This paper shows that there can be equilibria in which exchange rates display randomness unrelated to fundamentals. This is demonstrated in the context of a two currency, one good model, with three agent types and cash-in-advance constraints. A crucial feature is that the type i agents, for i=l, 2, must satisfy a cash—in-advance constraint by holding currency i, while type 3 agents can satisfy it by holding either currency. It is shown that real allocations vary across the multiple equilibria if markets for hedging exchange risk do not exist and that the randomness is innocuous if complete markets exist.

The classical and early neoclassical economists knew that the essential function of money was its role as a medium of exchange. Recently, this idea has been formalized using search-theoretic noncooperative equilibrium models of the exchange process. The goal of this paper is to use a simple model of this class to analyze four substantive issues in monetary economics: the interaction between specialization and exchange, dual fiat currency regimes, the welfare improving role of money, and the susceptibility of monetary economies to extrinsic uncertainty.

This paper proposes a theory of foreign reserves as macroprudential policy. We study an open economy model of financial crises, in which pecuniary externalities lead to over-borrowing, and show that by accumulating international reserves, the government can achieve the constrained-efficient allocation. The optimal reserve accumulation policy leans against the wind and significantly reduces the exposure to financial crises. The theory is consistent with the joint dynamics of private and official capital flows, both over time and in the cross section, and can quantitatively account for the recent upward trend in international reserves.

We explore monetary policy in a world without currency. In our world, money is a form of government debt that bears interest, which can be negative as well as positive. Services of money are a factor of production. We show that the national accounts must be revised in this world. Using our baseline economy, we determine the balanced growth paths for a set of money interest rate target policy regimes. Besides this interest rate, the only policy variable that differs across regimes is either the labor income tax rate or the inflation rate. We find that Friedman monetary satiation without deflation is possible. We also examine a set of inflation rate targeting regimes. Here, the only other policy variable that differs across policy regimes is the tax rate. There is a sequence of markets with outcome in each market being a Debreu valuation equilibrium, which determines the vector of assets and liabilities households take into the subsequent period. Evaluating a policy regime is an advanced exercise in public finance. Monetary satiation is not optimal even though money is costless to produce. A preliminary version of this paper circulated under the title “Monetary Policy with 100 Percent Reserve Banking: An Exploration.”

The purpose of this paper is to discuss some of the models used in New Monetarist Economics, which is our label for a body of recent work on money, banking, payments systems, asset markets, and related topics. A key principle in New Monetarism is that solid microfoundations are critical for understanding monetary issues. We survey recent papers on monetary theory, showing how they build on common foundations. We then lay out a tractable benchmark version of the model that allows us to address a variety of issues. We use it to analyze some classic economic topics, like the welfare effects of inflation, the relationship between money and capital accumulation, and the Phillips curve. We also extend the benchmark model in new ways, and show how it can be used to generate new insights in the study of payments, banking, and asset markets.

This essay articulates the principles and practices of New Monetarism, our label for a recent body of work on money, banking, payments, and asset markets. We first discuss methodological issues distinguishing our approach from others: New Monetarism has something in common with Old Monetarism, but there are also important differences; it has little in common with Keynesianism. We describe the principles of these schools and contrast them with our approach. To show how it works, in practice, we build a benchmark New Monetarist model, and use it to study several issues, including the cost of inflation, liquidity and asset trading. We also develop a new model of banking.

This essay reviews the development of neoclassical growth theory, a unified theory of aggregate economic phenomena that was first used to study business cycles and aggregate labor supply. Subsequently, the theory has been used to understand asset pricing, growth miracles and disasters, monetary economics, capital accounts, aggregate public finance, economic development, and foreign direct investment.

The focus of this essay is on real business cycle (RBC) methodology. Those who employ the discipline behind the methodology to address various quantitative questions come up with essentially the same answer—evidence that the theory has a life of its own, directing researchers to essentially the same conclusions when they apply its discipline. Deviations from the theory sometimes arise and remain open for a considerable period before they are resolved by better measurement and extensions of the theory. Elements of the discipline include selecting a model economy or sometimes a set of model economies. The model used to address a specific question or issue must have a consistent set of national accounts with all the accounting identities holding. In addition, the model assumptions must be consistent across applications and be consistent with micro as well as aggregate observations. Reality is complex, and any model economy used is necessarily an abstraction and therefore false. This does not mean, however, that model economies are not useful in drawing scientific inference.

The vast number of contributions made by many researchers who have used this methodology precludes reviewing them all in this essay. Instead, the contributions reviewed here are ones that illustrate methodological points or extend the applicability of neoclassical growth theory. Of particular interest will be important developments subsequent to the Cooley (1995) volume, Frontiers of Business Cycle Research. The interaction between theory and measurement is emphasized because this is the way in which hard quantitative sciences progress.

Most economic activity occurs in cities. This creates a tension between local increasing returns, implied by the existence of cities, and aggregate constant returns, implied by balanced growth. To address this tension, we develop a general equilibrium theory of economic growth in an urban environment. In our theory, variation in the urban structure through the growth, birth, and death of cities is the margin that eliminates local increasing returns to yield constant returns to scale in the aggregate. We show that, consistent with the data, the theory produces a city size distribution that is well approximated by Zipf’s Law, but that also displays the observed systematic under-representation of both very small and very large cities. Using our model, we show that the dispersion of city sizes is consistent with the dispersion of productivity shocks found in the data.