The proverbial tinfoil hat was once associated with the American left, but a lot can change in 50 years. Should you find yourself at a barbecue this summer cornered by someone frothing at the mouth about microchips in vaccines, pedophilia havens posing as pizza parlors, or machinations of the deep state predicted by supposed insiders on questionable online forums, you know you are speaking to a far-right conspiracy nut. (This is also your Q—excuse me, cue—to make a play for the bean dip and get the heck out of the conversation.)

Although there are exceptions to every rule, most Americans who trade in this sort of talk are likely planning to cast their vote for the twice-impeached former reality TV host and frozen steak salesman who was recently found guilty of 34 felony counts for mismanaging records related to a hush money payment to a porn star.

Yet there was once a time in which this kind of chatter was the purview of counterculture hippies. It surely existed throughout history—did Pliny the Elder shrug off Vesuvian rumblings as “fake news”?—but things really picked up in the United States in the late 1960s and ’70s, when conspiracy theories, heard over the sounds of Jefferson Airplane records and pot-grinding, spread not through vloggers but through Hollywood movies.

And not without good cause. Inconsistencies in the Warren Commission’s inquiry into the assassination of U.S. President John F. Kennedy (and the quick dispatch of the accused gunman, Lee Harvey Oswald, on live television) led to lawyer Mark Lane’s bestselling 1966 book, Rush to Judgment, which busted the door down for legitimate suspicion of official reports that continues today.

As U.S. involvement increased in Vietnam, many Americans questioned an alleged North Vietnamese strike against U.S. naval forces in the Gulf of Tonkin, a conspiracy theory that over time proved to be greatly based in truth. Not long after, the Pentagon Papers showed that—to put things mildly—President Lyndon B. Johnson was not entirely honest with the U.S. public about his Vietnam War policies. Throw in a few more assassinations and, eventually, Watergate, and it makes sense that U.S. citizens didn’t have a lot of trust in authority.

This unease was felt everywhere in the arts. (Foreign Policy readers might be particularly amused by the slim book Report From Iron Mountain, a 1967 prank written by wonks that many Americans believed was a bona fide document proving that Wall Street would never survive an end to the Vietnam War.) And by the early 1970s, Hollywood really sank its teeth into the genre.

As the filmmakers known loosely as “New Hollywood” gained prominence (a glorious albeit brief period in which artistry triumphed over profit margins), audiences suddenly found themselves inundated with movies suggesting that no immoral act was too insidious for the powers that be, righteousness could never prevail, and anyone who tried to take a stand would be doomed.

The apex came in 1974 with three titles, all released by Paramount Pictures, which was run at the time by Robert Evans, something of a notorious operator. Evans did most of his business from his mansion, sprawled out on his bed; that might not fly today, but compared with the out-of-touch stuffed shirts at the other studios, it proved in its own way that Paramount was the home for all that was hip and right and progressive.

Gene Hackman in a scene from The Conversation.Paramount Pictures

First out of the gate was The Conversation, written and directed by Francis Ford Coppola, which won that year’s Palme D’Or (then the Grand Prix) at the Cannes Film Festival. It stars Gene Hackman as a surveillance expert who thinks he has been hired to capture audio to prove marital infidelity but soon fears that the job is linked to major business affairs and potentially an assassination. The Conversation is one of those eerie movies where the whole point is that the viewer never really knows what’s going on. Coppola is dazzling in his use of then-cutting-edge technology to render this ambiguous and fragmented reality.

Late June saw the release of Roman Polanski’s Chinatown, one of the most celebrated movies of the 20th century. The film, which features Jack Nicholson, is a meditation on greed, corruption, and the failure of the U.S. project. Its iconic final line, “Forget it, Jake, it’s Chinatown,” became an instant motto for fatalists and found purchase among those in the counterculture movement who saw their political leaders gunned down and replaced by Nixonism. The young and often politically active scenesters underwent an immediate vibe shift after the Manson Family murders effectively ended the party in Los Angeles. (For more on the impact of these killings on the origin of Chinatown, check out Sam Wasson’s book The Big Goodbye; they were baked into the script long before Polanski, whose wife Sharon Tate was the most famous victim, was even attached as the director.)

Released between these two films was the less celebrated but, in my opinion, more radical The Parallax View. Starring Warren Beatty, Hollywood’s face of the idealistic left, Alan J. Pakula’s film begins with a political assassination of an independent senator atop Seattle’s Space Needle. Although it seems that the culprit was chased off the edge of the modernist structure to his death, more witnesses to the killing keep ending up dead. As Beatty’s character, a newspaper reporter struggling to overcome personal demons, investigates these deaths, he uncovers a shadowy and deeply organized malevolent force dedicated to maintaining the status quo.

The plot to The Parallax View is just a whisper. The United States is a panopticon, and the government will stop at nothing to cover its tracks, including nurturing a zombified secret police force to murder its own citizens. But the tone—enhanced by legendary cinematographer Gordon Willis’s use of negative space and unorthodox, color-rich frames—makes this more unsettling than most horror movies. At the center of the film is a scene where Beatty worms his way into the special ops recruitment center. Running at nearly six minutes, this film-within-a-film could stand on its own as a short in a modern art museum. It represents the zenith of paranoid 1970s form.

Beatty in a scene from The Parallax View. Paramount Pictures

It was Pakula’s next film, the Watergate explainer All The President’s Men, that took the idea of government cover-ups and made it a little more concrete. (It starred Robert Redford, hot off another paranoid thriller, Three Days of the Condor, and Dustin Hoffman, whose next project, Marathon Man, would also fit the bill.)

Perhaps it was the fact that Watergate really did happen, and President Richard Nixon actually was involved in a cover-up, that led to an eventual shift in the nature of conspiracy theories. As the 1970s moved on, so did New Ageism, which found its way into American culture—think of the Leonard Nimoy-hosted television series In Search of…; Jane Roberts’s “channeling” books such as Seth Speaks; or Stephen Hill’s radio broadcast “Hearts of Space,” which has been providing “slow music for fast times” in one form or another since 1973. This movement was less about outward politics and more about inward growth. In short, your lunatic aunt might truly believe in UFOs, but you could still have a Thanksgiving meal with her without incident.

But eventually something changed. To use movies as our guide, a significant shift is seen in Richard Linklater’s 2001 film Waking Life. As with his 1990 masterpiece Slacker, which essentially opened the floor to as many Austin, Texas, weirdos as would agree to go on camera, Waking Life is a portrait of street-corner philosophy. One of its most engaging scenes features a then-local television personality named Alex Jones, who would later become a notorious 9/11 “truther” found guilty for spreading lies about the Sandy Hook massacre. The sequence, played for laughs as Jones’s face changes into an inhuman red hue, is mostly him screaming paranoid ramblings. Nothing, you’d think, that anyone could ever take seriously—until you realize that it resembles the hazy, bad-faith sloganeering that has fueled QAnon for years.

What at the time seemed like a benign bit of open-mic frivolity now works as a canary in the coal mine. Linklater, who is not a far-right maniac but who did cast Jones a second time in 2006 for the adaptation of Philip K. Dick’s A Scanner Darkly, has since distanced himself from his old colleague. “Alex was just this guy on public access TV. I liked his energy, but he was kind of a joke,” the filmmaker said in 2017.

Unfortunately, enough people weren’t laughing—they were taking notes, and in the years since, they followed Jones-style personalities who copied his act all the way to the steps of the U.S. Capitol on Jan. 6, 2021. Not to sound too misty-eyed, but it does make one long for the day when delving into conspiracy theories meant seeing Beatty look cool in modernist architecture, not trying to tear the country apart.