Is Public Debt Growth-Enhancing or Growth-Reducing?

To understand mixed evidence provided by empirical studies for the relationship between the accumulation of public debt and economic growth, it is necessary to consider not only the crowd-out effect of public debt on economic growth but also the growth-enhancing crowd-in effect that cannot be uncovered by the traditional theoretical achievements. We develop a dynamic general equilibrium model with infinitely lived agents and derive an inverted U-shaped relationship between the accumulation of public debt and economic growth. The analysis focuses on both crowd-out and crowd-in effects that public debt has on private investment in a financially constrained economy and clarifies the mechanism inducing the inverted U-shaped relationship in the growth process. When the public debt-to-GDP ratio is below a certain threshold level, the crowd-in effect dominates the crowd-out effect and the accumulation of public debt promotes economic growth. When the public debt-to-GDP ratio exceeds the threshold level, the accumulation of public debt begins to hinder economic growth with the crowd-out effect dominating the crowd-in effect.