Key Figures in Exchange Rate Economics: Cassel, Keynes, White, Friedman, Mundell

Gustav Cassel (1866-1945)

A Swedish economist who did more than anyone to popularize purchasing power parity, the proposition that exchange rates should tend toward the level at which a given sum of money buys comparable baskets of goods in different countries. Cassel advanced the idea around 1918, when governments emerging from the First World War needed some principle for choosing new parities after years of suspended convertibility and divergent inflation. Purchasing power parity holds poorly over short horizons, since exchange rates are driven by capital flows and expectations far more than by goods prices, but it remains the standard long-run benchmark and the basis of familiar tools for comparing price levels across countries.

John Maynard Keynes (1883-1946)

Keynes shaped exchange rate debate twice. In 1925 he opposed Britain’s return to gold at the prewar parity, arguing in The Economic Consequences of Mr. Churchill that an overvalued pound would force deflation onto wages and employment — an early and vivid statement of the real cost of defending a fixed rate. At Bretton Woods in 1944, leading the British delegation, he proposed an International Clearing Union issuing a reserve unit called bancor, with adjustment pressure applied to surplus countries as well as deficit ones. The American plan prevailed, but Keynes’s argument about asymmetric adjustment burdens has resurfaced in every subsequent imbalance debate.

Harry Dexter White (1892-1948)

The senior U.S. Treasury official who led the American delegation at Bretton Woods and whose blueprint largely became the system adopted in 1944. Where Keynes wanted a genuinely supranational reserve asset and automatic overdraft facilities, White favored a stabilization fund of subscribed national currencies with the U.S. dollar at the center, convertible into gold. With the United States holding most of the world’s monetary gold and the decisive bargaining position, White’s design carried. The institutions it produced — the IMF and the World Bank — outlasted the peg system itself by decades and still structure international financial cooperation.

Milton Friedman (1912-2006)

Friedman made the intellectual case for floating rates well before they arrived. His 1953 essay “The Case for Flexible Exchange Rates” argued that if some price must adjust when a country’s external position changes, it is far less disruptive to move one price — the exchange rate — than to force adjustment through domestic wages and prices, which are slow and sticky. He also contended that speculation would generally stabilize rather than destabilize a floating rate, since profitable speculators buy low and sell high. When Bretton Woods collapsed in the early 1970s, Friedman’s framework became the standard defense of the regime that replaced it.

Robert Mundell (1932-2021)

The Canadian economist behind two ideas at the core of open-economy macroeconomics. With Marcus Fleming he developed the Mundell-Fleming model, showing how monetary and fiscal policy work differently depending on the exchange rate regime and the mobility of capital — the source of the impossible trinity, the result that a country cannot simultaneously have a fixed exchange rate, free capital movement, and an independent monetary policy. His 1961 paper on optimum currency areas asked what conditions make it sensible for regions to share a single currency, and became the standard reference in debates over the euro. He received the Nobel Memorial Prize in 1999.