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Article 6105 of comp.ai.philosophy:
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>From: rickert@mp.cs.niu.edu (Neil Rickert)
Subject: Re: Homunculus and the witch's brew
Message-ID: <1992Jun5.170951.3442@mp.cs.niu.edu>
Keywords: computation, transduction, homunculus, sensorimotor physiology
Organization: Northern Illinois University
References: <1992May31.212826.1778@news.media.mit.edu> <1992Jun1.020633.15541@Princeton.EDU> <BpDor5.J5B@psych.toronto.edu>
Date: Fri, 5 Jun 1992 17:09:51 GMT
Lines: 70

In article <BpDor5.J5B@psych.toronto.edu> michael@psych.toronto.edu (Michael Gemar) writes:
>In article <1992Jun1.020633.15541@Princeton.EDU> harnad@phoenix.Princeton.EDU (Stevan Harnad) writes:
>
>[in response to Minsky's claim that transducers involve many-to-one mapping]
>
>>Marvin, I'm not an engineer, so if I've picked a technical term that is
>>at odds with my intended meaning, I'd be happy to susbstitute the
>>correct one for it (what is the correct one?). I had no idea that a
>>many-to-one mapping was criterial for a transducer. I would have wanted
>>a term that leaves room for 1:1 analog transformations and through-put
>>too, as the dictionary definitions below do. Physiologists, I believe,
>>often refer to the sensory surfaces as transducers, yet many of those
>>simply transduce (traduce?) input in analog form. (But I have to add,
>>as a point of logic, that even if transduction refers only to a
>>many-to-one conversion, that does not necessarily make it homuncular.)
>>-- SH
>>
>>Collins:
>>trans+duc+er (traenz`dju:s) n. any device, such as a microphone or
>>electric motor, that converts one form of energy into another.
>>[C20: from Latin transducere to lead across, from
>>trans-+ducere to lead] 
>>
>>Websters:
>>transducer
>>L [italic transducere] to lead across, fr. [italic trans-] + [italic 
>>ducere] to lead -- more at [mini TOW]
>>a device that is actuated by power from one system and supplies 
>>power in any other form to a second system (as a telephone receiver 
>>that is actuated by electric power and supplies acoustic power to the 
>>surrounding air)
>
>These are the kinds of definitions that I would use as well, and they seem
>completely at odds with your claim that much of the *brain* involves
>transduction.

  I believe you are missing the point.  If I understand what Harnad is
claiming, I believe he is claiming that intelligence is not merely a
property of the brain.  At least some of the transductions he is
referring to occur outside the brain, and he believes these are
important to human intelligence.  Thought processes are known to
measurably affect other organs of the body, which in turn produce further
input to the brain.

  Let me add that I fully agree with this view of the importance of
such transduction to human intelligence.  My disagreement with Harnad
is that I do not accept that this implies any necessity that artificial
intelligence must completely follow the same route.

>               As I understand the term, transduction involves the conversion
>of energy from one form into another.

  This is a good definition, although perhaps it is excessively fussy to rule
out the case where the output energy form is the same as the input
energy form.  What is not allowed, however, is for the output to have
significant additional information content that was not already present in
the input.  This disallows treating the human as a single transducer.  But
remember that Harnad clearly admitted that is "You are a transducer" was
a substantial over simplification.

>                                       In the case of humans, *all* conversion
>of forms of energy occurs at the extreme periphery of the nervous system.

  I essentially agree, although it is possible to quibble.  But that does
not rule out the possibility that human intelligence might depend
significantly on information paths which leave the nervous system through
a transducer and then reenter through another transducer, with possibly
some additional information transformations occuring external to the
nervous system.



