IUBio

Rickert on embedded computation (was re: science of consciousness.)

Anders N Weinstein andersw+ at pitt.edu
Mon Apr 27 15:31:24 EST 1998


In article <6hqseq$q8n at ux.cs.niu.edu>, Neil Rickert <rickert at cs.niu.edu> wrote:
>When a computation is being carried out on my computer, a series of
>causal operations is taking place, using electrical signals and other
>kinds of physical operations.  There is also a symbol manipulating
>game used in our theories of computation to describe what is
>happening.  Whether we should say that the symbol manipulation game
>is actually going on is itself a tricky question.  

If I were to produce a few quite concrete symbol tokens, say on punched
cards, and move them around in accordance with certain pattern-governed
transfomrations, I presume there would be no question that I was 
manipulating some symbols in the physical world. (Or would there? From 
what you say, I'm actually not sure what *you* think on this).  
If a waiter inscribes signs (digits) using bits of graphite on paper while 
totalling the bill, there would be no question that there is symbol 
manipulation going on in the physical world, would there? For he is
certainly inscribing symbols and following rules.

But now, if we automate the process, and use a machine to manipulate
punched cards in accordance with rules, then, similarly I think we can
say there is concrete symbol manipulation going on in the machine in
the physical world. And an electrical computer is not any different in
this respect.

>When I am using the computer for ordinary things (like writing this
>message), I care only about the causal operations.  The particular
>choice of symbol manipulation game which somebody might choose to in
>their description language is completely irrelevant to the
>computation that is going on, as far as I am concerned as a user of
>the computer.

Sure as an outside user you don't care, but if something goes wrong, 
it can make a difference whether we lay blame to faulty hardware or 
a bug in the programming. But identifying the latter requires 
identifying a "symbol manipulation game".

>It seems to me that you are emphasizing only the symbol manipulation
>game, and ignoring the causal operations which I consider to be at
>the heart of computation.  I prefer to think of the symbol
>manipulation game as a story involving purely theoretical entities.

Why not think of symbols as concrete physical entities, described in a
certain vocabulary? Wittgenstein liked to emphasize that what
interested him was always words taken in a concrete sense, not some
ethereal abstractions; however, he (and others, like Saussure) compared
talking about language in terms of significance to talking about chess
pieces in terms of their role in the game. That is, actual chess pieces
are physical objects, and playing chess in the paradigmatic cases
requires physically moving them around in accordance with the rules.
Similarly, public language symbols are physical objects, and speaking a
language involves moving them around in what is, in a broad sense,
accordance with certain tacit norms.

That is to say: a chess move has a double aspect: it is both a physical
transtion, and a move in a game. The fact that we can abstract its
socio-functional properties and consider them separately, should not
show that the real chess game is an ethereal abstraction outside of
the physical world. Similarly, real symbols, signposts, say, are 
physical objects with socio-functional properties that determine them
as meaningful. 

It is true that two concrete marks objects that are physically
cotypical might nonetheless play different functional roles if caught
up in different languages (games). Still, there can be perfectly good
facts of a broadly social kind about which game a sign is produced in.
So there are usually facts about which symbol it is, at least for
public symbols. For example, it is a fact that the things on the road
signs outside my office are symbols of English and not Chinese.

It *is* trickier to develop an idea of *natural* computation, in the
absence of direct relation to human practices, I will agree with that.
But it does not seem impossible. Saying that a physical event in the
brain is part of one rather than another symbol manipulation game might
be comparable saying the heart is a natural pump and not a noise-making
device, something grounded in a teleological analysis of the system in
question.

>predictive theories.  But we don't actually believe they are more
>than convenient fictions.

Does this apply to the symbol in a public language, do you think? 
If not (as I hope), then mightn't it also be wrong for manipulations
in a conventional computer?

>Sure there is.  But that computation consists of causal operations,
>rather than the symbol manipulating game we might use to describe
>those operations.

But playing a symbol manipulation game with physical tokens *is*
a causal operation.



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