Science is revealing why American politics are so intensely polarized

ATKINSON, N.H. - They stood in line for hours, in steady snow that became steady sleet, to hear the leader of their tribe.

Fresh from a major victory in Iowa, former president Donald Trump was scheduled to speak at 5 p.m. The parking lot at the country club opened at 10 a.m. The doors opened at 2 p.m., and hundreds of people were already in line. When everyone finally got inside, most had to stand tightly packed for hours more until the snowstorm-delayed candidate finally arrived just before 7 p.m.

It’s not always logistically easy being in the Trump tribe, but people stuck it out - and when instructed to turn around and express their sentiments directly to the news media, they dutifully booed and raised middle fingers.

The antagonism that Trump supporters feel toward the media is a small piece of a broader political and cultural phenomenon. This country, though politically fractious since its founding, is more polarized than ever, the rhetoric more inflammatory, the rage more likely to curdle into hate. It’s ugly out there.

As the 2024 primary season revs up, and with the political stakes this year extraordinarily high, voters are both polarized and hardly budging. Pundits expect another close election that’s a repeat of 2020. There’s not a lot of wobble on either left or right.

Social scientists have taken note of these hardening political divisions, pumping out academic articles and books that add data to what appears to be a steady rise in tribalism.

One theme emerges in much of the research: Our politics tend be more emotional now. Policy preferences are increasingly likely to be entangled with a visceral dislike of the opposition. The newly embraced academic term for this is “affective polarization.”

“It’s feelings based,” said Lilliana Mason, a political scientist at Johns Hopkins University and author of “Uncivil Agreement: How Politics Became Our Identity.” “It’s polarization that’s based on our feelings for each other, not based on extremely divergent policy preferences.”

The tendency to form tightly knit groups has roots in evolution, according to experts in political psychology. Humans evolved in a challenging world of limited resources in which survival required cooperation - and identifying the rivals, the competitors for those resources.

“The evolution of cooperation required out-group hatred. Which is really sad,” said Nicholas Christakis, a Yale sociologist and author of “Blueprint: The Evolutionary Origins of a Good Society.”

This is just as true on today’s political stage. There are two major parties, and their contests are viewed as zero-sum outcomes. Win or lose. The presidency is the ultimate example: There are no consolation prizes for the loser.

No researcher argues that human nature is the sole, or even the primary, cause of today’s polarization. But savvy political operatives can exploit, leverage and encourage it. And those operatives are learning from their triumphs in divide-and-conquer politics.

The case of the warring Boy Scouts

People are instinctively prone to group identification.

“We wouldn’t have civilizations if we didn’t create groups. We are designed to form groups, and the only way to define a group is there has to be someone who’s not in it,” Mason said.

Experiments have revealed that “children as young as two will prefer other children randomly assigned to the same T-shirt color,” Christakis writes.

What’s most striking is that in the process of defining who is in and who is out of a group, enmity and derision can arise independently of any rational reason for it.

Mason and Christakis point to a famous-among-academics experiment from 1954. Social psychologist Muzafer Sherif took 22 Boy Scouts and separated them into two groups camping at Robbers Cave State Park in Oklahoma. Only after a week did they learn that there was another group at the far end of the campground.

What they did next fascinated the research team. Each group developed irrational contempt for the other. The boys in the other group were seen not just as rivals, but as fundamentally flawed human beings. Only when the two groups were asked to work together to solve a common problem did they warm up to one another.

The warring Boy Scouts “have a lot more in common with today’s Democrats and Republicans than we would like to believe,” Mason writes in her book.

“In this political environment, a candidate who picks up the banner of ‘us versus them’ and ‘winning versus losing’ is almost guaranteed to tap into a current of resentment and anger across racial, religious, and cultural lines, which have recently divided neatly by party.”

Shanto Iyengar, a Stanford political psychologist who coined the term “affective polarization,” explained in a 2018 paper why people typically identify with a group.

“Homo sapiens is a social species; group affiliation is essential to our sense of self. Individuals instinctively think of themselves as representing broad socioeconomic and cultural categories rather than as distinctive packages of traits,” he wrote.

Here’s where psychology gives way to political science. The American political system may cultivate “out-group” hatred, as academics put it. One of the scarce resources in this country is political power at the highest levels of government. The country has no parliamentary system in which multiple parties form governing coalitions.

Add to this fact the redistricting that ensures there are fewer truly competitive congressional races. The two parties have inexorably moved further apart ideologically, and leaders are more likely to be punished - “primaried” - if they reach across the aisle. And because many more districts are now deeply red or blue, rather than a mix of constituencies, House members have fewer reasons to adopt moderate positions.

How sorting feeds polarization

Human nature hasn’t changed, but technology has. The fragmentation of the media has made it easier to gather information in an echo chamber, Iyengar said. He calls this “sorting.” Not only do people cluster around specific beliefs or ideas, they physically cluster, moving to neighborhoods where residents are likely to look like them and think like them.

Partisan clustering has increased even within households. In 1965, Iyengar said, only about 60 percent of married couples had the same party registration. Today, the figure is greater than 85 percent, he said.

Research shows that affective polarization is intensifying across the political spectrum. Recent survey data revealed that more than half of Republicans and Democrats view the other party as “a threat,” and nearly as many agree with the description of the other party as “evil,” Mason said.

Asked in the summer of 2022 if they agree or disagree that members of the other party “lack the traits to be considered fully human - they behave like animals,” about 30 percent in both parties agreed, Mason’s research shows.

Now, even the partisans fret about polarization.

“We’re on the verge of a civil war, without a doubt,” said Brad Rowe, 40, a Republican who attended the talk of Gov. Ron DeSantis (R) in Hampton, N.H., on Wednesday and is leaning toward supporting independent candidate Robert F. Kennedy Jr.

Some voters find the polarization confusing, because they don’t see how anyone could possibly support a candidate on the other side. That’s the sentiment of Susan and Peter Delano, both 60, who also came to see DeSantis.

“If you are voting Democrat today, you are supporting Biden. I don’t understand it,” she said.

“We see the polls. We ask: Why are they still voting Democrat?” he said.

David Fox, 60, a limo driver who waited in the frigid line to cheer for Trump in Atkinson, said he thinks President Biden is a liar who stole the 2020 election. Fox is not fond of Democrats generally.

“I think they’re very angry people. I think they don’t hold doors open for people, they don’t wave to people, they don’t say hi to people,” Fox said.

Meanwhile, there are voters who can’t believe their choice this fall may come down to Trump or Biden.

“Trump is terrifying, and Biden I don’t think is cognitively there,” Karl Schumacher, 53, said Wednesday as he waited to hear Nikki Haley in Rochester, N.Y.

Trump’s polarization powers

Though partisan vitriol is intensifying across the spectrum, Trump looms large among researchers on polarization and group identity. He has cultivated an extraordinarily devoted base of supporters who see his long list of felony indictments not as evidence of potential wrongdoing, but as proof that the elites are out to get him.

Meanwhile, his opponents, including Biden, have described him as an aspiring dictator who poses an existential threat to democracy.

Rep. Dean Phillips, a long-shot Democratic candidate on the ballot here in New Hampshire, suggested Thursday that a reelected Trump might defy the constitutional limit on presidential terms and try to remain in power: “There may not be a 2028 [election] if we allow Donald Trump to return to the White House,” Phillips said Thursday during a pitch to New Hampshire voters in Manchester.

In an interview, he explained that he thinks Trump has taken cues from dictators abroad and may try to block the transfer of power: “He’s already tried it once and now he’s on a revenge mission.”

A recent paper published in the journal Science argued that the three core ingredients of political sectarianism are “othering, aversion, and moralization.” Trump has mastered that recipe. He activates emotional responses in his followers by telling them that they are threatened.

“I would give it to Trump: He figured out he could cash in on polarization,” Iyengar said.

Trump, he said, began running for president in 2015 when the country was already divided and he leveraged those divisions. He used inflammatory and racist language that violated political norms, called the media the “enemy of the people,” and promoted a vision of America besieged.

A New Hampshire campaign flier touting Trump shows him pumping his fist and looking combative, and quotes him: “They’re not after me, they’re after you. … And I’m just standing in the way!”

At the Trump rally Tuesday, former Republican presidential rival Vivek Ramaswamy told the crowd, “We are in the middle of a war in this country … between the permanent state and the everyday citizen.”

Trump “is not just saying be afraid. He’s saying, ‘Be angry,’” said Dannagal Young, a professor of communication and political science at the University of Delaware. “Anger is a mobilization emotion because it makes people do things. When you’re angry, you’re angry at someone.”

The media do their part to keep things inflamed. Conflict grabs attention.

“We’re evolutionarily predisposed to pay attention to conflict, because we might be in danger. We don’t turn our head really quickly to look at a beautiful flower. We turn our heads quickly to look at something that may be dangerous,” Mason said.

That’s a part of human nature anyone can exploit.

“There are politicians who are good at this,” Mason said. “Trump is the best.”