You have a genius for bad analogies. I don't think I have ever seen one more unrelated to the topic. The idea of gradual change came not from the need for such a process, but from the observation of the process in animal breeding. You would know this if you bothered to read.
Every bit of Darwin's reasoning begins with observations of processes that can be seen today. If you had taken geology you would be familiar with the the phrase, "The present is the key to the past."
Darwin would be familiar with the phrase, since it was coined in 1785.
microgood: And they would be correct to ask that.
Not if Behe's whole point is that there simply exists no evolutionary scenario by which a non-IC thing can become an IC thing. When it becomes stupefyingly obvious that such scenarios exist and are easy, it takes the snake-oil hawker creationist zero seconds to seamlessly and without acknowledgement shift his ground to, "What is the PROOF of that? Were you there inside the cell when the mutations happened?"
So let's break that down and see if it bears any resemblance to what is happening here. What is Behe's characterization of IC?
"An irreducibly complex system cannot be produced directly by numerous, successive, slight modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. .... Since natural selection can only choose systems that are already working, then if a biological system cannot be produced gradually it would have to arise as an integrated unit, in one fell swoop, for natural selection to have anything to act on." (Behe 1996b)As lifted from here. I could have chosen any of a dozen other characterizations of IC by various leading lights of creation/ID. What everyone supposedly understands about it is that it cannot have evolved by Darwin's successive slight modifications. Not that nobody was inside the cell watching the mutation happen, but it could not have happened, period.
So now it emerges in the dialogue with Miller that Behe's own example of blood clotting isn't really IC, at least in the more common non-cetacean versions. It's something like ONE OR TWO DELETION MUTATIONS AWAY FROM IC and Behe himself claims to have been saying it all along.
But one of the criticisms of Behe from the first is that he not only missed Muller's formulation of IC back when, but he missed Muller's answer to how IC things evolve. H. Allen Orr put it this way.
Behe's colossal mistake is that, in rejecting these possibilities, he concludes that no Darwinian solution remains. But one does. It is this: An irreducibly complex system can be built gradually by adding parts that, while initially just advantageous, become—because of later changes—essential. The logic is very simple. Some part (A) initially does some job (and not very well, perhaps). Another part (B) later gets added because it helps A. This new part isn't essential, it merely improves things. But later on, A (or something else) may change in such a way that B now becomes indispensable. This process continues as further parts get folded into the system. And at the end of the day, many parts may all be required.From Darwin v. Intelligent Design (Again).The point is there's no guarantee that improvements will remain mere improvements. Indeed because later changes build on previous ones, there's every reason to think that earlier refinements might become necessary...
I wish I could claim credit for this Darwinian model of irreducible complexity, but I'm afraid I've been scooped by eighty years. This scenario was first hinted at by the geneticist H. J. Muller in 1918 and worked out in some detail in 1939.
More detail and more specific scenarios from Don Linday.
So what is unreasonable? We know now that human and much other mammalian blood clotting has redundancies. "Two pathways" as Behe puts it. You can knock out at least one thing and there's still a route from A to Z.
So it would take at least one deletion mutation to knock out the redundancy to finally get the clotting to what most ID true believers thought it already is, a shining example of irreducible complexity. Is this somehow unthinkable? Are mutations unheard of? Do mutations only ADD genetic information and never STOMP on it? This sounds like the opposite of the usual cretinist dumb-dumbism. Aren't mutations ALWAYS "harmful?"
The creation/ID advocates's unwillingness to see or understand anything inconvenient is not science, although it probably does belong in higher education. I once took a course in Abnormal Psychology which could easily incorporate a study of creationist arguments and behavior.
If Behe is truly a scientist should he not be the one looking to falsify his own hypothesis? Is it not part of science to test your own hypotheses?