In the DVD Case For A Creator, in the Q&A section, Michael Behe was asked, How would you respond to the claim that intelligent design theory is not falsifiable?
The National Academy of Sciences has objected that intelligent design is not falsifiable, and I think that’s just the opposite of the truth. Intelligent design is very open to falsification. I claim, for example, that the bacterial flagellum could not be produced by natural selection; it needed to be deliberately intelligently designed. Well, all a scientist has to do to prove me wrong is to take a bacterium without a flagellum, or knock out the genes for the flagellum in a bacterium, go into his lab and grow that bug for a long time and see if it produces anything resembling a flagellum. If that happened, intelligent design, as I understand it, would be knocked out of the water. I certainly don’t expect it to happen, but it’s easily falsified by a series of such experiments.
Now let’s turn that around and ask, How do we falsify the contention that natural selection produced the bacterial flagellum? If that same scientist went into the lab and knocked out the bacterial flagellum genes, grew the bacterium for a long time, and nothing much happened, well, he’d say maybe we didn’t start with the right bacterium, maybe we didn’t wait long enough, maybe we need a bigger population, and it would be very much more difficult to falsify the Darwinian hypothesis.
I think the very opposite is true. I think intelligent design is easily testable, easily falsifiable, although it has not been falsified, and Darwinism is very resistant to being falsified. They can always claim something was not right.