Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!ll-xn!husc6!diamond.bbn.com!aweinste From: aweinste@Diamond.BBN.COM (Anders Weinstein) Newsgroups: comp.ai,comp.cog-eng Subject: Re: The symbol grounding problem Message-ID: <6867@diamond.BBN.COM> Date: Tue, 30-Jun-87 16:52:21 EDT Article-I.D.: diamond.6867 Posted: Tue Jun 30 16:52:21 1987 Date-Received: Wed, 1-Jul-87 06:40:43 EDT References: <764@mind.UUCP> <768@mind.UUCP> <770@mind.UUCP> <6174@diamond.BBN.COM> <6670@diamond.BBN.COM> <918@mind.UUCP> Reply-To: aweinste@Diamond.BBN.COM (Anders Weinstein) Organization: BBN Laboratories, Inc., Cambridge, MA Lines: 113 Summary: Why the psychology of categorization won't dent the problem of meaning Xref: mnetor comp.ai:592 comp.cog-eng:163 In reply to my statement that >> the *semantic* meaning of a symbol is still left largely unconstrained >> even after you take account of it's "grounding" in perceptual >> categorization. This is because what matters for intentional content >> is not the objective property in the world that's being detected, but >> rather how the subject *conceives* of that external property, a far >> more slippery notion... Stevan Harnad (harnad@mind.UUCP) writes: > > As to what people "conceive" themselves to be categorizing: My model > is proposed in a framework of methodological epiphenomenalism. I'm > interested in what's going on in people's heads only inasmuch as it is > REALLY generating their performance, not just because they think or > feel it is. I regret the subjectivistic tone of my loose characterization; what people can introspect is indeed not at issue. I was merely pointing out that the *meaning* of a symbol is crucially dependent on the rest of the cognitive system, as shown in the Churchland's example: >> ... primitive people may be able to reliably >> categorize certain large-scale atmospheric electrical discharges; >> nevertheless, the semantic content of their corresponding states might >> be "Angry gods nearby" or some such. >> > ... "Angry gods nearby" is not just an atomic label for > "thunder" (otherwise it WOULD be equivalent to it in my model -- both > labels would pick out approximately the same thing); in fact, it is > decomposable, and hence has a different meaning in virtue of the > meanings of "angry" and "gods." There should be corresponding internal > representational differences (iconic, categorical and symbolic) that > capture that difference. "Angry gods nearby" is composite in *English*, but it need not be composite in native, or, more to the point, in the supposed inner language of the native's categorical mechanisms. They may have a single word, say "gog", which we would want to translate as "god-noise" or some such. Perhaps they train their children to detect gog in precisely the same way we train children to detect thunder -- our internal thunder-detectors are identical. Nevertheless, the output of their thunder-detector does not *mean* "thunder". Let me try to clarify the point of these considerations. I am all for an inquiry into the mechanisms underlying our categorization ablities. Anything you can discover out about these mechanisms would certainly be a major contribution to psychology. My only concern is with semantics: I was piqued by what seemed to be an ambitious claim about the significance of the psychology of categorization for the problem of "intentionality" or intrinsic meaningfulness. I merely want to emphasize that the former, interesting though it is, hardly makes a dent in the latter. As I said, there are two reasons why meaning resists explication by this kind of psychology: (1) holism: the meaning of even a "grounded" symbol will still depend on the rest of the cognitive system; and (2) normativity: meaning is dependent upon a determination of what is a *correct* response, and you can't simply read such a norm off from a description of how the mechanism in fact performs. I think these points, particularly (1), should be quite clear. The fact that a subject's brain reliably asserts the symbol "foo" when and only when thunder is presented in no way "fixes" the meaning of "foo". Of course it is obviously a *constraint* on what "foo" may mean: it is in fact part of what Quine called the "stimulus meaning" of "foo", his first constraint on acceptable translation. Nevertheless, by itself it is still way too weak to do the whole job, for in different contexts the postive output of a reliable thunder-detector could mean "thunder", something co-extensive but non-synonymous with "thunder", "god-noise", or just about anything else. Indeed, it might not *mean* anything at all, if it were only part of a mechanical thunder-detector which couldn't do anything else. I wonder if you disagree with this? As to normativity, the force of problem (2) is particularly acute when talking about the supposed intentionality of animals, since there aren't any obvious linguistic or intellectual norms that they are trying to adhere to. Although the mechanics of a frog's prey-detector may be crystal clear, I am convinced that we could easily get into an endless debate about what, if anything, the output of this detector really *means*. The normativity problem is germane in an interesting way to the problem of human meanings as well. Note, for example, that in doing this sort of psychology, we probably won't care about the difference between correctly identifying a duck and mis-identifying a good decoy -- we're interested in the perceptual mechanisms that are the same in both cases. In effect, we are limiting our notion of "categorization" to something like "quick and largely automatic classification by observation alone". We pretty much *have* to restrict ourselves in this way, because, in the general case, there's just no limit to the amount of cognitive activity that might be required in order to positively classify something. Consider what might go into deciding whether a dolphin ought to be classified as a fish, whether a fetus ought to be classified as a person, etc. These decisions potentially call for the full range of science and philosophy, and a psychology which tries to encompass such decisions has just bitten off more than it can chew: it would have to provide a comprehensive theory of rationality, and such an ambitious theory has eluded philosophers for some time now. In short, we have to ignore some normative distinctions if we are to circumscribe the area of inquiry to a theoretically tractable domain of cognitive activity. (Indeed, in spite of some of your claims, we seem committed to the notion that we are limiting ourselves to particular *modules* as explained in Fodor's modularity book.) Unfortunately -- and here's the rub -- these normative distinctions *are* significant for the *meaning* of symbols. ("Duck" doesn't *mean* the same thing as "decoy"). It seems that, ultimately, the notion of *meaning* is intimately tied to standards of rationality that cannot easily be reduced to simple features of a cognitive mechanism. And this seems to be a deep reason why a descriptive psychology of categorization barely touches the problem of intentionality. Anders Weinstein BBN Labs