policy choice inevitably arises since a given social security system cannot be maintained by simply indexing retirement ages … longevity increases, the young generation contributes more, and the old generation faces lower benefits and a retirement age …

model with stochastic life expectancy across generations and endogenous retirement decisions. The social optimum is shown to … imply that retirement age should be proportional to longevity. Moreover, increasing longevity calls for pre-funding even if … sharing and retirement incentives are analyzed. …