Wednesday, January 23, 2013

"Nagel's nonsense on evolution"

In a tweet, Steven Pinker alerts us to an article by H. Allen Orr titled "Awaiting a New Darwin," a piece that Pinker characterizes as "another devastating review of Nagel's nonsense on evolution, in NYRB [The New York Review of Books]." Nagel is an atheistic philosopher who is nevertheless unsatisfied with the current reductionist-materialist explanation of the universe, life, and consciousness. His counterproposal is the sketch of a theory that Nagel styles naturalistic teleology, i.e., the idea that nature tends toward certain physical/evolutionary ends. Without this teleology, Nagel argues, science has no plausible explanation for the existence of evolved life, which could not possibly (according to Nagel) have reached its current level of proliferation and complexity through a mere series of accidents (in my opinion, this is a common misinterpretation of current evolutionary theory).

On reading this, I was reminded of Jacques Monod's Chance and Necessity (Le hasard et la nécessité in the original French), which speaks of "teleonomic" behavior in living organisms: ordered behavior tending toward definite ends, such as survival and reproduction.* Nagel seems to be suggesting that the entire universe has a teleonomic aspect-- a claim that Pinker, who may be in line to replace the acerbic Christopher Hitchens as the fourth of the Four Horsemen of atheism, obviously scoffs at. Nagel critic H. Allen Orr writes in his review:

Nagel’s teleological biology is heavily human-centric or at least animal-centric. Organisms, it seems, are in the business of secreting sentience, reason, and values. Real biology looks little like this and, from the outset, must face the staggering facts of organismal diversity. There are millions of species of fungi and bacteria and nearly 300,000 species of flowering plants. None of these groups is sentient and each is spectacularly successful. Indeed mindless species outnumber we sentient ones by any sensible measure (biomass, number of individuals, or number of species; there are only about 5,500 species of mammals). More fundamentally, each of these species is every bit as much the end product of evolution as we are. The point is that, if nature has goals, it certainly seems to have many and consciousness would appear to be fairly far down on the list.

Similarly, Nagel’s teleological biology is run through with talk about the “higher forms of organization toward which nature tends” and progress toward “more complex systems.” Again, real biology looks little like this. The history of evolutionary lineages is replete with reversals, which often move from greater complexity to less. A lineage will evolve a complex feature (an eye, for example) that later gets dismantled, evolutionarily deconstructed after the species moves into a new environment (dark caves, say). Parasites often begin as “normal” complicated organisms and then lose evolutionarily many of their complex traits after taking up their new parasitic way of life. Such reversals are easily explained under Darwinism but less so under teleology. If nature is trying to get somewhere, why does it keep changing its mind about the destination?

Alfred North Whitehead's process philosophy (and, by extension, the process theology of exponents like Charles Hartshorne, John Cobb, et al.) makes a similarly anthropocentric move: it contends that humanity represents something of a leading edge, the wave-front of a creative (and wastefully destructive) evolutionary process. Process philosophy is comfortable with the idea that life tends ever towards greater complexity, a notion that makes sense only if one assumes humanity (or any sapient life) to represent a sort of culmination, Omega Point, or crème de la crème of cosmic process. Orr is right to dismiss Nagel's pretensions, so similar to the claims of process philosophy, by citing the empirical fact that most life on earth is neither sapient nor particularly complex: the idea that life on the whole tends toward complexity is demonstrably false.

*On the pop-culture front we have Agent Smith in "The Matrix Reloaded" who, right before he and a hundred Smith replicas engage Neo in a massive kung fu battle, gives an impressive speech about the importance of purpose for any living being.


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