Xref: utzoo comp.ai:3236 talk.philosophy.misc:1922 sci.lang:4038 Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!uxc!deimos!rutgers!elbereth.rutgers.edu!harnad From: harnad@elbereth.rutgers.edu (Stevan Harnad) Newsgroups: comp.ai,talk.philosophy.misc,sci.lang Subject: Re: Categorization Summary: (1) Categorization is not primarily a linguistic problem (2) Children's categories are not under/overextensions of ours Keywords: Crisp Sets and Fuzzy Sets Message-ID: Date: 29 Jan 89 02:16:54 GMT References: <681@cogsci.ucsd.EDU> <2959@uhccux.uhcc.hawaii.edu> <2899@xyzzy.UUCP> <9750@bcsaic.UUCP> Organization: Rutgers Univ., New Brunswick, N.J. Lines: 94 rwojcik@bcsaic.UUCP (Rick Wojcik) of Boeing Computer Services AI Center, Seattle wrote: " Linguists have long been aware of the problems with all-or-none " categories. Stevan... simply defines the word 'categorization' to suit " his all-or-none criterion, without any regard for the way humans " actually assign categories. But consider the classic examples of " 'semantic vagueness'. We have the mental illusion that mountains and " waves are discrete objects. Questions like 'How many mountains are " there in the Cascades?' or 'How many waves are there in the ocean?' are " semantically well-formed, but impossible to answer from a conceptual " point of view. There are no natural discrete boundaries to these " categories, such that you can always tell where one mountain or wave " leaves off and another begins. The problem of how we categorize (i.e., sort and label objects and states of affairs) is basically not a linguistic one, though it of course makes contact with linguistics at some level (because the category labels form our lexicon, and language allows us not only to label categories, but to describe them). For example, how we manage to sort and label mountains and waves is basically a perceptual problem: What are the internal representations that allow us to categorize members and nonmembers of these categories successfully, in those many cases in which we are able to do so? It is those who ignore (or take for granted) this enormous core of reliable, correct, all-or-none categorization performance who are not showing due "regard for the way humans actually assign categories." The solution to the problem of HOW people manage to sort and label things as they actually do will not come from linguistics, it will come from a theory of perceptual and cognitive representation. Nor will how we categorize in most cases be determined from our introspective discourse about how we categorize, any more than how we perceive will be determined from our introspections about our perception. The explanation will come from theoretical inference and the building and testing of causal models for the underlying mechanism. I also remind the reader that the question to which these discussions were addresses was whether or not the representation that allows us to categorize is "classical," i.e., consists of features that are necessary and sufficient to sort members from nonmembers, NOT whether or not we can sort EVERY instance of ANYTHING we ever encounter in an all-or-none fashion. The question under discussion is simply moot for cases in which we CANNOT sort members from nonmembers (e.g., "vague" cases). Note that this point is a logical, not an empirical one; its only empirical aspect is the evidence (and it's all over the map -- unless you're in the grip of an introspective theory) that there do indeed exist myriad categories that we can and do sort and label in a reliable, correct, all-or-none fashion. " A child might use the word 'doggie' on different occasions to refer to " four-legged things, furry things (e.g. a blanket), things that move, " etc. Overextensions and underextensions seem to involve a fine-tuning " of categorization that looks more like the so-called 'classical' type. Indeed it does -- and the process leads ultimately to our asymptotic core of perfectly "classical" categories. My only quarrel with this terminology has been that to call this "overextension" and "underextension" is to adopt too omniscient or ontological a view. According to my theory, ALL categories are provisional and approximate, including our adult ones. Their context of interconfusable alternatives could always in principle be widened so as to show up our former representations as having been over- or underextended (based on hindsight). At a given point in its experience a child's category may accordingly NOT be over- or underextended relative to the actual sample of alternatives he has so far encountered and the feedback he has so far received from the consequences of miscategorization; the over/underextension may only be relative to OUR categories and their larger and more representative contexts. Subsequent experience may force the child to revise his categories and eventually converge on ours, but that does not necessarily mean they are over- underextended at THIS point. Sometimes we expect too much from children and other category learners on the basis of the data available to them; for similar reasons we sometimes also attribute too much to them (as in the chimpanzee "language" studies). It is only by taking account of the categorizer's actual sorting performance in its actual context of confusable alternatives that one can infer a category's actual extension and intension, and hence its underlying representation. (On the other hand, over- and underextension CAN be be defined during this actual learning phase WITHIN the child's actual local context of alternatives, while miscategorization with feedback is going on; this, however, is probably more perspicuously described as the formation or revision of the child's own provisional categories, guided by the consequences of miscategorization, rather than as the "fine-tuning" of OUR categories.) -- Stevan Harnad INTERNET: harnad@confidence.princeton.edu harnad@princeton.edu srh@flash.bellcore.com harnad@elbereth.rutgers.edu harnad@princeton.uucp BITNET: harnad@pucc.bitnet CSNET: harnad%princeton.edu@relay.cs.net (609)-921-7771