As the politics turns hard right, the creased face of an elderly Hungarian Jew has become the prime target for resurgent nationalists across the world. George Soros is their essential enemy. If he did not exist, they would have to invent him. As the “George Soros” they credit with supernatural power does not exist, you could say that they have invented him.

A trawl of corrupt regimes lands this haul. During his presidential campaign, Donald Trump ruled that Americans protesting against him were “professional” agitators. Roger Stone, who has worked for the filthy wing of the right since Nixon’s day, followed up by announcing he had discovered the agitators were “paid for” by none other than Soros.

Now it is commonplace for right-wing Americans to say that only Soros’s corrupt influence can explain why their fellow citizens take to the streets. A typically sly report in the Washington Times said one in three Trump voters believed Soros paid protesters to join the women’s march on Trump’s inauguration day. Naturally, it did not produce a shred of evidence to support the fantastic accusation. That the gormless believed a straight lie was all the proof it needed.

Republican senators are now trying to persuade the Trump administration to cut support for Soros’s campaign to promote democracy and human rights in eastern Europe. Soros’s Open Society Foundation has no difficulty in showing that their Putin-influenced propaganda is riddled with errors . But a better riposte is to turn to Europe and see why democracy and human rights might need promoting. It’s not just Putin who goes for Soros. Macedonia’s former autocratic prime minister, Nikola Gruevski, has called for a “de-Sorosisation” of society, as the country’s right uses every trick it can think of, including the threat of street violence by “patriotic associations”, to stop the opposition taking power.

In Hungary, Viktor Orbán’s self-proclaimed illiberal democracy is threatening the Soros-funded Central European University. Its president, the former Canadian Liberal party leader and former Observer columnist Michael Ignatieff, is bewildered. He protests that he is running a university, not an opposition political party that might take Orbán’s power away.

I could go on. Romania’s socialist elite imitates Trump and claims Soros pays citizens to take to the streets to demonstrate against corruption. The supposedly reputable financial analysts at Zero Hedge claim Soros “singlehandedly created the European refugee crisis”. Steve Bannon’s Breitbart says Soros’s funding of Black Lives Matter was part of an agenda to swing the US presidential election. The European far right claims he is trying to destroy Christian white Europe by importing Muslim refugees.

Rather than go on, however, it is better to understand what is going on. When fighting foul movements, the question arises whether you should play the man or the ball. Playing the ball is the sporting thing to do. Lies have to be nailed. The factual record has to be defended. You should never regard it as a chore to insist on the truth. It is a duty, which if you shirk it, leaves the field clear for race baiters and dictatorial movements. This is why historians take the time and trouble to shred the Labour left’s claim that Hitler was a Zionist. This is why Soros’s supporters give journalists detailed rebuttals of the conspiracy theories that swirl around him.

But playing the ball means playing the extremists’ game to some extent. You treat their arguments as worthy of debate. However wrong you show them to be, you acknowledge their point of view. When you are up against dangerous men, playing the ball is not enough. You must play the man, too, and expose not just what he says but why he says it.

I hold no brief for Soros. To my mind, it is natural for Republicans to dislike a hedge fund billionaire who finances their Democrat rivals. If it were up to me, billionaires would not be able to give money to politicians, even billionaires I agree with. That said, Soros is the recipient of a hatred far beyond normal partisan rancour. The satanic influence attributed to the man who escaped the Holocaust as a child and resolved after the fall of the Berlin Wall to use his wealth to stop xenophobia returning to Europe isn’t normal. Not remotely so. It is one of the most striking signs of the crisis in conservatism, which is threatening free societies across what we used to call “the west”.

Most of Soros’s charitable efforts are not devoted to funding politicians, but values conservatives once claimed to believe in: transparency, free elections, free speech and a free press. Instead of upholding them, the dominant faction on the right has turned to a nationalism that treats opposition as treason. To learn about its antecedents, listen to the antisemitic echoes of the Nazi and communist eras in the vilification of Soros. They are so loud they deafen.

Orbán says he is against “the globalists and liberals, the power brokers sitting in their palaces with ivory towers” and “the swarm of media locusts”. Behind them all stands the “transnational empire of George Soros, with its international heavy artillery and huge sums of money”. March against Orbán in Budapest or Trump in Washington, DC, and you are a hireling of Soros’s cosmopolitan conspiracy. I may be doing him a disservice, but Ignatieff sounded naive when he wondered why Orbán was attacking mere academics. Invented enemies are essential. Foreign agents must be found everywhere and if the only place to find them is a university, so be it. They allow the powerful to blacken legitimate opponents as traitors and keep the faithful in line.

Orbán controls most of the Hungarian media. Hungary’s opposition parties are no threat to him. Trump’s Republicans, in turn, control the White House, Senate, House and most of America’s governors’ mansions. It says all you need to know that, to maintain their power, both use Soros to create a state of perpetual paranoia.

I will not argue that our nationalists are as bad. Yet, as the independence referendum approaches, I wonder if the SNP will be able to resist the temptation to blacken their opponents as false Scots betraying their country to the English. As the problems with Brexit mount, I also wonder whether English nationalists will be able to refrain from casting their opponents as enemies of the people and servants of the cosmopolitan EU.

If it does happen here, it will not be enough to play the gentleman and play the ball. You will need to go in hard, with studs showing.