Bregman probes the perplexing question of why good people turn bad. He reflects on his past work that uncritically presented theories like Philip Zimbardo’s Stanford Prison Experiment, which proposed that evil resides in all humans, waiting for an opportunity to emerge. Bregman examines the latest evidence, much of which debunks many long-held beliefs about human nature. The author posits that many dark chapters in human history might be due to a “mismatch”—a clash between evolutionary predispositions and the modern world. While humans have evolved mechanisms for kindness, these same mechanisms have the potential to turn people cruel, especially in the face of societal constructs that are incompatible with human nature. Bregman sets the stage for exploring, in subsequent chapters, the reasons behind human cruelty and the possibility of a more harmonious society based on a realistic understanding of humanity.

During World War II, the social scientist Morris Janowitz embarked on a quest to decode what motivated Nazi soldiers. Contrary to prevailing views that ideological fervor was the driving force, Janowitz found that a sense of camaraderie or Kameradschaft was a more potent motivator. Studies involving wiretaps and interviews with POWs lent weight to Janowitz’s argument, revealing that a sense of community, rather than ideology, played a crucial role in bonding soldiers.