The basis of calling ID a non-science is Popper and Kuhn.
Although, this is an acceptable and to some canonical answer, it is not the only definition of science.
Their thesis that science is only about those subjects which can be reliably defined in such a way as plausably falsfied or tested.
The failure in much of the ID debate is the supposition of this thesis, and the misunderstanding of what is knowable and the realm of what is intelligent.
Even if we were to make a way to formally state a concept and apply a measure as to how 'true' it is, this truth is but a function of other measures.
One of the measures is How Scientific it is.
In this branch, there are many other sub-measures, and one of these is the Kuhn falsifiable measure.
What the proponents of the Kuhn model fail to detail is that mathematics can answer only a very small domain, and beyond this, relies on the mechanics of human reasoning, which is not 'reasoning' in any dependable fashion.
My use of a hammer as a tool is only as long as it randomly isn't cabbage, or other thing unlike a hammer.
Specifically, the Darwin theory relies on a optimization subject often lumped together as pareto curve (or surface) minimization, and is often cited in the realm of game theory (see 'A Beautiful Mind').
Now, optimization is related to another way to measure intelligence, and that is compression.
This idea states that you can recognize a concept only if you can make a smaller statement that is more general. I can 'recognize' an apple despite its many forms and settings. The recognition of the apple is vastly smaller than the sum of all its differences and settings.
Why are everyone's sentences going on and on without the wordwrap--I know there has been some changes, but even with wordwrap on, the posts come out longer than my screen.
ROFL! Wrong, but thanks for playing.