Аннотация:The manner in which the concept of reciprocity is implicated in functional theory is explored, enabling a reanalysis of the concepts of survival and exploitation. The need to distinguish between the concepts of complementarity and reciprocity is stressed. Distinctions are also drawn between (1) reciprocity as a pattern of mutually contingent exchange of gratifications, (2) the existential or folk belief in reciprocity, and (3) the generalized moral norm of reciprocity. Reciprocity as a moral norm is analyzed; it is hypothesized that it is one of the universal principal components of moral codes. As Westermarck states, To requite a benefit, or to be grateful to him who bestows it, is probably everywhere, at least under certain circumstances, regarded as a duty. This is a subject which in the present connection calls for special consideration. Ways in which the norm of reciprocity is implicated in the maintenance of stable social systems are examined.