From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.ecf!utgpu!cs.utexas.edu!uunet!mcsun!uknet!edcastle!aiai!jeff Tue May 12 15:49:46 EDT 1992
Article 5491 of comp.ai.philosophy:
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>From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Newsgroups: comp.ai.philosophy
Subject: Re: The Systems Reply I
Message-ID: <6687@skye.ed.ac.uk>
Date: 8 May 92 19:21:54 GMT
References: <1992Apr14.012458.7058@oracorp.com> <6641@skye.ed.ac.uk> <5@tdatirv.UUCP>
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In article <5@tdatirv.UUCP> sarima@tdatirv.UUCP (Stanley Friesen) writes:
>In article <6641@skye.ed.ac.uk> jeff@aiai.ed.ac.uk (Jeff Dalton) writes:
>|In article <1992Apr14.012458.7058@oracorp.com> daryl@oracorp.com (Daryl McCullough) writes:
>|>>>I can only reiterate what I have said before.  If you wish to show that
>|>>>computers lack something that humans possess, it seems to me that you
>|>>>need to show (a) that computers lack it, and (b) that humans possess
>|>>>it. If you only prove (a) then you have not proved your point.
>|
>|>I don't doubt human understanding. 
>|
>|>Nobody is disputing that humans understand,
>|
>|That should take care of (b).  Can we now look at the arguments
>|on (a) without further demands that we must also show (b)?
>
>No, the (b) that I am looking at is the *prior* assumption, that humans
>have some mechanism other than 'syntax' involved in thier cognitive
>processing.

I addressed the prior assumption aspect later in my message.

But let's at least agree that we will not dispute that humans
understand.  From this, it follows immediately that humans have
whatever is necessary for understanding.  (For if they lacked 
something necessary they wouldn't be able to understand.)

So if something other than syntax is necessary for understanding,
we can immediately conclude that humans have something other than
syntax.  Again, all such things follow immediately from the
statement we agreed to accept -- that humans understand.

The only prior assumption is the one you agreed not to dispute,
namely that humans understand.

>Now Searle's argument comes down to showing that what the CR is doing
>is different than what a human is doing.
>
>I cannot see that he has ever done so, all he has ever done is to appeal
>to intuition.  Well, intuition may be a useful mechanism for making quick
>decisions, but it is *far* from 100% reliable.

If this is so, you should have no trouble showing where Searle's
arguments break down.  You should not need to know how humans
understand.

>It takes more than premises that *seem* true to really show anything,
>you must show the premises are true by means of observational evidence.

This is wrong as philosophy of science, but that's for a different
newsgroup.

But, for example, how do you know what evidence is relevant?  You can't
show that even that conclusion about relevance is true purely by
observational evidence.

>|>It is an incomplete argument, an argument with steps missing.
>|
>|I don't agree.
>
>It fails to support its premises.

If this is true, you should be able to exhibit the argument and
show that it fails.  Merely asserting that it fails gets us nowhere.

As I have tried to show, the steps you claim are missing (ie, the
ones that show humans have the key property) and not, in fact, 
necessary to the argument at all.  If you still think they are
necessary, please show where the argument relies on them.

>It is the same question.  Why do you assume that humans have these
>undemonstrated capacities?  What evidence do you have for them. (I am not
>talking the capacity for understanding, I am talking about the capacities
>supposedly necessary for understanding).

I don't assume, I conclude.  If humans can understand, then it follows
immediately that they have whatever is required for understanding.  If
humans lacked any of these things, then (because those things are
necessary), humans couldn't understand.

>|Moreover, you seem to be assuming that the anti-AI arguments 
>|all have the form: computers can't understand because they
>|lack X (ie, "whatever is necessary").
>
>I have seen no others.

I really do not know what arguments you have in mind.

>|We will have an argument that looks like
>|
>|   <part 1>
>|   therefore: if something lacks X, it lacks underanding
>|   <part 2>
>|   therefore computers lack X
>|   therefore computers don't understand.
>|
>|Your complaint is _not_ that parts 1 and 2 fail to lead to their
>|conclusions but rather that we need to show
>|
>|   humans have X
>
>Or alternatively to show beyond possible doubt that part 1 is true.

If there's a flaw in <part 1>, exhibit the flaw!  Find a <part 1>
that's been used and show where it goes wrong.

Moreover, since that is one way to show the argument is wrong, it
cannot be necessary to show it is wrong in some other way -- such as
by showing humans lack X.

>Since the discovery that humans lack X would *disprove* part 1, then
>as long as this remains possible, part 1 is in doubt.

We look at <part 1> to see if it has flaws.  We don't find any.
So far as we can tell, it's a perfectly good argument.
But, according to you, it's still in doubt.

But is it in more doubt than all kinds of other things we're
usually willing to rely on, such as, say, scientific theories?

Since scientific theories are generally falsifiable, there is
generally some discovery that would show they were wrong.
So long as this remains possible, they are in doubt.

>I have seen too many 'proofs' of things that turned out to be false to
>put much trust in a 'proof' without objective evidence to back it up.

There have been lots of things backed by objective evidence
that turned out to be false too.

Look, if the most you can say agains Searle's arguments is
that maybe some day we'll discover something that's inconsistent
with them, then the same could be said against all sorts of
other things that we rely on all the time.  It's no more a
reason to reject Searle's arguments than it is to reject
those other things.

>It is only in the abstract realm of pure mathematics that proofs are final
>in themselves.

As I have said before, I am not trying to show anything with absolute
certainty.  And it seems to me that what you have against Searle's
arguments is precisely that he has not offered an absolute proof.

-- jd


