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From: is_s425@kingston.ac.uk (Hutchison C S)
Newsgroups: comp.ai.philosophy
Subject: Re: UNIFIED MODEL FOR KNOWLEDGE REPRESENTATION? (IMPOSSIBLE
Message-ID: <1991Jun14.111857.7374@kingston.ac.uk>
Date: 14 Jun 91 11:18:57 GMT
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In article <1991Jun12.221121.15828@watdragon.waterloo.edu>
cpshelley@violet.waterloo.edu (cameron shelley) writes:
> If you're after *the* truth, then you'll have to provide *the* definitions
> of "riot", "racist", and so on (as I guess John Bradshaw pointed out).  These
> are perceptual, possibly unique categories to each speaker and not things
> you can measure, weigh, or otherwise legitimately encode in a formal
> language---not and capture all the variations involved.  It might be
> tempting to define a 'correct' riot, and then assert others are incorrect,
> but then you've done nothing but become another interpreter with your
> own opinion.

This may seem old-fashioned, but I am of the opinion that words have meanings
which are public and publicly observable. Informally, those meanings are given
in dictionaries (though dictionary writers are, after all, only human and can
get it wrong); more formally, are functions from extensions to possible
worlds.  It is therefore not incumbent upon me to provide the definitions of
"riot", & cet, nor would I presume to pronounce on the correctness of the
definitions of others but would simply refer others to what I take (with
good reason and in the company of many another) to be a proper treatment of
meaning.  I assume there are necessary and sufficient conditions for someone
being a racist much as there are necessary and sufficient conditions for
someone being a policeman; I also assume that the intersection of the
extensions of the two expressions may be non-empty.

> What distinction would a truth-functional theory make between the following
> pair of utterances?
>
>	The cat sat on the mat.
>	The mat was sat on by the cat.

The answer is: none.

> if our communicative apparatus exists just to transmit the
> truth, why do we have more than one token for the same proposition?
> The only explanation comes from considering the speaker's desire to
> emphasize "cat" or "mat" (or conversely de-emphasize the other).  Even
> in a description of an uncontroversial and simple event, point of view
> can play a role.

The propositions expressed by sentences and the use to which sentences are put
are, I think, different issues, the one the concern of semantics, the other of
pragmatics.  Though in the case of the pair of sentences you give, choice
between the two is most likely to be textual (which, of the active and passive
forms, will, in context, produce the more cohesive text?) and thematic (what
is the topic of discourse?)  I can't see this has anything to do with matters
of meaning and truth.

> problem of handling reports about things which don't exist in some way (ie.
> unicorns, Sherlock Holmes, rained-out ball games, etc...).  A paper by
> Hirst I was forced to read lately (on KR of non-existence) suggests just
> going with a naive model.

"unicorns, Sherlock Holmes" and such like exist; it just so happens that (so
far as I am aware) they don't exist in the *actual* world.

> Basically, I would argue that you are trying to make your point by asking a
> lot of ill-formed questions!  It is not the QUANTITY of your questions that
> matters but rather their QUALITY!

With your first sentence I agree (almost) entirely.  It is a time-honoured
practice to raise awareness of issues by tossing around a few apt (nb. if
"inexact" rather than "ill-formed") questions.

> Rather than ask what a reader "knows," I would argue that you should be
> asking how that sentence impacts his behavior. At this point, you have to
> recognize that there is no such thing as a "generic" reader.  You can only
> ask about the behavior of a flesh-and-blood (so to speak) INDIVIDUAL, rather
> than an abstract sentence processor.  For example, for an
> international trader, "knowledge" is going to have to do with doing business
> in Africa.  If he has an office in Salisbury, he probably has to entertain a
> decision to shut that office down and evacuate his personnel.  On the other
> hand, a white middle-class reader in a relatively quiet town might start
> reflecting on his attitude towards the blacks who moved in down the lane,
> realizing that he has been unconsciously crossing to the other side of the
> street whenever he sees them.  We are not talking about text-based
> propositions which are true or false here.  We are talking about making
> decisions in the real world--a form of knowledge which, I believe, Donald
> Schoen has come to call "knowledge-in-action."

Again, I wholly agree with you that you "are not talking about text-based
propositions which are true or false".  I think you are talking about
something like 'perlocutionary effects'.  Of course the propositions expressed
by sentences will have effects on the behaviour (cognitive or physical) of
hearer-readers.  That is merely a matter of personal psychology, and has
nothing to do with the meanings of expressions, which is what I am concerned
with.

Finally, with regard to your last paragraph, if two people are never really
talking about the same things, then they can never come to any agreement about
the same things (since there are no such 'same' things to agree about). If you
are right (as you may be), then I marvel that people ever manage to
co-operatively get anything done in the world.  It may be that people simply
behave *as though* they were talking about the same things; this opens up
quite another can of worms (what is the ontological basis for this
"as-though-ness"?)

I feel slightly more sympathetic (but only slightly) towards Marvin Minsky's
contribution to the debate, which in large part echoes things I've been
thinking (thanks to two books by Jeremy Hayward, entitled, I think, 'Perceiving
Ordinary Magic' and 'Shifting Worlds, Changing Minds') for a long while, viz.

> When you and I both talk about "that
> chair over there", our internal models differ substantially, but not
> enough to make most practical interactions too difficult.  And the
> cchir itself changes imperceptibly from one moment to the next as it
> loses and gains atoms and suffers thermal agitations of its internal
> degrees of freedom.  There is no chair, indeed, from a modern physical
> point of view, only boundaries imposed by observers; my decorator
> friend regards this chair and that other one as a possibly conflicting
> pair, my fried the carpenter sees it as a possibly unsound linkage of
> glue and sticks, and so on.

But I rather think that to focus attention exclusively on "internal models"
is to dodge the issue.  The example I like is that of a filing cabinet.  When
I use the expression "filing cabinet" as a referring expression, I intend to
pick out for my hearer something more than a metal container, around 4ft 6in
high, with a small number of moving parts.  What I mean by "filing cabinet"
includes assumptions I have about its functionality, about practices of
producing and storing textual documents, about the history of such practices
within my culture, and about the graphemic storage and retrieval of
information.  I do indeed have an "internal model" of a filing cabinet, and I
take it that my having such a model is a necessary condition for my being
able to use the expression as the content of a referring act.  I just happen
to espouse a version of realism that allows the world to be populated with
filing cabinets (and other things like chairs) in the rich sense I outlined
above.  The internal model that I have of a filing cabinet (or of a chair or
of whatever else) is derivatve and dependent on the existence of filing
cabinets of just this kind 'out there' in the world.  It is by virtue of its
existing independently of any internal model that I (or anybody else, correct
or incorrect) may have of it that I can unproblematically refer to a filing
cabinet and feel confident that my hearer knows exactly what it is that I am
talking about.  If my hearer gets it wrong, that's his/her problem, and I can
put him/her right.

Now back to my "rioting blacks"/"racists"/& cet problem.  I assume there is a
real world out there in which things like "riots", "police", "racists", and so
on, are possible objects.  The question again is: are reports of events which
include such terms capable of being true or false?  (I think they are.)  If
so, how can conflicting reports be true at the same time?  Otherwise, if
not, why not?

Chris H