In an e-mail conversation, Paul Draper pointed out an error in my review of Plantinga’s most recent book, Where the Conflict Really Lies. The key background is at one point in the book, Plantinga responds to a paper by Draper which was, in turn, a critique of the work of intelligent design advocate Michael Behe. (“Irreducible Complexity and Darwinian Gradualism: a Reply to Michael J. Behe,” Faith and Philosophy 22 (2002), pp. 3–21.)
Plantinga’s discussion of Draper’s paper mentions three criticisms of Behe, but only one is explained in any detail, and therefore in the review I just referred to it as “Draper’s criticism.” Plantinga quotes Draper as follows:
The sort of route I have in mind occurs when an irreducibly complex and irreducibly specific system S that serves function F evolves from a precursor S* that shares many of S’s parts but serves a different function F*. Notice that parts that S and S* share and that are required for F need not be required for F* even if they contribute to F*, and parts that are irreducibly specific relative to F may be only reducibly specific relative to F*. Thus, both the parts of S* and their specificity may have been gradually produced by a direct evolutionary path. Then one or more additional parts are added to S*, resulting in a change of function from F* to F. And relative to F, the parts and their specificity, which had not been essential for F*, are now essential.
Referring to this as “Draper’s criticism,” though, was misleading, because other criticisms of Behe get equal billing in Draper’s actual article. Also, Draper’s argument as quoted by Plantinga reminded me of another criticism of Behe, made by Alan Orr:
Behe’s colossal mistake is that, in rejecting these possibilities, he concludes that no Darwinian solution remains. But one does. It is this: An irreducibly complex system can be built gradually by adding parts that, while initially just advantageous, become – because of later changes – essential. The logic is very simple. Some part (A) initially does some job (and not very well, perhaps). Another part (B) later gets added because it helps A. This new part isn’t essential, it merely improves things. But later on, A (or something else) may change in such a way that B now becomes indispensable. This process continues as further parts get folded into the system. And at the end of the day, many parts may all be required.
This led to me saying that Draper’s point had also been made by Alan Orr, but re-reading both paragraphs, the points are distinct (though they both make the same general point that “irreducible complexity” as defined by Behe does not in fact rule out evolution by natural selection).
Neither of these errors affects the point I was making in my review of Plantinga: the impression Plantinga gives of the scientific response to Behe is that unlike Draper, the scientists have no serious arguments. That impression is utterly, ludicrously wrong. That much is shown clearly by Orr’s review and many other examples in the scientific literature. (I need to emphasize that nothing in my original review of Plantinga was intended as a criticism of Draper.)
This is reinforced by the text of Draper’s paper, which he kindly e-mailed to me. Orr’s argument, made in the paragraph quoted above, does in fact show up, properly attributed to Orr. The footnote to that section of Draper’s paper notes that, “Orr’s point is echoed by numerous critics who make an analogy to the building of a stone arch, which requires scaffolding that is removed once the arch is complete.”Furthermore, Draper discusses a number of other scientific criticisms of Behe. Sometimes Draper endorses those criticisms, sometimes he criticizes them, but either way, how Plantinga could come away from reading Draper’s paper thinking the scientific critics of Behe hadn’t produced anything worth responding to is beyond me.
At this point, though, I do need to criticize Draper’s paper on a couple of key points. The issue for Plantinga’s book is that Plantinga gives the (again false) impression that the problems with Behe’s “irreducible complexity” argument is entirely a matter of highly speculative possibilities for how “irreducibly complex” systems might evolve. This is quite wrong, as has been demonstrated at length by Behe’s scientific critics.
The beef I have with Draper here comes from when he criticizes scientists for not understanding Behe’s argument. For example, Draper criticizes a paper by Niall Shanks and Karl Joplin for using for their examples complex biological systems that do not, Draper complains, meet Behe’s definition of “irreducibly complex.” However, I take it that Shanks and Joplin’s point was that nature gives us many examples of systems that might seem irreducibly complex at first glance, but which in fact aren’t.
Similarly, Draper criticizes Ken Miller for citing the mammalian inner ear as an example of an irreducibly complex system whose evolution is well-understood. Draper complains that Behe acknowledges that irreducibly complex systems can evolve through “indirect” routes, but Behe (according to Draper) argues that very complex irreducibly complex systems are very unlikely to evolve. The mammalian inner ear, according to Draper, is not complex enough to be relevant to Behe’s argument.
Draper is sort of right about how Behe’s argument works: there are a couple places in Darwin’s Black Box where Behe acknowledges the possibility of what he calls “irreducibly complex” systems evolving through “indirect” means, but then quickly dismisses that possibility because, he claims, the relevant systems are too complex.
However, Behe puts no real effort into arguing this point, nor does he acknowledge that there definitely cases where the evolution of certain “irreducibly complex” systems is well-understood. All in all, the claim about complexity comes off as a poorly thought-out patch to a poorly thought-out argument. In that context, pointing out that there are some “irreducibly complex” systems whose evolution is well-understood is certainly relevant.
The main take-away here is that Plantinga wildly understates the strength of the scientific case against Behe (indeed, there’s much more to that case than even I’ve said here). And while I had not set out to criticize Draper, his paper on Behe does strike me as a minor example of a philosopher being too eager to tell scientists they are wrong about science.