The basic premise of the so-called "Intelligent Design" movement, which only serves as a mask for creationism, is that the complexity we see in the world is a sign of intelligence. We see the same in our own creations, therefore we shouldn't deny the same evidence in divine creation. But is this connection really valid? No - all we have is evidence of human intelligence leading to human creations. We can't justifiably extrapolate from that to allegedly disembodied, divine intelligence.

Jason Rosenhouse quotes Larry Arnhart:

This confusion in intelligent design theory both affirming and denying recourse to the supernatural arises from equivocation in the use of the term “intelligent design.” Both Dembski and Behe speak of “intelligent design” without clearly distinguishing “humanly intelligent design” from “divinely intelligent design.” We have all observed how the human mind can cause effects that are humanly designed, and from such observable effects, we can infer the existence of humanly intelligent designers. But insofar as we have never directly observed a divine intelligence (that is, an omniscient and omnipotent intelligence) causing effects that are divinely designed, we cannot infer a divinely intelligent designer from our common human experience.

Rosenhouse himself comments:

At issue is what our experience tells us about what intelligence can and can not bring about. The baby who infers that his father is messing around with the ball is aided by the knowledge that his father actually exists and occasionally removes balls from view. An inference to design is always based on more than the features of the event or phenomenon to be explained. They are also based on our experience with what effects can arise from various sorts of causes.

Children might attribute to Santa Claus the presence of their gifts under the tree. Teenagers who persist in doing so despite having been presented with the more reasonable explanation that their parents placed the gifts under the tree (Santa Claus may exist, after all), are generally regarded as people in need of counselling. ID proponents regard them as scientists.

A harsh criticism, to be sure - but quite accurate, I think. What "Intelligent Design" proponents expect from scientists would be regarded as something akin to a mental illness in the average person. Sincere belief in Intelligent Design isn't justifiable - it can only be based on ignorance, willful deceit... or perhaps some sort of mental illness.

Read More:

• Evolution vs. Creationism
• What is Intelligent Design?
• What is Science?