Psychohistory and Cliodynamics

Tuesday, March 26th, 2013

Peter Turchin discusses the differences between Asimov’s imaginary psychohistory and his own real cliodynamics:

Asimov wrote Foundation in the 1940s — way before the discovery of what we now call ‘mathematical chaos.’ In Asimov’s book, Hari Seldon and psychohistorians develop mathematical methods to make very precise predictions years and decades in advance. Due to discoveries made in the 1970s and 80s we know that this is impossible.

In Asimov books Psychohistory, quite appropriately, deals not with individuals, but with huge conglomerates of them. It basically adopts a ‘thermodynamic’ approach, in which no attempt is made to follow the erratic trajectories of individual molecules (human beings), but instead models averages of billions of molecules. This is in many ways similar to the ideas of Leo Tolstoy, and indeed to cliodynamics, which also deals with large collectives of individuals.

What Asimov did not know is that even when you can ignore such things as individual free will, you still run against very strict limits to predictability.


In addition to the impassivity of precisely predicting the future, Asimov insisted that any knowledge of psychohistorian predictions must be kept hidden from the people. Otherwise, when people learn what is in store, that will affect their actions and cause the prediction to fail. There are several things wrong with it. For one, most people couldn’t care less about what some egg headed scientist predicts. For example, I feel quite safe making the prediction that there will be a peak of political violence in 2020 (plus/minus a few years). If this prediction fails, it will be a result of the theory going wrong, or some massive unforeseen event affecting the social system, or something completely unforeseen (the “unknown unknowns,” in the brilliant characterization of Donald Rumsfeld). But I am fairly certain it will not be because the American policy makers suddenly take a note of what an obscure professor wrote and take action to avoid this undesirable outcome.

And if they do, I will be quite happy. Prediction is overrated. What we really should be striving for, with our social science, is ability to bring about desirable outcomes and to avoid unwanted outcomes. What’s the point of predicting future, if it’s very bleak and we are not able to change it? We would be like the person condemned to hang before sunrise – perfect knowledge of the future, zero ability to do anything about it.

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