive as "free will"), then so is the free will to direct your attention now to this, then to that. Rather than to say that free will is an "illusion", we might say that it is something that features in the model people have about "themselves". Similarly, I think it is better to say that consciousness is not so much an illusion, but rather something to be found in that model. A relatively recent acquisition of that model is known as the "subconscious". A quite recent addition are "programs", "sub-programs", "wrong wiring", etc. A sufficiently "intelligent" machine, able to pass not only the dinner- conversation test but also a sophisticated Turing test, must have a model of itself. Using that model, and observing its own behaviour (including "internal" behaviour!), it will be led to conclude not only that it has an appetite, but also volition and awareness, and it will probably attribute some of its darker sides (about which it comes to conclude that it feels guilt, from which it deduces that it has a conscience) to lack of affection in childhood or "wrong wiring". Is it mistaken then? Is the machine taken in by an illusion? I propose to consider the question, "Can machines have illusions?" -- Lambert Meertens, CWI, Amsterdam; lambert@mcvax.UUCP ------------------------------ Date: 21 Nov 86 19:08:02 GMT From: rutgers!princeton!mind!harnad@lll-crg.arpa (Stevan Harnad) Subject: Re: Searle, Turing, Symbols, Categories: Reply to Cugini (2) [Part I. See the next digest for the conclusion. -- KIL] On mod.ai <8611200632.AA19202@ucbvax.Berkeley.EDU> "CUGINI, JOHN" wrote: > I know I have a mind. In order to determine if X [i.e., anyone else but myself] > 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.) These questions and reflections are astute ones, and very relevant to the issues under discussion. It is a matter of some ancillary interest that the people who seem to be keeping their heads more successfully in the debates about artificial intelligence and (shall we call it) "artificial consciousness" are the more sceptical ones, as you reveal yourself to be at the end of this module. The zealous advocates, on the other hand, seem to be more prone to flights of over-interpretative fancy, leaving critical judgment by the wayside. (This is not to say that some of the more dogged critics haven't waxed irrational in their turn too.) Now on to the substance of your criticism. I think the crucial points will turn on the difference between what you call "naively know" and "scientifically know." It will also involve (like it or not) the issue of radical scepticicm, uncertainty and the intersubjectivity and validity of inferences and correlations. Now, I am neither an expert in, nor an advocate of, phenomenological introspection, but if you will indulge me and do a little of it here, I think you will notice that there is something very different about "naive knowing" as compared to "scientific knowing." Scientific knowing is indirect and inferential. It is based on inference to the best explanation, the weight of the evidence, probability, Popperian (testability, falsifiability) considerations, etc. It is the paradigm for all empirical inquiry, and it is open to a kind of radical scepticism (scepticism about induction) that we all reasonably agree not to worry about, except insofar as noting that scientific "knowledge" is not certain, but only highly likely on the evidence, and is always in principle open to inductive "risk" or falsification by future evidence. This is normal science, and if that were all there was to the special case of the mind/body problem (or, more perspicuously, the other-minds problem) then a lot of the matters we are discussing here could be settled much more easily. What you call "naive knowing," on the other hand (and about which you ask "*how* do I know this?") is the special preserve of 1st-hand, 1st-person subjective experience. It is "privileged" (no one has access to it but me), direct (I do not INFER from evidence that I am in pain, I know it directly), and it has been described as "incorrigible" (can I be wrong that I am feeling pain?). The inferences we make (about the outside world, about inductive regularities, about other minds) are open to radical scepticism, but the phenomenological content of 1st-hand experience is different. This makes "naive knowing" radically different from "scientific knowing." (Let me add a quick parenthetical remark, but not pursue it unless someone brings it up: Even our inferential knowledge depends on our capacity for phenomenological experience. Put another way: we must have direct experience in order to make indirect inferences, otherwise the inferences would have no content, whether right or wrong. I conjecture that this is significantly connected with what I've called the "grounding" problem that lies at the root of this discussion. It is also related to Locke's (inchoate) distinction between primary and secondary qualities, turning his distinction on its head.) Now let's go on. You say that I "naively know" that my performance is caused by my mind and I "scientifically know" that my mind is caused by my brain. (Let's not quibble about "cause"; the other words, such as "determined by," "a function of," "supervenient on," or Searle's notorious "caused-by-and-realized-in" are just vague ways of trying to finesse a problematic and unique relationship otherwise known as the mind/body problem. Let's just bite the bullet with "cause" and see where that gets us.) Let me translate that: I know directly that my performance is caused by my mind, and I infer that my mind is caused by my brain. I'll go even further (now that we're steeped in phenomenology): It is part of my EXPERIENCE of my behavior that it is caused by my mind. [I happen to believe (inferentially) that "free will" is an illusion, but I admit it's a phenomenological fact that free will sure doesn't FEEL like an illusion.] We do not experience our performance in the passive way that we experience sensory input. We experience it AS something we (our minds) are CAUSING. (In fact, that's probably the source of our intuitions about what causation IS. I'll return to this later.) So there is a very big difference between my direct knowledge that my mind causes my behavior and my inference (say, in the dentist's chair) that my brain causes my mind. [Even my rational inference (at the metalevel) that my mind doesn't really cause my behavior, that that's just an illusion, leaves the incorrigible phenomenological fact that I know directly that that's not the way it FEELS.] So, to put it briefly, what I've called the "informal component" of the Total Turing Test -- does the candidate act as if it had a mind (i.e., roughly as I would)? -- appeals to precisely those intuitions, and not the inferential kind, about brains, etc. Note, however, that I'm not claiming we have direct knowledge of other minds. That's just an inference. But it's not the same kind of inference as the inference that there are, say, quarks, or cosmic strings. We are appealing, in the informal TTT, to our intuitions about subjectivity, not to ordinary, objective scientific evidence (such as brain-correlates). As a consequence (and again I invite you to do some introspection), the intuitive force of the direct knowledge that I have (or am) a mind, and that that causes my behavior, is of an entirely different order from my empirical inference that I have a brain and that that causes my mind. Consider, for example, that there are plenty of people who doubt that their brains are the true causes of their minds, but very few (like me) who venture to doubt that their minds cause their behavior; and I confess that I am not very successful in convincing myself, because my direct experience keeps contradicting my inference, incorrigibly. In summary: There is a vast difference between knowing causes directly and inferring them; subjective phenomena are unique and radically different from other phenomena in that they confer this direct certainty; and inferences about other minds (i.e., about subjective phenomena in others) are parasitic on these direct experiences of causation, rather than on ordinary causal inference, which carries little or no intuitive force in the case of mental phenomena, in ourselves or others. And rightly not, because mind is a private, direct, subjective matter, not something that can be ascertained -- even in the normal inductive sense -- by public, indirect, objective correlations. [To be continued ...] Stevan Harnad (609) - 921 7771 {allegra, bellcore, seismo, rutgers, packard} !princeton!mind!harnad harnad%mind@princeton.csnet ------------------------------ End of AIList Digest ******************** From in%@vtcs1 Mon Dec 1 10:58:48 1986 Date: Mon, 1 Dec 86 10:58:19 est From: vtcs1::in% To: ailist@sri-stripe.arpa Subject: AIList Digest V4 #269 Status: RO AIList Digest Wednesday, 26 Nov 1986 Volume 4 : Issue 269 Today's Topics: Philosophy - Searle, Turing, Symbols, Categories ---------------------------------------------------------------------- Date: 21 Nov 86 19:08:02 GMT From: rutgers!princeton!mind!harnad@lll-crg.arpa (Stevan Harnad) Subject: Re: Searle, Turing, Symbols, Categories: Reply to Cugini (2) [Part II] If you want some reasons why the mind/body case is so radically different from ordinary causal inference in science, here are two: (1) Generalizations about correlates of having a mind are, because of the peculiar nature of subjective, 1st-person experience, always doomed to be based on an N = 1. We can have intersubjective agreement about a meter-reading, but not about a subject's experience. This already puts mind-science in a class by itself. (One can even argue that the intersubjective agreement on "objective" meter readings is itself parasitic on, or grounded in, some turing-equivalence assumptions about other people's reports of their experiences -- of meter readings!) But, still more important and revealing: (2) Consider ordinary scientific inferences about "unobservables," say, about quarks (if they should continue to play an inferred causal role in the future, utopian, "complete" explanatory/predictive theory in physics): Were you to subtract this inferred entity from the (complete) theory, the theory would lose its capacity to account for all the (objective) data. That's the only reason we infer unobservables in the first place, in ordinary science: to help predict and causally explain all the observables. A complete, utopian scientific theory of the "mind," in radical contrast with this, will always be just as capable of accounting for all the (objective) data (i.e., all the observable data on what organisms and brains do) WITH or WITHOUT positing the existence of mind(s)! In other words, the complete explanatory/predictive theory of organisms (and devices) WITH minds will be turing-indistinguishable from the complete explanatory/predicitive theory of organisms (and devices) WITHOUT minds, that simply behave in every observable way AS IF they had minds. That kind of inferential indeterminacy is a lot more serious than the underdetermination of ordinary scientific inferences about unobservables like quarks, gravitons or strings. And I believe that this amounts to a demonstration that all ordinary inferential bets (about brain-correlates, etc.) are off when it comes to the mind. The mind (subjectivity, consciousness, the capacity to have qualitative experience) is NEITHER an ordinary, intersubjectively verifiable objectively observable datum, as in normal science, NOR is it an ordinary unobservable inferred entity, forced upon us so that we can give a successful explanatory/predictive account of the objective data. Yet the mind is undoubtedly real. We know that, noninferentially, for one case: our own. It is to THAT direct knowledge that the informal component of the TTT appeals, and ONLY to that knowledge. Any further indirect inferences, based on, say, correlations, depend ultimately for their validation only on that direct knowledge, and are always secondary to it, in that split inferences are always settled by an appeal to the TTT criterion, not vice versa (or some third thing), as I shall try to show below. (The formal component of the TTT, on the other hand [i.e., the formal computer-testing of a theory that purports to generate all of our performance capacities], IS just a case of ordinary scientific inference; here it is an empirical question whether brain correlates will be helpful in guiding theory-construction. I happen to doubt they will be helpful even there; not, at least until we get much closer to TTT utopia, when we've all but captured total performance capacity, and the fine-tuning [errors, reaction times, response style, etc.] may begin to matter. There, as I've suggested, the boundary between organism-performance and brain-performance may break down somewhat, and microfunctional and structural considerations may become relevant to the success and verisimilitude of the performance modeling itself. > 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. As I've tried to argue, these two types of knowledge are so different as to be virtually incommensurable. In particular, your knowledge that your brain causes your performance is direct and incorrigible, whereas your knowledge that your brain causes your mind is indirect, inferential, and parasitic on the former. Inferences about other minds are NOT ordinary cases of scientific inference. The mind/body case is special. > 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. For the time being, intelligence is as mind does. X3 may not be VERY intelligent, but if he has any mind-like performance capacity (to pass some variant of the TTT for some organism or other -- a tricky issue), that amounts to having some intelligence. As discussed in another module, intelligence may be a matter of degree, but having a mind seems to be an all-or-none matter. Also, having a mind seems to be a sufficient condition for having intelligence; if it's not also a necessary condition, we have the radical indeterminacy I mentioned earlier, and we're in trouble. So the case of severe retardation seems to represent no problem. Retarded people pass (some variant of) the TTT, and we have no trouble assigning them minds. This is fine as long as they have some (shall we call it "intelligible") performance capacity, and hence some intelligence. Comatose people are another matter. But they may well not have minds. (I might add that our inclination to assign a mind to a person who is so retarded that his performance capacity is reduced to vegetative functions such as blinking, breathing and swallowing, could conceivably be an overgeneralization, motivated by considerations of biological origins and humanitarian concerns.) I repeat, though, that these special cases belong more to the domain of near-utopia fine-tuning than the basic issue of whether it is performance or brain correlates that should guide us in inferring minds in others. Certainly neither TTT-enthusiasts nor brain-enthusiasts have any grounds for feeling confident about their judgments in such ambiguous cases. > 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? I don't think the moral choice is obvious in either case. However, I don't think you're imagining this case sufficiently vividly. Let's make it the one I proposed: A lifelong friend turns out to be robot, versus a human born (irremediably) with only vegetative function. These issues are for the right-to-lifers; the alternatives imposed on us are too hypothetical and artificial (akin to having to choose between saving one's mother or father). But I think it's fairly clear which way I'd go here. And what we know (or don't know) about brains has very little to do with it. > 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. Frankly, although it might disturb me for other reasons, I think that discovering I had complex, ill-understood electronic cicuits inside my head instead of complex, ill-understood biochemical ones would not sway me one way or the other on the basic proposition that it is performance alone that is responsible for my inferring minds in other people, not my (or anyone else's) dim knowledge about their inner structure of function. I agreed in an earlier module, though, that such a demonstration would be a bit of a blow to the sceptics about robots (which I am not) if they discovered THEMSELVES to be robots. On the other hand, it wouldn't move an outside sceptic one bit. For example, *you* would presumably be unifluenced in your convictions about the relevance of brain-correlates over and above performance if *I* turned out to be X4. And that's just the point! Like it or not, the 1st-person stance retains center stage in the mind/body problem. > 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. Yes. But the problem for *you* is whether *I* (or some other candidate) have a mind, not whether *you* do. Moreover, no one suggested that the turing test was the basis for knowing one has a mind in the 1st person case. That problem is probably closer to the Cartesian Cogito, solved directly and incorrigibly. The other-minds problem is the one we're concerned with here. Perhaps I should emphasize that in the two "correlations" we are talking about -- performance/mind and brain/mind -- the basis for the causal inference is radically different. The causal connection between my mind and my performance is something I know directly from being the performer. There is no corresponding intuition about causation from being the possessor of my brain. That's just a correlation, depending for its causal interpretation (if any), on what theory or metatheory I happen to subscribe to. That's why nothing compelling follows from being told what my insides are made of. > 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). I would summarize it differently: In the 1st-person case, I know directly that my performance is caused by my mind. I infer (from the correlation) that my brain causes my mind. In the other-minds case I know nothing directly; however, I am intuitively persuaded by performance similarity. I have no intuitions about brains, but of course every confirmatory cue helps; so if you also have a brain, my confidence is increased. But split the ticket, and I'll go with performance every time. That makes it seem as if performance is still the decisive criterion, and brainedness is only a secondary correlate. Putting it yet another way: We have direct knowledge of the causal connection between our minds and our performance and only indirect inferences about the causal connection between our brains and our minds (and performance). This parasitism is hence present in our inferences about other minds too. > I agree that there are some additional epistemological problems, > [with subjective/objective causation, as opposed to > objective/objective causation, i.e., with the mind/body problem] > compared to the usual cases of causation. But these don't seem > all that daunting, absent radical skepticism. But "radical" scepticism makes an unavoidable, substantive appearance in the contemporary scientific incarnation of the other-minds problem: The problem of robot minds. > 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. There is not quite as much disagreement here as there may seem. We agree on (1) the basic mystery in objective/subjective causation -- though I disagree that it is no more mysterious than objective/objective causation. Never mind. It's mysterious. I also agree that (2) I would feel (negligibly) more confident in inferring that a candidate who passed the TTT had a mind if it had a real brain than if it did not. (I'd feel even more confident if it was my identical twin.) We agree that (3) the brain causes the mind, that (4) the brain can be studied, that (5) there are anatomical and physiological correlations (objective/subjective), and that (6) these are very probably causal. Where we may disagree is on the methodology for arriving at a causal theory of mind. I don't think peeking-and-poking at the brain in search of correlations is likely to generate a successful causal theory; I think trial-and-error modeling of performance will, and that it will in fact guide brain research, suggesting what functions to look for implementations of, and how they cause performance. What I believe will fall by the wayside in this brute-force correlative account -- I'm for correlations too, of course, except that I'm for objective/objective correlations -- is subjectivity itself. For, on all the observable evidence that will ever be available, the complete theory of the mind -- whether implemented as a brain or as some other artificial causal device -- will always be just as true of a device actually having a mind as of a mindless device merely acting as if it had a mind. And there will be no way of settling this, short of actually BEING the device in question (which is no help to the rest of us). If that's radical scepticism, it's come home to roost, and should be accepted as a fact of life in mind-science. (I've dubbed this "methodological epiphenomenalism" in the paper under discussion.) You may feel more confident in attributing a mind to the brain-implementation than to a synthetic one (though I can't imagine you'll have good reasons, since they'll be functionally equivalent in every observable and ostensibly relevant respect), but that too is a question we will never be able settle objectively. (Let me add, in case it's not apparent, that performances such as reporting "It hurts now" are perfectly respectable, objective data, both for the brain-correlation investigator and the mind-modeler. So whereas we can never investigate subjectivity directly except in our own case, we can approximate its behavioral manifestations as closely as the expressive power of introspective reports will allow. What's not clear is how useful this aspect of performance modeling will be.) > 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". I plead no less guilty than you. Neither of us is responsible for the fact that scepticism looms large in making inferences about other minds and how they work, which is what cognitive science is about. I do disagree, though, that these considerations are irrelevant to one's research strategy. It does matter whether you choose to study the brain directly, or to model it, or to model performance-equivalent alternatives. Other issues in this discussion matter too: modeling toy modules versus the Total Turing Test, symbolic modeling versus robotic modeling, and the degree of attention focused on modeling phenomenological reports. I also agree, of course, about the grandiose over-interpretation of which AI (and, lately, connectionism too) has been guilty. But in the papers under discussion I try to propose principled constraints (e.g., robotic capacity, groundedness, nonmodularity and the Total Turing Test) that might restrain such excesses, rather than merely scepticism about artificial performance. I also try to sort out the empirical issues from the methodological and metaphysical ones. And, as I've argued in several iterations, "inetlligence" is not just a matter of definition. > 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. Thank you for the kind words. One of course hopes that consciousness will be captured somewhere along the road to Utopia. But my methodological epiphenomenalism suggests that this may be an undecidable metaphysical problem, and that, empirically and objectively, total performance capacity is the most we can know ("scientifically") that we have captured. -- Stevan Harnad (609) - 921 7771 {allegra, bellcore, seismo, rutgers, packard} !princeton!mind!harnad harnad%mind@princeton.csnet ------------------------------ End of AIList Digest ********************