              If so much captures Aristotle’s dominant argument for teleology, then his view is unmotivated. The argument is problematic in the first instance because it assumes an exhaustive and exclusive disjunction between what is by chance and what is for the sake of something. But there are obviously other possibilities. Hearts beat not in order to make noise, but they do so always and not by chance.  Second, and this is perplexing if we have represented him correctly, Aristotle is himself aware of one sort of counterexample to this view and is indeed keen to point it out himself: although, he insists, bile is regularly and predictably yellow, its being yellow is neither due simply to chance nor for the sake of anything. Aristotle in fact mentions many such counterexamples (Part. An. 676b16–677b10, Gen. An. 778a29–b6). It seems to follow, then, short of ascribing a straight contradiction to him, either that he is not correctly represented as we have interpreted this argument or that he simply changed his mind about the grounds of teleology. Taking up the first alternative, one possibility is that Aristotle is not really trying to argue for teleology from the ground up in Physics ii 8, but is taking it as already established that there are teleological causes, and restricting himself to observing that many natural phenomena, namely those which occur always or for the most part, are good candidates for admitting of teleological explanation.