While there is much that we do not know about the biochemistry of living systems, it would appear to be premature to claim that there is a principled objection to the claim that the biochemical level of the biological hierarchy is itself a product of evolutionary processes. Behe claims that biochemical
systems and processes manifest a species of complexity -- irreducible complexity -- that could not have evolved and must have been intelligently designed. We have shown, first, that systems satisfying Behe's characterization of irreducible biochemical complexity can arise naturally and spontaneously as the result of self-organizing chemical processes. Second, we have argued further that evolved biochemical and molecular systems exhibit redundant complexity -- this kind of complexity simultaneously accounts for the stability of evolved biochemical systems and processes in the face of even quite radical perturbations, for biochemical and metabolic plasticity, and, mainly as a result of gene duplication, for extant structures and
processes to get co-opted in the course of evolutionary time, to serve novel functional ends.
In the end, Behe overestimates the significance of irreducible complexity because his simple, linear view of biochemical reactions results in his taking snapshots of selective features of biological systems, structures and processes, while ignoring the redundant complexity of the context in which those
features are naturally embedded. Real biological systems are quite unlike economically designed engineering artifacts such as mousetraps. His case against evolution is a good example, in fact, of the perils of being "trapped" by a metaphor.
Of course, for some types of engineering problems, human engineers are not afraid to build in redundancy and back-up systems. Perhaps, Behe might want to argue, these sophisticated artifacts, with their redundant back-up systems, constitute a more sophisticated design metaphor by means of
which to conceptualize nature. The trouble here is that naturalistic, evolutionary processes, notoriously, give rise to similar redundancies. And evolutionary processes do so without appeals to engineers of unknown identity and methods, be they cosmic, or merely alien, thereby commanding
our attention on the basis of the scientific virtue of simplicity.