Today humanity is reaching new heights of scientific understanding₆and 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 theorizing? Pinker rejects the cynical clich ̌that humans are simply irrational, cavemen out of time saddled with biases, fallacies, and illusions. After all, we discovered the laws of nature, lengthened and enriched our lives, and set out the benchmarks for rationality itself. We actually think in ways that are sensible in the low-tech contexts in which we spend most of our lives, but fail to take advantage of the powerful tools of reasoning we₂ve discovered over the millennia: logic, critical thinking, probability, correlation and causation, and optimal ways to update beliefs and commit to choices individually and with others. These tools are not a standard part of our education, and have never been presented clearly and entertainingly in a single book, until now.