The second problem is that definition: what is science? Our current definition of science is quite narrow compared to all that ‘science’ was thought to encompass from the ancient world through the Renaissance. Our current definition of science involves examining mechanisms in a closed system. By way of crude analogy (that A.V. came up with), if a man brings a modern scientist a car and tells him that something is wrong with the brakes, the modern scientist will test out the brakes, examine the car, examine the brake pads, check the brake fluid, etc. If this man is coming in every week telling the modern scientist that something is wrong with the brakes, the scientist will continue doing the same tests to try to fix the brakes. The modern scientist will not begin to wonder if perhaps the man is a reckless driver with anger management issues who repeatedly hits the accelerator and then slams on his brakes during the drive home. The modern scientist makes the assumption that the answers are “in here” – under the hood of the car – and not “out there”–something is wrong with the driver. (Actually, most scientists would eventually begin to wonder if user error was the problem, which is where the analogy falls apart, but I think you can get the picture.) There is no room to teach ID or creationism in a science classroom – they are not science, as it is currently defined. Now if we were to expand the definition of science (and the tools science uses), it might be possible to teach these things as competing “theories.” (Tycho Brahe and Johannes Kepler, after all, were both astronomers and Neoplatonists, without conflict, where the one informed the other.) But that would involve a larger debate about science, education, and our general philosophical approaches.
When the proponents of ID demand that it be taught in the science classroom, they concede to modern science all the points that matter: modern science, instead of being one way of knowing about some components of our universe, is the best way of knowing; truth can only be uncovered through empiricism, naturalism is the only correct philosophical approach. Most discussions by ID proponents don’t revolve around the problems of naturalism as a philosophical approach, but are instead attempts to say that ID should be included by association with naturalism, the rules of modern science. And that’s affirming that the philosophy behind modern science has superiority above all others for understanding truth.