Prerequisites Versus Diffusion : Testing Alternative Explanations of Social Security Adoption

Social security is one of the most important means by which modern nations protect the welfare of their citizens. The first appearance of social security represents a particularly important policy juncture at which many nations broke from the anti-welfare doctrine of traditional liberalism. The bulk of scholarship on social security treats its adoption as an explanation for other aspects of the social security experience, instead of an outcome to be explained. This article analyzes two alternative explanations of the timing of adoption: the prerequisites hypothesis, involving the level of development within nations, versus diffusion among nations. Three patterns emerge. Among the earliest adopters, social security diffuses up a developmental hierarchy of nations rather than down a hierarchy; in the middle group of adopters, a pattern of spatial diffusion is present in which social security is rapidly diffused among countries at widely different levels of modernization; and among the latest adopters, a combination of hierarchical diffusion and a prerequisite explanation appear to be the most satisfactory means of accounting for the pattern of adoption