How does intelligent design use the idea of irreducible complexity?

Supporters of intelligent design use the concept of "irreducible complexity" to argue against the theory of evolution. They define a system as irreducibly complex if it is composed of multiple well-matched, interacting parts that contribute to its basic function, such that the removal of any one part causes the entire system to cease functioning.1

From this premise, proponents—most notably molecular biologist Michael Behe—infer that such systems could not have evolved through the gradual, step-by-step process of natural selection, as each intermediate stage would lack the necessary function to provide a survival advantage. Consequently, they argue that these systems must have been created in their entirety by an intelligent designer.1

Critics, however, maintain that this argument rests on a misunderstanding of evolutionary biology. They point out that it ignores the existence of precursor systems and that molecular biology has provided evidence for how such complexity can arise through natural means, including self-organizing biochemical processes and the redundancy of organic structures.1