Political Intergenerational Risk Sharing

In a stochastic two-period OLG model, featuring an aggregate shock to the economy,
ex-ante optimality requires intergenerational risk sharing. We compare the level
of time-consistent intergenerational risk sharing chosen by a social planner and by office
seeking politicians. In the political setting, the transfer of resources across generations
- a PAYG pension system - is determined as a Markov equilibrium of a probabilistic
voting game. Negative shocks represented by low realized returns on the risky asset
induce politicians to compensate the old through a PAYG system. Unless the young are
crucial to win the election, this political system generates more intergenerational risk
sharing than the (time consistent) social optimum. In particular, these transfers are
more persistent and less responsive to the realization of the shock than optimal. This is
because politicians anticipate their current transfers to the elderly to be compensated
through offsetting transfers by future politicians, and thus have an incentive to overspend.
Perhaps surprisingly, aging increases the socially optimal transfer but makes
politicians less likely to overspend, by making it more costly for future politicians to
compensate the current young.