In both countries, a new dominant tribe has formed, and has then radicalised. This wasn't inevitable. Each tribe's leaders haven't simply intuited what their followers wanted. Rather, the leaders are taking the followers on a journey that most followers had never imagined.
Trump hasn't merely revealed an existing tribe; he is creating one, day by day. He has converted the existing Republican tribe — more than 90 per cent of whom voted for him — into a Trump tribe. It's true that he is doing so by tapping into racist traditions that are as old as the US.
"Send them back", for instance, is a trope designed to tell immigrants or native-born non-whites that they aren't real Americans. The nativist strand in American politics long predates Trump. But Trump didn't have to prioritise that strand.
There are other paths in US history, other ways this could have gone. Most Republicans previously voted for pro-immigrant presidents such as George W Bush and Ronald Reagan, and many didn't have strong views on immigration before Trump. They might have cared more about taxes, abortion or private healthcare, or perhaps they rarely thought about politics at all.
In other words, a leader with exceptional communication skills can alter his followers' minds, just as a good advert can make you crave something you'd never considered before. Trump communicates so powerfully that he has even created an enemy tribe too: he has done a better job of mobilising American liberals than any liberal leader in history.
Tribal formation in Britain has been even more revolutionary: a new Leave tribe has displaced the old Conservative tribe. (About four in 10 Conservatives voted Remain in the referendum.) The Leave tribe doesn't have a clear leader: Johnson and Nigel Farage have been competing for control since 2016. But Leave, and its mirror tribe, Remain, have eclipsed all previous tribal identities: more Britons now identify as Leavers or Remainers than with any party or religion.
All these new tribes help save their members from loneliness. In our atomised societies, ever more adults are single, don't identify with their jobs and don't belong to a clear economic class, religious grouping or trade union. Especially for people of Trump's age group who live alone with their TV sets, the new tribes provide a community of soulmates.
The tribes don't prioritise policymaking; Brexiters haven't executed any policies, and Trump not many, though his Supreme Court appointees will shape the US for decades, notably by blocking environmental regulations. For most tribal members, the tribes function above all as cultural movements, comparable to punk in the 1970s or today's "incel" subculture of angry young men.
The movements aren't always entirely serious. The writer Fintan O'Toole has remarked on Johnson's campness, his "comic persona that evades the distinction between reality and performance". The same applies to Trump. Their vocation is as entertainers.
Both men could have turned their tribes into big-tent movements that drew in opponents. Johnson would probably have liked that. Instead, the tribes are in a constant process of radicalisation, as they build an identity that sets them apart from the enemy tribes.
Every time Trump breaks an American taboo on race, and takes his followers with him, it's as if his tribe has sworn a communal blood oath: liberals demonise them, and so Trumpsters are bound together in thrilling, transgressive comradeship. No wonder Trump's support among Republicans rose after he told the Congresswomen to leave the country.
Now Leavers have adopted a new radical belief: the only real Brexit is no-deal. If no-deal inflicts pain and chaos on their own country, and enrages Remainers, that will only solidify the Leave tribe.
Meanwhile, the tribes keep purifying themselves. Any member who balks at any stage of the journey — Theresa May, Paul Ryan, perhaps Johnson himself if he doesn't leave the EU on October 31 — is branded a "traitor", chucked overboard and stripped of their identity and community. No wonder most tribal members stay on the ship no matter how far from their original homes the journey takes them.
Written by: Simon Kuper
© Financial Times
