The world dollar standard is an accident of history that greatly facilitates international trade and exchange-even trade not directly involving the United States. Since 1945, the dollar has been the key currency for clearing international payments among banks including interventions by governments to set exchange rates, the dominant currency for invoicing trade in primary commodities, and the principal currency in official exchange reserves.

Although the strong network effects of the dollar standard greatly increases the financial efficiency of multilateral trade, nobody loves it. Erratic...