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> Excerpts from netnews.comp.ai: 8-Feb-90 Re: Can Machines Think? Randy
> Appleton@ms.uky.ed (549)

> I just read the Jan Scientific American, the one with Searle and so on.
> Here is the one burning question I have.  I think a satisfactory answer to this
> will convince me that Searle is right, and strong-AI is wrong.  But until
> then, I find Searle's argument to be imprecise gobbly-gook.

> What exactly IS the difference between "understanding" and "the formal
> manipulation of syntatic symbols"?  He uses those two phrases quite alot,
> and I think it is this difference that is his main argument.  BUT HE NEVER
> SAYS WHAT IT IS! ARG!

> Well, thanks
> Randy
 
Surprisingly, none of the postings on this subject ever dealt with this
question directly. However, I believe that a clear distinction exists
between symbol manipulation and "understanding". 
      I would say a system "understands" iff  , given  a certain event
in some representation , the system can retrieve from its memory (this
can be called the "case-base") a previous event which is "related " to
the current event in some way . The case-base is a collection of
previous experiences either manually input or acquired thru learning.
The above mentioned relation between events can be quite subjective,
just like responses to a certain question can be quite subjective. It is
possible to design a test , which I call the case-retrieval test, to
determine whether a system understands a certain event. Should the
system be "intelligent" to "understand" things ? This depends on what we
mean by "intelligence". However, it is possible to deal with the
question of whether a system "understands" without defining
"intelligence". The system ,however, should be able to reason by what is
called as the "analogical reasoning" or in general "case-based
reasoning".
           On the other hand, a system which can only manipulate symbols
or rather, which can give "good" responses to input symbols need not
"understand "at  all. 
            On the basis of the above, I agree with Searle that the
person in the chinese room need not *necessarily* understand the
question. However, I don't agree with him when he says " It is
impossible to build an 'understanding' system which manipulates only
symbols." 
            Note that he also doesn't define what semantics is . I
believe that even semantics is basically a group of symbols. (If
interested see my Feb.7 posting in comp.ai titled "Semantics are
symbols").

        You might wonder on what basis I say that  case retrieval is
"understanding". I'll give an example. Do you understand  "x" ? If no,
can you say why you don't understand "x" ? Is it because it is
meaningless? But, why is it "meaningless" ? 
        Do you "understand" the following group of symbols : "John
walked yesterday."
         Do you "understand" this : " xyzgf#$  ran  yesterday ".
         Do you "understand" this : " John walked $$3ewr"
         Do you "understand" this : " John ee##2323 yesterday."
         Do you "understand" this : " $%#$@ #@@@@ FGGFd "
I think you will notice the difference in the degree of  your
"understanding" the above sentences.

For the first one , you were able to retrieve a "complete" case from
your memory with respect to object, action ,time etc. However, this
is'nt the extreme case. Suppose you had a friend whose name was John and
you actually saw him walking yesterday then the above sentence might
have retrieved that case.  I call this exact matching as "knowing" and
the particular case as "knowledge" cf. rules in an expert system. Coming
back to the above examples, you'll notice that you understand them
lesser and lesser ie., retrieve  more  inexact cases until you reach the
last one where you may not able to retrieve any case at all. You'd say
that you don't understand the last sentence completely, but do
understand the others partially.
       Interestingly, note that if you "know" something then you don't
require to understand it. For example do you "understand" that 2 X  2 =
4 ? 

Narasimhan.