That branch of mathematics that deals with the overall
reactions of large groups of human beings to given stimuli under given conditions In other
words, it is supposed to predict social and historical changes.
Hari Seldon
modeled his science of psychohistory on the kinetic theory of gases. Each atom or
molecule in a gas moves randomly so that the position or velocity of any one of them
cannot be known. Nevertheless, using statistics, the rules governing their overall
behaviour can be worked out with great precision. In the same way, Seldon intended
to work out the overall behaviour of human societies even though the solutions would not
apply to the behaviour of individual human beings.