A positive theory of government debt

A government that cannot commit to future policy choices faces a trade-off that explains the level of debt. On the one hand, there is an incentive to increase debt and delay taxation, so as to reduce current distortions. On the other hand, inflating current prices lowers the real value of nominal debt and so there is a motive to reduce it now. The size of long-run debt will depend on the interaction of these two opposing incentives. The critical determinant is the willingness of households to substitute away from goods being taxed by inflation. Numerical simulations show that the model matches some qualitative and quantitative properties of U.S. policy variables, including the fact that wars are frequently financed with a mix of instruments. The theory interprets the unusual post-World War II inflation and fast liquidation of accumulated debt as being due to higher long-run debt and expenditure in the period leading up to the war.