Michael Behe says we need intelligent design to deal with holes in our ability to explain the pathways and structures in living things.
Dr. Lovegrove: Michael Behe is one of the experts on intelligent design that discusses the complexity of life and the fact that things seem to be too complex to have arisen by chance. An evolutionist responds as you suggested with the idea that we're just using that as a cover for our ignorance. When we're ignorant of how something could have happened, we blame it on God. God is how we explain what we don't understand. That is a misunderstanding of creationism. That is a misunderstanding of Michael Behe's argument.
That is not what Behe is saying at all. He is not saying merely that we don't understand how things work and, therefore, we blame them on God. He is saying that there are things that we actually understand well enough to understand that they could not have evolved. Evolution would be impossible for these systems; not just that we don't know, but we know well enough that we can say that it is not going to happen.
Now, he recognizes two factors that he says make this true. The first of them is irreducible complexity. This is what Michael Behe refers to as a system where the removal of any one of the parts causes the system to effectively cease functioning. Now, here is why that is important. Suppose I have a system (and he is not saying that we don't know how it works; we don't know what the parts are) and we know the parts that make it up. We have discovered that it needs all of its parts, or it can't work. His example is a mouse trap. A mouse trap is a simple device constructed of just a few parts. If you take any one part away, it's not that the mousetrap doesn't work as well, it's that the mousetrap doesn't work at all. That's what he means by irreducible complexity. Something that has parts like that, you can't build up part by part through a process of evolution. You need all the parts all at the same time or you have nothing, nothing to select, nothing to evolve, nothing to work with. That's called irreducible complexity.
Behe also recognizes a second factor that is called minimal function. He defines this as the ability to accomplish a task in physically, realistic circumstances. This addresses those parts of life where a system could conceivably be built up part-by-part, could conceivably be gradually improved. But he says you have to go in at least big enough steps to make a noticeable improvement. If the steps are so small that I don't even get a minimum of functionality, then evolution is not going to happen. There has to be a minimum level of usefulness or evolution can't even work.
So in summary, no. On the basis of these two factors we're not just arguing that we don't understand how evolution could have happened. We're arguing that evolution is impossible for what Behe calls irreducible systems.
Now, I might add here that some evolutionists call this the "God of the Gaps" idea. This is how they summarize what they think is our position: when there is a gap in our knowledge, when we are ignorant about something, we appeal to God. God explains the gaps. Like in mythology, lightning bolts were supposedly handcrafted and thrown down to earth by Thor, the god of thunder. Then they say that scientists discovered electricity, and they filled in that gap; and we don't need God anymore. So the suggestion is that as scientists learn more and more about nature, there will be fewer and fewer gaps until there is no room for God. Now what is wrong with that? This is what Behe is trying to argue: that there really are gaps in nature, there are holes that we're never going to fill in. Not just because we don't have the evidence, not just because we are ignorant of the explanation, but there are holes in nature that were done by God, some of the creative acts of God, some of the miracles of God. Try as you want, a scientist is never going to fill in that hole. It's not a gap just in our knowledge; it's a gap in reality in nature. And when we find those gaps that it's impossible for evolution to bridge, we are looking at the handiwork of God. So Behe argues in essence that there are gaps in nature that cannot be filled by science, that have to be filled by an intelligent designer—we would say by God.