THE protest sign to beat all protest signs was brandished by an pleasant-looking, white-haired old woman in Poland last year. In response to a proposed a ban on abortion by the country’s government, it read, bluntly: “I can’t believe I still have to protest this f***ing s***”. That’s what you call getting your message across – little wonder the image went viral [minus The Herald's asterisks].

Word it as you fancy – I regard both phrasing and sentiment as unimprovable – but most of us will today be feeling a bit like that doughty, understandably wearied campaigner. The events in Charlottesville at the weekend were so unexpectedly grotesque, so grimly and distressingly antediluvian, that the only acceptable emotion was surely a form of species-shame. If you didn’t experience that soul-sapping desolation, then this column – this century – is not for you.

I’m still rubbing my eyes in disbelief. After the many advances towards racial, sexual and gender equality in recent decades, which have served to increase the sum total of human happiness, the most privileged caste of all has taken to the streets of America, bristling with weaponry, purple-cheeked with fury, carrying totemic torches and chanting slogans like “blood and soil” and “f*** you faggots’. I don’t know which face of white nationalism terrified me more: the heavily-bearded thugs with their shop-bought army fatigues, body armour and assault rifles, or the clean-cut, preppy young men with footballers’ haircuts, university degrees and David Duke posters in their bedrooms.

“Give me your tired, your poor,/ Your huddled masses yearning to breathe free,/ The wretched refuse of your teeming shore./ Send these, the homeless, tempest-tost to me,/ I lift my lamp beside the golden door!” Emma Larazus’s great poem, inscribed on the Statue of Liberty, was as much a mission statement for that young nation, that city on a hill, as the Declaration of Independence and the Constitution. Of all the places where the world-historical evil of Nazism might stage a sordid comeback, the US must be among the unlikeliest. It has always had its isolationists, its America First-ers, but in practice it has been the great melting pot, a roiling mass of humanity of every shape, colour and predilection. More than 400,000 of its sons died fighting totalitarianism in the Second World War; at the weekend some of their modern-day equivalents, who have enjoyed lives of incomparable ease, proudly marched with swastikas. The hatred and brutality that has accompanied the elevation of Donald Trump to the presidency – or perhaps the descent of that great office to his tawdry level – and the continued tolerance shown by the Republican establishment, make a lie of America’s sense of itself as a beacon, as the indispensable country. Shame on them.

Like most violence, large and small, from razor gangs on the streets of Glasgow to 1980s football hooliganism to the Rwandan genocide to the gas chambers of the Second World War, you do not have to dig very hard into what’s happening across the Atlantic to uncover a politics of identity at its root. This vile creed seems baked in to human nature, and has been exploited by chancers, demagogues, and the plain wicked throughout the centuries. Its tenacity mocks the idea that we are any more morally evolved than those who have come before, or that we will ever be so. We may be able, in our Western fastness, to turn away from the immiseration of, say, the North Korean people, or the monarchical score-settling of Tsar Putin, but it’s all one world, and every country displays its own variety of decay. As Albert Einstein put it, “nationalism is an infantile sickness. It is the measles of the human race.”

For some of us, it was an allergy to this tribalism, to the spasmodic urge to divide into us and them, that made a Yes vote in the independence referendum of 2014 utterly unthinkable. This is not to suggest the leaders of the SNP were culpable (although the dreadful Alex Salmond sailed close to the wind), but it was easily found among the wider Yes movement. After writing an article explaining why I’d be voting No, I was subjected to days of online vitriol and called, among other things, a white supremacist, a racist, a cap-doffing lickspittle, a ridiculous cringing joke of a human being, Uncle Tom in a kilt, and a bitter traitor. If the intention was to woo me to the cause, I confess the chosen method fell short.

It was there again during the Brexit campaign, from Nigel Farage’s appalling nativist posters to the rise in reported attacks on immigrants. Blame economic anxiety all you like, but in a country as wealthy as Britain there was something darker fuelling the Leave vote than a noble if misguided desire for restored sovereignty and free trade. Racism was a tiger ridden by normally sensible people who let their ultimate ambition get in the way of their moral judgment.

A debate based on identity affects and coarsens us all. I found myself happily watching videos of American white supremacists being chased, thumped and maced. I hoped the anti-fascist protestors would catch the guy who drove his car into the crowd and beat the hell out of him. I wanted to see suffering on the faces of those pathetic young men shouting racist and homophobic abuse. I felt the same cold fury and lack of care for their fate as I do towards those who belong to that ultimate identity movement, Islamic State. They drag you down with them.

Further, this politics of identity, this coarsening, crowds out the politics of ideas. Every improvement that we have seen to our global society, however small, has begun with a good idea. When the political climate gives us the space to focus on policy and people, rather than borders and difference, we can make great strides forward. But before too long we always seem to get caught up in deciding who we are and who we’re not, who’s a friend and who’s an enemy, who’s entitled and who’s got uppity. When we can’t move on from those base questions, which usually have the basest of answers, the result is always grief and pain. Very bad ideas replace good ones.

Perhaps, to be pessimistic, it’s simply the true human condition. Round and round we go. So, here we are again: still protesting this f***ing s***.