In biology, when you encounter something that has the superficial appearance of design there are two possible explanations. Either it evolved by entirely natural processes or God did it.
In the Intelligent Design Creationist literature, 99% of the effort is spent on trying to prove that evolution cannot produce the appearance of design.1 They have to focus on the anti-evolution argument because if they admit that evolution can do the job then there's no reason to invoke the supernatural.
The frequent criticism of this negative anti-science rhetoric is an embarrassment to many Intelligent Design Creationists so they often make up stories about the "positive" argument for design.
Sometimes it's fun to watch them twist and turn. Here's Casey Luskin performing: How James Carville’s New Book, 40 More Years Misrepresents Intelligent Design.
1. The remaining 1% is uninterpretable gibberish.