We are living with the politics of the fake orgasm.

The leaders of the Brexit campaign are obliged to join in with the ecstasies of their followers. They must let out a few polite yelps of satisfaction. But a week on, it is increasingly clear that theirs is a phony consummation. The earth may have moved – but not for them.

As shown by Boris Johnson’s retreat from the prospect of having to actually govern the new kingdom he did so much to create, it was all a performance. It will not be long before those they embraced – the alienated, the dispossessed – realise that they have been had in more ways than one.

Like the followers of Donald Trump in the US, white working-class Brexit voters are experiencing a new kind of political relationship. These movements may look like the reactionary populism we have seen many times before, but they are profoundly different in one crucial respect.

The old reactionary politics is utterly serious: its leaders really intend to do what they say they will do, and they really mean to reshape systems of government to allow them to do it. When they say they are going to cut out the contagion that is corrupting society – the Jews, the Catholics, the blacks, the communists – they really mean to act on their twisted obsessions, and they have every intention of creating the authoritarian systems that will allow it to happen.

What’s different about the new reactionaries is that they are not at all serious. The farce of Boris Johnson’s abortive leadership bid is just a token of a deeper truth: this is a game of thrones that is all game and no throne.

In the days after the Brexit vote, a number of rueful commentators were drawn to WB Yeats’s lines from the apocalyptic poem The Second Coming: “The best lack all conviction, while the worst/Are full of passionate intensity.”

But this is to miss the point of our particular political moment in the Anglophone world. It may be true that the best lack conviction, but the second part of Yeats’s comparison emphatically does not apply. The worst are not full of passionate intensity; they are, to borrow from a different Yeats poem, just a pretty bellows full of faux-angry wind. They have no serious intention – no plan and no means – of doing the things they say they will do.

Here are some of the things that are not going to happen in the next few years, even in the unlikely event that we end up with president Donald Trump and prime minister Michael Gove.

There will not be a wall across the Mexico/US border and Mexico will not pay for it. Muslims will not be barred from entering the United States on the grounds of their religion. Immigration into the UK will not be drastically reduced. An extra £350 million a year will not be put into the National Health Service. British fisherman will not be hauling in greatly increased catches. Vast steel plants will not reopen in Pennsylvania and Port Talbot.

The point is that neither Trump nor the Brexit leaders have ever believed for one moment that any of these promises are real.

Consider the evolution of Trump’s most lurid (and, according to the polls, most resonant) proposition: the ban on Muslims entering the US. It is indeed a staggering suggestion – it would overthrow the US constitution. But we can say with some certainty that one person who has never taken it seriously is Trump.

As recently as last September, he was saying Syrian refugees should be allowed into the US: “Something has to be done. It’s an unbelievable humanitarian problem.” By December, however, he called for a “total and complete shutdown of Muslims entering the United States until our country’s representatives can figure out what the hell is going on.”

He then said customs agents would be instructed to ask incoming travellers if they are Muslim, and that those who said yes would be turned away. In May he retreated, saying the whole thing was “just a suggestion until we find out what’s going on”.

On June 13th, Trump changed his mind again, saying he would ban everyone from “areas of the world where there is a proven history of terrorism against the United States, Europe or our allies”. (This would, of course, include Ireland, Germany and Italy.) Then he corrected this to say that it applied only to Islamist terrorism.

This is not a politician refining a serious policy proposal or even a fascist planning an outrage. It is just a spoofer trying to remember what spiel he came up with last.

Consider, too, the now infamous £350 million a week that the official pro-Brexit campaign claimed was being “sent” to Brussels and would, after Brexit, be spent on the British National Health Service. (The Leave referendum broadcasts featured a split-screen before and after hospital emergency department, one coldly indifferent and overcrowded with dark-skinned men, the other so empty the staff were only too delighted to meet the sick old lady who came in.)

This was a double lie: there was no £350 million a week, and Johnson, Gove and their allies were also promising large chunks of it to farms, education and research.

But even calling this a lie is to miss the point about the new politics. A lie has a relationship, albeit an inverse one, to the truth. The truth content of the £350 million claim is absolute zero. It floats freely above any actual intention to do something in the real world. Like Trump’s Mexican wall and ban on Muslims, it is a statement of the sort invented by the linguistic philosopher Noam Chomsky: “Colourless green ideas sleep furiously.”

Chomsky pointed out that this sentence is entirely grammatical; it follows all the rules of the way we construct statements of fact. But it is still nonsense. It refers to nothing whatsoever.

When Trump says “I will build a wall and Mexico will pay for it” or Boris Johnson and Michael Gove say “We send the EU £350 million a week – let’s fund our NHS instead”, they are actually saying “Colourless green ideas sleep furiously.” Their claims have the form and grammar of traditional political promises, but they bear no relation to anything they actually intend to do.

The problem with pure nonsense is that is cannot be contradicted: it is no good arguing that colourless green ideas don’t really sleep at all. And so it is with these claims. You can point out, for example, that even if Trump could build his wall, it would have to run through the middle of the Rio Grande. But in order to do so, you are depending on something that is entirely irrelevant to Trump’s claim: the real world.

In the old politics, we know what would have happened to the £350 million claim. Once it was comprehensively proven to be a lie, the Leave side would have had to withdraw it and the Remain side would have made hay. In the new politics, however, the protestations of the Remain side that their opponents had been caught out in a huge lie were entirely ineffectual. Exposing the lie was like revealing that Snow White didn’t live with seven dwarves. People simply shrug and say that maybe she lived with six dwarves instead. So what?

Where is this new politics of fake reaction coming from? Like all products, it has a supply side and a demand side.

The supply side is the world of media and branding. The Leave campaign was the product, not just of media barons such as Rupert Murdoch and Paul Dacre, but of the Frankensteins they have specialised in creating – chimeras who are half politician and half professional journalistic provocateur.

It says it all that Johnson’s first pronouncement on what the campaign he had led actually meant for the lives of UK citizens came, not in a press conference or a public speech, but in his “exclusive” Daily Telegraph column, for which he is paid £275,000 a year.

Johnson and Gove have followed the same path, from the Oxford Union where they learned to argue opposite sides of any case with an equal pretence of conviction, to Murdoch’s Times to the Tory Party and high office. They are, as Nick Cohen put it in the Observer, “the worst journalist politicians you can imagine: pundits who have prospered by treating public life as a game”.

Both are highly practiced in a kind of meta-politics, in which commentary and activity, medium and message, are fused into one. In that meta-politics, what the US satirist Stephen Colbert called “truthiness” – stuff that feels like it should be true – trumps the truth every time.

Trump is even further along this postmodern road, a longtime harbinger of the new world in which you don’t make money by creating and selling things, but by being known as a guy who makes money. His real business career is pockmarked with bankruptcies. But he had the genius to understand early on that reality was entirely irrelevant. He went into self-branding.

As a New York Times investigation of Trump’s business career concluded: “Putting his name on products and services – and collecting fees – was often where his actual involvement began and ended.”

Trump is a performer who acts out the role of mogul: an act perfected and popularised, of course, on The Apprentice. In that role, he has learned that political statements may be even more powerful when they have the same relationship to reality as his mogul brand has to actual business: none whatsoever.

On the demand side of the equation, we know, of course, that this new reactionary politics appeals to something all too real. That is the desperation of people who have been dumped out of the working- class lives of industry and aspiration they once knew and into the humiliating experience of being discarded as human set-aside.

We should not underestimate the extent to which Trump and the Brexiters feed off the sheer anomie of life in left-behind communities. Yes, it thrives on anger, but it also thrives on boredom.

Working-class communities have been taught by late capitalism to consume fantasies. They know very well that buying and wearing an acrylic T-shirt with the colours and advertising logos of Manchester United or the Cleveland Browns doesn’t really make you one with the multimillionaire sports star whose name is on the back. And they know that cheering for Trump or having a selfie taken with Boris doesn’t actually make you one with these entitled scions of the ruling class. But there is a comfort in the illusion: it breaks the boredom of a hopeless existence.

Listening to Trump tell you that he is going to build a wall or to a Brexit leader telling you that there will be no more immigration is like buying a lottery ticket. You don’t have to actually believe that you are going to win $100 million or £100 million this week. For even if the chance is one in a billion, it’s a chance: it keeps the boredom at bay by introducing a fantastic possibility.

In this logic, the bigger and more outlandish the political claim (No more Muslims! Your industrial job is coming back!), the more reason there is to buy the ticket. You don’t have to actually believe that Trump is telling the truth when he says he will build a wall. You just have to believe that there’s a one in a million chance he might. The more desperate you are, the more brightly the prospect of a transformative moment glimmers on the distant horizon of your dreams.

The problem now is that, with Brexit, many of these people think their numbers have actually come up. Brexit, to its leading champions a mere linguistic construct, has become a real world event. The transformative moment has arrived. And then their leader, Boris Johnson, walks away, tacitly admitting that his successful advocacy of this great upheaval was no more serious than winning a debating competition at the Oxford Union.

He was only playing, after all. But he was playing with fire. The fantasies that he and Trump have pumped into public life are not harmless – these dreams are other people’s nightmares.

And these dilettantes may have opened the door for more serious people. It would be entirely in keeping with this weird postmodern drama that the simulacrum could become a reality, that the cod reactionaries could usher in the real ones.

In the fake orgasm scene of When Harry Met Sally, Meg Ryan’s performance of ecstasy is observed by another customer in the cafe, who mistakes it for reality and tells the waitress: “I’ll have what she’s having.”

Now that xenophobia, ruling-class anarchism and self-destruction have been placed on the menu of popular political stimulants by the reckless fabulists, the rapidly disillusioned millions may be ready to place the same order.

Perhaps another Yeats line will have its day: “We had fed the heart on fantasies,/ The heart’s grown brutal from the fare . . . ”