06 April 2005

Notions of Evolving Form

The key paragraph of Fran O'Rouke's "Aristotle and the Metaphysics of Evolution" is this:

Although Aristotle never espoused it, I suggest that with certain modifications his metaphysics is compatible with evolution, understood as the development of virtualities latent within specific form. This would entail extending the meaning of potency beyond individual members of the species, viewed in isolation, to the prospective potency of the entire species, that is, beyond the phenotype to the genotype and genepool itself. Such evolution would be governed for Aristotle by a teleonomy rooted in the bond between formal and final causes, and influenced by the external circumstances of generation (45).
But on this picture, wouldn't an earlier species become, then, the (logical) genus, in relation to which a later species, evolved from it, would be a (logical) species--because that later species would be just one among various definite ways in which the earlier kind might have evolved, and therefore one among various possible specifications of it? --Not that that's a bad result, since the science of cladistics, I believe, classifies living things in roughly that way.

Yet even if this suggestion were sound, it would render Aristotelian metaphysics compatible only with the fact of evolution, not the mechanism of natural selection. Natural selection is the more difficult case, because it is non-teleological. O'Rourke quotes Stephen Jay Gould who explains that, according to Darwin, chance selection takes place after "variation occurs with no preferred orientation in adaptive directions" (33). I don't see that O'Rourke ever answers this point. After quoting Gould, Ernst Mayr, and others, he simply says:
From the Aristotelian perspective it must be stressed, however, that even if the development of an organ comes about through random mutation, with the nonsurvival of countless unsuccessful stages, whichever one becomes established must be in some sense preordered in the nature of things (34).
But in what sense are developments 'preordered in the nature of things'? Isn't 'preordering' excluded by the mechanism of natural selection? We can't insist that that's how things 'must be' on an Aristotelian perspective, when the soundness of that perspective is what is at issue.


Anonymous said...

I think we can insist that things must be in some sense pre-ordained from the Aristotelian perspective. What we can't simply insist is that the Aristotelian perspective is correct; but taking the issue of the compatibility of Aristotelian metaphysics and 'evolution' on its own, we can insist that things must be pre-ordained from the Aristotelian perspective, simply because it would be hard to see what would remain Aristotelian about it if they weren't. The defensibility of the position is a different matter, of course.

If natural selection can account for everything in the biological world, then it looks like most Aristotelian or quasi-Aristotelian thought has to go. Someone suggested once on this board that recent trends in 'sociobiology' were compatible with Aristotelian ethics on the grounds that a Darwinian causal explanation for the 'human nature' that Aristotle describes does not change that nature. But of course it does, since the nature that Aristotle describes is in very important ways different from the kind of human nature that can be exhaustively accounted for in terms of Darwinian processes. Aristotelian ethics demands a telos for human nature, which Darwinism cannot give it. Furthermore, Darwinian nature cannot be normative in the same way that Aristotelian nature can. If human nature is the source of normativity, yet human nature can admit of indeterminate varieties of change, then norms admit of indeterminate varieties, as well. And on a Darwinian account, the individual members of the human species have much less in common than they would on an Aristotelian account, so the variety would not simply be 'human-nature-as-it-is-in-the-beginning-of-the-21st-century' or even 'human-nature-as-it-is-among-the-Westerners,' but perhaps even 'human-nature-as-it-happens-to-be-among-any-given-human-population.' Perhaps the Darwinian conception of the relationship between an individual member of a species and the species itself would even allow for significantly different 'natures' among individuals.

The options would appear, then, to be something like Protagorean relativism or some kind of quasi-Platonic view positing the ultimate source of normativity as something outside Darwinian nature. The problem for the latter view would be to explain how, on a Darwinian scheme, human beings could have evolved in such a way as to become cognizant of that transcendent source of normativity -- though this seems only a little more difficult than explaining how we could have evolved into beings that can understand mathematics and construct a true theory of evolution by means of natural selection. The problems for Protagorean relativism are, of course, well-known.

So, do we seek a stable element in human nature despite Darwin, or do we seek a stable element in normativity beyond Darwinian nature? Or do we merely seek a more mentally stable and philosophically astute interlocutor than me? ;-)