Along the way, he examines the differences between propensity and probability, the maddening habit of falling victim to confirmation bias (believing what we want to believe and never mind contrary evidence), the workings of the conjunction rule (by which we conflate suppositions about people and events based on little or no factuality), and our tendency to mistake coincidence for pattern. Discussing beliefs in ghosts and haunted houses, the author wryly points out that 5% more people believe in the latter than in the former, which means “that some people believe in houses haunted by ghosts without believing in ghosts.” Rationality is not the same thing as logic, Pinker argues, though there are points in common. Unfortunately, “among our fiercest problems today is convincing people to accept the solutions when we do find them.” That’s because so many people are so-well, irrational, or at least encumbered by bad habits of thinking and presuppositions. Rationality, writes the author, “emerges from a community of reasoners who spot each other’s fallacies.” In other words, it has a social dimension, and it invites good company in order to wrestle with big problems such as climate change.

Much-published psychologist Pinker looks at the not-so-common roots of common-sensical thinking.

Steven pinker rationality book review