Those are fighting words, since many of our most influential economists over the past 30 years made their reputations precisely by working on one of the three major attempts to give macroeconomics more respectable microfoundations. In the 1970s, the University of Chicago's Robert Lucas attracted a wide following with his "equilibrium business cycle" theory, which attempted to explain recessions and recoveries in terms of the rational behavior of individuals with imperfect information. It was a valiant effort that eventually garnered him a Nobel Memorial Prize in Economic Sciences, but in the end it failed: The models simply could not generate the sustained booms and slumps we see in real life. In the 1980s, some of the equilibrium macro faithful retreated to "real business cycle" theory, which basically says recessions are natural and healthy, and there's nothing you can or should do about them. While real business cycle papers continue to be written by the basketful, however, the inherent implausibility of the story seems to have been recognized even by some of the movement's founders; people such as Carnegie Mellon University's Edward Prescott have quietly started to put Keynesian "sticky prices" back into their models.

Finally, in the 1980s, there was also a movement known as "new Keynesian" economics, which may be roughly described as an attempt to explain why "almost" rational workers and firms might not cut prices and wages in a recession. Among the leading new Keynesians were Janet Yellen, now chair of the Council of Economic Advisers, and the aforementioned Greg Mankiw. Alas, initial high hopes that new Keynesian ideas would allow us to derive the existence of recessions have been disappointed. Mainly they have served simply as an excuse for assuming sticky prices, and then going from there--the tactic followed, for example, in the magisterial new book on international macroeconomics by Maurice Obstfeld and Kenneth Rogoff.