Why are superstitions and prejudices so tenacious, and scientific knowledge often meets stubborn resistance in society? Why are the masses manipulated by crude technology? How did the rapid development of social networks affect our picture of the world? Hugo Mercier, a renowned cognitive psychologist who has worked at leading research centers in France and the United States, seeks answers to these and other questions by challenging the ingrained notion that humans are inherently gullible. It introduces the reader to the peculiarities of our perception of information, re-comprehends various phenomena of ancient and modern history, from the tragic episodes of the Peloponnesian War and the trial of the Salem "witches" to the election of Trump and persistent suspicion of vaccination. Proving the fallacy of ideas about our inability to filter the flow of information, the author of the book, not without humor, warns against taking his arguments on faith.