If you’re surprised, that means that you were part of the problem
Now Krugman tells us that in this crisis a "lot of the blame goes to the economists, by the way, who abandoned what they used to know." But the thing is that the mainstream of the profession has been dominated by the academic equivalent of the Tea Party for a very long time. My point is that if you didn't know that economists forgot certain things about recessions, and never learned a few other things, you have not been paying attention and/or you must be part of the problem too.
Krugman knows this well, since he argued that:
“By the early 1980s it was already common knowledge among people I hung out with that the only way to get non-crazy macroeconomics published was to wrap sensible assumptions about output and employment in something else, something that involved rational expectations and intertemporal stuff and made the paper respectable. And yes, that was conscious knowledge, which shaped the kinds of papers we wrote. So you could do exchange rate models that actually had realistic assumptions about prices and employment, but put the focus on rational expectations in the currency market, so that people really didn’t notice. Or you could model optimal investment choices, with the underlying framework fairly Keynesian, but hidden in the background. And so on.”That is, in order to publish (in 'respectable' journals) you had to wrap your reasonable assumptions in crazy models. So it should have been clear back then that rational expectations, real business cycles, supply siders, and their political counterparts in the Reagan administration were more dangerous that Old Keynesians and New Old Keynesians (or Old New Keynesians for that matter) were willing to admit.
The problem is not just that New Keynesians of all sorts and political affiliations (Ben Bernanke, Brad DeLong, Paul Krugman, Greg Mankiw, Christina Romer or Larry Summers) can be seen as equivalents to the old Neoclassical Synthesis, the modern equivalents of John Hicks and Alvin Hansen, trying to incorporate the Keynesian insights that lack of effective demand was behind the Great Depression (now our Great Recession), and that fiscal stimulus is necessary, while maintaining the contradictory argument that the price and quantity of all "factors of production", including labor, can be determined by the equilibrium in the labor market. [If this is true lower real wages should equilibrate the labor market and involuntary unemployment should vanish].
Hansen (1938, p. 34), in the book depicted above, said that the profession was: "living in a time when economics stands in danger of a sterile orthodoxy." [The time, by the way, was the 1937-38 recession]. We are in that position again, and people like DeLong and Krugman, as I said before, the best within the mainstream, would miss the opportunity of providing a more solid foundation for economic theory if they do not recognize the importance of the heterodox contributions of the more radical disciples of Keynes and Kalecki. We do not need another Neoclassical Synthesis, and we should try not to miss this new opportunity to complete the Keynesian Revolution.
Further, although we have our Hansens, so to speak, we do not have our Lauchlin Currie or our Marriner Eccles. That is, the real heterodox Keynesians within the administration. Currie, by the way, wrote an unpublished review of the General Theory, for the eyes of the Board only, that is far better than most responses in academia, which did not rely in either interest rate (liquidity trap) or real wage rigidity. In fact, Currie argues correctly that (following chapter 19 of the General Theory) falling wages would make things worse. If respectable economists in the mainstream, like Krugman and DeLong, miss this opportunity this period will be remembered as 'the years of low theory.'
PS: For a discussion of Eccles and Currie see here. The classic book on Currie is by Roger Sandilands here.