Does irreducible complexity imply Intelligent Design? Michael Behe's "irreducible complexity," according to "design theorists," implies Intelligent Design of biological systems. In fact, such a conclusion lacks a logical foundation. Irreducible complexity can even more reasonably be construed as an argument against Intelligent Design

Michael Behe is a university professor of biochemistry. Although he has to his credit a number of papers published in professional journals on biochemistry, he is much better known as the author of the popular book Darwin's Black Box (Behe 1996). Widely reviewed, both exorbitantly acclaimed and sharply critiqued, this book introduced the concept of "irreducible complexity" (IC) of protein systems in biological cells. IC, according to Behe, is a common feature of very complex protein "machines" performing vital functions in bio cells. A protein assembly which is IC, according to Behe, can only properly function if all of its constituent proteins are present; if even a single component of such a system is missing, the system becomes nonoperational. If a system is IC, concludes Behe, this indicates it cannot be a result of "blind" evolution but more reasonably has to be attributed to "design."

Michael Behe's concept of irreducible complexity (IC) (Behe 1996) has been critically discussed by experts in biology. The attitude of many professional biologists to Behes IC concept has found its most uncompromising expression in Kenneth Miller's words: "... the notion of irreducible complexity is nonsense" (1999, p. 150).

While critical analysis of IC by professional biologists seems to be sufficient to dismiss Behe's alleged great discovery in biology, there is another aspect to IC which, to my mind. makes the very notion of "IC implies Intelligent Design (ID)" implausible.

A concept that's identical in all but name to irreducible complexity was around for a long time before Behe. It was applied to the problems with the evolution of various anatomical structures, such as the mammalian eye (recall the many-times-answered question. "What good is half an eye?") or snakes' apparatus for venom injection (Marcell 1976).

An even more relevant and practically identical concept, "interlocking complexity," had been already discussed from the standpoint of genetics nearly eighty years earlier (Muller 1918. 1939L Even the application of the concept of IC to the molecular assemblies within a biological cell (which is Behe's playing field) was put into circulation some ten years before Behe (Cairns-Smith 1985). Unlike Behe and his supporters, these predecessors did nor claim that irreducible complexity constituted a great discovery or implied Intelligent Design, so this prior version would hardly invoke Miller's categorical rejection quoted above.

The critical discussion of Behe's idea has mainly concentrated on three specific aspects of IC:

1. The very definition of IC has been a subject of much discussion. For example. Behe's colleague, William Dembski (viewed by the ID advocates as their leading logician), admitted that Behe's idea of IC was "neither exactly correct nor wrong" (Dembski 2002, 280).

2. The question of whether molecular systems offered by Behe as examples of IC are indeed IC has likewise been subject in critique. A number of biologists pointed out that systems such as bacterial cilia or blood-clotting cascades which, according to Behe, exemplify IC, are in fact reducible without losing their "basic function " (See, for example. Miller 1999.)

3. Behe asserts that IC systems, exemplified by the protein assemblies in biological cells, cannot have evolved via a direct "Darwinian" path because such a path necessarily goes through a sequence of intermediate stages at which the system performs the same "basic" function. Since any system comprising fewer pairs than the IC system in question is, by definition of IC, dysfunctional, it could not be an evolutionary precursor of an IC system, or so says Behe. Regarding the evolution of an IC system via an indirect evolutionary path, Behe admits that such a process is possible but, in his opinion, so highly improbable that it cannot be considered a feasible option.

The last point has been disputed by professional biologists. They suggest detailed scenarios showing how, for example, a bacterial flagellum could have evolved from evolutionary precursors with a sufficiently high likelihood (Matzke 2003, Ussery 2004, Musgrave 2004). The consensus of the vast majority of professional biologists seems to favor the views of Behe's opponents. Except for vague protestations, wherein Behe and his supporters demand from their opponents highly detailed proofs of the factual occurrence of indirect evolutionary paths leading to IC systems, Behe seems to be unable to offer substantive counterarguments.

Even if the IC concept is valid, and even if many biological systems are indeed IC, this in itself does not logically lead to the design inference. I contend that IC in itself can more reasonably be construed as an argument against the design inference.

In an essay titled "Irreducible Contradiction" posted on the Internet in 1999 (Perakh 1999), I suggested critical comments to Behe's Darwin's Black Box. In the nearly six years since that essay appeared, Michael Behe has never uttered a word acknowledging the existence of my critical remarks. Nor has William Dembski, who has actively promoted Behe's concept of irreducible complexity, ever mentioned those comments. Neither did anybody else from the Intelligent Design camp.