In a series of classic science fiction stories, Isaac Asimov imagined a scientific discipline called “psychohistory”: a way to predict the future of an interstellar empire. Psychohistory could not foresee individual choices, but it could supposedly predict collective behavior over the course of millennia. At one point in the Foundation series, however, a charismatic figure named the Mule threatened to upend psychohistory’s predictions: he was a mutant, acting in ways the original model could not anticipate. In the universe Asimov imagined, the Mule alone seemed to possess true individual agency. Resisting a powerful model of human behavior, he offered instead a story about a person.