Philosophical Objections to Intelligent Design: Response to Critics

——————————————————————————– Michael J. Behe Discovery Institute July 31, 2000

I. Is Intelligent Design Falsifiable? Some reviewers of Darwin’s Black Box (Behe 1996) have raised philosophical objections to intelligent design. I will discuss several of these over the next few sections, beginning with the question of falsifiability. To decide whether, or by what evidence, it is falsifiable, one first has to be sure what is meant by “intelligent design.” By that phrase someone might mean that the laws of nature themselves are designed to produce life and the complex systems that undergird it. In fact, something like that position has been taken by the physicist Paul Davies and the geneticist Michael Denton in their recent books, respectively, The Fifth Miracle: The Search for the Origin and Meaning of Life (Davies 1999) and Nature’s Destiny: How the Laws of Biology Reveal Purpose in the Universe. (Denton 1998) That stance also seems to pass muster with the National Academy of Sciences:

Many religious persons, including many scientists, hold that God created the universe and the various processes driving physical and biological evolution and that these processes then resulted in the creation of galaxies, our solar system, and life on Earth. This belief, which sometimes is termed “theistic evolution,” is not in disagreement with scientific explanations of evolution. Indeed, it reflects the remarkable and inspiring character of the physical universe revealed by [science]. (National Academy of Sciences 1999, 7)

In such a view even if we observe new complex systems being produced by selection pressure in the wild or in the laboratory, design would not be falsified because it is considered to be built into natural laws. Without commenting on the merits of the position, let me just say that that is not the meaning I assign to the phrase. By “intelligent design” I mean to imply design beyond the laws of nature. That is, taking the laws of nature as given, are their other reasons for concluding that life and its component systems have been intentionally arranged? In my book, and in this essay, whenever I refer to intelligent design (ID) I mean this stronger sense of design-beyond-laws. Virtually all academic critics of my book have taken the phrase in the strong sense I meant it.

In the strong sense ID is no longer approved by the National Academy, for a specific reason: “[I]ntelligent design . . . [is] not science because [it is] not testable by the methods of science.” (National Academy of Sciences 1999, 25) In his review of Darwin’s Black Box for Nature, Jerry Coyne, professor of evolutionary biology at the University of Chicago, explains why he also thinks intelligent design is unfalsifiable.

If one accepts Behe’s idea that both evolution and creation can operate together, and that the Designer’s goals are unfathomable, then one confronts an airtight theory that can’t be proved wrong. I can imagine evidence that would falsify evolution (a hominid fossil in the Precambrian would do nicely), but none that could falsify Behe’s composite theory. Even if, after immense effort, we are able to understand the evolution of a complex biochemical pathway, Behe could simply claim that evidence for design resides in the other unexplained pathways. Because we will never explain everything, there will always be evidence for design. This regressive ad hoc creationism may seem clever, but it is certainly not science. (Coyne 1996)

Coyne’s conclusion that design is unfalsifiable, however, seems to be at odds with the arguments of other reviewers of my book. Clearly, Russell Doolittle (Doolittle 1997), Kenneth Miller (Miller 1999), and others have advanced scientific arguments aimed at falsifying ID. (See my articles on blood clotting and the “acid test” on this web site.) If the results with knock-out mice (Bugge et al. 1996) had been as Doolittle first thought, or if Barry Hall’s work (Hall 1999) had indeed shown what Miller implied, then they correctly believed my claims about irreducible complexity would have suffered quite a blow. And since my claim for intelligent design requires that no unintelligent process be sufficient to produce such irreducibly complex systems, then the plausibility of ID would suffer enormously. Other scientists, including those on the National Academy of Science’s Steering Committee on Science and Creationism, in commenting on my book have also pointed to physical evidence (such as the similar structures of hemoglobin and myoglobin) which they think shows that irreducibly complex biochemical systems can be produced by natural selection: “However, structures and processes that are claimed to be ‘irreducibly’ complex typically are not on closer inspection.” (National Academy of Sciences 1999, p. 22)

Now, one can’t have it both ways. One can’t say both that ID is unfalsifiable (or untestable) and that there is evidence against it. Either it is unfalsifiable and floats serenely beyond experimental reproach, or it can be criticized on the basis of our observations and is therefore testable. The fact that critical reviewers advance scientific arguments against ID (whether successfully or not) shows that intelligent design is indeed falsifiable.

In fact, my argument for intelligent design is open to direct experimental rebuttal. Here is a thought experiment that makes the point clear. In Darwin’s Black Box (Behe 1996) I claimed that the bacterial flagellum was irreducibly complex and so required deliberate intelligent design. The flip side of this claim is that the flagellum can’t be produced by natural selection acting on random mutation, or any other unintelligent process. To falsify such a claim, a scientist could go into the laboratory, place a bacterial species lacking a flagellum under some selective pressure (for mobility, say), grow it for ten thousand generations, and see if a flagellum–or any equally complex system–was produced. If that happened, my claims would be neatly disproven.(1)

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