Alliance theory is based on the incest taboo: according to it, only this universal prohibition of incest pushes human groups towards exogamy. Thus, inside a given society, certain categories of kin are forbidden to inter-marry. The incest taboo is thus a negative prescription; without it, nothing would push men to go searching for women outside their inner kinship circle, or vice versa. This theory echoes with Freud's Totem and Taboo (1913). But the incest taboo of alliance theory, in which one's daughter or sister is offered to someone outside a family circle, starts a circle of exchange of women: in return, the giver is entitled to a woman from the other's intimate kinship group. Thus the negative prescriptions of the prohibition have positive counterparts.Claude Lévi-Strauss, Les structures élémentaires de la parenté, Paris, Mouton, 1967, 2ème édition, p.60 The idea of the alliance theory is thus of a reciprocal or a generalized exchange which founds affinity. This global phenomenon takes the form of a "circulation of women" which links together the various social groups in one whole: society.
