Do you think you're someone who makes rational decisions? Today, humanity is reaching new heights of scientific understanding—and also appears to be losing its mind. How can a species that developed vaccines for Covid-19 in less than a year produce so much fake news, medical quackery, and conspiracy theorising? In Rationality, Steven Pinker rejects the cynical cliché that humans are simply irrational—he explores how the rational pursuit of self-interest, sectarian solidarity, and uplifting mythology can add up to crippling irrationality in a society as advanced as ours.