An Argument from Ignorance?
Editor’s note: We are delighted to welcome the new and greatly expanded second edition of The design inference, by William Dembski and Winston Ewert. The following is excerpted from the Introduction.
Tacitly in the first edition of The Design Inference and explicitly in its sequel, No Free Lunch, I argued that natural selection and random variation could not create the sort of complexity we see in living things. My approach in applying the design inference to biology was to piggyback on the work of design biologists such as Douglas Axe and Michael Behe. They had identified certain subcellular systems (e.g., bacterial flagella and beta-lactamase enzymes) that proved highly resistant to Darwinian explanations.
Our joint task was to put plausible numbers to these systems so that even factoring in Darwinian natural selection, the probability of these systems arising was exceedingly small. Note that the specification of these systems, as in their exhibiting the right sort of pattern for a design inference, was never in question. The issue was always whether the probabilities were small enough. In using specified improbability to draw a design inference for biology, I therefore needed to argue that the probabilities for Darwinian processes producing certain biological systems, such as those identified by Axe and Behe, were indeed small.
Misguided and Irrelevant
As far as Darwinists were concerned, however, all attempts to show such biological systems to be vastly improbable were misguided and irrelevant. Any design inferences meant to defeat Darwinian evolution were, according to them, arguments from ignorance. For them, unidentified Darwinian pathways could never be decisively ruled out, so their mere possibility invalidated any design inference applied to biological evolution. In short, no calculated improbability could ever convince the Darwinian critics that the probabilities were actually small.
It didn’t matter that Darwinists were ignorant of any detailed evidence for such Darwinian pathways, and thus had no counter-probabilities to offer. It was enough for them merely to gesture at the possibility of such pathways, as though raising a possibility could itself constitute evidence for an argument from improbability. To ID proponents critical of Darwin’s theory, the argument-from-ignorance objection seemed to apply more aptly to the Darwinists themselves for positing unsubstantiated Darwinian pathways that offered no nuts and bolts, no nitty-gritty, just hand-waving.
No matter. For Darwinists to refute ID, they merely needed to postulate unidentified, and perhaps forever unidentifiable, indirect Darwinian pathways in which structure and function coevolved and led to the complex biological features in question. Brown University biologist Kenneth Miller led the way. Michael Behe had defined a system (biological or otherwise) to be irreducibly complex if its function was lost by removing key parts. He argued that such systems resisted Darwinian explanations. Miller countered that Behe’s concept of irreducible complexity was ill-conceived because removing parts from, or otherwise simplifying, a biological system could always yield a system with a different function. To convinced Darwinists like Miller, design in biology was therefore a nonstarter. Darwinian pathways to all complex biological systems had to exist, and any inability to find them simply reflected the imperfection of our biological knowledge, not any imperfection in Darwin’s theory.
Dawkins’s “Laziness Challenge”
Richard Dawkins, better than anyone, has publicly championed the dogma that Darwinian pathways can and must always exist for any biological system. In a 1990s television interview he memorably took Behe to task for claiming that irreducibly complex biochemical machines, of the sort Behe popularized in Darwin’s Black Box, were beyond the reach of Darwinian processes. Dawkins charged Behe with being “lazy” (yes, he used that very word) for seeing in the irreducible complexity of these machines a reason to conclude design, and thus to rule out any further effort to discover how Darwinian processes could have formed, say, a bacterial flagellum. That is, instead of concluding that these systems were designed by a real intelligence, Behe should get back into the lab and redouble his efforts to discover how Darwinian evolution could have produced them apart from design.
The reaction of the ID community to Dawkins’s “laziness challenge” was that he might just as well have recommended to physicists that they keep trying to construct a perpetual motion machine. Yet why did one task seem futile (constructing a perpetual motion machine) but not the other (discovering Darwinian pathways to irreducibly complex biochemical machines)? Physicists had the second law of thermodynamics to rule out the charge of laziness. That’s why Dawkins would never have said to a physicist, “You’re just being lazy for giving up on inventing a machine that can run itself forever.”
Even so, Dawkins’s “laziness challenge” was and remains misguided because Behe’s skepticism is based not on ignorance but on careful study of the obstacles that Darwinian evolution must overcome and its consistent failure to do so. To seal the deal, however, the ID research community still needed something like the second law for biology. We found it in the law of conservation of information. This law logically completes the design inference. We’ll address this law in the epilogue.
No comments:
Post a Comment