This article argues that the moral dimensions of the term 'culture' have been under-theorized in anthropology. The argument stems from a particular reading of the Western philosophy of ethics. Based in economic anthropology, I explore how an understanding of the moral imperative can illuminate differences in processes of accumulation. After a discussion of the concept of morality in philosophy and in recent anthropology, I go on to examine the principles of altruism and reciprocal utility in the light of theories of kinship and of rational choice. I then outline an argument concerning the general form of moral reasoning. According to this argument, kinship classifications function logically to synthesize variable distributions in different societies of two interconnected principles—altruism and reciprocal utility.