We analyze the interaction between risk sharing and capital accumulation in a stochastic OLG model with production. We give a complete characterization of interim Pareto optimality. Our characterization also subsumes equilibria with a PAYG social security system. In a competitive equilibrium...

We develop a general equilibrium stochastic OLG model with heterogenous households. Households differ with respect to their productivity. Productivity depends stochastically on parents' unobservable investment in their child's human capital and an aggregate productivity shock. We introduce a...

This paper analyzes the impact of demographic aging on capital accumulation and welfare in economies with unfunded pensions. Using a two-period overlapping generation model with potentially endogenous retirement decisions, it shows that both the type of aging, i.e. declining fertility or...

We ask whether a pay-as-you-go financed social security system is welfare improving in an economy with idiosyncratic productivity and aggregate business cycle risk. We show analytically that the whole welfare benefit from joint insurance against both risks is greater than the sum of benefits...

When markets are incomplete, social security can partially insure against idiosyncratic and aggregate risks. We incorporate both risks into an analytically tractable model with two overlapping generations. We derive the equilibrium dynamics in closed form and show that joint presence of both...

In his seminal model (Feldstein, 1985), the government operates a social security system to counter the representative worker's myopia. (i) For a complete myope, he determined a sizable optimal tax rate (and the corresponding benefit level). (ii) For a partially shortsighted worker, he...

Paul Samuelson made a series of important contributions to population theory for humans and other species, evolutionary theory, and the theory of age structured life cycles in economic equilibrium and growth. The work is highly abstract but much of it was intended to illuminate issues of...