A RUDE but incoherent comment by President Donald Trump last week revealed the damage partisanship has done to America’s body politic. The president described a group of Hispanic gangsters, or illegal immigrants at large, or maybe both, as “animals”. It is impossible to know whom he was referring to. Yet most Americans thought they knew. Republicans heard Mr Trump’s comment as tough talk on a bunch of killers, while Democrats heard it as a dehumanising slur against migrant parents and their children. Partisanship has altered Americans’ hearing.

It has also changed their view of what is required to be human. No longer able to fathom how their partisan rivals can hear, and also see, think and say the things they do, Americans are increasingly liable to consider them lesser beings. Research by Alexander Theodoridis and James Martherus and colleagues finds that 77% of respondents considered their rivals to be less evolved humans than members of their own side. Americans are also prone, surveys suggest, to find their subhuman opponents extremely disagreeable. No wonder Republicans and Democrats cannot bring themselves to make the compromises upon which the healthy functioning of American democracy depends.

This malady has produced some interesting new research and efforts to treat it. To observe one, Lexington went to the Mütter Museum of medicine in Philadelphia. There, in a room lined with ancient medical manuals—“Treatise on Dislocation”, “Treatise on Fractures”—five Republican and five Democratic voters had been gathered by a group called Better Angels for a day of mutual re-humanising. “I want to understand how the progressive mind works,” said Greg, a grey-haired Tea Partier wearing denim jeans and braces, as he eyed a row of bearded college graduates seated opposite him. He had perhaps noted the pickled brain displayed outside the door.

Better Angels was launched in 2016 with the aim of awakening America’s citizenry from its partisan nightmare. Its method, importantly and unlike several groups formed in response to the rancorous 2016 election, is not to forge consensus on issues. Rather it is to persuade voters to stop thinking of the other side as their enemy. Backed by a high-powered bipartisan board, the group has recruited over 3,000 members and held over 100 workshops across the country. Yet your columnist’s day at the museum mainly showed how resistant to such laudable efforts Americans are.

Drawing on counselling techniques, the workshop began by separating the red (Republican) and blue (Democratic) teams and asking each to list the stereotypical views the other side held towards their party. They were then told to say why the stereotypes were unfounded and whether they contained a kernel of truth. The red team came up with: racist, homophobic, anti-immigrant, gun-loving, hateful. Only on guns, with which two of their members, 20-something brothers from hardscrabble South Philly, were obsessed, did the reds consider the type remotely justified.

The blue team’s members were more educated and self-critical. They imagined the reds thought Democrats a bunch of smug, godless, politically correct traitors to the constitution. They confessed there was a bit of truth to much of that. Yet their humility did not make them less partisan. In an exercise that involved each side asking the other to justify their most divisive positions, the blues showed the flipside of their greater learning. They were better at mobilising arguments to justify partisan positions that, in truth, they probably held unthinkingly. The bearded graduates’ full-throated defence of abortion, a difficult topic, illustrated that.

By the end, most of the participants said they had learned that the other side contained more diverse views than they had thought. That was useful. Yet by classifying the participants as red or blue, then asking them to defend highly partisan issues, the workshop also seemed to reaffirm their mutual antagonism.

The problem is structural: the root of tribalism is human nature, and the current state of American democracy is distinctly primeval. People have an urge to belong to exclusive groups and to affirm their membership by beating other groups. A new book by the political scientist Lilliana Mason, “Uncivil Agreement”, describes the psychology experiments that proved this. In one, members of randomly selected groups were told to share a pile of cash between their group and another. Given the choice of halving the sum, or of keeping a lesser portion for themselves and handing an even smaller portion to the other group, they preferred the second option. The common good meant nothing. Winning was all. This is the logic of American politics today.

How passion got strained

The main reason for that, Ms Mason argues, is a growing correlation between partisan and other important identities, concerning race, religion and so on. When the electorate was more jumbled (for example, when the parties had similar numbers of racists and smug elitists) most Americans had interests in both camps. That allowed people to float between, or at least to respect them. The electorate is now so sorted—with Republicans the party of less well-educated and socially conservative whites and Democrats for everyone else—as to provide little impediment to a deliciously self-affirming intertribal dust-up.

A national crisis, such as a big terrorist attack, might ease the partisan warring. Yet because its causes are so fundamental, the relief would be temporary. A more lasting peace would take one of two things. One is electoral reform, with a view to ending the two-party system. More parties would lead to more cross-cutting identities, less zero-sum politics, so less discord. Alternatively—and more likely—Americans must wait for another of the political realignments that ended previous spells of intense partisanship, including the antebellum rivalry that stirred Abraham Lincoln’s appeal to “the better angels of our nature”. The civil war, which led to one such rearrangement, started the following month.