One of those facts “everybody knows” is that journalists are liberal. It’s even true up to a point. (Actually, it’s more accurate to say that very few journalists identify as conservatives. 53% call themselves moderates, so the typical journalistic duo is not exactly Marx and Engels.)

But in spite of Sarah Palin’s fantasies of persecution by the “lamestream media”, coverage often tilts in the opposite direction. When conservatives want something like ClimateGate or the ACORN pimp video to become a national story, it usually does, whether it deserves to or not. When public opinion differs radically from the facts — believing, say, that climate scientists are more-or-less evenly divided on global warming, that Saddam was involved in 9-11, or that Al Gore claimed he invented the internet — the error is usually in the direction pushed by conservatives.

It’s hard to see how that could happen unless actual coverage slanted to the right.

Just last week, I gave numerous examples of right-slanted coverage: Unprovoked police attacks on nonviolent Occupy protesters have been covered “even-handedly” (police and protesters “clashed” like mismatched colors) or passively (“mayhem broke out”).

So how does that work? How do left-leaning journalists regularly produce coverage that leans right? Recently, Grist’s David Roberts has written some excellent posts documenting how media bias works against environmentalists. But before we get into that, let’s back up a little: What does it even mean for coverage to slant one way or the other?

The Hallin Sphere Model. “Media bias” usually makes liberals think of the everyday trickery on Fox News. (Recently, Fox labelled would-be Obama-assassin Oscar Ramiro Ortega-Hernandez “the Occupy shooter” even after police said he had no connection to the Occupy protests.)

I don’t want to minimize the impact of such in-your-face propaganda. (For example, repetition has inured us to hearing President Obama described as “socialist” or even a “Marxist”. It doesn’t raise the kind of ire conservatives felt when President Bush was called a “fascist”.) But the more serious damage is done subtly in mainstream outlets like CNN or the New York Times — news sources that allegedly form “the liberal media”.

A useful way to think about news coverage in general comes from Daniel Hallin’s 1986 Vietnam book The Uncensored War. Hallin says that a factual claim can be reported in one of three ways: as the consensus of knowledgable people, as a controversy that reasonable people might disagree about, or as a deviant claim believed only by a lunatic fringe. Schematically, it looks like this:

A claim in the Sphere of Consensus can be reported as a simple fact, in the journalist’s own voice, without offering a contrary view. So a news story would say “Water runs downhill”, not “According to many scientists, water runs downhill” — balanced later by a quote from an anti-water-runs-downhill spokesman.

But claims in the Sphere of Controversy call for that kind of balance; the reporter should not take sides. So a news story should not say that Obamacare’s individual mandate either is or isn’t constitutional. The reporter should describe arguments made on each side and say that the Supreme Court will rule by June.

Finally, claims in the Sphere of Deviance can be rejected outright in the reporter’s own voice, or just ignored. So an American news story about Al Qaeda will probably not consider that the jihadists might be the good guys. Some people actually hold that view, but they are deviant; they can be ignored.

The boundaries. Politically, it’s very important what claims end up in what spheres.

For example, former Louisiana Governor Buddy Roemer is running for the Republican nomination for president. He’s the only candidate in either party making a serious attack on the dominance of money in politics. But only true political junkies know that, because Roemer’s whole campaign is happening in the Sphere of Deviance. He gets no mainstream coverage and doesn’t appear in televised debates. It’s self-justifying: He gets no coverage because “he can’t win”, and he certainly can’t win if he gets no coverage.

During the health care debate in Congress, no congressperson had to explain why his/her plan was better than a single-payer system, because single-payer was in the Sphere of Deviance.

On its merits, the claim that the planet is getting hotter should be in the Sphere of Consensus and the claim that it isn’t in the Sphere of Deviance. It’s a measurement, not an opinion. But somehow both usually wind up in the Sphere of Controversy.

In short, if you want to bias your coverage, outright lying and distortion is a ham-handed way to do it. It’s much cleaner and more effective to slot claims into the spheres that serve your interests.

Process. Who makes these decisions and how? Journalism professor Jay Rosen believes that it’s an unconscious group process among journalists. They just “know” what is news, what isn’t, and what kind of news it is. Sphere placement is

an intrinsic part of what [journalists] do, but not a natural part of how they think or talk about their job. Which means they often do it badly. Their “sphere placement” decisions … are often invisible to the people making them, and so we cannot argue with those people. It’s like trying to complain to your kid’s teacher about the values the child is learning in school when the teacher insists that the school does not teach values.

No Curia or Politburo holds hearings or announces its rulings. The press makes these decisions collectively, as “an unthinking actor, which is not good”.

Manipulation. As advertisers have long known, people who make unconscious decisions are open to outside manipulation. Maybe “we cannot argue with those people”, but that doesn’t mean that they’re beyond influence by other means.

A year and a half ago I told you about a Kennedy School study documenting that the claim “waterboarding is torture” abruptly moved from the Sphere of Consensus to the Sphere of Controversy in 2004. In 2003, a reporter could have blithely written “Waterboarding is torture.” But a 2004 reporter could only say “Critics claim waterboarding is torture.”

How did that happen? I summarized several sources:

Waterboarding-as-torture didn’t become “contentious” because some new information threw previous judgments into doubt. It became contentious because an interested party — the U.S. government — started contending against it in defiance of all previous objective standards.

In short, journalists didn’t change their ideology or even rethink the specific issue of waterboarding. Instead, outside pressure manipulated their unconscious groupthink about what is controversial.

David Roberts vs. the mainstream press. In recent months, Grist’s David Roberts has been contrasting mainstream reporting of two environmental stories:

The Solyndra bankruptcy, which is being widely covered as a “scandal” in spite of the fact that nothing actually scandalous has yet been uncovered. Also, the loss to the public is purely financial and fairly small by U.S. government standards — a half billion dollars.

The proposed Keystone XL Pipeline, which promotes the use of tar sands (the most carbon-intensive of fossil fuels) and endangers ground water sources in our agricultural heartland. Environmentalists have been using everything from blogs to civil disobedience to get this story out, but it hasn’t really taken off.

Roberts comments:

Solyndra and Keystone XL are real things in [a real world], not just dueling narratives. And by any conceivable metric — energy, money, pollution, corruption — Keystone XL is a much more significant phenomenon. Solyndra was a bum loan that will be forgotten within a year as the solar industry continues its explosive growth. Keystone XL is a huge, dirty, expensive pipeline that would run down the middle of the country; it’s being pushed through via a rigged process; and its consequences for our energy system and our climate will last for decades.

Zeroing in specifically on Politico’s handling of the stories, he observed:

Republican talking points are delivered as first-order news. Liberal talking points are wrapped in meta-news about liberals and their talking points.

A few weeks later Roberts isolated a classic example of this pattern from a New York Times story about the EPA’s thwarted attempt to implement higher smog standards:

Environmental and public health groups challenged the Bush standard in court, saying it would endanger human health and had been tainted by political interference. Smog levels have declined sharply over the last 40 years, but each incremental improvement comes at a significant cost to business and government.

So the NYT presents the claim that smog endangers human health as something environmental groups say (Sphere of Controversy), and the claim that decreasing smog involves significant costs as a simple fact (Sphere of Consensus).

But the merits of the two claims are exactly reversed: It’s a provable fact that smog endangers public health, while the net economic impact of higher smog standards is debatable. (Increased costs at the smokestack are balanced by fewer sick days and higher productivity, not to mention that everything in our cities corrodes more slowly.)

That’s media bias in action. But does it happen because Politico and NYT reporters are ideologically anti-green? I suspect not.

Money buys controversy. Like the waterboarding example, environmental issues become “contentious” not because new information throws them into doubt, but because powerful actors contend against them.

In some sense this is not new: Public relations is the science of manipulating the press, and it is at least a century old. But reporters have long known to take official PR releases with a grain of salt. So when American Tobacco insisted that Lucky Strikes didn’t cause cancer, that by itself didn’t make the claim controversial.

Tobacco-causes-cancer, though, was the end of one era and the beginning of another. As outlined in the books Doubt Is Their Product and Merchants of Doubt, the Tobacco Institute and the academic research it funded was the beginning of whole new layer of corporate PR infrastructure.

Today, when you read a “balanced” story about climate change, you are probably hearing the voice of Exxon-Mobil, disguised as an “independent” researcher for an “independent” institute at some university. The economics professor quoted in an article about the deficit might have been hired directly by the Koch brothers or the bank holding company BB&T. The article will not tell you this, and the reporter may not even know. (In an era of massive newsroom lay-offs, who has time to trace the funding of everyone he quotes?)

Simultaneously, corporations and the billionaires who own them have been creating a unified pro-capitalist information infrastructure — Chamber of Commerce, American Enterprise Institute, Heritage Foundation, etc. — as envisioned by the famous Powell Memo of 1971. They have also achieved a vastly higher degree of message discipline within the Republican Party’s elected officials, and established an ideological media empire around Fox News, Rush Limbaugh, the Washington Times, the Wall Street Journal, and other outlets.

The result is what conservative-in-exile David Frum calls “an alternate reality”.

Backed by their own wing of the book-publishing industry and supported by think tanks that increasingly function as public-relations agencies, conservatives have built a whole alternative knowledge system, with its own facts, its own history, its own laws of economics.

And so blatant absurdities are now “controversial” simply because the conservative power structure chooses to assert them: Tax cuts raise revenue. Budget cuts that lay off teachers and cancel public works projects create jobs. White Christian Americans are the real victims of discrimination. Poor people and government regulators created the economic collapse. The Founders intended the Bill of Rights to apply to corporations.

Conversely, if the threat of unlimited corporate campaign spending and smearing by the conservative media empire can cow Democratic leaders into silence, the Sphere of Consensus can be expanded to include any number of shaky ideas, and their alternatives can be consigned to the Sphere of Deviance: Taxing the rich is politically impossible. Social Security is going bankrupt. The EPA costs jobs. Everyone (except the wealthy) needs to sacrifice. We can’t afford a social safety net any more (but we could afford a new war with Iran). And so on.

These ideas move from one sphere to another not because reporters have become more conservative, but because external power has changed their perceptions of which claims will be contested and which won’t.

What can liberals do to counter? Although we don’t dare abandon any battlefields completely, we can’t hope to beat the corporations financially and institutionally. And that’s why we have to be in the streets (and conversely why the Powers That Be smear and intimidate the people who are). When reporters are told that “everybody knows” one thing and “nobody really believes” something else, large numbers of ordinary people have to make it obvious that those claims are wrong.