The Mind/Body Debate
Dennis L. Feucht
5275 Crown St.
West Linn, OR 97068
From: PSCF 43 (March 1991): 71-72. Response: Dembski
I would like to respond to several points in Dr. Dembski's rather substantial paper on the mind-body problem and cognitive science ("Converting Matter into Mind," December 1990 Perspectives). First, artificial intelligence (AI) and cognitive science are not distinguished in the paper but they are not the same. AI is not constrained to devise models that represent the findings of cognitive psychology and the neurosciences. Consequently, AI is not bound to model the mind of human beings, and largely does not attempt to. (Scan the titles of the MIT AI Lab bibliography; very few would have anything to do with mind modeling.) Perhaps "knowledge engineering" would be a better descriptor than AI in that the emphasis is on what can be done to automate that which we attribute to cognition, perception and actuation in humans and also animals.
For cognitive science, it would be a medieval saving of the phenomena to consider models of mind and simulation ("the exhaustive imitation of behaviors requisite for intelligence" [p. 208]) to be a spurious distinction. Whether Zenon Pylyshyn is correct or not about computation being the right model (if any), he is not merely attempting to imitate mental behavior. Some of the models of early science were inadequate in capturing the richness of that which they modeled, but were nevertheless an attempt to express its inherent rationality. Perhaps computation is the wrong form of representational theory for mind, but to settle for ways of accounting for mental activity without understanding its underlying rationality is to fail to do science.
In Hans Moravec's book, Mind Children, while some materialist presuppositions are evident (namely, references to Richard Dawkins' blind watchmaker), it is unfair to criticize his predictions of "Human Equivalence in 40 Years" (p. 68) on philosophical grounds since he gives a scientific basis for it. (Moravec is director of the mobile robot lab; Raj Reddy is director of the Robotics Institute.) He extrapolates computing power per dollar in time and estimates the amount of computation in the human brain. The issue here is not how information-theoretic analyses of neural behaviors relate to intelligence or personhood but instead how much is going on, by computational measure, in the brain. The curve fit is fairly good, and by 2030 A.D., 1014 bits/s (at $1,000) equals his estimate for brain activity. The real issue is whether, given this much computational power in a PC, it could be made to satisfy reasonable criteria of intelligence.
The more substantial point Dr. Dembski addresses, however, is the underlying mind-body assumptions of Moravec's (and others) prophecies. Even Moravec, though showing no Christian leanings, tends to hol--"the process going on in my head and body, not the machinery supporting that process. If the process is preserved, I am preserved. The rest is mere jelly" (p. 117). MacKay's view, like Michael Polanyi's ("Life's Irreducible Structure," Science 160, 1968) or my own ("The Mind-Brain Problem..." JASA, December 1986) is a multi-level or hierarchically-based explanation.
Though words such as emergence can be used to describe the relationship between levels, the description Dr. Dembski gives of supervenience does not accurately describe these multi-level views. Lower levels do not constrain higher levels in a way that results in reductionism. A particular higher level need not result from a lower level. The lower-level constraints are necessary but not sufficient to determine higher levels. A higher level is free to be organized within the constraints of the lower level, but these constraints by no means determine what the higher level is. Levels are related by the appropriate representational theory; a causal theory relates structural and behavioral levels but a functional or teleological theory is needed to relate behavior to function. Dr. Dembski's "semi-materialism" is not epiphenomenalism without causation.
MacKay's free will argument, based on self-referencing logic, addresses the Parable of the Cube problem and the relationship of God's (presumed) determination of the physical world without freedom of will, though the author did not address it. In my view, the mind is as real as the brain (or body), but does not exist in our space-time apart from it. Our awareness of our mind is independent of our knowledge that it is related to or sustained by our body. Consequently, we know in the most immediate, existential way of the reality of something that is not material in itself. But it does not necessarily follow that mind exists non-materially in the same way that matter exists materially. That is, why must we assume that our explanation for the soul (like our explanation for the body) is best understood according to a structural theory; why not a functional (or other) theory instead? Our understanding of the I of the mind/body is not independent of I, for it is us as minds/bodies who are contemplating it. Sorting out epistemological distinctions between mind and body from ontological ones is central to the issue. That is why I or patterns of matter are as real as the matter that embodies them, while also being dependent upon them. This approach is not materialism, not semi-materialism, nor spiritualism.
The material body/non-material (spiritual) soul/mind dualism creates plenty of its own problems. How does the spiritual relate to the physical? Are they differentiable or simple substances? Is there a separate "spiritual physics" or are we to assume that spiritual/physical interactions are ultimately unknowable? By what mode do these spiritual entities exist? The problems posed by physical/spiritual dualism encumber us with the kind of questions that preoccupied the medievals (such as Aquinas) and Platonic Greeks. In contrast, the biblical or Hebrew perspective, such as from the Apostle Paul, viewed the soul (nephesh) as primarily his vitality, his life_never a separate "part" of man. (I Believe in the Resurrection of Jesus, George Eldon Ladd, Eerdmans, 1975.) Paul shrunk back from a non-embodied state of existence (2 Corinthians 5:4) in acceptance of full creaturehood as the way God upholds our existence in this age. Even in the age to come, we will be embodied "with a heavenly body." This is far from being a disembodied spirit or immortal soul, a doctrine of the Orphic sect, the spiritual ancestry of Plato. Instead, the biblical affirmation is that we will be a resurrected body in a renewed world.
Finally, after saying all this, I commend Dr. Dembski for challenging our thinking on this difficult topic. It is important and he has presented much with which to stir up our thinking in our common quest for knowing the truth about the nature of our existence.