The sociologist Will Davies, describing the lesser-remarked conundrum of the Boris Johnson prime ministership (would the hardliners who anointed him ever be satisfied with any Brexit?), borrowed a phrase from American politics: asymmetric polarisation. It is an elegant, economical way of saying “the other side has gone bananas”, which is funny because it’s true.

Let’s park the litany of examples for a second to concentrate on Nigel Farage. He appeared at a rightwing gathering in Australia on Saturday night – you could tell it was “alternative” because journalists were barred – and laid into Prince Harry and Meghan Markle in a way that was somewhat astonishing, but mainly completely bats.

Prince William must live for ever – according to the man who claims to represent all that is good, true and traditional about the nation but doesn’t understand royal succession at all – to stop Harry becoming king. The younger prince’s undoing is that he cares about the environment; apparently, for that reason, he plans to limit his family to two children.

It pleases the new right to call this a culture war, partly because that throws up the cultural fog of who started it

His father shares the same fatal flaw, but at least he’s always been that way. Harry used to be fun. He used to go to fancy-dress parties. He used to be a bad boy. A lot of this is insinuation, as is so often the way with Farage, who could hint at a political stance using only eau de tabac and leather elbow patches; but it appears, sincerely, to be the hard-right view that Harry was one of them when, as a 20 year-old, he dressed up as a Nazi, and now that he’s married some woman, and started talking about science, and evidence, and responsibility, he’s one of the other. A libtard; a snowflake; a despicable.

It pleases the new right to call this a culture war, partly because that throws up the cultural fog of who started it. How is this Farage’s salvo? Surely Harry himself attacked first, by talking about the environment at all?

It’s not a war. In no understood meaning of the words could worrying about the climate crisis be classed as hostile, or extreme, or even opinionated. In no schematic of human discourse is dressing up as a Nazi on one side of the centre, and being married to a woman who thinks about the future, and her family’s place in it, on the other. One side has polarised and the other hasn’t.

Yet nobody remains unaffected. It’s like having an arms dealer move in next door. You haven’t changed, but suddenly you’re a raging pacifist. Soon they’ll be putting white feathers through your letterbox, and you’ll be thinking, “Yup. I really don’t agree with getting rich off the machinery of violent death. So I guess that’s fair.”

Nigel Farage attacks Harry and Meghan, jokes about 'overweight' Queen Mother Read more

We understand one another so well, the polarised and the rest. I knew in my bones that one of these clowns would go after the royal family next. I wrote a week ago on how peculiar it feels to hold the Windsors as liberal allies, to have to defend them from splenetic political attack. It made no rational sense – why would ethno-nationalists turn against their own royal family? – but I understood it with my reptile brain.

We all knew before Johnson even became prime minister that his attention would turn to the United States for ideological and economic allegiance, and away from the European Union, even though that makes no sense either: the world is full of rules-based trading blocs, and the reasonable nation tends to favour the one that is closest, most lucrative, in which it had a hand in making the rules. Yet there they all vamoosh, these cabinet ministers, to America, returning with vacuous elegies to the warmth of their welcome, and the important bit is, we saw this coming. When you wake up on a Wednesday pondering dignity in prisons, by Sunday the prime minister will be threatening to lock people up and throw away the key.

Of course it is in the nature of extremism that you can see it coming a mile off. But the idiosyncrasies of its agenda are as obvious to us as if it were our own; and it is not because anyone has read a blog by Dominic Cummings.

Farage and his legion imitators get our foibles pretty well, also: he understands that the more nonsensical he is, the harder he is to ignore (again, irrational: because if asymmetric polarisation happened on a bus, which would look like one angry man ranting, ignoring him is exactly what we’d do). He understands that all you have to do is draw a false equivalence (there are some liberals on Twitter who are pretty extreme!), and we’ll spend the next decade arguing about why that is or isn’t the same, as if this whole caper were a burst piñata and every sensible point landed some sweets.

We understand each other fine: what I do not understand is why we all have to be dragged to participate in a polarisation that we do not share; that is not a sign of the times; that is not a divided nation, six of one, half a dozen of the other; that is, plainly, asymmetric.

• Zoe Williams is a Guardian columnist