From: tobis@meteor.wisc.edu (Michael Tobis)
Subject: Re: Brain and Mind (was: Logic and God)
Organization: University of Wisconsin, Meteorology and Space Science
Date: Thu, 8 Oct 92 21:16:40 GMT

In article <1222@tdat.teradata.COM> swf@tdat.teradata.com (Stanley Friesen) writes:
>In article <1992Oct6.204155.13168@meteor.wisc.edu> tobis@meteor.wisc.edu (Michael Tobis) writes:

>|My point is that, since presumably most procedures are not conscious, since
>|it is so widely believed that some procedures are conscious, it is
>|problematic what sort of distinction arises between them.

>True, until we have some characterization of what constitutes consciousness
>in the human brain, we cannot precisely formulate what is necessary for
>a process to be conscious.

>However, the fact that the brain, performing physico-chemical operations,
>can achieve it indicates that at least *one* process achieves consciousness.

Well, it indicates that there is a process, but it indicates nothing about
whether that process can be properly described as algorithmic. Your -chemical
caveat seems designed to include Searle on your side here, which is fair
but I would note that it also indicates that the process isn't as fully
explained as you seem to imply.

>The only way in which it can be shown that the execution of an algorithm
>of some particular sort cannot achieve consciousness is to show that some
>critical portion of the process used by the human brain is not representable
>as some algorithm.

We are in disagreement as to where the burden of proof lies. 

[...]

>But you *are* making 'extravagant' claims about consciousness.

I don't make extravagant claims about it. Consciousness exists. That is
extravagance enough. To claim that you have "explained" it is dubious, though,
while merely to claim that it exists hardly is.

>What is subjectivity other than some form of recursive self-modelling?

I see no meaningful content in that question, since a model is not a model
without a consciousness to interpret it.

>|In particular, the defense that a Chinese understanding consciousness
>|somehow comes into existence contingent on my following some rules seems
>|to be flawed. Those who insist on defending its existence should come
>|up with plausible arguments as to what makes them believe that the sequence
>|of rule-implementations could be conscious, when clearly no individual
>|rule-implementation can be.

>Analogy with nuerons, for which the same arguments acan be made.
>No single neuron can be conscious, only a properly designed system composed
>of many interacting neurons can be so.

Well Searle, and apparently Penrose, think there are physical characteristics
of the brain that are not representable algorithmically or at least
not functionally identical with their algorithmic representation. There is much
room for doubt in your hypothesis that the essential feature of the neurons
is their algorithmic nature. On the other side, we have a phenomenon of
subjective existence that is not obviously reducible to physical processes.

>If I used your argument, I would have to conclude that consciousness is
>impossible, and must not exist, since a system of multiple parts cannot
>have features not intrinsic in the parts.

That is actually not too far from my position. I think consciousness
is utterly mysterious, and we ought to at least respect that fact as
long as it remains the case.

I can claim that a starfish has pentagonal symmetry, even though the
cells of the starfish do not have that property. However, I can define
that property in terms of the parts. In any other case where a property of
a whole "emerges" from the relationship among the parts, I can, at least
in principle, provide a formal definition of the property in terms of the
relationships among the parts. To claim that the situation regarding
mind and brain is comparable misses the point entirely. Consciousness
is not defineable in terms of the relationship among the parts in any
obvious or even obviously plausible way. The gap between subjective 
experience and physiological facts is not one that has been bridged by
defining one in terms of the other. 

And as I have said before, it is hard for me to see, if a plausible
proposal arises that goes beyond handwaving about recursion and emergent
properties, how such a hypothesis can be verified, since no objective test
for the existence of subjective experience exists.

>You seem to be a bit behind in neurobiology.  A great many components of
>brain function are understood now, more than most people realize.

I think I know about as much about it as the average scientist who is not in 
AI, psychology, or the life sciences.

>Furthermore, there is tremendous evidence, from deficit studies, simulated
>neural network studies, PET scans, neural connectivity studies, and others
>that most, or all, sorts of capabilities shown by humans can be, and are,
>generated by the activities of the components of the brain (mostly neurons).

I do not deny that the brain has something to do with it. I just deny
that we know what that is, or even have anything resembling a hypothesis
of what that might be.

>Thus, the idea that there is more there *does* become unscientific, in that
>it lacks any supporting data, and makes no testable claims.

Well, the supporting datum is my experience, admittedly a lone observation
but a pretty robust one. I can't really demonstrate this datum to you,
but I can hope you have a similar observation available to yourself.
This phenomenon is not defineable in terms of or reducible to any known
physical processes.

>Thus, in the absence of any evidence to the *contrary* it is more appropriate
>to tentatively assume that the physical components of the brain are sufficient
>to explain its operation.

I have no objection to the tentative assumption. I only object to treating
that assumption as demonstrated fact. Stating assumptions clearly, and
showing assumption A implies result B is science. Tacitly assuming A and
claiming B is demonstrated because A implies B is not science. Hiding
assumption A behind a wall of authority and mystification may reduce the
controversiality of assertion B but it doesn't increase its certainty.

mt