The 1953 book that contained Friedman's essay on "The Methodology of Positive Economics" also contained a chapter titled "The Case for Flexible Exchange Rates." In it, Friedman argued that "current economic and political conditions" demanded "a system of flexible or floating exchange rates exchange rates freely determined in an open market primarily by private dealings and, like other market prices, varying from day to day." Such a regime, he claimed, was "absolutely essential for ... the achievement and maintenance of a free and prosperous world community engaging in unrestricted multilateral trade" (Friedman 1953b, p. 157).

Donald MacKenzie, An Engine, Not a Camera, loc. 646