We propose an objective and justifiable ethics that is contingent on the truth of evolutionary theory. We do not argue for the truth of this position, which depends on the empirical question of whether moral functions form a natural class, but for its cogency and possibility. The position we propose combines the advantages of Kantian objectivity with the explanatory and motivational advantages of moral naturalism. It avoids problems with the epistemological inaccessibility of transcendent values, while avoiding the relativism or subjectivism (...) often associated with moral naturalism. Our position emerges out of criticisms of the contemporary sociobiological views of morality found in the writings of Richard Alexander, Michael Ruse, and Robert Richards. (shrink)