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From: aweinste@Diamond.BBN.COM (Anders Weinstein)
Newsgroups: comp.cog-eng
Subject: Re: The symbol grounding problem
Message-ID: <6721@diamond.BBN.COM>
Date: Mon, 22-Jun-87 15:45:19 EDT
Article-I.D.: diamond.6721
Posted: Mon Jun 22 15:45:19 1987
Date-Received: Tue, 23-Jun-87 05:07:37 EDT
References: <764@mind.UUCP> <768@mind.UUCP> <770@mind.UUCP>
Reply-To: aweinste@Diamond.BBN.COM (Anders Weinstein)
Organization: BBN Laboratories, Inc., Cambridge, MA
Lines: 56

In article <8309@ut-sally.UUCP> berleant@ut-sally.UUCP (Dan Berleant) writes:
>>                For example, we'd probably like to say that a frog has a
>>fly-detector which is sometimes wrong, rather than a "moving-spot-against-a-
>>fixed-background" detector which is infallible. Again, this distinction seems
>>to depend on fuzzy considerations about the purpose or functional role of the
>>concept in question.
>
>             The world is fuzzy enough that logical deduction is not
>going to work infallibly, so every time there is inference, as in
>categorizing=identifying=classifying a percept, errors in the results
>are guaranteed some of the time. Thus errors may be expected to occur
>anywhere in the path from percptual icon to concept symbol, rather than,
>say, only at the point on this path where purposes or functions come
>into play.

Sure, but the philosophical problem is to say why any response should count
as an *error* at all. What makes it wrong? I.e. who decides which "concept"
-- "fly" or "moving-spot..." -- the frog is trying to apply? The objective
facts about the frog's perceptual abilities by themselves don't seem to tell
you that in snapping out its tongue at a decoy, it's making a *mistake*. To
say this, an outside interpreter has to make some judgement about what the
frog's brain is trying to accomplish by its detection of moving spots.  And
this makes the determination of semantic descriptions a fuzzy matter.

It's true that evolutionary considerations might take you some of the way
towards defining an objective sense of "purpose" to use here, but I don't
think they can eliminate the difficulty entirely, as the purpose of
particular adaptations can not always be expected to be clear or even fully
determinate.

>>Some of the things you say also suggest that you're attempting to resuscitate
>>a form of classical empricist sensory atomism ... unfortunately, no one has 
>>ever been able to make [this] work.
>
>                         Conceptual combination allows us to go
>from 'tomato' and 'juice' to 'tomato juice'. I assume there is no
>argument that this new category may be acquired, sight unseen, 
>by symbolic processing. Presumably there must be atomic=primitive
>concepts, however, and where do these come from? It must be
>by a process different from that usable to acquire the concept
>'tomato juice'. What are the alternatives to acquisition "by 
>acquaintance" (I'm not familiar with the term "by acquaintance")? Also,
>what is meant by the contention that noone has been able to make it
>work? 

Of course *some* concepts can be acquired by definition. However, the
"classical empiricist" doctrine is committed to the further idea that there
is some priveleged set of *purely sensory* concepts and that all non-sensory
concepts can be defined in terms of this basis.  This is what has never been
shown to work. If you regard "juice" as a "primitive" concept, then you do
not share the classical doctrine. (And if you do not, I invite you try giving
necessary and sufficient conditions for juicehood.)

The phrases "knowledge by acquaintance" and "knowledge by description" come
from Bertrand Russell, who thought at the time that we were "directly
acquainted" with our sense-data.