Can reading a book make you more rational? Can it help you understand why there is so much irrationality in the world? These are the goals of Rationality, Steven Pinker's follow-up to Enlightenment Now. In the twenty-first century, humanity is reaching new heights of scientific understanding - and at the same time 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, quack cures and conspiracy theorizing?Pinker rejects the cynical cliche that humans are an irrational species - 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 the benchmarks for rationality itself. Instead, he explains that we 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 have built up over the millennia: logic, critical thinking, probability, correlation and causation, and decision-making. These tools are not a standard part of our educational curricula, and have never been presented clearly and entertainingly in a single book - until now.Rationality also explores its opposite: how the rational pursuit of self-interest, sectarian solidarity and uplifting mythology by individuals can add up to crippling irrationality in a society. Collective rationality depends on norms that are explicitly designed to promote objectivity and truth. 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 insight and humour, Rationality will enlighten, inspire and empower.Steven Pinker is an experimental cognitive scientist. Currently Johnstone Professor of Psychology at Harvard, he has also taught at Stanford and MIT. He has won many prizes for his research, teaching, and eleven books, including The Language Instinct, How the Mind Works, The Blank Slate, The Better Angels of Our Nature, and The Sense of Style. He is a member of the National Academy of Sciences, a two-time Pulitzer Prize finalist, a Humanist of the Year, a recipient of nine honorary doctorates, and one of Foreign Policy's 'World's Top 100 Public Intellectuals' and Time's '100 Most Influential People in the World Today'.