We view sustainability as a requirement that welfare should not be expected to decline over time. We impose this requirement as a prior constraint on the consumption-savings-investment problem, and study its implications for saving, risky investment, and the social discount rate. The constraint...

We study cointegrating relationships among fiscal variables and output and use them to introduce a new measure of the government's fiscal position. In the US since World War II, we find that the primary surplus-GDP ratio and the government debt-GDP ratio are nonstationary, which invalidates...