NEW YORK TIMES BESTSELLER • From the renowned astronomer and author of Cosmos comes a “powerful [and] stirring defense of informed rationality” (The Washington Post Book World) in a world where fake news stories and Internet conspiracy theories play to a disaffected American populace.LOS ANGELES TIMES BOOK PRIZE WINNER • “Glorious . . . A spirited defense of science . . . From the first page to the last, this book is a manifesto for clear thought.”—Los Angeles TimesHow can we make intelligent decisions about our increasingly technology-driven lives if we don’t understand the difference between the myths of pseudoscience, New Age thinking, and fundamentalist zealotry and the testable hypotheses of science? Casting a wide net through history and culture, Pulitzer Prize–winning author and distinguished astronomer Carl Sagan argues that scientific thinking is critical not only to the pursuit of truth but to the very well-being of our democratic institutions. He examines and authoritatively debunks such celebrated fallacies as witchcraft, faith healings, demons, and UFOs. And yet, disturbingly, in today’s so-called information age, pseudoscience is burgeoning, with stories of alien abduction, “channeling” past lives, and communal hallucinations commanding growing attention and respect.  As Sagan demonstrates with lucid eloquence, the siren song of unreason is not just a cultural wrong turn but a dangerous plunge into darkness that threatens our most basic freedoms.