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From: ellis@spar.UUCP (Michael Ellis)
Newsgroups: net.philosophy
Subject: Re: Humans and Turing Machines
Message-ID: <608@spar.UUCP>
Date: Mon, 21-Oct-85 16:45:54 EDT
Article-I.D.: spar.608
Posted: Mon Oct 21 16:45:54 1985
Date-Received: Wed, 23-Oct-85 06:08:08 EDT
References: <227@rtp47.UUCP>
Reply-To: ellis@spar.UUCP (Michael Ellis)
Organization: Schlumberger Palo Alto Research, CA
Lines: 93

>> I don't believe human beings are deterministic. I also don't accept the
>> laws of physics as absolute. I accept them as an absolutely brilliant
>> model but not as complete truth. I don't accept the notion that the
>> human being is just a very complex machine.
>
>These, however, are *assumptions*.  They are not *proven* by anybody I
>am aware of.

     Electrons, atoms, molecules, biochemical processes, etc..  are not
     causally deterministic mechanisms, at least if the advances in
     knowledge about natural phenomena since 1930 are allowable as evidence.
        
     Therefore, the idea that "our behavior might be deterministic" is
     profoundly unscientific.
     
>By the way, I'd be interested in knowing *why* you "don't accept the
>notion that the human being is just a very complex machine." Do you also
>"not accept" the notion that "the human being is just a primate", or
>that "the human being is just a mammal"?  How about "insects are just
>complex machines"?  "Reptiles are just complex machines"?  "Mammals are
>just complex machines"?  "The (other) primates are just complex
>machines"?
>
>In other words, just what *is* "machine-like" and what is not, and why
>do you draw the dividing line where you do.  I hope you don't think I'm
>being nasty here, I'd really like to know.  I myself don't see any
>definite boundaries here to point to as the reason for definitely
>segregating humans from "machine-like things" (that is, things that
>"merely" follow the "laws of physics").

     The word `machine' is used with many meanings, of course (even
     Searle refers to the brain as a machine that causes mind).
     I do not use the word `machine' this way.

     To many people, machines are things like those our technology has
     produced -- collections of simple inert objects interconnected using
     simple causal relationships, hierarchically constructed so as to
     produce a specific effects in response to associated inputs. The
     machines's goodness is usually related to how precisely that it
     responds to control inputs. Energy efficiency, reliability, modularity
     of design.. are other qualities a `good' machine should possess.

     To my knowledge, animals have some of these qualities. However, their
     designs incorporate many unusual features -- they are autonomous, they
     have minds, feelings, and desires, they anticipate events yet to occur,
     they rely on many nonhierachical design principles (feedback loops,
     interactions between different functional levels) they exist `for
     themselves', they do not lend themselves to understanding in causal
     terms. They are profoundly indeterministic. They evolve.

>> *IS THERE ANYONE THAT AGREES WITH ME THAT THE HUMAN MIND IS PROVABLY
>>  NOT EQUIVALENT TO A TURING MACHINE?*
>
>It would help if you said what proof you are talking about.  If you mean
>"Is Godel's incompleteness theorem such a proof?", the answer is
>"definitely not".
>
>If anybody *does* agree with you that the human mind is *PROVABLY* "more
>powerful than" a general recursive formal system, I'd be interested in
>hearing what they think the proof is.  (In my opinion, God Himself is no
>more powerful than a general recursive formal system :-)
 
    I agree that Lucas's `Goedelization' argument is not very convincing
    in support of the notion that human rationality surpasses that of
    Turing machines. After all, formal logic is something at which
    our digital computers show great promise.

    Where human thinking differs from machine thinking is in its
    fuzzy, holistic, massively parallel characteristics. We not
    only analyze the world in ways that resemble the logical symbolic
    nature of the Turing machine, we also directly experience the world
    without any thinking whatsoever.
    
    Can mental processes really be characterized by a finite number of
    discrete values, transformed from one frame to the next in a recursive
    deterministic way? Who knows? In the past, science has seen us in terms
    of the technology of the age -- as pulleys and gears, then as analog
    electronics, then in terms of stimulus/response and reinforces, and
    now Turing machines.

    These different models have all helped science to progressively add to
    our knowledge, but I doubt that we have come anywhere close to a true
    understanding of ourselves. Basically, we do not have enough of a grasp
    of what mind is to rigorously compare its powers with those of a Turing
    machine.

    Personally, I do not believe that our current models yet possess enough
    descriptive power to explain the qualities of living consciousness. For
    one thing, any reductionistic model that depends on classical causal
    notions is already too weak -- such models cannot even explain the
    workings of simple electrons!

-michael