Mr. Iyengar doesn’t mean that the typical Democratic or Republican voter has adopted more extreme ideological views (although it is the case that elected officials in Congress have moved further apart). Rather, Democrats and Republicans truly think worse of each other, a trend that isn’t really about policy preferences. Members of the two parties are more likely today to describe each other unfavorably, as selfish, as threats to the nation, even as unsuitable marriage material.
Surveys over time have used a 100-point thermometer scale to rate how we feel toward other groups, from cold to warm. Democrats and Republicans have been giving lower and lower scores — more cold shoulder — to the opposite party. By 2008, the average rating for members of the other party was barely above 30. That’s significantly worse than how Democrats rated even “big business” and how Republicans rated “people on welfare.”
By 2016, that average dropped by about five percentage points, dragged down in part by a new phenomenon: For the first time, the most common answer given was zero, the worst possible option. In other words, we now feel downright frigid about each other.
Last year, for the first time since it began asking the question in 1992, Pew reported a majority of Democrats and Republicans said they held “very unfavorable” views of the opposing party. Since Pew published those findings last summer, that extreme distaste has receded a bit: So far this year, 45 percent of Democrats and 46 percent of Republicans hold “very unfavorable” views of the opposing party.
That conclusion follows a sweeping 2014 Pew study that found that “partisan antipathy is deeper and more extensive” than at any point in the last two decades.
That negativity appears to have fed a growing perception that the opposing party isn’t just misguided, but dangerous. In 2016, Pew reported that 45 percent of Republicans and 41 percent of Democrats felt that the other party’s policies posed a threat to the nation.
The fear of what harm the other party could cause appears to be a major motivator behind party affiliation. “It’s at least as much what I don’t like about the other side as what I like about my own party,” said Jocelyn Kiley, associate director of research at the Pew Research Center.
When asked why they identified as Republican, 68 percent of respondents told Pew that a major factor was the harm that Democratic policies posed, just surpassing the 64 percent who cited the good that could come of their own party’s policies. Among Democrats, 62 percent said fear of Republican policies was a major factor for their affiliation, while 68 percent cited the good of their own party’s policies.
Independents, who outnumber members of either party and yet often lean toward one or the other, are just as guided by fear. More than half who lean toward either party say a major reason for their preference is the damage the other party could cause. Only about a third reported being attracted by the good that could come from the policies of the party toward which they lean.
Partisans are also likely to find each other harder to reason with. Last year, Pew found that 70 percent of Democrats and 52 percent of Republicans considered members of the opposing party to be more close-minded than other Americans. They also considered opposing partisans exceptionally immoral, lazy and dishonest, though Democrats held those views somewhat less. About a third of either party viewed the opposition as less intelligent than other Americans.
Past surveys show that such views have worsened with time. Americans in 1960 were more likely to allow that members of the other party were intelligent, and they were less likely to describe opposing partisans as selfish.
In 1960, just 5 percent of Republicans and 4 percent of Democrats said they would be unhappy if a son or daughter married someone from the other party. In a YouGov survey from 2008 that posed a similar question, 27 percent of Republicans and 20 percent of Democrats said they’d be “somewhat” or “very upset” by that prospect. By 2010, that share had jumped to half of Republicans and a third of Democrats.
Today, partisan prejudice even exceeds racial hostility (although the two are intertwined) in implicit association tests that measure how quickly people subconsciously associate groups (blacks, Democrats) with traits (wonderful, awful). That’s remarkable, given how deeply ingrained racial attitudes are in the United States, and how many generations they’ve had to harden, according to work by Mr. Iyengar and the Dartmouth political scientist Sean J. Westwood.
“We have all of these data which converge on the bottom-line conclusion that party is the No. 1 cleavage in contemporary American society,” Mr. Iyengar said.
Political scientists suspect that attack ads, which have grown in number and nastiness, have played a role. And the rise of partisan media — Fox News on the right, MSNBC on the left, for example — has amplified the rhetoric of campaigns, providing confirmation of our worst stereotypes about each other.
Mr. Iyengar also points out that we’re willing to impugn members of the other party in ways that aren’t publicly acceptable with other groups, like minorities, women or gays. There simply aren’t strong social norms holding us back. And critics fear that the president’s own contributions to incivility are further eroding what norms do exist.
Over time, a part of the problem is also that we’re less likely to have the kind of interpersonal contact across party lines that can dampen our harsh beliefs about each other. Our neighborhoods, workplaces, households and even online dating lives have become politically homogeneous. We’re less likely today to have neighbors who belong to another party than we were a half century ago. Bipartisan marriages are on the decline.
Just as interpersonal contact has been shown to ease prejudice against racial minorities and gays, psychologists believe that more such contact would be good for political civility, too. But we increasingly live in a world where that contact is hard to come by — and we go out of our way to avoid it.