We analyze a dynamic stochastic general‐equilibrium (DSGE) model with an externality—through climate change—from using fossil energy. Our central result is a simple formula for the marginal externality damage of emissions (or, equivalently, for the optimal carbon tax). This formula, which...

We study the optimal provision of insurance against unobservable idiosyncratic shocks in a setting in which a benevolent government cannot commit. A continuum of agents and the government play an infinitely repeated game. Actions of the government are constrained only by the threat of reverting...

We consider an environment in which agents' skills are private information and follow arbitrary stochastic processes. We prove that it is typically Pareto optimal for an individual's marginal benefit of investing in capital to exceed his marginal cost of doing so. This wedge is consistent with a...

In this paper, we generalize the notion of Pareto efficiency to make it applicable to environments with endogenous populations. Two efficiency concepts are proposed: 𝒫-efficiency and 𝒜-efficiency. The two concepts differ in how they treat potential agents that are not born. We show that these...

We study the optimal Mirrlees taxation problem in a dynamic economy with idiosyncratic (productivity or preference) shocks. In contrast to the standard approach, which implicitly assumes that the mechanism is operated by a benevolent planner with full commitment power, we assume that any...

In this paper, we generalize the notion of Pareto-efficiency to make it applicable to environments with endogenous populations. Two efficiency concepts are proposed, P-efficiency and A-efficiency. The two concepts differ in how they treat people who are not born. We show how these concepts...

This paper studies dynamic non-linear taxation in a two-period model without government commitment and a continuum of agents with privately known skill parameters, which are constant overtime. The government is utilitarian but cannot commit at t=1 to the tax scheme that she will propose at t=2....

The paper analyzes an implementation of an optimal disability insurance system as a competitive equilibrium with taxes. The problem is modeled as a dynamic mechanism design problem in which disability is unobservable. We show that an asset-tested disability system in which a disability transfer...

This paper studies a mechanism design model of financial intermediation. There are two informational frictions: agents receive unobservable shocks and can participate in markets by engaging in trades unobservable to intermediaries. Without regulations, intermediaries provide no risk sharing...