You can see divisions hardening in Britain, like rigor mortis spreading through a corpse. Joints are stiffening everywhere you look. If you doubt me, turn your eyes to the right and notice how politicians and commentators speak as if they are reading from a script, which allows no debate or argument about detail.

No Brexiter says, for instance, they support Britain leaving the EU, but think we should stay in the customs union to protect the hard-won peace in Ireland. In theory, there are dozens of different ways of leaving. In practice, everyone on the right wants the same Brexit, even though with the clock ticking, now is the time when argument is needed more than ever.

No right-wing equivalent of the Vatican or Central Committee of the Chinese Communist Party gives out the approved dogma. The crowd chants in unison – apparently of its own volition.

The British establishment was once described as ‘a committee that never meets’. It’s an umimprovable description of how conformism works in a country where party lines are spread by nods and winks rather than proclamations. There’s no list of prohibited thoughts or banned books. Peer pressure, which social media has amplified a thousand times, and groupthink ensure you know the party line without needing to be told.

Anyone watching Labour must have noticed that criticisms of the far left, which were everywhere a year ago, have vanished. Labour’s relatively good performance in the 2017 general election explains much of the silence. Doubtless, it quietened the worst type of Labour MP, who only ever had practical objections to the far left. When their argument that it couldn’t win fell apart, they could not turn to the more powerful point that it shouldn’t win. Their imaginative failure does not excuse the rest of us. If Corbyn or a successor from the far left is likely to be prime minister, it is more important to make the case against them now than in 2015 or 2016. But as on the Brexit right, argument has stopped just when it is most needed.

Once again, there is no coercion. The left wing establishment’s version of the committee that never meets does not have to call an unprecedented emergency session. Leftists know the score and will follow it. They don’t need a conductor to prompt them. Hugo Rifkind wrote recently about ‘a swelling roster of unmentionables’. There was no point in arguing about Brexit, Scotland, Trump, gender, antisemitism, immigration, or Islam with friends and family when argument only brought bitterness.

Because our work is political, journalists feel the change more than most. Colleagues I have spoken to agree with me that some editors – and I emphasise some editors so that other editors don’t go off in a huff – have shifted in the past year. Conservatives among them bristle when writers criticise any aspect of right-wing ideology, however small and repugnant it may be. Editors on left wing news sites mimic them. It’s not that you can’t get pieces published in their pages. But you must fight for them, and even the most thick-skinned among us can’t help but notice that a certain coolness – nay, iciness – descends as the committee that never meets delivers pointed hints that it would be better for all concerned if you shut up.

Extremists benefit when ideologies have to be brought whole or not at all. Criticism of, say, Brexit fanatics and anti-Muslim bigots on the right, or Leninists and anti-Semites on the left is no longer house cleaning but treasonable talk that aids the hated enemy.

You can make a case that the web has encouraged groupthink by keeping people in silos and never exposing them to contrary views. Cass Sunstein’s deservedly influential experiment showed how, when you put US Republicans together in one place and US Democrats in another, they became more intolerant and less sceptical.

Given the material circumstances of the West you can add that division is to be expected. Only innocents believed that the consensus of the late 20

th

century could survive the shocks that have battered it. Mass immigration, with the certainty of more to come as the population of the poor world explodes, had to produce a nativist backlash. Whether you condemn it or praise it, it’s inevitable. The failure of Western economies to deliver prosperity to the majority of working and middle-class people is an event of equal significance. In Britain and America, pay rises have become gifts your parents knew. As I write, the Resolution Foundation is publishing research that shows real average earnings are still £15 a week below their 2008 peak – and going backwards. No population will stay content with a status quo that has failed them for so long.

Changes in technology, migration patterns and the economy, do not fully explain the conformism that has descended on public life, however. More than any other western country Britain has moved on to the next stage when the backlash against the status quo propels extremists to power in both government and opposition.

I wonder if Conservative realise how loathed they are. First they gave us seven years of austerity, which deliberately targeted the working poor. Now, we have a Brexit in which everyone from Theresa May downwards refused to take account of the views of nearly half the country. As predicted, Brexit is pushing up inflation and causing the fall in real wages mentioned above. As it harms livelihoods, it wrecks the Conservative’s reputation for economic competence. If Tories now say Corbyn is a fanatic, the reply comes back: 'that’s rich coming from you’.

In these circumstances, it may be intellectually and morally indefensible to follow the doomed Alexander Kerensky and cry ‘no enemies to the left’. Psychologically, though, it makes sense.

Meanwhile the right faces Corbyn, a man whose life has been a grim parade of love-ins with men of violence who mean us only harm. The consequences are startling to watch. Conservative MPs, who know that Brexit is a betrayal of the national interest, always pull back when I ask if they will vote against it in the Commons. No, they say. They cannot do anything that might help Labour gain power. When the crunch comes, they will be silent.

As will so many others. On left and right, wherever you look, the committee that never meets has never enjoyed such power.