Teleology

 From Leroi

Although I have counterposed, as he does, Aristotle’s use of teleological and material explanation, he clearly thinks that usually there is no conflict between them at all. When explaining the association of parts he sometimes appeals to functional harmony, sometimes to bodily cconomics, but often ecumenically opts for both. Rays have cartilaginous skeletons because they need to be flexible given how they swim and because, having spent all their earthy matter on their hard skins, they don’t have anything left for the skeleton. Such double-barrelled arguments appear to be redundant, but in fact they're not; they are merely missing an additional premise. For Aristotle, functional demands and the allocation of resources are harmonized because ‘nature does nothing in vain’. In their Principles of Animal Design (1998) Weibel and Taylor call this the ‘principle of symmorphosis’. 

The history of Western thought is littered with teleologists. From fourth-century Attica to twenty-first-century Kansas, the Argument from Design has never lost its appeal. Aristotle and Darwin, however, share the more unusual conviction that though the organic world is filled with design there is no designer. But if the designer is dead for whose benefit is the design? It’s the prosecutor’s question: cui bono? 

Darwin answered that individuals benefit. Biologists have batted the question about ever since. The answers that they’ve essayed are: memes, genes, individuals, groups, species, some combination or all of the above. Aristotle, however, generally appears to agree with Darwin: organs exist for the sake of the survival and reproduction of individual animals. This is why so much of his biology seems so familiar. 

Yet there isa deep difference between Aristotle’s teleology and Darwin's adaptationism, one that appears when we follow the chain of explanation that any theory of organic design invites. Why does the elephant have a trunk? To snorkel. Why must it snorkel? Because it’s slow and lives in swamps. Why is it slow? Because it’s big. Why is it big? To defend itself. Why must it defend itself? Because it wants to survive and reproduce. Why does it want to survive and reproduce? Because... 

Because natural selection has designed the elephant to reproduce itself. Darwin gave teleology a mechanistic explanation. He halted the march of whys. It is for this reason that Ogle celebrated Darwin as Democritus reincarnated. For, where Aristotle’s organismal teleology is imposed upon recalcitrant matter, Darwin showed how, given a few simple conditions, it emerges from it. Darwin is an ontological reductionist; Aristotle is not. 

Why, then, should Aristotelian animals strive to survive and reproduce? Aristotle can hardly invoke natural selection. (He’s dismissed at least one version of it.) He could have said ‘they just do’, and left it at that, but then he would not be Aristotle, so he does have an answer, beautiful and a little mystical. Living things, he says, desire to survive and reproduce so that they can ‘participate in the eternal and the divine’. When he asserts that living things desire to participate in the eternal he means that they are designed not to become extinct. Cui bono? It turns out that organismal design is not, after all, for the sake of individuals, for they always die, but to ensure that their forms kinds, their species, persist for ever. 

When Aristotle speaks of the divine he is not the point must be made again invoking a divine craftsman for none exists; rather, he is telling us that immortality is a property of divine things and that reproduction makes animals a little bit divine. 

We are beginning to touch on Aristotle’s theology, his ultimate explanation for why the cosmos is arranged the way it is and its relationship to an immortal God. Why should animal kinds be immortal? This is where we come to the end of explanation, to one of those indemonstrable axioms that lie at the bottom of every Aristotelian science, and from which all else flows, and it is simply this: it is better to exist than not to exist.