But because psychohistory works on statistical people en masse, it is presumed not to work against an anomalous person such as the Mule, who was a mutant.
He also creates a 'Second Foundation' at the 'other side of the galaxy', to store and expand on his understanding of psychohistory, and to watch over the burgeoning new civilization from afar.
In the trilogy's second installment, Foundation and Empire, however, psychohistory seems to take a beating.