“Part of that was, what occurred almost immediately after the assassination, in the years afterward, was Vietnam,” Thompson said, “And over time, a complete loss of confidence in what ever the government was saying about Vietnam. That was not just from the presidency, that was from the government itself.”

This was also a period in which some of the most dramatic ideas that had been disparaged as conspiracy theories turned out to be true. “I am not a crook,” Nixon had insisted. Less than a year later, he resigned. Nixon and Trump are compared not infrequently. Not all presidents are so thin-skinned and antagonistic to the press. Jennifer Senior, reviewing a recent Nixon biography, wrote that “the similarities between Nixon and Trump leap off the page like crickets.” Nixon may have been increasingly paranoid in the final months of his presidency, but he didn’t have access to the technology that Trump uses to showcase his conspiracy mindedness.

“With real conspiracy theorists, there’s a kind of—how to put it—almost a dialectic operative,” Thompson says. “Like Trump. You have to keep making wilder and wilder pronouncements over time to hold your audience.”