This paper reviews and puts into perspective recent work reassessing the first and second Fundamental Theorems of Welfare Economics. It assesses the implications of the Greenwald-Stiglitz theorem establishing the (constrained) Pareto inefficiency of market economies with imperfect information...

Firm size follows Zipf's Law, a very fat-tailed distribution that implies a few large firms account for a disproportionate share of overall economic activity. This distribution of firm size is crucial for evaluating the welfare impact of economic policies such as barriers to entry or trade...

Natives benefit from immigration mainly because of production complementarities between immigrant workers and other factors of production, and these benefits are larger when immigrants are sufficiently `different' from the stock of native productive inputs. The available evidence suggests that...

This lecture examines the effects of tax policy and social security retirement benefits on capital accumulation and economic welfare. The paper begins by examining how capital income taxes reduce the real return to savers and then discusses the welfare loss of capital income taxation relative to...

We show that the welfare of a country's infinitely-lived representative consumer is summarized, to a first order, by total factor productivity (TFP) and by the capital stock per capita. These variables suffice to calculate welfare changes within a country, as well as welfare differences across...

This paper develops an analytical framework for the analysis of adjustment to adverse shocks in the presence of limited access to the international credit market. We consider an economy producing traded and non-traded goods and experiencing a permanent, unanticipated drop in the availability of...

I propose and formalize an argument for why economists working in the welfarist normative tradition should include nonwelfarist principles in how they judge economic policy. The key idea behind this argument is that the world is too complex, and our ability to model it too limited, for us to...

We propose a broad generalization of standard choice-theoretic welfare economics that encompasses a wide variety of non-standard behavioral models. Our approach exploits the coherent aspects of choice which those positive models typically attempt to capture. It replaces the standard revealed...

This paper derives a portfolio diversification rationale for a trade policy regime that insures returns to nondiversifiable human capital investment. In the absence of complete insurance markets for human capital, the decentralized equilibrium is characterized by excessive specialization. The...