On December 2nd, while the awful news from San Bernardino was erupting, bit by unconfirmed bit, I was surprised by the crisp self-assurance of a couple of bloggers whose names were new to me. They were on it—number of victims, names of shooters, police-radio intercepts. Soon, though, the bloggers veered off from the story that other news sources were slowly, frantically putting together. The information being released by the authorities did not match the information the bloggers were unearthing, and the latter quickly deduced that, like other “mass shootings” staged by the government, in Newtown, Connecticut, and elsewhere, this was a “false flag” operation. The official account was fiction. One Web site that carried the work of these “reporters” was called Infowars. I made do with other sources for news. But I kept an eye on Infowars and its proprietor, Alex Jones, who is a conspiracy theorist and radio talk-show host in Austin, Texas. Jones’s guest on his show the morning of the shooting had been, as chance would have it, Donald Trump. Jones had praised Trump, claiming that ninety per cent of his listeners were Trump supporters, and Trump had returned the favor, saying, “Your reputation is amazing. I will not let you down.”

Jones’s amazing reputation arises mainly from his high-volume insistence that national tragedies such as the September 11th terror attacks, the Oklahoma City bombing, the Sandy Hook elementary-school shooting, and the Boston Marathon bombing were all inside jobs, “false flag” ops secretly perpetrated by the government to increase its tyrannical power (and, in some cases, seize guns). Jones believes that no one was actually hurt at Sandy Hook—those were actors—and that the Apollo 11 moon-landing footage was faked. Etcetera. Trump also trades heavily in imaginary events and conspiracy theories. He gained national traction on the American right by promoting the canard that President Obama was born outside the United States—a race-baiting lie that the candidate still toys with on Twitter. But birtherism is only the best-known among Trump’s large collection of creepy political fairy tales. You’ve probably heard the one about vaccines and autism. He even pushed that during a Presidential primary debate, on national television. Do you really believe that Obama won the 2012 election fairly? Wrong. Fraud. (At the same time, it’s Mitt Romney, total loser, who let everyone down.) Bill Ayers, not Obama, wrote “Dreams from My Father.” There is no drought in California, and the Chinese, outwitting us per usual, invented the concept of global warming to undermine American manufacturing. And so on.

Does Donald Trump actually believe any of this? Or is he laughing up his sleeve as apoplectic fact-checkers throw themselves into the thankless work of disproving his absurdities? To cover himself, he prefaces his more outlandish remarks with disclaimers like “I hear” or “A lot of people think.” (To back up his contention that “thousands and thousands” of Muslims publicly celebrated the 9/11 attacks in New Jersey, he tweeted a link to Infowars. His source for the California-drought denial also seemed to be Infowars.) The Huffington Post assigned a team of researchers to document the fabrications in a single hour-long Trump appearance on CNN. They counted seventy-one, or one fib for every hundred and sixty-nine words uttered (including Anderson Cooper’s words). Huff Post readers were presumably appalled, but were any Trump supporters given pause about the character of their man by this brain-fogging list of falsehoods? It seems doubtful. Trump is playing a different game. He gestures toward beliefs, hunches, prejudices, and constituencies on the margins. He is playing to Americans who do not trust the media or traditional information sources, such as the government. He offers alternative narratives, fantasies that shock and satisfy. He entertains. On “Meet the Press,” after Chuck Todd asked him for evidence supporting his claim that a protester at one of his rallies had ties to the Islamic State, Trump said, “All I know is what’s on the Internet.” He said that.

Even after Trump (and Sean Hannity, of Fox News) fell victim to a joke—a parody news story “reporting” that two hundred and fifty thousand Syrian refugees would be settled on U.S. Indian reservations—he continued to repeat the bogus figure for months. (He knew better than to touch, from the same Web site, “Trump: I Would Have Prevented the Asteroid from Killing the Dinosaurs.”) His appetite for facts appears to be tiny. In a GQ profile of Hope Hicks, his spokeswoman, by Olivia Nuzzi, Trump’s daily news briefing is described as printouts of “30 to 50 Google News results for ‘Donald J. Trump.’ ” Trump goes at the items with a marker and, according to a GQ source, “He reads something he doesn’t like by a reporter, and it’s like, ‘This motherfucker! All right, fine. Hope?’ He circles it. ‘This guy’s banned! He’s banned for a while.’ ” So what Trump knows can perhaps be narrowed further. He knows what a Google search of his own name turns up. To date, he has “banned,” in addition to many individual reporters, the Washington Post, Univision, BuzzFeed, Politico, The Daily Beast, The Huffington Post, and the Des Moines Register.

Trump’s groundless insinuations hit a new low last week, after the mass shooting in Orlando, when he repeatedly suggested that President Obama secretly supports the Islamic State. This idea can be found in odd corners of the Internet—it is gospel on Infowars—but Trump’s version of it provoked such a storm of criticism, including from fellow-Republicans, that he felt obliged to tweet a link to a report from Breitbart News, a hapless dispenser of right-wing agitprop, headlined “HILLARY CLINTON RECEIVED SECRET MEMO STATING OBAMA ADMIN ‘SUPPORT’ FOR ISIS.” The memo in question was a declassified 2012 field report from Iraq, compiled by an unspecified source at the Defense Intelligence Agency. ISIS, as now constituted, did not exist at the time. The field report described the state of the Syrian opposition, made no policy recommendations, and could not in any way be interpreted as “stating” American “support” for ISIS or for its predecessor, Al Qaeda in Iraq. Michael Morell, a former C.I.A. director, demolished the Breitbart story, and Trump, in a column for Politico.

But the notion that the United States secretly supports ISIS (ladies and gentlemen, please disregard those thousands of air strikes against ISIS by U.S. bombers) is not confined to the loonier quarters of the American right. It’s a powerful line of Iranian government propaganda, disseminated and widely believed among Iraqi Shiites, who proclaim it even in parliament in Baghdad. Does Donald Trump know anything about this? Unlikely. He is an insult machine, not a policy wonk. He may know, on some level, that the nonsense he speaks and tweets is nonsense, but that doesn’t mean he actually knows anything else about the world. He has gut instincts for pleasing members of a fact-averse crowd—for speaking what’s on their minds. He seems to be a narcissist of bottomless insecurity and need. His fast-twitch response to the Orlando massacre showed a man devoid of the most basic empathy. The idea that he might come to power is, to say the least, unsettling. Earlier this month, Senator Mark Kirk, the Illinois Republican, had heard enough. “Given my military experience,” Kirk announced, “Donald Trump does not have the temperament to command our military or our nuclear arsenal.”