system
Given the following post, respond as if you're commenting on Reddit:
human
[Foundation] What exactly is psychohistory?
gpt
It is the study of human interaction.  Not at interpersonal levels, but at this if entire societies.    As with anything, long term study of a field lets patterns emerge, and those can, if universal enough, be called "laws." Hari Seldon codified this into a branch of mathematics, with a complete internal logic built up around his understanding of these laws. This then allowed him to make predictions about societies, so long as they could not see them themselves.