Edmund Strother Phelps, Jr. (born July 26, 1933) is an American economist and the winner of the 2006 Nobel Memorial Prize in Economic Sciences. Early in his career he became renowned for his research at Yale s Cowles Foundation in the first half of the 1960s on the sources of economic growth. His demonstration of the Golden Rule savings rate, a concept first devised by John von Neumann and Maurice Allais, started a wave of research on how much a nation ought to spend on present consumption rather than save and invest for future generations. His most seminal work inserted a microfoundation —one featuring imperfect information, incomplete knowledge and expectations about wages and prices—to support a macroeconomic theory of employment determination and price-wage dynamics. This led to his development of the natural rate of unemployment —its existence and the mechanism governing its size.