Nobody can...

Nobody can tell what design actually is. Oh, there are some who try but the answer always comes back to the flawed watchmaker analogy. We know artificial from organic but when genetic manipulation came along we became unsure of even that benchmark.

Behe actually had a halfway decent premise... if we could find something in biology that can't be accounted for by evolution then we'd have to figure out how it came to be. An "intelligent designer" would fit the bill. I've just never understood the leap from "found a hole in your theory" to "goddidit."