Can reading a book make you more rational? Can it help us understand why there is so much irrationality in the world? Steven Pinker, author of Enlightenment Now, answers these important questions here. 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 theorizing? Steven Pinker rejects the cynical cliché that humans are simply irrational- cave dwellers out of time saddled with biases, fallacies, and illusions. 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 we've 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. Rationality also explores its opposite: how the rational pursuit of self-interest, sectarian solidarity, and uplifting mythology can add up to crippling irrationality in a society. Rationality matters. It leads to better choices in our lives and in the public sphere, and is the ultimate driver of social justice and moral progress. Brimming with Pinker's customary insight and humor, Rationality will enlighten, inspire, and empower.