From: mls@cbnewsm.cb.att.com (mike.siemon)
Newsgroups: talk.origins
Subject: Re: The rise of consciousness
Summary: not algorithmic
Keywords: brain,evolution,consciousness
Date: 1 Sep 92 16:07:23 GMT
Organization: AT&T

In article <emc.715349961@uhura>, emc@doe.carleton.ca (Eli Chiprout) writes:

> But this explanation is going in circles.  You (or Edeleman) 
> are describing an algorithm:

Nope.  That is just what *you* are reading into the rather sketchy
statement I gave of Edelman's thesis.  He argues, rather cogently,
that our mental processes are NOT (in general) algorithmic (this
is not to say that we can't *model* algorithmic processes in the
system we actually employ).  Edelman places learning (especially
perceptual cagtegory formation -- which he has successfully modeled
in the terms of his "neural Darwinism" theory -- and conceptual
links of perceptual categories) in the context of what he calls a
"recognition system."  His type example (the field he is coming
from, after all) is the vertebrate immune system (which, he says,
is evolutionarily related to the nervous system, BTW).  The point
is a three-fold structure (which one will instantly recognize as
having one representation in Darwinian evolution of species)

	o  a source of variation *independent of* the environment
	o  adaptive selection of some variants by constraints in
	   that environment
	o  a mechanism for differential survival of the selected
	   variants to face later selection/adaptation

This whole thing is *very* different from algorithmic computation
a la Turing.  Edelman remarks, about this:

	"The facile analogy with digital computers breaks down for
	several reasons.  The tape read by a Turing machine is marked
	unambiguously with symbols chosen from a finite set; in
	contrast, the sensory signals available to nervous systems
	are truly analog in nature and therefore are neither unam-
	biguous nor finite in number.

	[note: this is *not* in conflict with the purely engineering
	result that *given* a particular range of analog signals, a
	digital representation in finite numbers of bits can faithfully
	preserve any predetermined level of information -- the point is
	rather that we are not given any such engineering specification
	for the operations of our nervous systems]

					"Turing machines have by
	definition a finite number of internal states, while there are
	no apparent limits on the number of states the human nervous
	system can assume (for example, by analog modulation of large
	numbers of synaptic strengths in neuronal connections).  The
	transitions of Turing machines between states are entirely
	deterministic, while those of humans give ample appearance
	of indeterminacy..."		[_BA, BF_, p. 225]

I am not urging that Edelman is "obviously" right and the positions he
critiques wrong -- all sides are currently highly speculative and very
controversial.  Merely that anyone with an interest in the matter should
give Edelman a serious read, see what he is saying and consider the im-
plications for the biology and psychology of mind.  Edelman is concerned
(unlike some of the philosophers arguing in the area) with constructing
testable, biologically well-founded theories and seeing them worked out.
-- 
Michael L. Siemon		The Son of Man has come eating and drinking;
				and you say "Behold, a glutton and a drunkard,
mls@usl.com			a friend of tax collectors and sinners."  And
standard disclaimer		yet, Wisdom is justified by all her children.
Newsgroups: talk.origins