Saturday, October 9, 2010

Is "Darwinism" Supported by Metaphysics Rather than by Evidence?

Why keep you in suspense, assuming I could?  No, evolutionary theory is supported by evidence.

This is not, however, conceded by Cornelius Hunter, who in his latest blog article again informs us that evolution is supported only by arguing against design, and not by actual evidence.  This perversely ingenious argument, the centerpiece of his book Darwin's God, was earlier raised by Phillip Johnson in Darwin on Trial, who argued that while it was utterly legitimate to invoke a Designer as an explanation for complex adaptions, it was illegitimate to argue that some designs in nature make no sense in terms of either human design philosophies or those traditionally ascribed to God.  This was, he declared, an attempt to introduce theology into a purely scientific question.  I could not quite see Johnson's point, and cannot quite see it when Hunter raises it again: on the one hand, how can you allow God as a scientific explanation, yet disallow theological arguments?   Conversely, if the Designer need not be God (an argument advanced now and then by ID proponents) , then speculation on the Designer's nature and motives is not necessarily theological.

Hunter sometimes seems to strain to avoid understanding arguments.  He repeats Darwin's comment that much of biology is "utterly inexplicable if species are independent creations," and wonders what scientific experiment could test it.  Hunter conflates "explanation" with "logically conceivable cause," and neglects the obvious point: a Designer of sufficient power and perversity could in principle be the cause of any set of biological facts, but that would not tell us why the Designer, e.g. put identically-disabled pseudogenes in humans and other old-world anthropoids, or why He came up with so many different variants of the proboscidean body plan over millions of years (to pick a couple of examples Hunter discusses).  It could not tell us why the Designer chose to make things one way rather than any number of other possible ways.  Evolutionary theory can tell us why such things are so.  

Evolutionary theory makes myriad testable predictions; ID makes one: evolutionists will not be omniscient; sometimes they will be unable to explain things and sometimes they will be wrong.  To Hunter, though, all this counts for naught: the only evidence for evolution is the metaphysical assumption that "if God were real, He wouldn't do it that way."  To be sure, he does harp frequently on the admittedly numerous successes of ID's only prediction.

Hunter posts some of Kenneth Miller's testimony from Kitzmiller v. Dover, though, in which Miller says that evolution wouldn't do it some way: i.e. evolution wouldn't cause humans, other apes, and old world monkeys to share identically-disabled pseudogenes if we didn't inherit them from a common ancestor.  Hunter argues that Miller is simply trying to hide the anti-God metaphysics of evolutionary theory here, and committing perjury by misstating the evolutionists' argument.  But in fact, evolution (almost certainly) wouldn't do it "that way."

There are many ways to disable a gene and turn it into a pseudogene.  Guinea pigs, like old world anthropoids, have a pseudogene for the GULO (or lGGLO) gene that in most animals helps them make vitamin C.  This is presumably because guinea pigs, like anthropoid primates, get a lot of vitamin C from the fruit in their normal diets and don't need to make their own vitamin C.  But in guinea pigs, the GULO gene is disabled in a distinctly different manner from the way that the primate pseudogene is disabled.  From this, it is obvious that, even if there is some natural selective advantage to having the gene disabled if a species eats a lot of fruit, we would not expect the same disabling changes just by wild random coincidence in humans, chimpanzees, gorillas, orangutans, gibbons, and macaques.  If the pseudogenes arose independently, we'd expect them to be disabled in different ways in different "kinds."

Note that this argument does not depend on the assumption that "Darwinian" evolution is at work.  It applies equally to Lamarckian evolution (in which separately-originating lineages "climb the evolutionary ladder" in parallel), or to any other sort of evolutionary mechanism or design scenario one might conceive.  If there's more than one way to disable a gene to make it a pseudogene, and both are found in nature, then branching descent with modification is the only reasonable explanation for the distribution of these genes we find.  There might be an unreasonable but true explanation: a perverse Designer, or insanely unlikely coincidences in the course of some utterly non-Darwinian sort of evolution, but why would it be reasonable to prefer an unreasonable explanation to a reasonable one, an explanation that yielded no testable predictions to one that could?


  1. Haven't read Hunter, but is it possible his argument is some variation on this one (which I've heard from Paul Nelson and other ID folks)?

    1. Opponents of "equal time" type laws typically insist that teaching standard evolutionary theory is religiously neutral;
    2. Much of the evidence adduced for evolution comes in the form of arguments from "undesign" (the panda's thumb, disabled genes, etc.);
    3. But arguments from "undesign" implicitly or explicitly make theological claims about what a creator/designer (God, to put it bluntly) would or would not have done;
    4. So it should not be argued that creationism/ID is religious, but standard evolutionary theory is not.

    (This would be less an argument about whether standard evolutionary theory was well-attested than one about whether teaching it in public schools meets certain standards of U.S. law.)

  2. Hunter raises exactly that point, although he doesn't usually apply it explicitly to the constitutionality of teaching "both sides" in public schools; he's trying to make a more general case. On the other hand, in this particular post, he seems to make a claim stronger than Nelson's: that evolutionary theory must make theological arguments, even when its proponents seem to be avoiding them (e.g. Miller must mean "God wouldn't do it that way" even when Miller says "evolution wouldn't do it that way."

    I'm not sure what, other than Hunter's actual beliefs on the matter (which would not seem to be a matter of constitutional law) would prevent the same logic from applying to, e.g. teaching in geology class about the age of the Earth, or in astronomy class about the evidence for heliocentrism.

  3. Well, if I wanted to play Designer's Advocate for the moment I might say, "In the case of geology, we begin with a well-attested natural principle (the half-lives of certain isotopes) and the conclusion proceeds directly from that principle; in the case of evolution, we begin with a set of brute facts (e.g. certain organisms have certain genes disabled in identical places) and conclusion proceeds from an assumption that these resemblances are a product of common descent rather than design."

    In propria persona I'd probably re-reply by saying something like "every scientific theory begins with the assumption that patterns come from natural causes rather than unaccountable, supernatural interventions." Anything you would add?