Link: https://slatestarcodex.com/2019/09/02/book-review-ages-of-discord/
I.
I recently reviewed Secular Cycles, which presents a demographic-structural theory of the growth and decline of pre-industrial civilizations. When land is plentiful, population grows and the economy prospers. When land reaches its carrying capacity and income declines to subsistence, the area is at risk of famines, diseases, and wars – which kill enough people that land becomes plentiful again. During good times, elites prosper and act in unity; during bad times, elites turn on each other in an age of backstabbing and civil strife. It seemed pretty reasonable, and authors Peter Turchin and Sergey Nefedov had lots of data to support it.
Ages of Discord is Turchin's attempt to apply the same theory to modern America. There are many reasons to think this shouldn't work, and the book does a bad job addressing them. So I want to start by presenting Turchin's data showing such cycles exist, so we can at least see why the hypothesis might be tempting. Once we've seen the data, we can decide how turned off we want to be by the theoretical problems.
The first of Turchin's two cyclic patterns is a long cycle of national growth and decline. In Secular Cycles' pre-industrial societies, this pattern lasted about 300 years; in Ages of Discord's picture of the modern US, it lasts about 150:
