Monday, March 11, 2013

Evolution and the Mind/Body Problem

by Mike Dorf

Just before I began my lecture at Tulane last week, an otherwise-sophisticated audience member with whom I was chatting asked me "what's Cartesian dualism?", referring to a term in the title of my talk.  I made a joke about how I didn't want to spoil the surprise of the lecture, but the question led me to devote a couple of minutes in the lecture to explaining what I meant by the term: namely, the so-called mind/body problem.  I explained that Descartes struggled with the problem and that modern scientists don't have a satsifactory answer either. The question is this: How do purely physical processes in the brain (and elsewhere in the nervous system) give rise to the mental phenomenon of consciousness?  Neuroscience teaches that physical processes in fact cause consciousness (in humans and many other animals), but the physical events in the brain are not themselves consciousness.  Thus we are left with a puzzle.

In my lecture, I simply noted the puzzle and moved on, because I was not, after all, giving a lecture on science or philosophy.  My point was that something like the mind/body dichotomy might be what judges and Justices are thinking about when they distinguish between events in the world that can give rise to cognizable "injuries" in federal court and those that cannot.  I ultimately rejected that dichotomy as unsound if offered as a justification for the doctrine, however.  There are numerous non-physical setbacks to wellbeing that count as injuries.  I gave the example of the tort of intentional infliction of emotional distress as a fairly routine one.

Here I want to come back to the mind/body problem in its own domain.  Tom Nagel, the NYU philosopher and longtime co-convenor of what was generally just called the "Dworkin/Nagel" seminar on law and philosophy, has written a new book in which he argues that our failure to solve the mind/body problem is indicative of deeper problems with materialist neo-Darwinism.  At least according to a recent review by biologist H. Allen Orr, Nagel's argument gets biology wrong in an important way.  I haven't read the Nagel book yet, but I think there's probably a still deeper problem with the Nagel view.

At least according to Orr (and again, I want to emphasize that I haven't yet read the Nagel book, so I'm assuming that Orr has accurately described Nagel's argument), Nagel's book argues that Darwinian natural selection seems implausible without some as-yet-unknown teleological force in the universe--something that drives evolution towards consciousness.  Orr notes that Nagel does not insist that this force must be Divine; indeed, Nagel is an atheist; but the idea is that random events won't plausibly produce consciousness without something in nature that drives towards consciousness.  I think Orr shows why Nagel's intuition that random forces cannot produce consciousness is almost certainly wrong.  I would add to Orr's argument that Occam's Razor points against Nagel's hypothesis as well.  None of the known laws of nature is teleological and teleology is certainly not necessary to produce the evolution of consciousness, even on Nagel's account.

But Nagel's critique of neo-Darwinianism is misguided not only because it puts him in the company of creationists and other cranks.  It's also completely beside the point because the mind/body problem is a problem regardless of whether consciousness is the product of neo-Darwinian evolution or some teleological process or, for that matter, even if the Biblican account of Creation in six days is literally true.  The problem for us, as it was for Descartes (who was, after all, a Christian), is that we don't have an account of how physical events produce mental events.  Or vice-versa, since mental events (like the thought "I shall blow my nose") also produce physical events (like the complex set of movements of my arms, hands and fingers that are involved in my blowing my nose).

Religion doesn't provide anything other than a hand-waving sort of answer.  You might say that human beings consist of bodies plus souls, and the mental phenomena occur in their souls, but this would have to be immediately amended to cover all animals that exhibit intentionality.  Descartes himself would have resisted this amendment, as he equated consciousness with reason, which he believed only humans possess.  But the problem is not how reason is produced.  The problem is how consciousness is produced.  In any event, even limiting our puzzlement to humans, saying that humans have souls tells us nothing about how those souls interact with bodies.  It simply reproduces the mind/body problem as the "soul/body" problem.

I want to be clear that I agree with Nagel, and with Orr for that matter, that the mind/body problem really does look like a problem.  But it is a quite distinct problem from how consciousness arose.  It is possible, I suppose, that the neo-Darwinian account of evolution will eventually have to be supplemented with some teleological account of the origin of consciousness AND that this account will also lead to some breakthrough in our understanding of the interaction between physical and mental events.  On the evidence we now have, however, I don't see any reason to expect such a development.  I would be especially interested if any readers who have read Nagel's book might shed further light on the matter in the comments.