…but intelligent design still isn’t. Even if certain structures were found to be irreducibly complex, this would not count as evidence for intelligent design. Consider the following.
Irreducible complexity, of course, is the hypothesis that some structures are too complex to have arisen by the slow accumulation of changes over time. Its champion is Dr. Michael Behe of LeHigh University. His favorite example to pull out is the flagellum of certain bacteria, which is operated by a molecular motor which propels the only freely spinning axle in the natural world. This is all well known.
The irreducible complexity hypothesis is perfectly scientifically valid, because it yields testable predictions. For any structure postulated to be irreducibly complex, it must be impossible find a plausible sequence of evolutionary intermediates. Either the whole structure is in place, or it is useless, and thus can’t evolve by slow degrees. Therefore, if the structure in question does in fact have a sequence of plausible intermediates, then it is proven not to be irreducibly complex. The hypothesis is perfectly falsifiable (and of course has been falsified for every case in which it is proposed.)
What would happen if a structure were rigorously established as irreducibly complex? Just one thing, and one thing only: that structure would be proven not to have arisen by evolution. This might weaken the position of evolutionary theory, since it would no longer be possible to claim that natural selection and drift are wholly responsible for the origin of biological complexity. There are many things that would empatically not happen, and these are more important.
- It would not disprove the evolution of structures whose history is well-established.
- It would not undermine the mountainous evidence in favor of common descent and evolutionary theory.
- It would not provide any positive evidence at all for the central claim of intelligent design, being that life at some level is the intentional work of an intelligent agent.
So irreducible complexity, scientific though it may be, is a dud from the start from the intelligent design standpoint. If a valid example were shown, all it would do would be to undermine (slightly) the importance of evolution.
Allow me to finish with a testable prediction: such an example will not be found.