There is a simple reason why Boris Johnson and European leaders failed to find common ground over Brexit at last week’s G7 summit. They are not even talking about the same thing. For the British prime minister, Brexit is a matter of national character that cannot be described in legal documents. For continental politicians, legal texts contain the true meaning of a project that only exists in the real world as a set of rules to be implemented. To Johnson, the withdrawal agreement was a single-use tool for levering himself out of a tight spot. For Brussels, it is the chamber into which Britain levered itself. That difference will continue to cause friction because it is not a misunderstanding. Johnson knows that legal arguments over the Northern Ireland protocol favour the European position. He chooses not to care. To concede on the principle that any part of the UK is subject to European regulatory standards – the compromise he signed to avoid a land border on the island of Ireland – would be to admit that a portion of sovereignty was conceded in the negotiations. That would be a stain on his self-image as the man who made a clean break from Brussels. He finds confrontation more appealing, not least because he expects it to achieve more than compliance. Whether that is true depends on how you define achievement. Johnson’s calculation doesn’t prioritise peace in Northern Ireland. If it did, he would spend time telling the Unionist community that customs checks at Irish Sea ports were an administrative fact of life after Brexit but not a precursor to severance from the UK. He would have applied some effort to rebutting the most paranoid, sectarian interpretations of the protocol. Instead he has gamed and inflamed the grievance in the belief that the threat of conflagration puts pressure on the EU to make concessions. If Northern Ireland is on fire, any insistence from Brussels on maximum implementation of rules on sausage imports will look callous and disproportionate. The prime minister expects to avoid meeting his treaty obligations in much the same way that an arsonist expects to avoid paying insurance premiums on the house he is torching. That technique will not do much for Britain’s reputation abroad, but Johnson’s mind rarely strays far from his domestic audience, to whom he will explain that everything is the EU’s fault. His party and most of the media will endorse that interpretation, as it always has done. Labour will shuffle uncomfortably on the opposition benches. It is a wearyingly familiar conundrum for Keir Starmer: how to prove that Johnson is the author of European strife, without sounding like Brussels’ barrister, appealing against a verdict already handed down by the court of public opinion. When Johnson’s critics say he must be held accountable for Brexit, they use that word to mean the process and cost of severing ties with Britain’s neighbours and losing frictionless access to their markets. That is the remainer definition, even when used by people who accept there is no remain cause left to fight. When Tories say “Brexit” they mean it in the wider sense of a cultural revolution, sustained by belief and national pride. All revolutions demand constant vigilance against disloyalty. The project’s goals are too abstract to be attainable in any economically useful sense – there are no new jobs in the sovereignty-manufacturing sector – so momentum is maintained by always reimagining and refighting the old enemy. Starmer has no intention of disinterring EU membership. He knows that Labour’s route to a Commons majority passes through many leave-voting constituencies. But for the same reason, Johnson needs Labour to represent a suite of social attitudes that indicate persistent remainishness of the heart. In Downing Street’s strategic conception of the electorate, the prime minister represents a mainstream of commonsense, red-blooded patriots, while the Labour leader stands for nitpicking, naysaying, “woke” scolds and herbivores. The cleavage is artificial but resonant. Even when Starmer is closer than the Tories to majority opinion – as he has been on the need for timely lockdowns and cautious reopenings during the pandemic – he gets no credit because he is typecast as that guy who tuts on the sidelines. He sounds remainy even though he never talks about Europe. This is the long tail of Brexitism – a political mode that has its genesis in the referendum but has evolved into something much wider. Its defining feature is the flight from complex reality to symbols and fantasy. That is the habit that devotees had to cultivate in themselves to win the 2016-19 liberation struggle. Theresa May was broken by the attempt to divert the frothing stream of leaver demands down narrow channels of responsible statecraft. Her successor declared such restraint unnecessary, and then appeared to prove the point by getting a Brexit deal done. The trick was to sign the treaty without intending to honour it. All who serve in the current cabinet have signed up to the Johnsonian code of conduct that makes evidence and truth subordinate to the performance of boosterism. Sometimes facts fight through. Science has prevailed in the formulation of Covid policy, but not always by the most direct route. In other areas Brexitism sets the tone. There are ambitions for “levelling up” and “building back better”, but they are rhetorical zeppelins, floating on the political horizon, carrying no cargo of policy. Real-world government is a sequence of arguments over what is available on current budgets and, if more cash is needed, who will pay. Any serious plan for green energy, or reducing NHS waiting lists or reforming social care begins by telling the public about tough choices and present sacrifice for future gain. Johnson has been forced to deliver unpalatable messages in many live coronavirus press conferences over the past year, and visibly hated every second of it. Po-faced seriousness was supposed to lie abandoned on the far shore of the Rubicon that was crossed to reach Brexit. And the journey continues, because Brexit is not really a destination but a state of mind. It is not something that government can do, but a way of deferring all the things government should be doing but would rather not contemplate. It is the drink that British politics takes in the morning to postpone the hangover for another day, and Johnson is the national bartender. He keeps the tab open and the punters in good cheer, while the ever-sober Starmer pounds his joyless temperance drum outside. Rafael Behr is a Guardian columnist