negative reciprocity with outsiders (i.e. outside the community). The kind of reciprocity reflects the moral nature of the social relationship, hence morality is not universal, but dependent on social distance. Sahlins' model thus views reciprocity as socially, morally and economically structured and "the structure is that of kinship-tribal groups" not a universalizing moral ethic. Reciprocity and kinship rank With rank come privileges. However, in traditional societies "social inequality is more the organization of economic equality. Often, in fact, high rank is only secured or sustained by o'ercrowing generosity." Rank is usually generational, with elders having seniority, but still held by the bounds of close kinship. Generalized reciprocity by such elders may be a "starting mechanism" for more general hierarchy, by placing many in the giver's debt. This leads to the question, "when does reciprocity give way to redistribution." Sahlins argues that chiefly redistribution is not different in principle and nothing but a highly organized form of kinship-rank reciprocity. Reciprocity in market-based societies David Graeber argues, in contrast, that balanced gift exchange and market exchange have more in common than normally assumed. Since both are balanced, the social relationship created through the sense of debt and obligation is constantly in danger of being ended by the return gift/exchange. He thinks it better to contrast "open" and "closed" reciprocity. Open reciprocity "keeps no accounts because it implies a relation of permanent mutual commitment." This open reciprocity is closed off precisely when it is balanced. Thought of in this way, we can see the relationship as a matter of degree, more or less open or closed. Closed reciprocity of gifts is most like market exchange. It is competitive, individualistic and may border on barter. Reciprocity and marital alliance The alliance theory (or general theory of exchanges) is the name given to the structural method of studying kinship relations. It finds its origins in Claude Lévi-Strauss's Elementary Structures of Kinship (1949). According to Levi-Strauss, the universal prohibition of incest pushes human groups towards exogamy where certain categories of kin are forbidden to marry. The incest taboo is thus a negative prescription; without it, nothing would push men to go searching for women outside of their inner kinship circle, or vice versa. In a process akin to the division of labour which makes exchange necessary, one's daughter or sister is offered to someone outside a family circle, and starts a circle of exchange of women: