Saturday, April 04, 2009

Aristotle, Darwin, and Marjorie Grene

Marjorie Grene, a retired professor of philosophy at Virginia Tech University, died March 16 in Blacksburg, Virginia, at the age of 98. Her obituary in the New York Times surveys her life.

Grene was a major scholar of philosophy who became known as one of the leaders in the philosophy of biology. When I first began (about 25 years ago) to think about the philosophy of biology--and especially the comparison of Aristotelian biology and Darwinian biology--I studied some of her writings and found them both illuminating and confusing.

Her book on Aristotle--A Portrait of Aristotle (1963)--was illuminating in showing how Aristotle's biology influenced all of his philosophic thought. But the book was also confusing, because while much of what she wrote suggested that Aristotle's biological thought was still defensible today, she also declared that the evolution of species was an "incontrovertible fact" that refuted Aristotle's science. From the evolution of species, it follows that:

"there is no being-what-it-is of each kind of thing, no ultimate and final definition of each natural class of substances, from which, with the necessary definiteness and precision, an Aristotelian science could take its start. We live for better or worse in an evolutionary universe, and, in the last analysis, evolution and Aristotelian science will not mix" (232).

But then in this same book, she seems to criticize Darwin and Darwinian science as unduly mechanistic and reductionistic. "The mysterious multifariousness of living nature, formerly a massive obstacle to mechanistic thinking, was transformed by Darwin's genius into an indefinite aggregate of random changes mechanically maintained. Life itself became machinery, made by no one for no purpose except barely to survive" (228). In later writings, however, she confessed that this was a misinterpretation of Darwinian science based on her then limited understanding of Darwin.

Grene's growing respect for Darwin in her later writings suggested to some readers that she saw common ground between Aristotle and Darwin. For example, David Depew (at the University of Iowa) is a scholarly student both of Aristotle and Darwin who co-authored a book on the history of the philosophy of biology with Grene. He suggests, in his contribution to The Philosophy of Marjorie Grene (The Library of Living Philosophers, 2002), that Grene was promoting a reconciliation between Aristotle and Darwin. But then Grene responded to him by denying this--"I don't want to effect a rapprochement between Aristotle and Darwin."

I am not enough a student of Grene's work to clear up this confusion. But I will say that reading her work--especially the writings collected in her book The Understanding of Nature (1974)--helped me to think through three critical issues--(1) reductionism, (2) teleology, and (3) the concept of species. Even if she herself saw no rapprochement between Aristotle and Darwin, she helped me to see some possible agreement between Aristotelian and Darwinian thinking on these three points. (Chapter 9--"The Ends and Kinds of Life"--of Darwinian Natural Right is my one piece of writing most pertinent to these issues.)

(1) Aristotle denies that living nature can be completely reduced to mere matter in motion. Although some biologists have argued for such materialist reductionism, this has never been achieved, and this failure points to the necessity for hierarchical explanations of life in which higher levels of formal organization cannot be simply reduced to lower levels. For example, the sequence of nucleotide bases in a DNA chain can convey genetic information only if the sequence has not been simply determined by physical-chemical laws.

(2) Although modern science may have refuted the idea of cosmic teleology--the idea that everything in the universe is directed to some hierarchy of ends or purposes--modern Darwinian science must still appeal to immanent teleology in that particular organic processes and particular species show some direction to particular ends. Reproduction, growth, feeding, healing, courtship, parental care for young--these and many other activities of organisms are goal-directed.

(3) Many Darwinians (such as Ernst Mayr and David Hull) have asserted that Aristotle's "essentialist" or "typological" conception of species has been refuted by the "populationist" conception of species in evolutionary science. If Aristotle believed that each species manifested an eternal "essence"--an unchanging set of traits that constitute the necessary and sufficient conditions for defining a species--then the Darwinian claim that all species evolve through history--coming into being and passing away--would seem to deny Aristotle's position.

As I have indicated in my post on David Buller's argument, one could conclude from this that there is no such thing as human nature, because the human species like every other species is a contingent product of evolutionary history that is too variable to constitute an eternal essence. Buller's reasoning is derived from David Hull. And I respond to Buller the way Grene responds to Hull. "Why, just because something does not last forever, should it lack a nature?," Grene asks. "That animals are born and die doesn't mean you can't tell one from another while it lasts, or even after it is dead." Although species are not eternally fixed, since they have evolved from ancestral species, that does not make them any less real during the time of their existence.

Richard Richards, a philosopher of biology at the University of Alabama, has suggested to me another way of stating this idea. Hull and Buller are correct to say that there are no necessary and sufficient conditions--essential conditions in the strong sense--that determine the membership of a living individual in a biological class. But there can still be "diagnostic" traits that distinguish one species from another. So even if there are no "essential" traits in the strong sense that define Homo sapiens, we can still see the stability in the diagnostic traits that identify human beings as human beings. And that's enough for speaking about "human nature." Moreover, Richards suggests, the view of Mayr and Hull that Aristotle was a strict "essentialist" in some strong sense is false.

The Darwinian affirmation of the historicity of life--that both living individuals and the species of life come into being and pass away--is compatible with an Aristotelian study of living nature and human nature. But many people will find this deeply disturbing. Those of a Platonic bent will worry that without eternal essences, everything collapses into a nihilistic flux. Those influenced by Biblical religion will worry that without an eternal Creator, evolving nature provides no enduring standards of thought or action.

But these worries from Platonic philosophy and Biblical religion arise from a false dichotomy of eternal fixity versus incoherent flux. Despite the historicity of nature in evolutionary time, the patterns in living nature are stable enough over long periods of time to enable our apprehension of natural kinds as enduring features of the world.

Shouldn't we consider ourselves lucky to have emerged from the natural history of life as the one form of life capable of studying that natural history and wondering what it all means?

I have elaborated some of these points in other posts.


John S. Wilkins said...

One point on this: I think Aristotle denied that final causes, or aitia, applied to the nonliving world - Plato certainly held a cosmic teleology but I don't think Aristotle did.

Kent Guida said...

Great treatment. In my experience this is the most frequently raised issue in discussions of your work. You are criticized from both left and right, but your position seems far more reasonable than the alternatives. After all, how often is anyone stumped by the question, 'man or not man?' Except maybe Rousseau and the orangutan.

Willem van Hoorn said...

If we take Darwin's personal aesthetics into account, as he describes this in the "Diary of the Beagle", then teleology and evolutionism are probably not incompatible.
In neo-Darwinims this is certainly the case because the splendour of Nature herself has been thrown out as irrelevant to the human mind.

Willem van Hoorn said...

if we take this seriously then Darwin and teleology are not incompatible.