Matthew Hutson is a science writer in New York and author of The 7 Laws of Magical Thinking: How Irrational Beliefs Keep Us Happy, Healthy, and Sane.

In March, students at Middlebury College disrupted a lecture by the conservative political scientist Charles Murray because they disagreed with some of his writings. Last month, the University of California, Berkeley, canceled a lecture by the conservative commentator Ann Coulter due to concerns for her safety—just two months after uninviting the conservative writer Milo Yiannopoulos due to violent protests. Media outlets on the right have played up the incidents as evidence of rising close-mindedness on the left.

For years, it’s conservatives who have been branded as intolerant, often for good reason. But conservatives will tell you that liberals demonstrate their own intolerance, using the strictures of political correctness as a weapon of oppression. That became a familiar theme during the 2016 campaign. After the election, Sean McElwee, a policy analyst at the progressive group Demos Action, reported that Donald Trump had received his strongest support among Americans who felt that whites and Christians faced “a great deal” of discrimination. Spencer Greenberg, a mathematician who runs a website for improving decision-making, found that the one of the biggest predictors of voting for Trump after party affiliation was the rejection of political correctness—Trump’s voters felt silenced.


So who’s right? Are conservatives more prejudiced than liberals, or vice versa? Research over the years has shown that in industrialized nations, social conservatives and religious fundamentalists possess psychological traits, such as the valuing of conformity and the desire for certainty, that tend to predispose people toward prejudice. Meanwhile, liberals and the nonreligious tend to be more open to new experiences, a trait associated with lower prejudice. So one might expect that, whatever each group’s own ideology, conservatives and Christians should be inherently more discriminatory on the whole.

But more recent psychological research, some of it presented in January at the annual meeting of the Society of Personality and Social Psychology (SPSP), shows that it’s not so simple. These findings confirm that conservatives, liberals, the religious and the nonreligious are each prejudiced against those with opposing views. But surprisingly, each group is about equally prejudiced. While liberals might like to think of themselves as more open-minded, they are no more tolerant of people unlike them than their conservative counterparts are.

Political understanding might finally stand a chance if we could first put aside the argument over who has that bigger problem. The truth is that we all do.



***

When Mark Brandt, an American-trained psychologist now at Tilburg University in the Netherlands, first entered graduate school, he wondered why members of groups that espouse tolerance are so often intolerant. “I realized that there was a potential contradiction in the literature,” he told me. “On the one hand, liberals have a variety of personality traits and moral values that should protect them from expressing prejudice. On the other hand, people tend to express prejudice against people who do not share their values.” So, if you value open-mindedness, as liberals claim to do, and you see another group as prejudiced, might their perceived prejudice actually increase your prejudice against them?

Brandt approached this question with Geoffrey Wetherell and Christine Reyna in a 2013 paper published in Social Psychological and Personality Science. They asked a variety of Americans about their political ideologies; how much they valued traditionalism, egalitarianism and self-reliance; and their feelings toward eight groups of people, four of them liberal (feminists, atheists, leftist protesters and pro-choice people) and four of them conservative (supporters of the traditional family, religious fundamentalists, Tea Party protesters and pro-life people). Participants reported how much each group violated their “core values and beliefs,” and they assessed how much they supported discrimination toward that group, by rating their agreement with statements such as “Feminists should not be allowed to make a speech in this city” and “Prolife people deserve any harassment they receive.”

As predicted, conservatives were more discriminatory than liberals toward liberal groups, and liberals were more discriminatory than conservatives toward conservative groups. Conservatives’ discrimination was driven by their higher traditionalism and by liberal groups’ apparent violation of their values. Liberals’ discrimination was driven by their lower traditionalism and by conservative groups’ apparent violation of their values. Complicating matters, conservatives highly valued self-reliance, which weakened their discrimination toward liberal groups, perhaps because self-reliance is associated with the freedom to believe or do what one wants. And liberals highly valued universalism, which weakened their discrimination toward conservative groups, likely because universalism espouses acceptance of all.

But these differences didn’t affect the larger picture: Liberals were as discriminatory toward conservative groups as conservatives were toward liberal groups. And Brandt’s findings have been echoed elsewhere: Independently and concurrently, the labs of John Chambers at St. Louis University and Jarret Crawford at The College of New Jersey have also found approximately equal prejudice among conservatives and liberals.

Newer research has rounded out the picture of two warring tribes with little tolerance toward one another. Not only are conservatives unfairly maligned as more prejudiced than liberals, but religious fundamentalists are to some degree unfairly maligned as more prejudiced than atheists, according to a paper Brandt and Daryl Van Tongeren published in January in the Journal of Personality and Social Psychology. To be sure, they found that people high in religious fundamentalism were more cold and dehumanizing toward people low in perceived fundamentalism (atheists, gay men and lesbians, liberals and feminists) than people low in fundamentalism were toward those high in perceived fundamentalism (Catholics, the Tea Party, conservatives and Christians). But this prejudice gap existed only if the strength of the perceiver’s religious belief was also very high. Otherwise, each end of the fundamentalist spectrum looked equally askance at each other. And while liberals and the nonreligious sometimes defend themselves as being intolerant of intolerance, they can’t claim this line as their own. In the study, bias on both ends was largely driven by seeing the opposing groups as limiting one’s personal freedom.

Other researchers have come forward with similar findings. Filip Uzarevic, from the Catholic University of Louvain, in Beligium, has reported preliminary data showing that Christians were more biased against Chinese, Muslims and Buddhists than were atheists and agnostics, but they were less biased than atheists and agnostics against Catholics, anti-gay activists and religious fundamentalists (with atheists expressing colder feelings than agnostics). So, again, the religious and nonreligious have their own particular targets of prejudice. Perhaps more surprising, atheists and agnostics were less open to alternative opinions than Christians, and they reported more existential certainty. Uzarevic suggested to me after the SPSP conference that these results might be specific to the study’s location, Western Europe, which is highly secularized and where the nonreligious, unlike Christians, “do not have so many opportunities and motivations to integrate ideas challenging their own.”

If liberalism and secularism don’t mute prejudice, you can guess what Brandt found about intelligence. In a study published last year in Social Psychological and Personality Science, he confirmed earlier findings linking low intelligence to prejudice, but showed it was only against particular groups. Low cognitive ability (as measured by a vocabulary test) correlated with bias against Hispanics, Asian Americans, atheists, gay men and lesbians, blacks, Muslims, illegal immigrants, liberals, whites, people on welfare and feminists. High cognitive ability correlated with bias against Christian fundamentalists, big business, Christians (in general), the Tea Party, the military, conservatives, Catholics, working-class people, rich people and middle-class people. But raw brainpower itself doesn’t seem to be the deciding factor in who we hate: When Brandt controlled for participants’ demographics and traditionalism (smart people were more supportive of “newer lifestyles” and less supportive of “traditional family ties”), intelligence didn’t correlate with overall levels of prejudice.



***

So what’s at the root of our equal-opportunity prejudice? Conservatives are prejudiced against feminists and other left-aligned groups and liberals are prejudiced against fundamentalists and other right-aligned groups, but is it really for political reasons? Or is there something about specific social groups beyond their assumed political ideologies that leads liberals and conservatives to dislike them? Feminists and fundamentalists differ on many dimensions beyond pure politics: geography, demographics, social status, taste in music.

In a paper forthcoming in Psychological Science, Brandt sought to answer those questions by building prediction models to estimate not only whether someone’s political views would increase positive or negative feelings about a target group, but also precisely how much, and which aspects of the group affected those feelings the most.

First, Brandt used surveys of Americans to assess the perceived traits of 42 social groups, including Democrats, Catholics, gays and lesbians and hipsters. How conservative, conventional and high-status were typical members of these groups? And how much choice did they have over their group membership? (Some things are seen as more genetic than others—Lady Gaga’s anthem “Born This Way” was adopted by homosexuals, not hipsters.) Then he looked at data from a national election survey that asked people their political orientation and how warm or cold their feelings were toward those 42 groups.

Conservative political views were correlated with coldness toward liberals, gays and lesbians, transgender people, feminists, atheists, people on welfare, illegal immigrants, blacks, scientists, Hispanics, labor unions, Buddhists, Muslims, hippies, hipsters, Democrats, goths, immigrants, lower-class people and nerds. Liberal political views, on the other hand, were correlated with coldness toward conservatives, Christian fundamentalists, rich people, the Tea Party, big business, Christians, Mormons, the military, Catholics, the police, men, whites, Republicans, religious people, Christians and upper-class people.

Brandt found that knowing only a target group’s perceived political orientation (are goths seen as liberal or conservative?), you can predict fairly accurately whether liberals or conservatives will express more prejudice toward them, and how much. Social status (is the group respected by society?) and choice of group membership (were they born that way?) mattered little. It appears that conflicting political values really are what drive liberal and conservative prejudice toward these groups. Feminists and fundamentalists differ in many ways, but, as far as political prejudice is concerned, only one way really matters.

In another recent paper, in the Journal of Personality and Social Psychology, Crawford, Brandt and colleagues also found that people were especially biased against those who held opposing social, versus economic, political ideologies—perhaps because cultural issues seem more visceral than those that involve spreadsheets.

None of this, of course, explains why liberals’ open-mindedness doesn’t better protect them against prejudice. One theory is that the effects of liberals’ unique traits and worldviews on prejudice are swamped by a simple fact of humanity: We like people similar to us. There’s a long line of research showing that we prefer members of our own group, even if the group is defined merely by randomly assigned shirt color, as one 2011 study found. Social identity is strong—stronger than any inclination to seek or suppress novelty. As Brandt told me, “The openness-related traits of liberals are not some sort of prejudice antidote.”

Brandt further speculates that one’s tendency to be open- or closed-minded affects one’s treatment of various groups mostly by acting as a group definition in itself—are you an Open or a Closed? Supporting this idea, he and collaborators reported in the Journal of Personality and Social Psychology in 2015 that, although openness to new experiences correlated with lower prejudice against a wide collection of 16 social groups, it actually increased prejudice against the most closed-minded groups in the bunch. Open-minded people felt colder than closed-minded people toward “conventional” groups such as evangelical Christians, Republicans and supporters of the traditional family. And, unsurprisingly, closed-minded people were more biased than open-minded people against “unconventional” groups such as atheists, Democrats, poor people, and gays and lesbians. Research consistently shows that liberals are more open than conservatives, but in many cases what matters is: Open to what?



***

Knowing all this, can we change tolerance levels? You might think that the mind-expanding enterprise of education would reduce prejudice. But according to another presentation at the SPSP meeting, it does not. It does, however, teach people to cover it up. Maxine Najle, a researcher at the University of Kentucky, asked people if they would consider voting for a presidential candidate who was atheist, black, Catholic, gay, Muslim or a woman. When asked directly, participants with an education beyond high school reported a greater willingness to vote for these groups than did less-educated participants. But when asked in a more indirect way, with more anonymity, the two groups showed equal prejudice. “So higher education seems to instill an understanding of the appropriate levels of intolerance to express,” Najle told me, “not necessarily higher tolerance.”

Education’s suppression of expressed prejudice suggests a culture of political correctness in which people don’t feel comfortable sharing their true feelings for fear of reprisal—just the kind of intolerance conservatives complain about. And yet, as a society, we’ve agreed that certain kinds of speech, such as threats and hate speech, are to be scorned. There’s an argument to be made that conservative intolerance does more harm than liberal intolerance, as it targets more vulnerable people. Consider the earlier list of groups maligned by liberals and conservatives. Rich people, Christians, men, whites and the police would generally seem to have more power today than immigrants, gays, blacks, poor people and goths. According to Brandt, “We’ve understandably received a variety of pushback when we suggest that prejudice towards Christians and conservatives is prejudice.” To many it’s just standing up to bullies.

Conservatives, however, don’t view it that way. “Nowadays, as the right sees it, the left has won the culture war and controls the media, the universities, Hollywood and the education of everyone’s children,” says Jonathan Haidt, a psychologist at New York University who studies politics and morality. “Many of them think that they are the victims, they are fighting back against powerful and oppressive forces, and their animosities are related to that worldview.”

Robbie Sutton, a psychologist at the University of Kent in England, presented preliminary findings at SPSP that touch on the issue of which intolerance is more justifiable. He found that people who endorsed denialist conspiracy theories about climate change (e.g., “‘Climate change’ is a myth promoted by the government as an excuse to raise taxes and curb people’s freedom”) were more likely than those who endorsed warmist conspiracy theories (e.g., “Politicians and industry lobbyists are pressuring scientists to downplay the dangers of climate change”) to want to censor, surveil and punish climate scientists, whereas warmists were more likely than denialists to want to punish and surveil climate change skeptics. But are these sentiments equally harmful? Many people would say that’s a subjective question, but it’s hard to ignore the evidence, for instance, that Exxon has hidden its knowledge of climate change for years, and the fact that that the current Republican administration has placed new restrictions on Environmental Protection Agency scientists. Who is more vulnerable, and backed by scientific evidence: Exxon or environmental researchers?

Regardless of who has the more toxic intolerance, the fact remains that people have trouble getting along. What to do? “One of the most consistent ways to increase tolerance is contact with the other side and sharing the experience of working toward a goal,” Brandt says. He suggests starting with the person next door. “Everyone benefits from safe neighborhoods, a stimulating cultural environment and reliable snow removal,” he says. “If liberal and conservative neighbors can find ways to work together on the local level to improve their neighborhoods and communities, it might help to increase tolerance in other domains.” (If you can find a neighbor of the opposite party, that is.)

Progressives might see the conservatives trailing history as being on its wrong side, but conservatives might feel the same way about the progressives way ahead of the train. Getting everyone onboard simultaneously could well be impossible, but if we share a common vision, even partially, maybe we can at least stay on the tracks.