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Article 4297 of comp.ai.philosophy:
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>From: minsky@media.mit.edu (Marvin Minsky)
Newsgroups: comp.ai.philosophy
Subject: Re: Definition of understanding
Keywords: meaning, understanding
Message-ID: <1992Mar6.012217.25722@news.media.mit.edu>
Date: 6 Mar 92 01:22:17 GMT
References: <1992Mar4.210627.28060@psych.toronto.edu> <1992Mar5.001144.28065@beaver.cs.washington.edu> <1992Mar5.203720.4209@psych.toronto.edu>
Sender: Marvin Minsky
Organization: MIT Media Laboratory
Lines: 82
Cc: minsky


========  Understanding Understanding =============

It seems to me that this discussion has become somewhat unproductive
because of non-agreement about the meaning of "understanding". Some
discussants assume that whatever "to understand" means, it is an
absolute, all or none attribute of a system.  Others say that it must
depend on something called "semantics" but aren't very clear about
what a semantic might be.

Instead, it seems to me that in the rest of the world of comonsense
conversation the word is usually used in a more relative way, and that
this has two aspects crucial to the present discussion.

First, the expression "B understands C" seems to be taken too seriously, 
whereas the actually situation is really of the form:

   "A maintains (believes, assumes, etc.) that B understandB"

Once you notice this, the issues now turn on whether A thinks that the CR 
understands Chinese, etc.  Then the issue turns into your evaluation of A's 
judgment, etc.  Not very philosophical, after all.

Second, there is an implicit idea that there is a definition or meaning to 
"understand" -- provided that we could only agree upon it.  My view is that 
this word, like many other terms from commonsense psychology, have a 
very different and very useful usage, but one that is quite different from an 
absolute two-argument relationship.  Namely, consider the commonsense 
assertion that if a certain person  P can tell you only a certain definition D 
of a term W, then you are inclined to say things like "P doesn't really 
understand W, but has only memorized the definition by rote."  

Here's my explanation, then of why you philosophers are having so much 
trouble agreeing on what 'meaning' or 'understanding" means.  It is partly 
because meaning is no single thing, nor is understanding a single act.  But it 
is really a bit worse than that, because there is a subtlety implicit in what 
"ordinary people' are doing when they use the term.  To put it in the form 
of an epigram (that is, a definition):

   "If you understand something only one way then you scarcely understand 
it at all."

This is in recognition that the activities of human thought engage a large 
society of different structures and processes.   For example, to illustrate 
my own particular theory of what's going on, consider what it would mean 
for you to undserstand the statement "Mary gave Jack her book."  Well, 
perhaps one part of the brain represents this as a sort of sequential action-
script describing a few steps in the book's physical trajectory.  Another 
part of the brain might represent it in the form of what I call a "trans-
frame" which combines two other representations (of the situation before, 
and the situation after, the giving-action takes place) in a structure with 
slots for pointing to representations of what caused the event, what 
instrument was used (Mary's hand, say) etc.  Yet another part of the brain 
might represent the transfer of possession (or control, or ownership, or 
right to keep) the book.  

Now if you have only one or two of these representations, another person 
would say that you don't really understand, or that you barely understand, 
etc.  If you have a dozen of them, someone might perceive that you 
"understand it quite deeply", being able to predict future consequences 
more impressibvely than usual, etc.

And of course, you don't really get awfully far if your doen different 
representations have no interconnections or interconvertibility at all; 
however, every normal person is equipped with linguistic and other 
machinery for making systematic metaphors and conversions.  

Now what is the value of this?  Simply, that if you "understand" something 
only one way -- that is, using only one representation -- then when 
something goes wrong, you have nowhere to go.  And that is the dead end 
that we by by the vernacular complaint that "A knows B only by rote."  
The point is that with a single definition of representation, A is very likely 
to get stuck in a way that we describe as "not really understanding".

There's more of course.  Because one would also say that the secret of what 
X means to us lies not only in isolated definitions but also in how our 
representations of X connect to other things we know.  In my view, this is 
where logical representations usually get stuck.  There's nowhere to go.  
But brains (and computers) can use multiply-connected representations, so 
that when one approach fails you can try another.  Like turning ideas 
around in your mind and trying out alternative perspectives till you find 
one that works.  And that's what we mean by thinking! 


