It’s not “An Inconvenient Truth” — yet. But for a movie focused on climate change, Sony Pictures Classics’ “Merchants of Doubt” — based on the widely read book of the same name by historians Naomi Oreskes and Erik Conway, and directed by Robert Kenner (“Food, Inc.”) — is already generating a huge volume of discussion. It seems poised to become a must-watch film in the climate debate.

The film, which opens today in Washington, D.C., explores a long history of challenges to the science behind a variety of environmental and public health risks. Smoking. CFCs. Acid rain. Climate change. In many cases, these challenges were linked to corporate interests — thus the tobacco industry, for many years, questioned the emerging science of smoking’s risks.

“Merchants of Doubt”is certainly landing in the right news cycle. It comes out in the wake of reports — including by The Washington Post — about energy interests’ funding of climate “skeptic” researcher Willie Soon, of the Harvard-Smithsonian Center for Astrophysics. In a statement posted on the Web site of the Heartland Institute, a conservative think tank, Soon responded that he had been the subject of “attacks” in the media, but acknowledged that his research had been partly “supported” by “some energy producers” – something he said had “long been a matter of public record.” Soon added that “in submitting my academic writings I have always complied with what I understood to be disclosure practices in my field generally, consistent with the level of disclosure made by many of my Smithsonian colleagues.”

It all plays into a common narrative: That industry doesn’t want government regulations, so it tries to cast doubt on the science behind them. Many of those who go to see “Merchants of Doubt” will, I suspect, go with such a narrative in their minds.

But the film itself presents a more complex picture. True, “Merchants of Doubt” focuses a great deal on the role of industry in supporting scientific arguments that are consistent with less regulation. But it also shows that denial of science on issues like climate change is about much more than that. It’s about certain deep seated beliefs and ideologies — particularly those championing the free market and individual liberty (which we tend to call libertarianism).

“None of this is about the science,” says Oreskes, a Harvard historian and co-author of the book behind the film, in the movie. “All of this is a political debate about the role of government.”

In another segment, the film follows libertarian-leaning Skeptic magazine founder Michael Shermer as he tries to convince his ideological compatriots that climate change isn’t just something that liberals made up. Shermer concludes that the whole issue has become tribal. Indeed, you can see the emotion on screen at one point as Shermer is challenged from the audience at a libertarian gathering, where he’s gone to present the case for climate change being real.

So what really drives attacks on certain bodies of environmental and public health science? Is there a “root cause”? To address that question in the context of “Merchants of Doubt,” I called the woman behind it all — Oreskes. In our conversation, I asked Oreskes — whom I’ve known for a long time — about my concern. And she brought up what I considered a very good analogy to help both address it and also explain it.

“That’s the chicken and egg thing,” she explained. “There’s two stories to be told: One is the supply of disinformation, and the other is the demand, why do people accept it, and buy it. Our book is definitely a supply side story, because we stumbled across a supply side story. I think the demand side is also important to understand.”

Supply and demand. It fits the situation nicely. Supply in this context would refer to the volume of arguments and claims in the public arena that challenge mainstream science with respect to environmental or public health risks. For many of these issues, these claims take a similar form. Scientists have asserted the existence of a risk — say, smoking causes lung cancer — and the claims in question then sow doubt about this conclusion. (Hence the film and book title.

The more people who make these doubt-mongering arguments (and the farther they are broadcast), the greater their supply in the marketplace of ideas. Moreover, there’s no doubt that if there are funding sources available, whether for think tanks that attack the science of climate change or for the scientists that they embrace and promote, a greater supply of arguments can be generated.

But there’s also demand: Who believes and embraces these arguments. Who needs them. And this varies with time and many other factors. There’s little demand now for arguments that raise doubts about smoking’s health risks — our culture seems to regard the question as settled — but there’s still demand for doubt on climate change. That’s because it’s a live political issue that goes straight to the heart of the role of government in the economy, an ideological live-wire issue.

Demand can generate new supply: To reinforce their beliefs, people create arguments, and if they’re smart, they may even generate novel and insightful ones. But these come from a need for something to say to support one’s beliefs.

Thus, you can’t argue that our fights over science are just about the role of industry in wanting to stop regulation. They’re also about the beliefs of citizens who want less government, and who are naturally sympathetic to industry because it represents an ideal to them — people striving to succeed in life based on merit, insight, innovation  and hard work.

Which is not to go easy on the resulting, often questionable scientific claims. “By supplying the disinformation, it keeps the controversy alive,” says Oreskes. “It keeps the whole thing muddled, and especially for people who aren’t really paying attention, it keeps the background noise going.”

But that’s not the only factor — as “Merchants of Doubt”itself shows. The film ends by telling the story of Bob Inglis, the conservative former South Carolina congressman who changed his mind about global warming, accepted that it was real, and — for this reason among others — was voted out of office in the Tea Party sweep of 2010. Inglis now makes it his job to talk to conservatives in their own language about climate change, and to try to move them — meaning he’s perhaps closer than anyone to the sources of resistance.

So it’s appropriate to end with a quotation from him in the film, showing just how powerful the “demand” side remains:

It’s not just a head thing, this is very much a heart issue. … Many conservatives I think see action on climate change as really an attack on a way of life. The reason that we need the science to be wrong is otherwise, we realize that we need to change. That’s really a hard pill to swallow — that the whole way I’ve created my life is wrong, you’re saying? That I shouldn’t have this house in the suburbs, that I shouldn’t be driving this car. … And you’re not going to tell me to live the way that you want to live. And along come some people with sowing some doubt, and it’s pretty effective, because I’m looking for that answer. I want it to be that the science is not real.