というEvonomics記事が上がっている原題は「How New Keynesian Economics Betrays Keynes」、H/T Mostly Economics)。ロジャー・ファーマーの以下の本からの引用との由。

Prosperity for All: How to Prevent Financial Crises

Prosperity for All: How to Prevent Financial Crises


Although Samuelson’s neoclassical synthesis was tidy, it did not have much to do with the vision of the General Theory. Keynes envisaged a world of multiple equilibrium unemploy­ment rates where the prevailing rate is selected by the propen­sity of entrepreneurs to take risks. He called this propensity animal spirits.

In Keynes’ vision, there is no tendency for the economy to self- correct. Left to itself, a market economy may never recover from a depression and the unemployment rate may remain too high forever. In contrast, in Samuelson’s neoclassical synthe­sis, unemployment causes money wages and prices to fall. As the money wage and the money price fall, aggregate demand rises and full employment is restored, even if government takes no corrective action. By slipping wage and price adjust­ment into his theory, Samuelson reintroduced classical ideas by the back door— a sleight of hand that did not go unnoticed by Keynes’ contemporaries in Cambridge, England. Famously, Joan Robinson referred to Samuelson’s approach as “bastard Keynesianism.”

The New Keynesian agenda is the child of the neoclassical synthesis and, like the IS- LM model before it, New Keynesian economics inherits the mistakes of the bastard Keynesians. It misses two key Keynesian concepts: (1) there are multiple equilibrium unemployment rates and (2) beliefs are funda­mental. My work brings these concepts back to center stage and integrates the Keynes of the General Theory with the mi­croeconomics of general equilibrium theory in a new way.






In a survey paper published in 2014, I distinguished between first- and second- generation endogenous business cycle models. I used the term endogenous business cycle models to mean models in which confidence influences outcomes independently, as opposed to “RBC models,” in which all economic fluctuations are caused by shifts in technology.

In first- generation endogenous business cycle models, the economy retains the self- correcting mechanisms that Frisch described in his rocking- horse metaphor. Confidence shocks do rock the horse, but in this respect they are no different from productivity shocks, strikes, hurricanes, and monetary disturbances. Classical economists like Arthur Pigou, who wrote about business cycles in his 1927 book, Industrial Fluctuations, would not have been surprised by the notion that confidence matters for economic activity. All the work cited in the previous section, including that described in The Macroeconomics of Self- fulfilling Prophecies, falls into this category. These models lead to Pareto- inefficient fluctuations, but the social cost of business cycles is small.

In a more recent book, Expectations, Employment and Prices, published in 2010, I described a second generation of endogenous business cycle models. In these models, confidence does not just rock the horse; it knocks it over. The difference is between models in which the economy can be pushed away temporarily from its steady state and models in which it can be pushed into an entirely different steady state. In the first case, the economy is self- stabilizing and, most of the time, the allocation of resources is “almost” Pareto efficient. In the second case, the stabilization mechanism is broken and the allocation of resources is very far from being Pareto efficient most of the time. In my opinion, the idea that economic equilibrium can be Pareto inefficient, most of the time, is the most important idea to emerge from Keynes’ General Theory.






Macroeconomics of Self-fulfilling Prophecies (MIT Press)

Macroeconomics of Self-fulfilling Prophecies (MIT Press)


Expectations, Employment and Prices

Expectations, Employment and Prices

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