Donald Trump was to the point last week: “Hillary Clinton meets in secret with international banks to plot the destruction of U.S. sovereignty in order to enrich these global financial powers, her special interest friends, and her donors.” Trump has for years now appealed to such conspiracy theories to explain America’s perceived problems. Did you hear, for instance, that global warming is a hoax created by the Chinese in order to weaken U.S. manufacturing? That the media refuses to report the tens of thousands of people attending his rallies, just as it “orchestrated”—in coordination with the Clintons—the sexual assault allegations against him? That, as he repeated at the third presidential debate this week, the election has been “rigged” by these very same forces?

Why does Trump spout such theories, and, more importantly, why do they resonate in some corners of American society? He and his followers see a country in decline, which raises this paradox: How come America, the greatest country in the world, isn’t great anymore? Conspiracy theories provide a satisfying explanation: Someone must be sabotaging us, from within or without.

In his oft-cited 1964 essay, “The Paranoid Style in American Politics,” Richard Hofstadter connected Joseph McCarthy’s paranoia about Communists in the 1950s to the anti-Freemasons and anti-Jesuits of the eighteenth and nineteenth centuries, among other movements. Samuel Morse, the celebrated portraitist and inventor of the telegraph, was a leading anti-Jesuit. “Austria is now acting in this country,” he wrote in his Foreign Conspiracies against the Liberties of the United States from 1835. “She has devised a grand scheme… She has her Jesuit missionaries traveling through the land; she has supplied them with money.” “Popery is now, what it has ever been,” Morse concluded, “a system of the darkest political intrigue and despotism, cloaking itself to avoid attack under the sacred name of religion.”

This long history of conspiracy theorizing is grounded in America’s self-conception as a chosen people. Since the first settlers arrived America has conceived of itself as unique in its moral purity and possibility, as the “City on a Hill” in the Puritan leader John Winthrop’s grand vision. Somewhere along the way, though, America has augmented this moral self-conception to incorporate the ideal that the nation is also destined for—and indeed deserving of—greatness and power on Earth, down in the valley below the Hill. Consider that after World War II the U.S. produced half of the world’s economic output, by some estimates.

It is in the context of such civilizational chosenness that periods of perceived decline can generate a disturbing cognitive dissonance: How could we, the necessarily greatest community, be weak or even non-dominant? Many Americans sense that we are now experiencing such a moment, as the nation descends from Cold War colossus to a post-recession “leader from behind” that’s no longer capable of imposing its will upon the globe or of guaranteeing long-term economic growth at home. They may also implicitly connect America to “white America” (now inclusive of Catholics, Morse’s protestations notwithstanding) and view the increasing political and cultural influence of minority communities as further evidence of decline. In his book Time to Get Tough! Making America #1 Again, Trump captures the mood succinctly: “The country I love is a total economic disaster right now. We have become a laughingstock, the world’s whipping boy, blamed for everything, credited for nothing, given no respect. You see and feel it all around you, and so do I.” Greatness is relative, and, by comparison with the ascending Soviets, McCarthy perceived a similar moment of American decline from the end of World War II to the early 1950s. The period was marked, in particular, by the Communist Party’s unexpected victory over the American-backed Nationalists in China, and by President Harry Truman’s announcement that the Soviet Union had detonated an atomic bomb.