Paul Krugman: Microfoundations and the Parting of the Waters:
Phelps… [made] two observations… nominal shocks had large real effects… [and] with everyone acting rationally, money should have been neutral even in the short run. Traditional Keynesian analyses… [only provided] ex-post rationalizations…. So the Phelps crowd came up with a lovely story…. Individuals and firms couldn’t tell… whether a rise in the price… represented a shock specific to them… or a general change in demand… confusion could explain why short-run aggregate supply seemed upward-sloping…. This meant that the apparent tradeoff between unemployment and inflation would be unstable…. The stagflation of the 70s seemed to confirm this prediction, and brought the microfoundations project immense prestige…. Freshwater economists gleefully proclaimed Keynes dead, the subject of nothing but ‘giggles and whispers’.
But… Phelps-Lucas/type microfoundations quickly collapsed both intellectually and empirically. Intellectually… rational individuals simply should not have been confused in [that] way…. Empirically… slumps last too long…. Microfoundations in macroeconomics… failed utterly at the one thing it was sold, above all, as being able to do…. Time, you might think, to reconsider…. But many… had so committed themselves to the idea that Keynes was dead and rationality roolz that they simply dug in deeper….
Now we have people debating whether models with microfoundations lead to better predictions… [even though] the microfoundations are wrong…. But what you want to realize is that this isn’t going to convince the microfoundations crowd. After all, more than thirty years ago they decided that the joy of microfoundations trumped the utter failure of microfounded models to work… and… have now trained successive cohorts of students in this view. There are, it’s true, some hints of a guilty conscience… the odd tendency of freshwater types to immediately accuse anyone with saltwater ideas of being dishonest. (I’m not a nice guy, but if look at what I said about, say, Cochrane, it was that he was ignorant, not corrupt.)…
The notion that there had been a convergence of views by 2007, which was then ruptured by the crisis, was a saltwater delusion. People like Olivier Blanchard convinced themselves that the other side was listening; it wasn’t. The hysterical reaction to the notion that fiscal policy is effective at the zero lower bound demonstrated that the freshwater types had never bothered to learn…
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