Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!edcastle!aiai!jeff
From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Newsgroups: comp.ai
Subject: Re: Sci. American AI debate: No Contest
Keywords: Searle Churchland Speed
Message-ID: <1521@skye.ed.ac.uk>
Date: 9 Jan 90 18:59:23 GMT
References: <12679@phoenix.Princeton.EDU> <199@fornax.UUCP>
Reply-To: jeff@aiai.UUCP (Jeff Dalton)
Organization: AIAI, University of Edinburgh, Scotland
Lines: 80

In article <199@fornax.UUCP> jones@lccr.UUCP (John Jones) writes:
>One of the beauties of this argument is that it allows Searle to avoid any
>definition of 'understanding'.  We know what it is like to understand
>something, so introspection provides the sole and universal test for the
>presence of understanding.  If we are faced with an entity of a new type,
>we have simply to imagine ourselves in the place of that entity and
>introspect.

I think you're right as far as Searle not needing a definition is
concerned.  In the Chinese room story, he's just using our common
sense notion of understand, as in "do you understand Chinese?".

I think it's clear that the person in the C.R. wouldn't find that he
understood Chinese.  I don't think that this conclusion requires that
we accept introspection as a sole and universal test, however.  All
we're being asked to do is to imagine ourself in the place of a
person, not an arbitrary entity of a new type.  (Of course, Searle
tries to get us to think that whether or not the person understands
shows whether or not there's any understanding at all, but that's
another matter.)

>The inadequacy of imagination-plus-introspection as a criterion for
>understanding can be demonstrated with less exotic examples than the Chinese
>room.  Consider one of the split-brain patients described by Sherrington.
>Asked to describe an object that he is allowed to handle but not to see,
>the patient can write down that it is a pipe, but states verbally that he
>has no idea what it is.  This behaviour is no more extraordinary than might
>be expected from the man-plus-book; Searle's criterion is no more helpful
>in one case than in the other.
>
>We have two alternative criteria for understanding; an operational criterion, 
>such as the Turing test; and the imagination-introspection criterion proposed
>by Searle.  It is, of course, meaningless to ask which criterion represents
>true understanding.  [...]

I don't think that's all there is to it.  First, I don't think the
Turing test is a test for understanding at all.  Maybe it will turn
out that it really does test for understanding, but that has to be
shown.  Otherwise, understanding would just mean having certain
behavior; and if that's there is to it, it turns out not to be very
interesting after all (because it doesn't connect to our internal
experience) -- at least to me.  I'd want to ask about something else,
consciousness perhaps.

Second, is introspection the only alternative?  Perhaps it is now,
when we don't have any machines that can pass the Turing Test and
don't know all that much about how the human mind works.  But maybe
when we know more we will find other interesting, relevant differences
between humans and Turing-capable machines.

As an example of something that's roughly the sort of thing I have in
mind, consider dreams.  By introspection, what we know is that,
sometimes, when we wake to a certain extent we can remember dreams.
We don't know whether the dream took place over a period of time or
just appeared all at once as a memory.  But later, we discover the
link between dreams and REM sleep, and then we have some other
evidence (although not absolutely conclusive evidence) that dreams
don't appear all at once.  Once we know more, new kinds of evidence
can become available.  [Some people would count this sort of thing as
behavior too, but it's not the sort of behavior considered by the
Turing Test.]

As another example, consider two programs that play Chess.  They might
have more or less the same behavior but work quite differently inside.
Perhaps one is just a brute force search and while the other tries to
emulate human play by using structures representing goals and plans.
A significant internal difference doesn't have to show up in behavior,
or at least not in such a way that we could be sure which program was
which without looking inside.

What I'm trying to suggest is that at some point we may be able to
look inside both humans and machines and find relevant differences.
Maybe it will be clear from this that the machines are just faking it,
or maybe it will be clear that they should count as understanding
after all, even if they get there in a somewhat different way.

Of course, it may be that nothing of the sort becomes clear at all.
But I think we still have to accept it as a possibility.

-- Jeff