Must-Read: Larry Summers: Advanced Economies Are so Sick We Need a New Way to Think About Them: “Standard new Keynesian macroeconomics… [and] to an even greater extent… dynamic stochastic general equilibrium (DSGE) models…

…imply that… the only effect policy can have is on the amplitude of economic fluctuations, not on the [average] level of output. This assumption is problematic…. The assumption is close to absurd. It is surely reasonable to assume that better policy could have avoided the Depression or the huge output losses associated with the financial crisis without having shaved off some previous or subsequent peak…. Contrary to the now common view that macroeconomics is best understood by studying the stochastic properties of stationary time series, the most important macroeconomic events are in some sense one off. Think of the Depression or the Great Recession or the high inflation of the 1970s. The problem has always been that it is difficult to beat something with nothing. This may be changing as topics like hysteresis, secular stagnation, and multiple equilibrium are getting more and more attention…
https://www.washingtonpost.com/news/wonk/wp/2015/11/03/larry-summers-advanced-economies-are-so-sick-we-need-a-new-way-to-think-about-them/