Brexit is not the first thing Boris Johnson has found difficult, but it might be the first difficult thing he cannot simply abandon. The path by which he arrived in Downing Street is strewn with jettisoned jobs, principles and relationships. He finds other people’s needs burdensome, and is used to shrugging them off. But now he is yoked to an onerous national duty. His discomfort was obvious in parliament today.

Johnson’s traditional repertoire of glibness and bluster served him poorly as his authority and his majority melted away. The first significant test of his command of the Commons resulted in humiliation. He was defeated by a majority of 27, forfeited control of the legislative agenda, desperately threw a general election gauntlet across the chamber and watched helpless as the leader of the opposition dodged it.

Earlier in the day Johnson’s statement on last week’s G7 summit had been upstaged by a Tory MP, Phillip Lee, ostentatiously quitting his seat on government benches and swapping it for a berth with the Liberal Democrats. When MPs, including former chancellor Philip Hammond, demanded evidence of progress in Brexit talks, the Conservative leader could not even wriggle with eloquence, let alone defend himself with facts. The prime minister does not look like a man with well-laid plans coming to fruition.

There is a reason for that. Johnson chose the leave side in the 2016 referendum, thinking it would probably be beaten. He intended to earn kudos among Eurosceptic Tories, while evading responsibility for turning their romantic fantasy into reality. He flaunted his unreadiness to own the result, withdrawing from the subsequent Conservative leadership race on the day of his campaign launch. He served in Theresa May’s cabinet only for as long as he could be idle in a grand office. When the time came to commit to a workable Brexit model, he resigned.

In part, Johnson is captive to the public school cult of effortless dilettantism that despises diligence as vulgar and swotty. He is also a hostage to his own breezy rhetoric. Even now that the technical complexities and economic hazards of Brexit are indisputable, the prime minister pretends that obstacles are trifling or illusory. He claims that leaving the EU without a deal would not be a calamity, but also that the threat of calamity is necessary to persuade the EU to grant a deal. He says that MPs’ demands for an article 50 extension make it harder to negotiate in Brussels because continental leaders will compromise only when they see that the UK is beyond reason. In short: there is no cliff, and even if there was one, the way to avoid it is by driving towards the edge at full speed with no brakes.

This is a new incarnation of Brexit’s oldest falsehood. It is the pretence (or fools’ belief) that the choice to leave the EU gives Britain more leverage over the bloc than it had as a member and, in Michael Gove’s pre-referendum words, “we hold all the cards”. That untruth was quickly exposed. A bloc of 27 nations collaborating to protect their combined interest trumps a lone state with no grasp of where its interests even lie. But instead of re-evaluating the strength of their hand, the hardline Brexiters rejected the rules of the game.

The real reason talks are not progressing in Brussels is that Johnson is not negotiating. His position is that the Irish backstop must go, but he will not say what should replace it. The backstop exists because the UK wants its own regulatory regime, beyond EU jurisdiction, the enforcement of which requires border checks. But the absence of those checks is a vital ingredient for peace in Northern Ireland, guaranteed by the Good Friday agreement. Johnson’s solution to this problem is to deny its existence. He rejects the December 2017 “joint report”, which codified commitment to a seamless Irish border (and accepted obligations regarding citizens’ rights and the EU budget).

Facebook Twitter Pinterest ‘Johnson’s actions are best explained by his congenital aversion to things that are hard. He wants a deal but not the effort of getting a deal.’ Photograph: POOL/Reuters

Brexit ultras cheer the Tory leader’s disregard for May-era commitments, imagining it makes him a more serious player than his predecessor. In Brussels, it achieves the opposite. It confirms that the UK has slipped its moorings in the realm of grownup diplomacy. The prorogation of parliament adds a whiff of tyrannical caprice, as does the heavy hint from Downing Street that Johnson’s government does not feel bound by laws if they are drafted by its opponents.

Here is a British prime minister building on a formidable reputation for dishonesty, reneging on debts, revelling in contempt for legal norms and trashing protocols that underpin democracy. He asks Angela Merkel and Emmanuel Macron to dispense with clauses in a deal that exist to protect the integrity of the single market and honour an international peace treaty. If their answer is no, the reason is not MPs seeking an article 50 extension.

Boris Johnson is threatening his own MPs, but I’ll be voting to stop no-deal Brexit | Sam Gyimah Read more

Does the prime minister really want a deal, or is the display of brinkmanship meant actually to bundle Britain over the brink? Would he rather avoid an election or has he been gaming the opposition to provoke one? Johnson’s actions are best explained by his congenital aversion to things that are hard. He wants a deal but not the effort of getting a deal. He is lying to the public when he blames the opposition or Brussels for his predicament – but lying also, one suspects, to himself. A man who spent years in estrangement from the truth is unlikely to seek its company now.

It is possible that Johnson knows most of what he says about Europe is fiction, but also that he believes it. His talent is as a narrator of political myths, casting himself as the hero. His greatest creation is the character called “Boris” who has recruited a devoted following in the Conservative party, much of Britain’s print media and a sizeable chunk of the electorate. It is a cycle of mutually reinforcing delusion.

He wins applause by making Brexit sound easy, and the credulous ovation sustains him in refusal to consider the prospect that he is wrong. Like all theatrical performances, it works by suspension of disbelief. But continental critics can see the artifice plainly and feel no need to indulge it. They are just waiting for the inevitable moment when the pantomime must end, and British politics emerges blinking into the cold daylight of a true-life Brexit.

• Rafael Behr is a Guardian columnist