In a lengthy comment to my post on probability and evolution, I pointed out that for scientists engaged in biological research, natural selection is not an abstract principle. It is not something that is invoked casually as a catch-all explanation for whatever complex biological system crosses their path. Rather, it is a tool that they use for generating testable hypotheses about the origin and history of whatever they are studying.
This point is highly significant, since anti-evolutionists tend to argue at a very abstract level. This is especially prominent in the work of William Dembski, who tries to use abstract mathematical arguments to argue in principle against the ability of natural selection to craft complexity. It is trivial to poke holes in his arguments on the merits. But even without that there would be reason to be skeptical, for the reason I have given in several recent posts. When the physical evidence strongly implies that something happened, but an abstract mathematical model says it cannot happen, there is probably something wrong with the model.
After posting my comment, I wandered over to the blog of the National Center for Science Education. You can imagine my surprise when I noticed that Glenn Branch had been writing about similar issues. In this post he discusses Dembski’s idiosyncratic take on the subject of falsifiability. It is a continuation of this earlier post on the same subject. The part that caught my eye was this:
Scientists who actually are engaged in investigating the evolutionary history of the bacterial flagellum aren’t interested in what processes could or could not produce the system; they are interested in what processes in fact produced the system. And their hypotheses about those processes are falsifiable; for example, when Mark Pallen and Nicholas J. Matzke suggested in a 2006 paper in Nature Reviews Microbiology that the ur-flagellum arose from mergers between several modular subsystems, they were going out on a limb, empirically: their hypothesis would be falsified by, e.g., the discovery that the flagellum predated those subsystems.
Bingo! That is precisely the point I was making. Branch goes on to write:
The only argument, if it can be called that, on offer in Dembski’s books seems to be based on the observation that despite the fact that there is not presently a generally accepted and thoroughly detailed explanation in “Darwinian” terms of the origin of the bacterial flagellum, scientists are confident that such a explanation is in principle possible. (In principle, even if it is ultimately unavailable to us, e.g., if the evidence necessary for distinguishing between alternative scenarios is no longer available due to the passage of time—a common problem in the historical sciences). The observation is reasonable; the conclusion that Dembski bases on it is not. For Dembski regards such confidence as manifesting nothing more than a dogmatic commitment, come what may, to the unfalsifiable doctrine of “Darwinism”: “Darwinism is wonderfully adept at rationalizing its failures and therefore just keeps chugging along.”
But, again, scientists who actually are engaged in investigating the evolutionary history of the bacterial flagellum aren’t interested in “Darwinism” as Dembski and Behe define it; they’re interested in framing and testing hypotheses about what processes in fact produced the bacterial flagellum. Hypotheses that appeal to natural processes are, by and large, testable, so it’s not surprising that those scientists are inclined to concentrate on them. If there were alternatives that were testable, then they would not be necessarily disregarded; there’s no dogma in place. Rather, the proponents of “intelligent design” have consistently failed to present any testable hypotheses of their own, instead hoping to batten on the supposed failures of evolution.
The Pallen/Matzke paper referred to by Branch is just one of a very long list of possible examples. George C. Williams discusses others in his book Plan and Purpose in Nature, as does Ken Miller in Finding Darwin’s God. Several of the contributions to the Edis/Young anthology Why Intelligent Design Fails provide still further instances.
The bottom line is that scientists are not going to abandon a highly successful research program just because some creationist waves his hands and slings some jargon. The critics will have to do better.