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.

In recent years, economists have increasingly debated whether multilateral development banks, such as the World Bank, should switch from making subsidized loans to giving outright grants. It is no small question. The combined loans of the World Bank Group and brethren regional entities such as the Asian and Inter-American Development Banks, approach $300 billion. Their funds constitute a main channel through which rich country governments provide assistance to developing country governments. In Bulow and Rogoff (1990), we first developed the case for a shift to outright grants. We argued that under the status quo, a vastly disproportionate share of aid goes to middle income countries via disguised interest subsidies, rather than to the poorest countries. We also argued that a shift to grants would protect donor banks from sometimes having to play a “bad cop” role when trying to collect net repayments rather than fully rolling over loans. The “Meltzer Commission” (International Financial Institution Advisory Commission, 2000) report on government sponsored international lending institutions famously took a similar view. Supporters of the status quo often argue that development bank loans to middle income countries are in fact highly profitable, and are essential for allowing institutions like the World Bank to subsidize aid to poor countries. We shall argue that the Bank’s profitability is an accounting artifice that greatly underestimates the risks of the Bank’s portfolio. Another argument for loans is that multilateral development banks have a superior enforcement technology that helps international debt markets to function more efficiently. Thus loans allow financially strapped governments, including in middle-income countries, to borrow more than they could otherwise. We will argue that this benefit, too, is an illusion. In those cases when official lending does expand a developing country government’s borrowing capacity, it effectively enables the government to commit the country to repayment levels beyond that supported by domestic political consensus, creating moral hazard for shortsighted rulers. In theory, better credit access to finance, say, public infrastructure projects can be highly beneficial. In practice, however, the increased risk of debt crisis all too often outweighs any gain ordinary citizens might enjoy from the loans. Furthermore, moral hazard on the part of lenders, who may be able to induce rich countries into subsidizing the bailout of troubled middle-income borrowers, may mean that aggregate lending is excessive even if multilaterals merely displace equivalent private debt. We do not argue for eliminating assistance to middle-income countries. On the contrary, we would favor expanding aid in general, albeit in far greater proportion to the world’s poorest countries. Note that in principle, any country with market access could use grant flows to help defray interest rate costs on loans if it so chose, but development banks would never need to assume a “bad cop” role in enforcing debt.

The Federal Reserve's mandate has evolved considerably over the organization's hundred-year history. It was changed from an initial focus in 1913 on financial stability, to fiscal financing in World War II and its aftermath, to a strong anti-inflation focus from the late 1970s, and then back to greater emphasis on financial stability since the Great Contraction. Yet, as the Fed's mandate has expanded in recent years, its range of instruments has narrowed, partly based on a misguided belief in the inherent stability of financial markets. We argue for a return to multiple instruments, including a more active role for reserve requirements.

A year ago, we presented a historical analysis comparing the run-up to the 2007 US subprime financial crisis with the antecedents of other banking crises in advanced economies since World War II (Reinhart and Rogoff 2008a ). We showed that standard indicators for the United States, such as asset price inflation, rising lever age, large sustained current account deficits, and a slowing trajectory of economic growth, exhibited virtually all the signs of a country on the verge of a financial crisis—indeed, a severe one. In this paper, we engage in a similar com

Taking advantage of key recent advances in long-run economic and financial data, we analyze the statistical properties of global long-maturity real interest rates over the past seven centuries. In contrast to existing consensus, we find that real interest rates are in fact trend stationary and exhibit a persistent downward trend since the Renaissance. We investigate structural breaks in real interest rates over time and find that overall the Black Death and the 1557 “Trinity default” appear as consistent inflection points. We further show that demographic and productivity factors do not represent convincing drivers of real interest rates over long spans.