Over the years I have had a number of problems with the calculations of folks who try and mathematically prove the impossibility of evolution. If you've been following this blog, you know about my Playing Card Analogy.
OK, now you are familiar, or you already were familiar with my analogy. Larry Moran, over on his Sandwalk blog, had an interesting post "Targets, arrows, and the lottery fallacy". He relates the most common problem when Creationists (Yes, I include the Discovery Institute in that list.) calculate the probabilities for evolution. It is an assumption that the outcome was in some manner predetermined, or that it is the only possible outcome. As with my card analogy, the odds calculation makes no sense unless the order of the cards was the only possible outcome or the predicted outcome.
So the question, and it's certainly a philosophical one and not a scientific one, is whether or not the human form is the intended outcome? If you claim 'yes', then my next question will be for you to prove it. I can imagine someone whipping out an appropriate Biblical reference about being 'created in his image', but that does not constitute proof. Obviously there isn't anything that mandates the human form. We are a result, no one can prove we are a predicted, or the only possibility. We are only a result.
So let's apply this to the 'thinking' of folks like Behe and Dembski. When they declare something as Irreducibly Complex and use a 'design filter' to support that declaration, what they are in fact saying is that looking at the present state of the example, claiming it was the only possible outcome, therefore the odds are astronomical. They don't see, by intent, that the current state is a result, not a prediction. The reality is that some magical hindsight is nothing more than wishful thinking. Something like "I want there to be a God, so therefore I have to invent things that the God had to have done in order to fulfill my desire." Isn't that exactly what folks 'calculating' such probabilities are really saying?
Larry had this to say:
"Do you see the fallacy? Just because we observe a complex adaptation or structure does NOT mean that it was specified or pre-ordained. There are certainly many different structures that could have evolved—most of them we never see because they didn't happen. And when a particular result is observed it doesn't mean that there was only one pathway (target) to producing that structure"