From one of the world’s most celebrated intellectuals, a brilliantly insightful work that explains how we think about each other’s thoughts about each other’s thoughts, ad infinitum. It sounds impossible, but Steven Pinker shows that we do it all the time. This awareness, which we experience as something that is public or “out there,” is called common knowledge, and it has a momentous impact on our social, political, and economic lives.

Common knowledge is...