As an example Weizmann cited a recent argument over whether morality really can be derived from Darwinism, as E.O. Wilson seems to suggest, and as Larry Arnhart, a political scientist at the University of Northern Illinois, has argued on the list. It's a commonplace of most discussions about evolutionary psychology and Darwinism generally that you cannot derive moral imperatives from the strategies that are successful in nature. Science can tell us what will work, but only morality can tell us whether we should do it. Arnhart argues that this can't be true in a completely natural world, where supernatural explanations are rejected. He would argue that right and wrong are not transcendental categories but to some extent species specific.
Humans can only follow human goals.
Dogs can only pursue doggy goods, and so on. So to decide what humans should regard as good, we should look at what fulfills our evolved needs. But this means that there is no cosmic or transcendent standard of right or wrong independent of human nature. By contrast, Kant assumed that all 'rational beings' would have the same ethical principles, because such principles would be a priori imperatives of reason independent of natural desires. Proponents of evolutionary psychology who insist on a sharp dichotomy between the moral 'ought' and the natural 'is' are following the tradition of Kant and rejecting the tradition of Darwin.