The Amazing Randi insists that the public wants to be fooled, that it's easier and more comforting for us not to see unromantic truths — you can see him proclaiming this, a little sadly, in Justin Weinstein and Tyler Measom's documentary, An Honest Liar, which plays like a companion piece to Robert Kenner's sly and enraging Merchants of Doubt. Randi, now north of 80, dedicated a lifetime to exposing frauds, deceivers and liars, only to see such scoundrels triumph again not long after their exposure. Now, Merchants argues, those frauds have co-opted the spirit of Randi — committing their deceptions (and jeopardizing our world) as they themselves adopt the mantle of principled skepticism.

The great debunker never appears in Merchants, but his ideological progeny do. Sleight-of-hand master and principled skeptic Jamy Ian Swiss serves up jeweled axioms about why we believe, and in Merchants he even gets a couple seconds to dazzle with his card tricks, at one point explaining how he pulled one off. The tape plays back, and we see the hand we weren't looking at the first time. How could we have missed it? And how can magicians trust in democracy when they know how easily gulled the rest of us are?

In An Honest Liar, Swiss marvels at our luck that Randi uses his powers of deception for good; in Merchants, Swiss and a host of journalists and scientists lament how rare that choice is. The film, based on the book by Naomi Oreskes and Erik Conway, lays bare the way that moneyed interests sell doubt to keep us from believing in things that actually are true — and damaging for business.

An episodic narrative vaults from the lies of the tobacco companies, which for half a century pretended there was no link between smoking and cancer, to those of the think tanks that today have convinced about half the American public that pretty much every scientist in the world has thrown in together to concoct the myth of climate change. (Even if that were possible, at what point do all those presumably paid-off scientists profit from the lie?)

This material might be familiar to Frontline viewers and readers of serious magazines, but Kenner's telling of the stories proves independently dramatic: It's heartening to hear Chicago Tribune reporters Patricia Callahan and Sam Roe dish about exposing the lies in the testimony of an expert witness for the manufacturers of flame-retardant (and carcinogenic) furniture. The scene would make a great Good Wife episode.

Kenner finds a magnificent antihero in Marc Morano, a cheery, chatty prevaricator who has made a mint by muddying water. His job is to promote skepticism of a truth that even Skeptic magazine believes in, and since Morano's cocksure, and good at yelling on TV, he steamrolls over climate scientists on cable despite his lack of expertise. In interviews, he's disarmingly guileless, happy to brag about all the times he's posted online the email addresses of climate scientists, some of whom turn up to read aloud from the death threats they get.

The film and Morano agree on one thing: All that the deniers of climate change have to do to succeed is reduce the country's certainty. They've been wildly successful, as Kenner demonstrates — remember back in 2008, when Mitt Romney, John McCain and Newt Gingrich all stated publicly that carbon emissions are the cause of global warming? Today, what office-seeking Republican would dare?

One of the last who did dare is former South Carolina congressman Bob Inglis. After visiting Antarctica, and discovering scientists aren't all in cahoots with Karl Marx and the Masons, or whatever, Inglis dared to call for a carbon tax from the floor of the House. Now an apostate without base or seat, he attempts to press the conservative case for not recklessly destroying the world.

The film's most upsetting scene finds Inglis attempting to talk sense to Paul Gallo, a Mississippi talk-radio blowhard. Gallo is as unchangeable as the ice caps used to be, and he blinks at Inglis in confusion while booming nonsense to his listeners with the voice of God: “We've got more polar bears than we've ever had before!” and “I don't believe that humans are creating this, and neither do, apparently, a vast majority of climatologists!”

Inglis pipes in, wanly, with facts, but he's like a third-chair flautist competing against a first-rate guitar shredder. Who's even listening?

Later, addressing Kenner's camera, Inglis tells a truth about the public as despairing as James Randi's. “Many conservatives see action on climate change as really an attack on a way of life,” Inglis sighs. “The reason we need the science to be wrong is that otherwise we realize that we need to change. That's a hard pill to swallow.”

He's likely right to despair, but I'd quibble with his metaphor. If there's one thing Americans love, it's swallowing pills. That's why it's hard to take issue with Kenner's choice to cut, on occasion, to Swiss' card tricks, to clips from The Twilight Zone, to anything else: Gel-capping is the least that truth tellers can do.

MERCHANTS OF DOUBT | Directed by Robert Kenner | Sony Pictures Classics | Landmark