The original Lucas version of the new-classical macroeconomics combined the undeniable appeal of rational expectations with two more dubious assumpti… - Robert J. Gordon

The postwar era has not surprised Arthur Burns, for business cycles have continued their "unceasing round." although the United States recession of 1981-82 was the eighth since World War II and the deepest postwar slump by almost any measure, the 1983-84 recovery displayed an upward momentum sufficient to befuddle forecasters and delight incumbent politicians. Nor would a reincarnated Joseph Schumpeter be disappointed in the current status of business cycle research in the economics profession. To be sure, interest in business cycles decayed during the prosperity of the 1960s, as symbolized in the 1969 conference volume, Is the Business Cycle Obsolete? and in Paul Samuelson's remark the same year that the National Bureau of Economic Research "has worked itself out of one of its first jobs, namely, the business cycle."

Since the late 1960s macroeconomic debates in the United States have centered on the competing interpretations of the new classical and new Keynesian macroeconomics. The initial new classical model developed in the early 1970s by Robert E. Lucas, Jr., combined market-clearing, imperfect information, and rational expectations. After much testing, it was eventually rejected in the late 1970s for failing to explain why business cycles lasted on average four years while information delays lasted only a few weeks. It was soon replaced by a second new classical approach, the Real Business Cycle (RBC) model, which was also based on continuous market clearing and competitive equilibrium, but now generated the business cycle through serially correlated procyclical technology shocks.

But business cycles as a subject for study have enjoyed a revival for at least a decade now, stimulated in part by the severity of the 1974-75 and 1981-82 recessions and in part by the intellectual ferment surrounding the development of the "equilibrium business cycle model" and the attention paid to the seminal work of Robert E. Lucas, Jr., contained in his book Studies in Business Cycle Theory (1981). Indeed, there is no longer any need to lament the passing of economics courses explicitly carrying the title "Business Cycles," since the topic of business cycle behavior and analysis has so infiltrated courses carrying the title "Macroeconomics" that the two subjects have become almost interchangeable. 2 In this light it is fitting that the major research program of the NBER in this area is called "Economic Fluctuations" rather than "Macroeconomics."