Superforecasting: The Art and Science of Prediction

by Philip E. Tetlock

In his 1972 classic, Victims of Groupthink, the psychologist Irving Janis—one of my PhD advisers at Yale long ago—explored the decision making that went into both the Bay of Pigs invasion and the Cuban missile crisis. Today, everyone has heard of groupthink, although few have read the book that coined the term or know that Janis meant something more precise than the vague catchphrase groupthink has become today. In Janis’s hypothesis, “members of any small cohesive group tend to maintain esprit de corps by unconsciously developing a number of shared illusions and related norms that interfere with critical thinking and reality testing.”3 Groups that get along too well don’t question assumptions or confront uncomfortable facts. So everyone agrees, which is pleasant, and the fact that everyone agrees is tacitly taken to be proof the group is on the right track.