In his Tractatus, Wittgenstein said (4.1122): ‘The Darwinian theory has no more to do with philosophy than has any other hypothesis of natural science.’ When, later, Wittgenstein stood the philosophy of the Tractatus on its head, and thereby provided a basis for the dominant philosophy of the mid-century, he still retained this part of the earlier position. In fact, nothing could be more false: there is no realm which can enjoy such total apartheid from the contents of the sciences. Yet the example is well chosen to illustrate the mistaken point. Amongst scientific theories, some do and some do not have philosophical implications, and they have them in varying degree. But in the front rank amongst claimants to our philosophic attention are the biological doctrines connected with the notion of evolution.