Intelligent Design is not a scientific theory.

Intelligent Design is a much of a scientific theory as sleeping is a sport (this isn't my point of contention, mind you). By any reasonable account of science, ID fails to qualify as a scientific theory. First, I look to Karl Popper's account of science for support. Popper's principle contribution to the philosophy of science is the concept of falsification; that is, a proposed theory must have the capable of refutation. Theories that escape refutation are not necessarily unhelpful or even incorrect, they are simply not scientific. To wit: a proponent of a theory must specify what evidence would cause him or her to abandon a theory. While ID is in principle falsifiable (every "gap" in evolution could be theoretically filled and thus the mechanism of natural selection could explain how every species that ever existed came to be), it is not in practice. The ID supporter will simply make ad hoc modifications for their theory to escape refutation (this is not always a bad thing, but in the case of ID, it is). For example, once the mammalian eye was shown to be capable of developing via natural selection (likely methods have been put forth), the ID proponent will simply switch focus, claiming that another feature of life can only be explained by invoking a supernatural designer. Thomas Kuhn's account of science is also helpful for the purpose of this discussion. Kuhn suggests that a theory is only scientific if it works within a framework that gives rise to "puzzles" to solve. The rules of the framework must be strict enough for a theory to give rise to problems to be pursued (so research can be performed). ID gives rise to no such problems. It makes no predictions of its own. The deft reader might notice that this ties into my first point because a theory must make predictions that, if they fail, will lead to refutation of the theory, e.g. if my theory of astronomy predicts that the moon will turn into a frog every November, come November, my theory will be falsified because of its failed prediction. For a less absurd example, consider Einstein's prediction that stars near the sun would appear to have been slightly shifted because their light had been curved by its (the sun) gravitational field. Eddington's famous solar eclipse experiment confirmed Einstein's prediction. Had Einstein's prediction failed, the validity of general relativity would been severely undercut (if not entirely falsified). The point is that general relavity makes predictions that can tested, which ID fails to do. Also, ID is negative theory. Again, it makes no predictions of its own, so it is not a positive theory. ID is essentially a theory against evolution and nothing more. Finally (sorry I must resort to such sophomoric transitions), even if a supernatural force made certain features of nature "irreducibly complex," how would we test this hypothesis? There is no way to test (and therefore verify) if ID is correct. The ID proponent must simply appeal to a supernatural force when a feature in the phylogenetic tree of life has not been explained (as a side not, ID supports often confuse what is unknown with what is unknowable). ID lacks the aforementioned qualities and is therefore not scientific. With this in mind, pray tell, how is ID a scientific alternative to the theory of evolution, as its most vocal supports assert?