While the scientific model of evolution by natural selection has observable and repeatable facts to support it such as the process of mutations, gene flow, genetic drift, natural selection, and speciation, the "Intelligent Designer" in ID is neither observable nor repeatable, violating the scientific requirement of falsifiability. Intelligent Design violates another cornerstone of the scientific method called Occam's Razor, creating an entity to explain something that has a simpler and scientifically supported explanation not involving outside help.

From point of view of empirical science, ID is similar to the claim "we don't know how the Egyptians could have built the pyramids, therefore aliens must have helped." (link)