by Darel Rex Finley, January 6, 1998
"ComplexityYes! IrreducibleMaybe! UnexplainableNo!," Terry M. Gray of the Calvin College chemistry department reponds to Michael J. Behe's thesis of irreducible complexity, as presented in Behe's book Darwin's Black Box.
Terry Gray's response to Behe is divided into four sections, which he outlines at the beginning of his article. I will use his outline as a header to my comments.
1. "Within a Christian theistic framework evolutionary explanations do not necessarily imply the absence of design"
That a flexible interpretation of the Bible can be reconciled with Darwinian evolution does not have anything to do with the problem of irreducible complexity in biochemical systems.
Though Gray may not have intended it this way, his section 1 suggests to the reader that biblical literalism is the only real reason that anyone would object to evolution; an implication that is strongly encouraged by many evolutionists, and by the popular media. When an empirical challenge to evolution is met with assurances that Christian religion is safe, the empirical challenge is being dismissed, not answered.
2. "Concrete responses to the biochemical arguments"
This is the really promising section of Gray's article, but disappointment seems imminent the section begins with a huge caveat: Detailed explanations will not be rendered, only "broad outlines and hints of an explanation." This is most discouraging, since one of the main points of Behe's book is that outlines and hints are not a substitute for real explanations, especially when they depend on the presumptive truth of evolution for their validity.
The suspicion that Gray's explanations may depend on the presumptive truth of evolution is further exacerbated by the even bigger caveat that follows: "It may be the case that the detailed evidence for the origin of specific examples of complex structures is hidden too deeply in the evolutionary past." So, even if explanations are never forthcoming, the past must still be considered "evolutionary."
Despite these rather severe causes for worry, Gray's examples deserve to be examined:
2a. "Hemoglobin the evolution of a molecular machine"
Gray cites a detailed evolutionary explanation of hemoglobin by Richard Dickerson and Irving Geis which may indeed be correct although Gray himself calls it "no doubt wrong in many of the details." Dickerson and Geis's scenario is limited to explaining how myoglobin (a very similar oxygen-binding protein) might have evolved by chance mutations into hemoglobin.
Hemoglobin is discussed very briefly in Behe's book (p. 206-207), and on those pages Behe concedes that with hemoglobin "the case for design is weak" and that the evidence for design in hemoglobin is "intriguing, but far from convincing." With Behe therefore admitting that hemoglobin (from myoglobin) does not illustrate the irreducible complexity that is the focus of his argument, one may wonder why Gray would use hemoglobin as a response to Behe.
2b. "Hints about the evolution of cilia"
Unlike hemoglobin, cilia is indeed one of the four major examples of irreducible complexity that Behe used in his book. Gray offers only a "broad outline" of cilia evolution, which in practice means noting that some components of cilia are used in other parts of the cell, and that the first cilium could have "arisen from a novel assembly of those already existing components."
Gray's suggestion strikes me as a very weak response to the following charges from "Darwin's Black Box" (p. 66-67):
Intriguing as [the novel assembly explanation] may sound, though, critical details are overlooked.|
The mutated protein that accidentally stuck to microtubules would block their function as "highways" for transport. A protein that indiscriminately bound microtubules together would disrupt the cell's shape just as a building's shape would be disrupted by an erroneously placed cable that accidentally pulled together girders supporting the building. A linker that strengthened microtubule bundles for structural supports would tend to make them inflexible, unlike the flexible linker nexin. An unregulated motor protein, freshly binding to microtubules, would push apart microtubules that should be close together. The incipient cilium would not be at the cell surface. If it were not at the cell surface, then internal beating could disrupt the cell; but even if it were at the cell surface, the number of motor proteins would probably not be enough to move the cilium. And even if the cilium moved, an awkward stroke would not necessarily move the cell. And if the cell did move, it would be an unregulated motion using energy and not corresponding to any need of the cell. A hundred other difficulties would have to be overcome before an incipient cilium would be an improvement for the cell.
Given these factual arguments, it would appear that Gray has based his response to Behe on the hope that his readers will not bother to read Behe's book.
2c. "Hints about the evolution of the molecular basis of vision"
Although this is not one of his four major examples, Behe does use vision as an introductory example of irreducible complexity in Chapter 1.
Gray's response here is similar to that for the cilium: Preexisting components were adapted and combined by evolution into the light-sensing mechanism of the retinal nerve cell. Only three components are cited, one of which is the nerve cell itself. The other two, transducin and rhodopsin, are assumed to have developed from similar proteins used for other purposes such as hormone reception.
The explanation suffers from the same lack of detail, and probably the same sorts of lack-of-improvement roadblocks as with the cilium, but Gray nonetheless feels that "the evolutionary explanation for complexity is not only plausible but likely."
If evolution is a philosophical certainty, then Gray's section 2 does provide some "hints" as to how it happened. If, on the other hand, evolution is what it is so widely claimed to be a scientific theory of how life acquired its complex functionality then a detailed mechanistic explanation is what is required, and broad hints are no substitute.
3. "Self-organization as an explanation of the origin of irreducible complexity"
In this section, Gray draws from The Origins of Order by complexity theorist Stuart Kauffman of the Santa Fe Institute. Kauffman's claim is that under the right conditions, chemicals might exhibit spontaneous organizing tendencies, which would not depend on the alleged craftsmanship of natural selection.
Kauffman's proposals might be relevant to a prebiotic world of free-floating chemicals, but in the world of cellular life, components are tightly regulated and controlled. Only modifications to the genetic system of component production and regulation could (even in theory) yield new structures. Thus, Kauffman's work is an origin-of-life issue, not an origin-of-vision or origin-of-immunity issue.
Although Gray's article is a response to Behe's book, Gray fails to even mention that Behe talked about Kauffman in "Darwin's Black Box." One particular Behe quote is especially relevant (p. 156):
Kauffman discusses his ideas in a chapter [of The Origins of Order] titled "The Origin of A Connected Metabolism," but if you read the chapter from start to finish you will not find the name of single chemical no AMP, no aspartic acid, no nothing. In fact, if you scan the entire subject index of the book, you will not find a chemical name there either. John Maynard Smith, Kauffman's old mentor, has accused him of practicing "fact-free science." [Emphasis in original.]
Gray uses an analogy to try to explain Kauffman's concepts:
Imagine a pile of rocks of lots of different sizes, say formed by some avalanche. Then by wind, water or other kinds of weathering, all the loose rocks are removed. What is left standing is the tightly knit complex structure where every piece is essential to the structural integrity of the whole. It might even appear as if all the rocks were carefully placed to give the final sturdy structure, i.e. that the whole structure was designed.
This analogy suffers from a serious problem: How many piles of rocks would have to be dumped randomly before even one highly specific combination of several well-fitted rocks was formed, of the type described above? In all likelihood, the weather would just erode away all the rocks leaving nothing. And this is not simply a weakness of the analogy the real likelihood of biotic chemicals forming by chance in any reasonable amount of time appears to be equally remote. In any case, the analogy is truly applicable only to unregulated origin-of-life scenarios anyway.
4. "Premature appeal to special divine activity to explain the world around us damages the Christian theistic apologetic"
Gray begins this section by making the accusation that was hinted in section 1:
The "intelligent design" approach as manifested by the irreducible complexity argument is motivated in part by apologetic concerns.
And the rest is basically an expansion of section 1 assurances to Christian theists that their beliefs are not harmed by the truth of evolution and so they should not try to formulate arguments like Behe's. Implicit in this argument is that naturalistic evolution is a fact consider these passages:
As I have already stated, I have no in principle objection to [deducing theism from nature]. However, I think that the scriptures have in mind a much broader application. The theistic apologetic ought to claim all of reality as evidence of God's eternal power and divine nature.|
Christians need to see the revelation of our Creator Lord in every square inch of reality.
In other words, to disbelieve evolution is to reject part of reality.
Gray believes that Christians like Behe are making a mistake, because if new evidence (unavailable today) shows that naturalistic evolution is true after all, then Christianity will be heavily damaged. But if Gray can be Christian and evolutionist at the same time, then surely others can do so as well if and when that new evidence arrives.
I think Gray is not giving adequate attention to the possibility that "Darwin's Black Box" might be motivated not by a desire to promote Christianity, but by a desire to reinstate scientific objectivity in this field of science. In his book Behe did not use the conclusion of design to support any particular religious belief. On pages 245-251, Behe emphasizes that the discovery of design tells us little or nothing about who the designer is.
The title of Gray's section 4 tells us that the appeal to "divine activity" (actually an unspecified designer) is "premature." For over 130 years, Darwinian evolution has been accepted in the scientific community and popular media not because of any thorough empirical confirmation, but simply because of the inherent plausibility of the idea. If Michael Behe has now illuminated a serious flaw in that plausibility, then what reason is left to give evolution the benefit of the doubt?
As any working scientist can attest, new scientific theories are automatically suspect until thoroughly confirmed, since most theories do not pan out. Given this necessary reality of scientific work, and the fact that in our experience complex machines seem to require intelligent design, it is Darwinian evolution that has been prematurely accepted.