On 29 July 2018, the anniversary of Benito Mussolini’s birth, Italy’s far-right interior minister Matteo Salvini posted on Twitter “tanti nemici, tanto onore” (“So many enemies, so much honour”)—a variation on the fascist dictator’s notorious motto. Salvini was reproached by the press and rival politicians, and many took it as a worrying sign of fascism’s creeping return to Italian politics. But the same sentiment—an exaltation of enemies, whether liberals, immigrants or “cultural Marxists”—can be seen across the world, as domestic politics becomes increasingly polarised.

In this febrile atmosphere, it’s no surprise the ideas of German legal theorist Carl Schmitt are, in the words of the Financial Times, “back in vogue.” A celebrated scholar, an avowed and unrepentant Nazi supporter and a Mussolini sympathiser, Schmitt saw politics as a constant combat between warring factions. Enemies—real enemies, the ones who’d be happy to see you dead—are essential to political identities, Schmitt thought. If they did not exist, they would need to be invented. “Tell me who your enemy is, and I will tell you who you are,” he said. Without enemies, he thought, we are nothing.

For decades after the Second World War, Schmitt’s anti-Semitism put him beyond the pale of serious scholarship, and he was never allowed to teach at German universities again. But since his death in 1985, age 97, Schmitt’s stature has grown. According to Jan-Werner Müller, professor of politics at Princeton University, he is “the [twentieth] century’s most brilliant enemy of liberalism.” The real worry today is not his rehabilitation—but his relevance.

Arguably Schmitt’s most influential work was The Concept of the Political, a short essay with a lasting legacy, recognised as one of the most important texts of modern political thought. Published in 1932, a year before he joined the Nazi Party, Schmitt’s essay starts from a simple premise: If the defining distinction in morality is between good and evil, in aesthetics between beauty and ugliness, and in economics between profitable and unprofitable, what then is the defining distinction in politics?

For a budding Nazi, Schmitt’s answer was not particularly astonishing, but the resolve with which he held it—and the depths to which he drilled it—reverberate to this day. “The specific distinction to which political actions and motives can be reduced is that between friend and enemy,” Schmitt declared. His fellow anti-democratic and decorated soldier Ernst Jünger described what followed as “a mine that silently explodes.”

For Schmitt, the friend/enemy antithesis was integral to politics in three senses: the enemy needed to be “something different and alien”; opposing such an enemy was the essence of identity; and, in the implicit combat that followed, these enemies posed an existential threat. “The friend, enemy, and combat concepts receive their real meaning precisely because they refer to the real possibility of physical killing,” Schmitt wrote. War was therefore “an ever present possibility.”

As the rhetoric of war suffuses Britain today, it’s often diagnosed as a symptom of Brexiteers’ hankering nostalgia for Britain’s past. But Schmitt’s work shows that war serves another purpose in the political imagination. It binds people together, and brings with it a sense of purpose and belonging. War creates a cohesive identity. As the enemy comes clearly into view, so do we.

This rallying fantasy is innate to nationalist movements. Immigration is relayed in the language of “invasion.” Internal opponents are attacked on the grounds of “treason.” Other enemies, including leftists and minorities, are construed as wanting to wreck the nation. In Hungary, the name of Prime Minister Viktor Orban’s party Fidesz evokes the Latin fides; fidelity, or loyalty. At Jair Bolsonaro’s inauguration, the former military captain held up a Brazilian flag and declared that it would “never be red, unless our blood is needed to keep it yellow and green.” It’s not only Brexiteers who have war in their dreaming.

In a world where strong social bonds and feelings of belonging are elusive, the psychological certainties of war offer perverse relief. Schmitt saw a similar alienation plaguing his own era. His belief that liberalism was to blame has always resonated with left-wing thinkers, from Walter Benjamin to Slavoj Zizek. He praised Karl Marx for his “mighty friend-enemy grouping” between the bourgeoisie and the proletariat. But Schmitt’s focus on foreign threats has ensured that his natural heirs are almost all on the right.

With prescient words, Schmitt attacked liberalism’s “onslaught against the political.” The doe-eyed denial of the friend-enemy distinction—which sought to replace conflict with economic competition and “perpetual discussion”—ended not in utopia, Schmitt argued, but in the dispiriting diktat that “there must no longer be political problems, only organizational-technical and economic-sociological ones.” This foreshadowed, some fifty years early, Fukuyama’s “End of History” thesis, but without any optimism. Schmitt believed that in a world where enemies were prohibited, wars would be far worse.

Schmitt's own Nazi Party disproved the theory that wars would be worse when nations had no enemies, although the liberal-led nuclear age has threatened to affirm his idea. Yet Schmitt’s critique of liberalism’s duplicity remains eerily prescient. He laid out the “manifest fraud” of those who declare the inhumanity of war while waging it. “The worst confusion arises,” Schmitt warned, “when concepts such as justice and freedom are used to legitimise one’s own political ambitions and to disqualify or demoralize the enemy.” Politics was no place for experts.

Indeed, in Schmitt’s view, liberals claimed the moral or rational high-ground the same way a military general might claim the literal high-ground, only so as to gain an advantage in combat. “Whoever invokes humanity wants to cheat,” Schmitt wrote. Today, the same cynicism steeps terms like “political correctness,” “the tolerant left,” and “social justice warriors”, which contain implicit connotations of hypocrisy—suggesting Schmitt’s suspicions are still widely shared. ­

What Schmitt saw—and what, in his anti-Semitism, he succumbed to—is the attraction of enmity. With little else to latch on to, in either economic or social spheres, adversity injects real meaning into life. For Schmitt, “the entire life of a human being is a struggle and every human being symbolically is a combatant”. The lure of this idea can be seen everywhere today, from the popularity of Jordan Peterson and Joe Rogan, pseudo-intellectuals who see the same fraught world in which man must fight for himself, to the current trend of “Nemesis Twitter,” where social media users vaunt their unnamed foes, affirming a strong identity through reference to opponents.

Brexit is many things, but it is partly a search for enemies. There’s a sense in which British society had become sterile and enfeebled. Brexit was a chance to restore its power. The EU was a perfect foil for this sentiment; framed in the right way, it represented three enemies in one: old continental rivals, namely Germany and France; immigrants with malign intentions; and an elite bureaucracy, untethered to any nation.

During the referendum, all of these “enemies”— enticingly wrapped up within a single institution — were said to embody wild, existential threats. The EU was compared to Hitler 2.0, eastern Europeans and refugees became potential ISIS terrorists, and even the most treasured of national traditions were at risk of annihilation by Brussels. “THE EUROPEAN UNION WANTS TO KILL OUR CUPPA,” one Leave campaign Facebook ad shrieked.

Brexit is often cast as a peculiarly British affliction—a post-imperial melancholy, a world war nostalgia, a delusion of grandeur—even as right-wing populism sweeps the world. But Brexit is actually more Schmittish than British. It stems from an obsession with sovereignty, an aggressive affirmation of identity and a wannabe-war with existential enemies.

This politics plagues every nation, and is why Brexit—despite its solipsistic patriotism—finds such support abroad, whether in Salvini, Trump or the Alternative fur Deutschland. Really, nationalism knows no borders, and all nationalists speak the same language. Schmitt may as well have written their script.

Samuel Earle writes for the Atlantic, London Review of Books, Times Literary Supplement and New Republic. He tweets @swajcmanearle