Asian economists who promote regional integration in Asia have observed the debate with amazement, in that the fault line is not based on economic philosophy like “Keynesians vs. Neoclassicals” or “Liberals vs. Conservatives,” but on a geographical, transatlantic divide. American economists, led by Martin Feldstein, have argued that the eurozone’s economies are too diverse, with too many institutional differences and labor-market rigidities, to form an optimal currency area.