In this paper, we investigate the importance of aggregate fluctuations for the assessment of the optimal level of public debt in an incomplete-markets economy. We start by building a steady state model in which households are only subject to uninsurable idiosyncratic risk and evaluate the optimal level of public debt. We then augment the model to allow for aggregate risk and measure the impact on the optimal level. We show that the cyclical behavior of the economy has a quantitative impact on this level that can be decomposed into the effects of the aggregate productivity shock and the cyclicality of unemployment. Moreover, we find that matching wealth distribution statistics substantially changes the optimal level of public debt.

Responding to the challenges of demographic ageing, the German system of old-age provision has undergone substantial changes during the past two decades and is in fact still under reconstruction. Benefit levels deriving from the public pay-as-you-go scheme will decline until 2060, while contribution rates may still go up substantially. Additional cover from private or occupational pension schemes is urgently needed. Thus far, steps in this direction have been half-hearted. The continuing crisis in financial markets and a more profound distrust in financial institutions and market-based instruments of old-age provision currently create obstacles to progress with this overhaul. Nevertheless, despite the differing traditions, Germany could learn important lessons now from other developed countries that have longer experience of funded pensions.

This paper analyzes aggregate wealth based on separable risk aversion and intertemporal substitution. In an infinite-period overlapping-generations model with survival uncertainty, economic growth, and permanent and temporary income shocks, our closed-form solution permits us to derive rich behavioral conclusions and to assess the relative importance of the major components of aggregate wealth. In particular, the separation of the attitudes toward risk and substitution allows us to disentangle behaviors relating to the intertemporal substitution motive from behaviors relating to the precautionary motive.