Irreducible complexity is the notion that a mechanism is so complicated and complete, that if any part of its whole were missing, it would not be able to function (The God Delusion, 122). Two common examples for this argument are the eye and the wing. Many creationists would claim that a partial eye or a fraction of a wing would be useless (123-124).
Dawkins disagrees with these two examples, bringing to attention the flatworm, whose eye is apparently less evolved than the human eye and can only detect shadows and light (124). While giving no real examples of creatures with partial wings, Dawkins rationalizes that a fraction of a wing—though not as good as a whole wing—is still functional. There is always a height from which a winglet can save you from a fall (123). (I find this logic somewhat silly.)
I am not going to pretend to know the anatomy and complexity of these or other organs. I couldn’t tell you one way or another whether an organ is irreducibly complex.
Dawkins admits that irreducible complexity would destroy Darwin’s theory of evolution:
The creationists are right that, if genuinely irreducible complexity could be properly demonstrated, it would wreck Darwin’s theory. Darwin himself said as much: ‘If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find no such case.’ (Dawkins, 125)
For some reason Dawkins believes irreducible complexity would be likewise as lethal to the intelligent design theory (125). I can’t figure out why. I should think irreducible complexity is absolutely necessary!
Complexity must either be infinitely reducible, so that we never reach a beginning in which case natural selection becomes an on-going (everlasting?) series of effects, with no definite initial cause. (And this would seriously contradict science in the law of causality.) OR there must ultimately be an actual eternal existence that has no beginning and has no end—whose complexity indeed is irreducible. Neither option is very accommodating to the theory of evolution.
Evolution only works within the construct of time. Dawkins already explained the cumulative process of natural selection. Over so many ‘billions’ or ‘trillions’ of years (far, far less than forever), we’ve supposedly evolved from the same primary life form. Wouldn’t that very first building block have to be irreducibly complex? If there is no end to the reducibility of complexity, then how do we dare frame the process of evolution within a supposed span of time?—(and so short a time at that.) The process of natural selection would go back forever. It would be eternal. This theory doesn’t make sense.
The origin of life must be BOTH eternal AND irreducibly complex if it is to initiate the whole process of natural selection. If neither of these attributes are present in the origin of life, then it remains nothing more than an effect. And we know that an effect cannot exist without a cause. There MUST be an ultimate cause.
We may not agree about who or what the ultimate cause actually is, but we certainly need to recognize the necessity of irreducible complexity and eternal existence.
I believe the ultimate cause is the eternal God, Creator of all things–including time. He is the source of life and is certainly irreducibly complex. Regardless of whether we acknowledge him as our Lord and Maker, we cannot exist without of him. Remove the cause and you remove the effect.
The creationist’s determination to hunt for irreducible complexity and other such “gaps” between stages of evolution seems to really annoy Dawkins. I guess this determination is not so different than the atheist’s obsession to spotlight holes in Scripture in order to find it unreliable. (Dawkins demonstrated this obsession himself in just the previous chapter.) This is NOT annoying. This is good! If there are holes in the ship wouldn’t we sure want to know about them? It is GOOD to critique and examine an argument, to be sure it is solid. Otherwise, you might find yourself on a sinking vessel.