Isaac Asimov’s Foundation series is about the fall of the future Galactic Empire. 30,000 years of barbarism are expected, but a man named Hari Seldon invents a new science that allows future events to be predicted with a high degree of statistical accuracy.

The name of this science is “psychohistory”, and the quality of its predictions allow for a plan to be developed and followed that shortens the dark age from 30,000 years to 1,000.

I remember being truly in awe of this idea when I heard about it as a kid. Predicting the future! With math! And reading the books now is still fun and interesting.

But I also realized that psychohistory is a fascinating and bizarre literary device to use, since you can be fairly sure about what will eventually happen.

In fact, because psychohistory’s predictions are viewed as ironclad within the novel’s universe, the protagonists don’t really take individual action, and they don’t think about choosing between several risk paths.

In fact, they wait to act until only path is available to them, because then they have been forced into their decision but what we are meant to presume is the operation of psychohistorical laws.

"Each successive crisis in our history is mapped and each depends in a measure on the successful conclusion fo the ones previous. This is only the second crisis and Space knows what effect even a trifling deviation would have in the end."

"That's rather empty speculation."
"No! Hari Seldon said in the Time Vault, that at each crisis our freedom of action would become circumscribed to the point where only one course of ction was possible... as long as more than one course of action is possible, the crisis has not been reached. We must let things drift so long as we possibly can, and by space, that's what I intend doing."
-- Isaac Asmiov, Foundation

Psychohistory has another interesting implication in that it’s very similar to Historicism, and it particularly reminds me of Marx’ historical materialism, in its prediction of an inevitable breakdown of capitalism and replacement with communism.

Psychohistory, of course, predicts events and not social conditions, but it follows a similar logic of historical inevitability.

This causes me to wonder why the developers, and acolytes, of psychohistory are heroes. In general, a prediction of strong determinism, or of historical inevitability, tends to lead to bad outcomes (as was the case in almost every Communist society in the 20th century). I’ve seen the opposite in the novels so far. But what is it about psychohistory that allows its outcome to be different?

And, what is it about psychohistory that allowed Seldon to stand outside it in order to formulate its rules?