A recent study that has been making the rounds argues that “academic psychology once had considerable political diversity, but has lost nearly all of it in the last 50 years.” The paper examines historical data and concludes that party and ideological affiliation in university psychology departments used to be split close to 50-50. By the 1960s, the ratio of Left to Right had climbed to about 4-to-1, and then in the 1990s academia was transformed. Conservatives were chased out, and current left-to-right ratios are estimated at 11-to-1 or higher.

Jonathan Haidt, the lead author of the study, is an honest liberal who admits—and the paper goes on to demonstrate this—that the dominance of the Left distorts the scientific output of academic psychologists. When there are no dissenting voices, it’s a lot easier to confirm each others’ biases.

I’m pretty confident you would get similar results for most other academic disciplines. When I was in college in the late 1980s and early 90s, my sense was that there was a generation of elderly scholars holding the line against “political correctness”—the term had just become popular—but as they retired or died, the new orthodoxy was taking over among their replacements. I’ve seen the same thing elsewhere: an older generation who are at the very least non-ideological and apolitical, followed by a younger generation who are steeped in the neo-Marxist dogmas of “race, class, and gender.”

Academia is likely to be the worst in this regard, since it is a parochial subculture isolated from “the real world out there” and highly resistant to influences that might correct its excesses. But much the same thing has happened in the other commanding heights of the culture, particularly the mainstream media, Hollywood, and the arts.

Current left-to-right ratios in university psychology departments are estimated at 11-to-1 or higher.

There are two ways to look at this trend: as evidence that we are doomed because the Left has taken over the key institutions of the culture—or as evidence that the Left has reached such a high degree of saturation that they have nowhere to go but down.

In other words: have we already reached peak leftism?

When you think about, its very dominance of cultural institutions means that the Left is up against a couple of big unfavorable factors. First, there is the law of diminishing returns. The more gains they make, the harder it gets to go any farther. When you’re going from a 50-50 split to an 80-20 majority, as many of these fields did up to the 1960s, that’s a really big change. You’re throwing the balance of the whole profession behind the Left’s agenda and creating a presumption that the next generation will follow in your footsteps. Likewise, when you go from an 80-20 majority to 95-5 dominance, as many of those fields have done from the 1960s to today, you are creating a rigid orthodoxy, in which dissenting views are marginalized and silenced.

But now you’re at the point where all that remains is to hound out the last few holdouts, demanding conformity from that final 5 percent. And that’s likely to be very difficult, because anyone who rises up today as an openly declared conservative or free marketer in academia, in Hollywood, in the mainstream media, or in the arts, is likely to be a pretty tough bird. He knows he’s in a hostile environment, he has accepted that, and he’s learned to cope with it.

Its very dominance of cultural institutions means that the Left is up against a couple of big unfavorable factors.

So this is a classic case of diminishing returns: those who are easy to chase out of these fields have already gone, and the Left has already experienced the big rewards of capturing the cultural high ground. But the cantankerous right-leaning folks who remain are not going to be shaken out easily, and getting rid of them wouldn’t change much anyway.

In short, the bad news for us is that the Left dominates the cultural high ground. The good news is that they’ve gone about as far as they can go.

Those 90-95 percent levels of ideological uniformity are as high as you can achieve without the actual imposition of censorship. Indeed, within these fields, you can often observe some of the psychology of a dictatorship: a cloying groupthink in which ideological enforcers police the slightest deviation and dissenters feel that they have to hide their true views if they want to keep their jobs. But without the ability to use actual force to suppress dissenters, the Left cannot go any farther.

Yet you can see why the Left would like to get rid of those last few holdouts, because they provide the germ for a resurgence of heretical views. And that is what should absolutely terrify the Left: the prospect of reversion to the mean.

The trend of the last 100 years is the Left’s takeover of the elite institutions, and that can seem final and inexorable—until you remember the old saying that trends continue until they don’t. Specifically, any trend that goes in a radical direction, moving a field or an institution way far out to one side, comes up against the problem of “reversion to the mean,” the natural tendency of a system to revert back to its historical averages.

Without the ability to use actual force to suppress dissenters, the Left cannot go any farther.

The usual example is to look at a very tall person—say, a man who is seven feet tall. On the one hand, you might assume that his progeny will all be seven feet tall as well, and that he will be the father of a new race of giants. In all likelihood, however, he is simply a genetic outlier. When he has children, their DNA will not have quite the same fortuitous combination as his own, and they will be shorter. When they have children, they will further dilute his tall genes among the gene pool of the general population, and over time his descendants will end up back near the middle of the bell curve.

What would reversion to the mean look like when it comes to the commanding heights of the culture?

The current situation is most definitely a historical outlier. Go back a hundred years, and views that would now be considered way far out on the Right were considered normal and natural among the cultural elite. I wrote a while back about Elbert Hubbard, the founder of the Roycrofters community of artists that flourished in the late nineteenth and early twentieth century, who started out as a socialist and ended up as a champion of free enterprise. (Best quotation: “Prison is a Socialist’s Paradise, where equality prevails, everything is supplied, and competition is eliminated.”)

At around the same time, two of the leading poets of the age—poets, mind you—were G.K. Chesterton and Rudyard Kipling, who would be considered howling reactionaries by today’s standards. Even later, Hollywood was filled with staunch conservatives like Cecil B. DeMille, who by happy coincidence ended up hiring a young Russian immigrant named Ayn Rand for his scriptwriting department. Rand would stay in Hollywood through the 1940s, spending a few years in between in New York City working as an assistant to a popular newspaper columnist (Isabel Paterson, who, along with Rand, would become one of the “founding mothers” of modern libertarianism). Not exactly what you would expect today.

So what happens if our culture reverts to the mean? Even a small change in that direction would be experienced as a massive cultural swing to the Right.

So what happens if our culture reverts to the mean? Even a small change in that direction would be experienced as a massive cultural swing to the Right.

When a field swings back from 95-5 dominance to just an 80-20 majority, that would be experienced as a quadrupling of the number of right-leaning voices in the field. Moreover, any such shift is likely to have a snowballing effect. Those who are sympathetic to the Right but were afraid to speak out would be more likely to declare themselves. Many people would be exposed to and convinced by pro-free-market arguments that they might not have heard under the old groupthink. People who might have given up on careers in academia or the mainstream media, on the assumption that their politics limit their career prospects, would be encouraged to persist and would find employers and mentors who share their views. Eventually, a critical mass of prominent right-leaning achievers in these fields would chip away at the automatic assumption that certain cultural markers—being young, being educated, being sophisticated, being artistic—are inherently associated with being on the Left.

The problem, for the modern Left, is that it has bet everything on those associations.

That’s how they hope to keep a lock on the youth vote. It’s how they rely on having millions of well-off and politically active college-educated supporters to serve as fund-raisers and volunteers. Above all else, it’s how they ensure that figures on the Left will get kid-glove treatment from Hollywood and the press—shows like “Saturday Night Live” could do savage caricatures of Republican presidents but can’t figure out how to make fun of Barack Obama—while having their political opponents consistently portrayed as the bad guys.

What if they lost those advantages?

The Left faces a related dilemma in the way they have bet their future on racial politics. If they lose the monolithic support of black and Hispanic voters, along with the presumption that their opponents must be racist, they will be in big trouble politically. In fact, as last November’s vote indicates, they are already in big trouble. In the last two presidential elections, Democrats were buoyed by unusually high turnout and enthusiasm among their core groups: the young, the educated elite, and racial minorities. But they don’t have the margin of error to survive a significant loss of support among any of these groups.

The Left is depending on a cultural dominance that is only a few decades old to continue and grow into the indefinite future.

I don’t mean to suggest that a cultural reversion to the mean is inevitable. The downfall of most predictions of a “permanent majority” is that they start by projecting some current trend into the future, without taking into account the possibility of a countervailing trend. But in this case, it is the Left that is depending on current trends to continue. It is depending on a cultural dominance that is only a few decades old to continue and grow into the indefinite future. As for countervailing trends, it seems more likely at this point that the Right will make inroads among the cultural elite than that the Left—which has invested heavily in a kind of contempt for the common man and his values—will regain the support it is rapidly bleeding among groups like blue-collar whites. Let’s just say that if you’re expecting Hillary Clinton to bring Joe Sixpack back to the Democratic Party, that seems like a slender reed to cling to.

What I mean to suggest is not that reversion to the mean is inevitable, but that this is an opportunity. The Left’s very strength, its nearly exclusive control of key cultural institutions, is also a weakness. Holding the line on a 95 percent groupthink in academia and the arts might end up being a lot harder than disrupting the leftist orthodoxy.

That disruption can happen only if a lot of people put forth a lot of effort to make it happen. But we have a powerful factor on our side: reversion to the mean.

Follow Robert on Twitter.