We construct an endogenous growth model that includes productive public capital and government debt. We assume that the government debt-to-GDP ratio is gradually adjusted to a target level, reflecting the permanent commitment rules in the Stability and Growth Pact or the Maastricht Treaty in the European Union (i.e., the well-known 60% rule). These rules affect government borrowing and public investment. Here, we examine the welfare implications of the permanent commitment rules. We find that fiscal consolidation based on the rules improves social welfare. Moreover, the improvement in welfare accelerates as fiscal consolidation progresses more rapidly. Last, we also discuss and derive the optimal long-run debt-to-GDP ratio.

In a small open economy model of endogenous growth with public capital accumulation, we examine the effects of a debt policy rule under which the government must reduce its debt-GDP ratio if it exceeds the criterion level. To sustain public debt at a finite level, the government should adjust public spending rather than the income tax rate. The long-run debt-GDP ratio should be kept sufficiently low to avoid equilibrium indeterminacy. Under sustainability and determinacy, a tighter (looser) debt rule brings welfare gains when the world interest rate is relatively high (low).

This paper constructs an endogenous growth model with overlapping generations, whose engine of economic growth is productive public capital. The government faces a trade-off in public policy between public investment and social security provision because of its budget constraint. Larger public investment accelerates economic growth. On the other hand, larger public investment reduces the social security provision. This may reduce the consumption stream of agents. We first show that when the government aims at growth maximization, it chooses no social security provision. However, we also show that the growth-maximizing policy does not maximize welfare levels of each generation on the balanced growth path. Early generations may demand social security provision because the benefits from economic growth caused by an acceleration of public investment are relatively small. In contrast, future generations may require no social security provision but a large amount of public capital. Additionally, by setting the tax rate below the level that maximizes the growth rate, the government can make the welfare levels of all generations from the initial state on the balanced growth path better off. Moreover, in an economy facing an aging population, an increase in the social security provision to the old rather than an increase in public investment can be preferable from the viewpoint of social welfare.

This study investigates the relationship between the sustainability of public debt and inequality in an endogenous growth model with heterogeneous agents. We show that the threshold for the sustainability of public debt is related to not only the relative size of public debt but also inequality. In addition, this study examines the effects of budget deficit and redistributive policies on the sustainability of public debt and inequality. We show that an increase in the deficit ratio or the redistributive tax makes public debt less sustainable. If the economy falls into the unsustainable region as a result of the policy change, both public debt and inequality continue to increase.

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