E. O. Wilson argues that we must use scientifically based reason to solve the values dilemma created by the loss of a transcendent foundation for values. Peter Singer allows that sociobiology can help us understand the evolutionary origin of ethics, but denies the claim that sociobiology or any science can furnish us with ultimate ethical principles. We argue that Singer's critique of Wilson's attempt to bridge the gap between fact and value using empirical reason is unconvincing and that Singer's own (...) ethical principle of disinterestedness requires major support from empirical reason and is not sustainable by pure reason alone. (shrink)