harnad@elbereth.rutgers.edu (Stevan Harnad) (03/06/89)
So far, few (perhaps none) of the responses to my postings about
Searle's Chinese Room Argument have shown evidence of having adequately
understood either Searle's arguments or my own. In fact, even those
that might appear to some readers to have been the most sympathetic to
some of the points I was making (particularly the points about
subjectivity) seem to be far from the mark. I am accordingly posting
the following clarification about dualism and the status of subjectivity
in the approach to cognitive modeling that I am advocating.
METHODOLOGICAL EPIPHENOMENALISM VS. METAPHYSICAL EPIPHENOMENALISM
The difference between "methodological epiphenomenalism" (MTE)
and "metaphysical epiphenomenalism" (MPE) is this:
MTE accepts that subjectivity exists, is real, and CANNOT BE SHOWN TO
BE the same as any physical structure or process. According to MTE, we
should simply accept this as an unavoidable constraint of cognitive
modeling and accordingly restrict ourselves to the sole
methodologically feasible strategy: To attempt to model only the
objective data -- first, our (total) performance capacity (the TTT),
then perhaps fine-tuning it to include the relevant details of our
brain's "performance" (the "TTTT"). The rest would just be hermeneutics
(overinterpreting our models) anyway, because of the "other minds" problem.
MPE accepts that subjectivity exists, is real, and IS NOT the same as
any physical structure or process. As such, MPE is a form of dualism,
although it agrees with MTE that subjectivity has no independent
causal power; only physical structures and processes have causal power.
The various forms of reductionism (the "identity" theories,
"functionalism," etc.) are NOT epiphenomenalist: They give arguments
(lousy ones, in my opinion) to try persuade you that subjective states
are really the same thing as certain objective states (for identity theory,
certain brain states -- for functionalism, certain formal states).
Unsatisfied with these arguments, MPE bites the bullet on dualism,
whereas MTE points out that there's no practical reason for a cognitive
theorist to commit himself one way or another, or even to worry about
it, from here to theory-complete eternity.
I advocate MTE and am agnostic about MPE.
Ref: Harnad S. (1989) Minds, Machines and Searle. Journal of Experimental
and Theoretical Artificial Intelligence" 1: 5-25
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(609)-921-7771bwk@mbunix.mitre.org (Barry W. Kort) (03/07/89)
Stevan, what would be the name of my model, which is neither MTE nor MPE: I believe that subjectivity exists, and reflects my brain's attempt to assemble a picture of the world, based on bits and pieces of sensory evidence that come trickling through my ears and eyes. I liken subjectivity to the map, which resembles the territory, but which is at best a crude replica. If my senses perceive the phenomena, my brain synthesizes the nuomena-- the theory or model which best explains the phenomena. It seems to me that my brain retains some sort of internal representation which codes for the structure of the external world. While we may be profoundly ignorant of the brain's knowledge representation system, I suspect that science will uncover nature's secret just as we learned how DNA codes for our genetic heritage. --Barry Kort