Political business cycle theories generally rely on nominal rigidities and voter myopia. This paper offers an equilibrium theory which preserves some basic insights from earlier models, though with significant refinements. The "political budget cycle" emphasized here is in fiscal policy rather than output and inflation; it arises via a multidimensional signal process. One can consider the welfare implications of proposals to mitigate the cycle, and the effects of altering the electoral structure.

We show that, under fairly general conditions, lending to small countries must be supported by the direct sanctions available to creditors, and cannot be supported by a country's "reputation for repayment." This distinction is critically important for understanding the true underlying structure of sovereign lending contracts, and comparing policy alternatives for dealing with the developing country debt problem.

FIRST ARTICULATED by scholars of the ISalamanca school in sixteenth century Spain,1 purchasing power parity (PPP) is the disarmingly simple empirical proposition that, once converted to a common currency, national price levels should be equal. The basic idea is that if goods market arbitrage enforces broad parity in prices across a sufficient range of individual goods (the law of one price), then there should also be a high correlation in aggregate price levels. While few empirically literate economists take PPP seriously as a short-term proposition, most instinctively believe in some variant of purchasing power parity as an anchor for long-run real exchange rates. Warm, fuzzy feelings about PPP are not, of course, a substitute for hard evidence. There is today an enormous and evergrowing empirical literature on PPP, one that has arrived at a surprising degree of consensus on a couple of basic facts. First, at long last, a number of recent studies have weighed in with fairly persuasive evidence that real exchange rates (nominal exchange rates adjusted for differences in national price levels) tend toward purchasing power parity in the very long run. Consensus estimates suggest, however, that the speed of convergence to PPP is extremely slow; deviations appear to damp out at a rate of roughly 15 percent per year. Second, short-run deviations from PPP are large and volatile. Indeed, the one-month conditional volatility of real exchange rates (the volatility of deviations from PPP) is of the same order of magnitude as the conditional volatility of nominal exchange rates. Price differential volatility is surprisingly large even when one confines attention to relatively homogenous classes of highly traded goods. The purchasing power parity puzzle then is this: How can one reconcile the enormous short-term volatility of real exchange rates with the extremely slow rate at which shocks appear to damp out? Most explanations of short-term exchange rate volatility point to financial factors such as changes in portfolio preferences, short-term asset price bubbles, and monetary shocks (see, for example, Maurice Obstfeld and Rogoff forthcoming). Such shocks can have substantial effects on the real economy in the presence of sticky nominal wages and prices. I See Lawrence H. Officer (1982, ch. 3) for an extensive discussion of the origins of PPP theory; see also Dornbusch (1987).

We develop an analytically tractable two-country model that marries a full account of global macroeconomic dynamics to a supply framework based on monopolistic competition and sticky nominal prices. The model offers simple and intuitive predictions about exchange rates and current accounts that sometimes differ sharply from those of either modern flexible-price intertemporal models or traditional sticky-price Keynesian models. Our analysis leads to a novel perspective on the international welfare spillovers due to monetary and fiscal policies.

We present a dynamic model of international lending in which borrowers cannot commit to future repayments and in which debtors can sometimes successfully negotiate partial defaults or "rescheduling agreements." All parties in a debt rescheduling negotiation realize that today's rescheduling agreement may itself have to be renegotiated in the future. Our bargaining-theoretic approach allows us to handle the effects of uncertainty on sovereign debt contracts in a much more satisfactory way than in earlier analyses. The framework is readily extended to analyze the conflicting interest of different lenders and of banks and creditor country taxpayers.

This paper uses an infinite-horizon model based on individual maximizing behavior to study whether explosive price-level paths unrelated to monetary growth--speculative hyperinflations--can be equilibrium paths under rational expectations. In a pure fiat money regime, speculative hyperinflations can be excluded only through severe restrictions on individual preferences; but when the government fractionally backs the currency by guaranteeing a minimal real redemption value for money, speculative hyperinflations are impossible, even if agents are not completely certain that they can redeem their money in any given period. The analysis also confirms that implosive price-level paths and divergent paths for capital asset prices are not equilibria under either monetary regime.

Society can sometimes make itself better off by appointing a central banker who does not share the social objective function, but instead places "too large" a weight on inflation-rate stabilization relative to employment stabilization. Although having such an agent head the central bank reduces the time-consistent rate of inflation, it suboptimally raises the variance of employment when supply shocks are large. Using an envelope theorem, we show that the ideal agent places a large, but finite, weight on inflation. The analysis also provides a new framework for choosing among alternative intermediate monetary targets.

It appears likely that the number of currencies in the world, having proliferated along with the number of countries over the past 50 years, will decline sharply over the next two decades. The question I plan to pose here is: where, from an economic point of view, should we aim for this process to stop? Should there be a single world currency, as Richard Cooper (1984) boldly envisioned? Should there remain multiple major currencies but with a much stricter arrangement among them for stabilizing exchange rates, as say Ronald McKinnon (1984) or John Williamson (1993) recommended? Building on Maurice Obstfeld and Rogoff (2000b, d), I will argue here that the status quo arrangement among the dollar, yen, and euro (which I take to be benign neglect) is not far from optimal, not only for now but well into the new century. And it would remain a good system even if political obstacles to achieving greater monetary policy coordination (or even a common world currency) could be overcome. Again, this is not a paper on, say, the pros and cons of dollarization for small and medium-sized economies, but rather on arrangements among the core currencies. Any blueprint for the future core of the world currency system involves some crystal-ball gazing. But at the same time, recent research in international macroeconomics offers several important insights that can help inform the discussion.

The past decade has witnessed the growth of a large literature on international cooperation in trade and macroeconomic stabilization policy. Virtually all the models developed to date, however, are based on one of two extreme assumptions concerning governments' ability to commit to international agreements. Either they assume that governments can make constitutionally binding long-term agreements, or else they assume that governments have no ability to make legal commitments whatsoever. In the latter case, international policy cooperation is possible only to the extent that reputational factors will allow.' In this paper, I consider a world in which there is no legal mechanism for enforcing long-term international agreements, but where governments must still incur some small direct costs if they renege. These small costs might arise due to legislative or administrative frictions. I also allow for the possibility that international economic policy agreements can include small sidepayments. For example, in negotiating a bilateral reduction in tariffs, two allies could simultaneously agree to redistribute the burdens of defense expenditures.