Irreducible complexity

Irreducible complexity is a property of any system whose internal workings are so complex that the removal or alteration of any part would prevent the system from functioning. For example, a car will not go without an engine. Indeed, the engine will not run without fuel and a starter motor. Designers must ensure that all parts work together to produce the intended function.

This concept has been used by astronomer Fred Hoyle and biochemistry professor Michael Behe to argue against the idea of evolution through natural selection. A biological system could not make a gradual transition via small successive steps, unless each step provided an advantage to the species.

Behe presents several examples of organs and cells which could not have evolved through natural forces alone due to their irreducible complexity.

Behe introduced and defined this term on page 9 of his work, "Darwin's Black Box":

Irreducible complexity is a "single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning."

It is therefore a state of interacting components that could not function without all its parts. In particular, the term is used by proponents of Intelligent Design to argue that irreducibly complex biological systems cannot evolve.

The most commonly used examples of irreducibly complex biological systems are the human compound eye, the blood clotting cascade, and the bacterial flagellum.

Legal aspects of the theory

During Behe's testimony at the trial of Kitzmiller v. Dover Area School District, opponents of Intelligent Design made the objection that this concept has not been published in peer-reviewed journals. Behe testified that his book was subjected to peer review as rigorous as that of journals:

Q (Plaintiffs' attorney). You would agree that peer review for a book published in the Trade Press is not as rigorous as the peer review process for the leading scientific journals, would you?

A (Michael Behe). No, I would not agree with that. The review process that the book went through is analogous to peer review in the literature, because the manuscript was sent out to scientists for their careful reading.

Furthermore, the book was sent out to more scientists than typically review a manuscript. In the typical case, a manuscript that's going to -- that is submitted for a publication in a scientific journal is reviewed just by two reviewers. My book was sent out to five reviewers.

Furthermore, they read it more carefully than most scientists read typical manuscripts that they get to review because they realized that this was a controversial topic. So I think, in fact, my book received much more scrutiny and much more review before publication than the great majority of scientific journal articles.

Q. Now you selected some of your peer reviewers?

A. No, I did not. I gave my editor at the Free Press suggested names, and he contacted them. Some of them agreed to review. Some did not.

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