We use a simple graphical approach to represent Social Welfare Functions that satisfy Independence of Irrelevant Alternatives and Anonymity. This approach allows us to provide simple and illustrative proofs of May's Theorem, of variants of classic impossibility results, and of a recent result on...

How much discretion should the monetary authority have in setting its policy? This question is analyzed in an economy with an agreed-upon social welfare function that depends on the randomly fluctuating state of the economy. The monetary authority has private information about that state. In the...

The marginal social value of income redistribution is understood to depend on both the concavity of individuals' utility functions and the concavity of the social welfare function. In the pertinent literatures, notably on optimal income taxation and on normative inequality measurement, it seems...

Recent work on collective intertemporal choice suggests that non-dictatorial social preferences are generically time inconsistent. We argue that this claim conflates time consistency with two distinct properties of preferences: stationarity and time invariance. While the conjunction of time...

Infrequent but turbulent episodes of outright sovereign default on domestic creditors are considered a "forgotten history" in Macroeconomics. We propose a heterogeneous-agents model in which optimal debt and default on domestic and foreign creditors are driven by distributional incentives and...

This paper reviews the literature on governments' motivations for negotiating and joining international trade agreements. I discuss both normative explanations for trade agreements and explanations based on political-economy concerns. Most of the paper focuses on the purpose of multilateral...

I study expertise acquisition in a model of trading under asymmetric information. I propose and implement a method to estimate the ratio of social to private marginal value of expertise. This can be decomposed into three sufficient statistics: traders' average profits, the fraction of bad assets...

How should we measure economic efficiency? The canonical measure is an unweighted sum of willingnesses to pay. In contrast, this paper provides efficient welfare weights that implement the Kaldor-Hicks tests for efficiency but account for the distortionary cost of taxation. The shape of the...

The government often provides relief against large risks, such as disasters. A simple, general rationale for this role of government is considered here that applies even when private contracting to share risks is not subject to market imperfections. Specifically, the optimal private sharing of...