That's what I think should be the standard response to "Intelligent Design" advocates. In order to call "Intelligent Design" a theory, in the scientific sense, its advocates need to start telling us what the theory predicts. The Theory of Evolution, for example, predicts that any feature you find on a modern animal will be a variation on a similar feature of the animal's ancestors. The important point about the prediction is that it gives you a way to test the theory.
In our previous example, you can test the Theory of Evolution whenever you discover a new species. You just try to place the species in the evolutionary "family tree" by comparing its features to those of other species (both modern and extinct) to identify its "relatives". Evolution predicts that every species will have its place in the tree, so discovering a species that has no "ancestors" on the tree would be evidence that something else is going on.
One of my internet acquaintances, who is an engineer, has written an essay on "Intelligent Design theory", which he has taken to calling "Incompetent Design theory". He argues that an intelligent designer would fix obvious problems with living organisms. For instance, in all land mammals, the trachea (your "wind pipe") and esophagus (the tube you swallow food down) meet at the back of the mouth. Why is that a problem? Have you ever choked on something? Have you ever heard of someone choking to death on something? Having those two tubes connected is a potentially lethal design flaw, and it's a flaw that exists in every vertebrate land animal.
Why bring that up? It goes back to predictions. What is the predictable response of an intelligent designer who discovers a flaw in one of his designs? What does it say about "Intelligent Design theory" that such a flaw is so widespread among modern species?