In 1950 the American Political Science Association issued a report expressing concern that Americans exhibited an insufficient degree of political polarization. What a difference a new millennium makes. As we approach 2020’s Election Day, the U.S. political landscape has become a Grand Canyon separating blue and red Americans.

So why is this happening? In a review of studies published today in the journal Science, 15 prominent researchers from across the country characterize a new type of polarization that has gripped the U.S. This phenomenon differs from the familiar divergence each party holds on policy issues related to the economy, foreign policy and the role of social safety nets. Instead it centers on members of one party holding a basic abhorrence for their opponents—an “othering” in which a group conceives of its rivals as wholly alien in every way. This toxic form of polarization has fundamentally altered political discourse, public civility and even the way politicians govern. It can be captured in Republicans’ admiration for Donald Trump’s ability to taunt and “dominate” liberals—distilled to the expression “own the libs.”

The Science paper addresses the rise of political sectarianism—the growing tendency of one political group to view its opponents as morally repugnant. This level of political divisiveness on both sides creates a feedback loop of hatred and leaves the U.S. open to manipulation by foreign powers that wish to further these internal rifts. On the horizon, however, are a few ideas about how to address these social and political divisions.

Scientific American delved into these issues with Eli J. Finkel, a psychology professor at Northwestern University and lead author of the new Science paper.

[An edited transcript of the interview follows.]

There’s a sense in the U.S. today that the country is more divided than ever before. Does the research bear out this impression?

No, 1861 was worse—with many, many hundreds of thousands of people dying in an extraordinarily bloody war. In some ways, 1968 was scarier, with all those assassinations and the protests at the Democratic [National] Convention in Chicago. But there is something new about the current type of polarization. What used to happen was: there were lots of conservatives in the Democratic party and lots of liberals in the Republican party. What we have [now] is an alignment of social identities that correspond to our political identities in a way that we’ve never seen before. In the paper, we talk about political polarization as a kind of mega identity that encompasses a whole bunch of other identities, so that African-American people and nonheterosexual people are overwhelmingly in the Democratic Party. You have this alignment in a way that the two sides feel increasingly different from one another.

Your paper proposes a new way of framing polarization, which you call political sectarianism. Can you explain what this is and the three core ingredients you have identified?

Sectarianism is a highly moralized political identity that views the other side as contemptible. The moral component is foundational. You can imagine that you are a member of a religious sect, and you very, very strongly believe that you possess the full moral truth and that the other people aren’t going to heaven or are evil. That is the tenor of the thinking that we see across the political divide these days.

The three key components: The first one is what we call “othering”—[labeling] these people as so different from us that they’re almost incomprehensible. The second part we call “aversion”—this idea that they’re not just different, but they’re dislikable. The third part is this “moralization,” where they’re morally bankrupt.

And when you face a situation like that, is it acceptable to suppress the vote a little bit or to engage in some sort of political chicanery that isn’t really best for democracy? Well, when those are the stakes, of course.

I live in a red county in a blue state, and this election cycle, I’m seeing something new. People aren’t just displaying political signs. They are flying Trump flags on flagpoles and from the back of their pickup trucks. Do you have any thoughts about the symbolism of the flag and this display of allegiance?

The debate going on is increasingly divorced from ideas. One of the things that people on the right love about Donald Trump is that he “owns the libs.” I mean, he drives liberals absolutely bonkers. That is very, very satisfying. That’s not about ideas. That’s about conquest. That’s about defeating the bad people on the other side. These identities are becoming increasingly central to who we are as people. In the 1960s, nobody cared if you married somebody from the other party. But how would you feel if your kid married somebody from the other party now? These days, it’s sort of a horrifying idea.

Polarization also seems to be warping people’s beliefs about members of the other party. What is happening?

Knowing about people’s political identity now tells you a lot about what their other social identities are likely to be, and there’s a vast exaggeration in our minds about what the other party looks like. Republicans vastly overestimated the proportion of Democrats that are sexual minorities, such as LGBT [individuals], and Democrats overestimate the percentage of Republicans that make at least $250,000 a year. And so you end up with a situation where you think, “I can’t relate to them, and they hate people like me.” So of course, you feel like if it’s reasonable to lash out at them or perhaps deny them some amount of democratic liberties if the stakes are high in terms of your political goals. But even just alerting people that actually, that other group is far less different or hates you far less than you think [it does] can soften the tendency to sacrifice democratic norms for partisan goals.

What role has the changing media landscape and the rise of social media played in this polarization?

Well, the effect appears to be large, and the research is still figuring out exactly what it is. One of the most interesting findings directly challenges the conventional wisdom that part of the reason why we have so much othering is that people are literally no longer living in the same information ecosystems, in contrast to an era where there were three broadcast news stations. A 2018 study had people who were partisan get exposed to some information on the other side. So if you’re Republican, you get to see what Hillary Clinton is saying, or if you’re a Democrat, you’re exposed to what Donald Trump is saying. And that actually made it worse. So the idea that if we expose people to what the other side is seeing, things will get better does not appear to be true. And I think that the science just hasn’t figured out how we can tweak algorithms in ways that get to something closer to a common worldview across the population without further sectarianizing the populace.

We know that Russia had an elaborate campaign to influence the outcome of the 2016 election and that it is continuing these efforts in 2020. Has political sectarianism made the U.S. more vulnerable to meddling from foreign actors?

Completely. [Russian agents] didn’t try to bomb us, and they didn’t even try to infect our computers. They knew that we hate each other—at least, highly sectarianized partisans hate each other—and so they didn’t have to do any of that fancy stuff. They just created avatars that were called things such as “Blacktivist” or “Army of Jesus,” and then they painted the other side as diabolical, and then they just let it go. And then we did it! We opened up this vulnerability, and all this geopolitical adversary has to do is to put the content and social media where people are likely to see it. We tweet it; we retweet it.

An important caveat here: research is ambiguous about how effective the campaign was, but there is no question at all that [Russia] tried to do it—and that extremists on both sides, especially on the conservative side, were especially likely to play exactly into Russia’s hands.

One solution you propose is to get individuals to talk to people from the opposite party. But how do we talk across the divide? How do you talk to someone whose party has called you the “enemy of the people”?

The pictures that we carry around in our head about the other side are nothing other than characters. One of the things that I think holds promise is that if we can just get through all the people who are profiting from all the divisions and get the truth out there, then, I think, some of the worst elements of the sectarianism will go away, because people [will] realize that they hate people that aren’t that different from them after all.

But how do you get people those facts? How do you get them to even come to the table and listen?

There are no silver bullets. One of the lines of work that holds some promise is some research showing that if you just remind everybody that Democrats and Republicans are all Americans, that can make them a little bit more open-minded.

How has sectarianism changed the way that politicians are governing? They’re not really doing so for all of their constituents anymore, are they?

No. I mean, why would they? We’re so deeply immersed in our ... side, and that’s how you get people like Donald Trump and other people saying, “We’re not going to pass a law that’s going to help blue states.” That’s not the way the government was supposed to function, but it is the logical end point of the highly sectarian world. In the highly sectarian political ecosystem, politicians lose the incentive to be responsive to the entire populace. And they also lose the incentive to compromise, because you’re much more likely to get accused of apostasy and lack of sufficient purity by your side. So you get this increasing emphasis on the most extreme candidates. This has been more true on the right than on the left, but to some degree, it has been true on both sides.

We have a pandemic response that has become extremely polarized, and the science has become a partisan thing. Do you see any solutions?

Look, I am not hugely optimistic about this, but what I would love to pose to your readers is that they should take personal responsibility for this. There are no longer people who speak to the middle. There’s no longer a Walter Cronkite. So to some degree, each individual person is going to have to take some amount of responsibility to say, “I’m going to debate ideas, and I’m going to debate them in ways that don’t talk about evil or hatred or shame but really understand the nuance and complexities.”