Paranoia comes in waves. The 1990s ended with a surge of pre-Millennial anxiety, fuelling belief in alien autopsies, satanic child abuse, and chemtrails. An earlier peak of paranoia had erupted from the death-throes of the 1960s. While there was no doubt some chemical distortion at work, JFK, MK Ultra, and CIA scheming in Latin America gave more reasonable grounds for suspicion than weird lights over Nevada. And yet, looking back, the ‘90s, and even the ‘70s, now seem more innocent times. Today’s conspiracists have altogether more efficacious tools with which to disseminate distrust. Lone Svengalis and numerous shady organisations, among them governments, use the internet to stoke paranoia; Trump parrots nonsense ripped from Infowars, and his opponents assert that Russian bots fixed everything from his election to Brexit.

To whom can we turn in such troubled times? That we might we look to artists was the proposition of the Metropolitan Museum’s recent exhibition Everything is Connected: Art and Conspiracy. The show was unprecedented in its focus, and very timely. Indeed, in some ways it seemed all too representative of its moment.

Curators Douglas Eklund and Ian Altever brought together two distinct categories of work. The first section of the exhibition comprised objects that set out to investigate, document and publicise the iniquitous actions of the powerful. Here we find the intricate diagrams of Mark Lombardi, tracing dirty money as it slips between shady organisations, and Hans Haacke’s elaborate exposé of corruption in New York’s real estate industry. The tone of these projects, both of which emerged out of the conceptual milieu, is objective and cool, whereas other works on display in this section – among them posters by AIDS activists Act Up and a video of young Black Panther leader Fred Hampton ­– are more impassioned. Yet all respond to undeniably real, and often deadly, abuses of power.

The second section of the show is announced by three videos by Jeremy Blake depicting the famously convoluted Winchester Mystery House. Psychedelic animations proclaim that we are not in Kansas anymore, and that the black and white of documentary veracity has been left behind. Instead Blake takes an appropriately hallucinatory approach to the story of a gun fortune heiress and her deluded belief that family bereavements had been caused by the spirits of people killed with Winchester rifles. Blake ‘excavates the nexus of American violence, paranoia and guilt’ – or so the curators tell us. But this is also the story of someone with more money than sense, indulging her own ludicrous fears at huge expense rather than, say, donating her ill-gotten wealth to redress the suffering her family had caused.

Self-indulgence seems a leitmotif of the following rooms, which show a collection of works produced by artists who studied together at CalArts in the 1970s, among them Tony Oursler, Sue Williams and Mike Kelley. As well as a certain stoner surrealism, they share a tendency to adopt the cranky involution of outsider art, an old avant-garde tactic that looks increasingly condescending. This impression is partly an effect of the unfortunate contrast with the high-minded criticality of the preceding section, and it should be added that there are some striking works on display in this latter half of the show.

Sarah Anne Johnson’s paintings and sculptures, which respond to the discovery that her grandmother was involuntarily given LSD by the CIA as part of the MK Ultra mind- control experiment, are both poignant and frightening. Jim Shaw’s installation The Miracle of Compound Interest, which adapts a found stage backdrop of hokey small-town Americana, is worth visiting the show for alone. Passing through the door of a rural gas station, visitors enter a darkened grotto in which three garden gnomes stand in homage around a glowing crystal. The scene is both comical and profoundly weird, combining shades of Disney and Wagner with critique of the oil industry and financialisation, and as such it’s an acute – and prescient, since it was made in 2006 – diorama of early twenty-first century America.

In the end, the inclusion of video footage of Hampton, who was shot by the FBI for his criticism of the American establishment, with the faux-paranoid concoctions of West Coast slacker artists, feels discordant and somewhat distasteful. Not all of the mental difficulties manifested here are affected, it must be said – Jeremy Blake and Mike Kelley both killed themselves, and Sarah Anne Johnson’s grandmother really was drugged by the CIA. But nevertheless, the collection of these pieces in one place, with minimal textual disambiguation on display, unsettles. Perhaps we are meant to leave with the impression that the madness of the artists in part two is justified by the real conspiracies unveiled in part one (just because you’re paranoid, after all…). This may have been the intention of the curators, but it’s unclear whether they’re seeking to criticise the confusion of the world beyond the gallery, or merely embodying it.

James Bridle tolerantly argues in his recent book New Dark Age that conspiracy theory ‘serves a vital and necessary function, by bringing into view objects and discourses otherwise ignored’. But in the process it also taints them, by making them irretrievably abject objects of knowledge, the province of swivel-eyed notebook scribblers. Doubtless this effect is cultivated by the unscrupulous. Like Bridle, who claims that conspiracy theories ‘might be a form of folk knowing’, this exhibition risks conflating real and imagined, accusation and affectation, with the result that we end up living in a world ruled by the reverse of William Burroughs’ dictum: ‘nothing is true, everything is permitted’. Then again, perhaps I’m just being paranoid.