Keynesian Economics, Monetary Policy and the Business Cycle - New and Old

After a brief review of the main differences between New andOld Keynesian economics from the sixties this paper focuseson a tension between traditional sluggish measures of potentialoutput commonly used by policymakers and the New Keynesian (NK)notion of this variable which conceptualizes it as the levelof output that would have been produced under perfect competitionhad all prices and wages been flexible. The paper shows that,under monopolistic competition, NK potential output is oftenmore volatile than the level of output produced under stickyprices and wages implying either of the following. Real lifepolicymakers mistakenly target smooth versions of output or(since actual economies are monopolistically rather than perfectlycompetitive) the flexible price and wage equilibrium does notnecessarily maximize welfare. The paper shows, that dependingon the shape of the utility function and of the distributionof productivity shocks either case is possible and proposesa criterion for discriminating between them. (JEL E3, E4, E5,E6)