It is a bit funny, but also quite sad: Those who preach the doctrine of global glut are tilting at windmills, when there are some real monsters out t… - Paul Krugman

Keynes didn’t make an all-out assault on Economic Man, but he often resorted to plausible psychological theorizing rather than careful analysis of what a rational decision-maker would do. Business decisions were driven by “animal spirits,” consumer decisions by a psychological tendency to spend some but not all of any increase in income, wage settlements by a sense of fairness, and so on.
But was it really a good idea to diminish the role of Economic Man that much? No, said Friedman, who argued in his 1953 essay “The Methodology of Positive Economics” that economic theories should be judged not by their psychological realism but by their ability to predict behavior. And Friedman’s two greatest triumphs as an economic theorist came from applying the hypothesis of rational behavior to questions other economists had thought beyond its reach.

Will the tax cut destroy America’s prosperity? Probably not. As Adam Smith observed, there’s a deal of ruin in a nation. We have a huge, resilient economy that can survive and recover from even quite bad government policies. Yet while the tax cut may not be a matter of economic life or death, it is a very serious issue. For one thing, like it or not, the tax cut has become the central political issue in the United States right now. Conservatives who want to reshape America view passage of a large tax cut as a first step toward realizing their vision. For that reason, those who do not share this vision feel, rightly, that they must oppose the plan.

As is often the case with major disputes in economics, the argument over fiscal policy went on for years, with some critics of fiscal policy still defending their position when this book went to press. It seems fair, however, to say that among economists a more or less Keynesian view of the effects of fiscal policy came to prevail. Careful statistical studies at the International Monetary Fund and else where showed that austerity policies have historically been followed by contraction, not expansion. Recent experience, in which countries like Spain and Greece that were forced into severe austerity also experienced severe slumps, seemed to confirm that observation. Furthermore, it was clear that those who had predicted a sharp rise in U.S. interest rates due to budget deficits, leading to conventional crowding out, had been wrong: U.S. long-term interest rates remained near record lows even during the years from 2009 to 2012, when the government ran very large deficits.