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From: marty1@houdi.UUCP (M.BRILLIANT)
Newsgroups: comp.cog-eng,comp.ai
Subject: Re: The symbol grounding problem
Message-ID: <1192@houdi.UUCP>
Date: Sat, 27-Jun-87 09:22:19 EDT
Article-I.D.: houdi.1192
Posted: Sat Jun 27 09:22:19 1987
Date-Received: Sun, 28-Jun-87 01:38:02 EDT
References: .... <6174@diamond.BBN.COM> <917@mind.UUCP>
Organization: AT&T Bell Laboratories, Holmdel
Lines: 55
Summary: Why require 100% accuracy in all-or-none categorizing?
Xref: mnetor comp.cog-eng:154 comp.ai:582

In article <917@mind.UUCP>, harnad@mind.UUCP (Stevan Harnad) writes:
> ...  blurred the distinction between the
> following: (a) the many all-or-none categories that are the real burden
> for an explanatory theory of categorization (a penguin, after all, be it
> ever so atypical a bird, ... is, after all, indeed a bird, and we know
> it, and can say so, with 100% accuracy every time, ....
> ... and (b) true "graded" categories such as "big," "intelligent," ...

> ......
> "games" are either (i) an all-or-none category, i.e., there is a "right" or
> "wrong" of the matter, and we are able to sort accordingly, ...
> ... or (ii) "games"
> are truly a fuzzy category, in which membership is arbitrary,
> uncertain, or a matter of degree. But if the latter, then games are
> simply not representative of the garden-variety all-or-none
> categorization capacity that we exercise when we categorize most
> objects, such as chairs, tables, birds....

Now, much of this discussion is out of my field, but (a) I would like
to share in the results, and (b) I understand membership in classes
like "bird" and "chair."

I learned recently that I can't categorize chairs with 100% accuracy. 
A chair used to be a thing that supported one person at the seat and
the back, and a stool had no back support.  Then somebody invented a
thing that supported one person at the seat, the knees, but not the
back, and I didn't know what it was.  As far as my sensory
categorization was concerned at the time, its distinctive features were
inadequate to classify it.  Then somebody told me it was a chair.  Its
membership in the class "chair" was arbitrary.  Now a "chair" in my
lexicon is a thing that supports the seat and either the back or the
knees.

Actually, I think I perceive most chairs by recognizing the object
first as a familiar thing like a kitchen chair, a wing chair, etc., and
then I name it with the generic name "chair."  I think Harnad would
recognize this process.  The class is defined arbitrarily by inclusion
of specific members, not by features common to the class.  It's not so
much a class of objects, as a class of classes....

If that is so, then "bird" as a categorization of "penguin" is purely
symbolic, and hence is arbitrary, and once the arbitrariness is defined
out, that categorization is a logical, 100% accurate, deduction.  The
class "penguin" is closer to the primitives that we infer inductively
from sensory input.

But the identification of "penguin" in a picture, or in the field, is
uncertain because the outlines may be blurred, hidden, etc.  So there
is no place in the pre-symbolic processing of sensory input where 100%
accuracy is essential.  (This being so, there is no requirement for
invertibility.)

M. B. Brilliant					Marty
AT&T-BL HO 3D-520	(201)-949-1858
Holmdel, NJ 07733	ihnp4!houdi!marty1