The Determination of Public Debt under both Aggregate and Idiosyncratic Uncertainty

Abstract

We use an analytically tractable model to show that the Ramsey planner's decisions to finance stochastic public expenditures under uninsurable idiosyncratic risk implies a departure from tax smoothing. In the absence of state-contingent bonds the government's attempt to balance the competing incentives between tax smoothing and individual consumption smoothing---even at the cost of extra tax distortion---implies a bounded stochastic unit root component in optimal taxes. Nonetheless, a sufficiently high average level of public debt to support individuals’ self-insurance position is welfare improving, consistent with the strictly positive quantity of government debt observed throughout human history.