When conspiracy theorists actually run the government, they can do enormous damage, diverting public funds and institutions to cope with imaginary threats. Srdja Popovic, a Serbian activist who helped overthrow the authoritarian leader Slobodan Milosevic, has reminisced about the day he switched on the television and learned of a “high-level CIA conspiracy to overthrow Milosevic by using well-paid student activists,” among them himself. Much later, he learned that police really were spending time and money searching the world for the international headquarters of his movement. In fact, it was in his parents’ living room in central Belgrade. In the Soviet Union, that kind of thinking led to mass murder.

I’m guessing that Americans’ long-standing aversion to conspiracy theory derives from our devotion to commerce: Businessmen, at the end of the day, need to have a grasp on reality to make money. But something did change in American public life with the appearance of Glenn Beck and other dodgy members of what the writer David Frum has called the “conservative entertainment complex .” The general deterioration of trust in the government and, after 2008, the financial establishment made the situation worse. Now Trump has placed conspiratorial thinking squarely at the center of the Republican primary. A whole generation of people who get their information from random sources on the Internet have eagerly taken up his invented stories and are reposting them as fast as they can. Trump’s lies and his distortions of reality don’t stick to him because his followers are not interested in truth. They prefer satisfying stories.