If the undiscovered principle is a natural cause is will be found in the course of mainstream science. Behe has already backtracked on the flagellum and blood clotting, becaus as science does its work, mysterious things are explained by natural causes.
What does ID want science to do? Stop looking?
The word "cause" is problematic. Months ago I read a short biography of Newton which gives a fascinating view of his intellectual development. He was a precious child, as many like him are, and from an earlt age he was fascinated with patterns. He tried to make sense of them. As he grew older he acquired the mathematcal tools to do so. I think that in this digital world we have forgotten that Newton's world was geometric. In our world the billard ball model seems to prevail. Do we forget the debate in the world ofmathmatics about the nature of that knowledge, since without there is no modern science? What is the significance of pattern? Is it real or is it an illusion? We can kick rocks all day and not answer that question.
Science will only look for alternatives when unremitting pressure is applied, especially in a charged atmosphere like today's. People are emotionally bound to their positions.
If NeoDarwinism has a touch of "phlogiston" in its structure, it will require some work to remove it. Somebody is simply looking for alternatives to difficult problems, and the name is ID.