In the introduction to Part 4, Bregman explores the psychology and philosophy of human expectations and their real-world consequences. This exploration is guided by an intellectual clash between Bertrand Russell’s rational empiricism and William James’s faith-based philosophy. Initially influenced by Russell’s insistence on factual truth over comforting beliefs, the text’s focus shifts to the transformative “Pygmalion Effect,” which demonstrates that positive expectations can improve performance. In contrast, the “Golem Effect” proves how negative expectations can cripple performance and perpetuate societal prejudices.

This nuanced analysis also introduces the term “Homo puppy” to describe humans’ innate tendency to mirror each other’s actions and emotions. While such mirroring fosters social cohesion, the flip side is the propagation of negative emotions and collective bad decisions. Case studies like economic bubbles exemplify this phenomenon, highlighting the risk of collective action based on perceived, rather than actual, value. A psychology lecture by Dan Ariely serves as a potent anecdote for “pluralistic ignorance,” where individuals, doubting their perceptions yet noting the seeming confidence of the crowd, choose not to question the status quo.

The text emphasizes the severe ramifications of pluralistic ignorance, pointing to its role in social ills ranging from binge drinking to terrorism and genocide.