The ongoing trial involving journalist Mark Steyn – accused of defaming climate change theorist Michael Mann – reflects an increasingly dangerous tendency among our intellectual classes to embrace homogeneity of viewpoint. Steyn, whose column has appeared for years on these pages, may be alternatingly entertaining or over-the-top obnoxious, but the slander lawsuit against him marks a milestone in what has become a dangerously authoritarian worldview being adopted in academia, the media and large sections of the government bureaucracy.

Let’s call it “the debate is over” syndrome, referring to a term used most often in relationship with climate change but also by President Barack Obama last week in reference to what remains his contentious, and theoretically reformable, health care plan. Ironically, this shift to certainty now comes increasingly from what passes for the Left in America.

These are the same people who historically have identified themselves with open-mindedness and the defense of free speech, while conservatives, with some justification, were associated more often with such traits as criminalizing unpopular views – as seen in the 1950s McCarthy era – and embracing canonical bans on all sorts of personal behavior, a tendency still more evident than necessary among some socially minded conservatives.

But when it comes to authoritarian expression of “true” beliefs, it’s the progressive Left that increasingly seeks to impose orthodoxy. In this rising intellectual order, those who dissent on everything from climate change, the causes of poverty and the definition of marriage, to opposition to abortion are increasingly marginalized and, in some cases, as in the Steyn trial, legally attacked.

A few days ago, Brendan Eich, CEO of the web browser company Mozilla, resigned under pressure from gay rights groups. Why? Because it was revealed he donated $1,000 to the campaign to pass Proposition 8, California’s since-overturned ballot measure defining marriage as between one man and one woman.

In many cases, I might agree with some leftist views, say, on gay marriage or the critical nature of income inequality, but liberals should find these intolerant tendencies terrifying and dangerous in a democracy dependent on the free interchange of ideas.

This shift has been building for decades and follows the increasingly uniform capture of key institutions – universities, the mass media and the bureaucracy – by people holding a set of “acceptable” viewpoints. Ironically, the shift toward a uniform worldview started in the 1960s, in part as a reaction to the excesses of Sen. Joseph McCarthy and the oppressive conformity of the 1950s.

But what started as liberation and openness has now engendered an ever-more powerful clerisy – an educated class – that seeks to impose particular viewpoints while marginalizing and, in the most-extreme cases, criminalizing, divergent views.

Today’s clerisy in some ways resembles the clerical First Estate in pre-revolutionary France, which, in the words of the historian Georges Lefebvre, “possessed a control over thought in the interests of the Church and king.” With today’s clerisy, notes essayist Joseph Bottum, “social and political ideas [are] elevated to the status of strange divinities … born of the ancient religious hunger to perceive more in the world than just the give and take of ordinary human beings, but adapted to an age that piously congratulates itself on its escape from many of the strictures of ancient religion.”

To be sure, there remains a still-potent camp of conservative ideologues, many associated with think tanks, such as the Heritage Foundation, and a host of publications, most notably the media empire controlled by the Murdoch family. But, for the most part, today’s clerisy in media and academia tilts in one basic direction, embracing a fairly uniform set of secular “truths” on issues ranging from the nature of justice, race and gender, to the environment.

Those who dissent from the “accepted” point of view may not suffer excommunication, burning at the stake or other public rituals of penance, but can expect their work to be vilified or simply ignored. In some bastions of the new clerisy, such as San Francisco, an actress with unsuitable views can be pilloried, and a campaign launched to remove her from a production for supporting a Tea Party candidate.

Nowhere is this shift more evident than in academia, as evidenced in Mann’s civil action against Steyn. The climate change issue, one of great import and worthy of serious consideration, is now being buried by the seemingly unscientific notion that everyone needs to follow orthodoxy on an issue that – like the nature of God in the Middle Ages – is considered “settled,” and those who do not agree deserve to be pilloried.

But climate change is just one manifestation of the new authoritarian view in academia. On many college campuses, “speech codes” have become an increasingly popular way to control thought at many campuses. Like medieval dons, our academic worthies concentrate their fire on those whose views – say on social issues – offend the new canon. No surprise, then, as civil libertarian Nat Hentoff notes, that a 2010 survey of 24,000 college students found that barely a third of them thought it “safe to hold unpopular views on campus.”

This is not terribly surprising, given the lack of intellectual diversity on many campuses. Various studies of political orientation of academics have found liberals outnumber conservatives, from 8-to-1 to 14-to-1. Whether this is a reflection of simply natural preferences of the well-educated or partially blatant discrimination remains arguable, but some research suggests that roughly two of five professors would be less inclined to hire an evangelical or conservative colleague than one more conventionally liberal.

Political uniformity is certainly in vogue. A remarkable 96 percent of presidential campaign donations from the nation’s Ivy League faculty and staff in 2012 went to Obama, a margin more reminiscent of Soviet Russia than a properly functioning pluralistic academy.

Sadly, this orthodoxy in the academy is duplicated throughout much of the media. Certain right-wing and skeptical perspectives fare better in the media than at the universities, due to both the media and the support of such media by wealthy conservatives. But many Americans know bias when they see it; overall, reports Pew, the percentage who think news is tilted to one side has grown dramatically, from 53 percent in 1985 to 77 percent in 2011.

There remain many important exceptions to this rule, notably the Fox News Channel and talk radio; sadly, they, too, tend to report news in a “party line” manner. But, for the most part, mainstream media, who, like Fox, advertise their “objectivity,” essentially follow a fairly predictable “progressive” line.

A detailed UCLA study found that, of the 20 leading U.S. news outlets, 18 were left-of-center, including not only the New York Times, NPR and the Los Angeles Times, but, perhaps surprisingly, the news pages of the Wall Street Journal.

These positions have political implications, providing almost lock-step support for President Obama. More than 16 prominent journalists have joined the Obama administration, which is something of a record.

“This press corps,” notes the former Jimmy Carter pollster Pat Cadell, “serves at the pleasure of this White House and president.”

Even Arnold Brisbane, a former ombudsman of the country’s premier news source, the New York Times, has noted that “so many share a kind of political and cultural progressivism – for lack of a better term – that this worldview virtually bleeds through the fabric of the Times.”

In some cases, for example, even mild skeptics of the clerical consensus have been banned from key website forums, or even from having their letters published in newspapers, such as the Los Angeles Times. Whatever one’s feelings on the issue, coverage of climate change has been tilted toward the conventional thesis that the planet is getting much hotter, with humans the primary cause. This limits discussion of such things as the decade-long “plateau” of temperatures, acknowledged even by the United Nations. This has been sparsely covered in the mainstream media, outside of conservative outlets, whose views may reflect somewhat their energy-industry-oriented financing.

This atmosphere of ideological rigidity may help explain why Steyn – who prevailed in court against Islamophobia allegations in Canada several years ago – may have piqued the fury of Mann, who has enjoyed the support of similarly thinking media. This is bad news for the future of discourse in this country. Rather than defend free speech and open inquiry, the tendency of the Left to believe that truth is “decided,” even if there is room for skepticism, seems far more medieval than progressive.

Register opinion columnist Joel Kotkin is R.C. Hobbs Professor of Urban Studies at Chapman University. He is the executive editor of www.newgeography.com.