One man’s vandalism is another’s political dissent. Back in 2012, researchers from Kent State University presented survey respondents a hypothetical news story: A partisan political group has been caught swiping yard signs and defacing campaign ads. Then they asked the respondents to rate both the seriousness of crime (which, technically, it is) and how justifiable it was to break the rules. The overwhelming response: It’s not that big of a deal and it is reasonably justifiable — at least, as long as the party affiliation of the group doing the vandalism matched the affiliation of the person answering the question. If the other guys are doing it, well, by jove, Geoffrey, that is just not how things are done. Drawing squiggly moustaches upon an opponent’s face is fine for me … but not for thee.

Now a stolen yard sign is not exactly an impeachable offense. But there is a lesson here about the more serious scandal currently threatening to swamp President Trump.

It is not your imagination — partisanship really does affect the way we understand evidence of a scandal and how we interpret that evidence. You can see that in the polls that came out this week, which show sharp divides between Democrats who overwhelmingly support impeachment proceedings and Republicans who overwhelmingly oppose them. You can also see it in the comments of politicians — while Democrats see obvious malfeasance in Trump’s pressuring the Ukrainian president to look into the Bidens, Republicans have called the conversation a “nothingburger” that Democrats are hyping as an excuse to reach a foregone conclusion. And while partisanship isn’t the only thing that creates those dueling realities, experts say it’s the biggest factor. And it probably matters more now than it did in the past.

There are many different personal factors that affect how people evaluate the evidence for or against a political scandal and what they think should be done about it. Gender — both the politician’s and the voters’ — is one example, said Nick Vivyan, a politics professor at the U.K.’s Durham University. He’s found evidence that female voters have more of an interest in punishing female politicians’ who misbehave, compared to how those same voters treat men. Male voters are also more likely to treat male politicians more leniently than they treat female ones. (This is just one of many structural reinforcements that makes the glass ceiling of politics so hard for American women to crack through.)

External social and political context also affect whether a scandal sticks and what impact it has. When Brendan Nyhan, professor of government at Dartmouth, studied Washington Post coverage of presidential scandals between 1977 and 2008, he found that controversies became news faster and were covered more extensively when presidents had lower approval ratings among opposition voters and when there was simply less happening in the news to distract the reporters.

But while those things matter, Vivyan told me, it’s partisanship that is “the most obvious and often the most salient” factor at play. “Partisanship is the biggest predictor we have,” he said, of whether someone who looks at a set of facts will see an im🍑ment waiting to happen or just so much rotten fruit.

And that effect has grown over time in the United States, as partisans of both parties dislike one another more and have stronger negative emotional reactions to the other side, said Eva Anduiza, professor of political science at Universitat Autònoma de Barcelona. This “affective polarization” is something that’s been measured by the American National Election Study’s “feelings thermometer” since the late 1970s. The survey asks respondents to rate their feelings about “Democrats” and “Republicans” on a 100-point scale and then compares how people rate the party they identify with vs. the one they don’t.

Since 1980, our average feelings about “the other guys” have become significantly chilly — falling from around 50 to around 25 points on the 100-point scale. In fact, almost all the significant increase in affective polarization is due to an increased dislike of the other side and not, say, an increased preference for your own side.

That kind of emotional partisanship matters for scandals because it increases the likelihood of motivated reasoning — basically upping our tendency to not want to hear things that contradict our previously held beliefs. In the case of politics, that means finding reasons why the other side’s scandals are a very big deal and/or finding reasons why our own preferred party’s scandals are not.

“People who are strong partisans will tend to have the blinkers on,” said Elisabeth Gidengil, professor of political science at McGill University in Canada. “They’ll try to discount what’s happening and say it’s not that serious. All the parties do this.” And she does mean all. Gidengil has found evidence of this effect in Canadian politics. Anduiza has seen it in Spain. Vivyan in the U.K. If it’s happening in multiple countries to many different political parties, you might be forced to accept that it’s also something you and your fellow partisans might be doing right here in the good old US of A.

There’s evidence political partisanship can make you more biased against others than racism does, at least in some circumstances. Nyhan even thinks this partisan affective polarization could be behind conflicting research that sometimes suggests the people who know the most about a controversial issue like climate change or a presidential scandal are more likely to dig in their heels and refuse to change their minds even in the face of new evidence. It’s not that knowing more details of a case makes you less willing to change your mind, he said. It’s more that the people who are the most affectively polarized to begin with also have the most reason to pay attention to the news. Maybe they know the details not because they’re doing thoughtful, unbiased observation, but because they’re keeping close track of the political ballgame and how their team scored points.

Of course, if what you want to hear is that Democrats and Republicans could really join hands and sing together in the spirit of harmony and peace, then all of this is rather disheartening. After all, there are good reasons why some scandals should stick (and others should not), and partisan divides get in the way of finding that middle ground.

But there is some good news. Researchers are finding that there are ways around strong partisan affective polarization — and they don’t even depend upon the two sides coming to an agreement on actual policy. In a 2019 study involving nearly 1,000 political partisans, “warm contact” between political leaders did more to reduce affective polarization and negative opinions about the other party than issue compromise. Maybe if the President wants out of impeachment, it’s time to invite Nancy Pelosi over for pie?