Britain’s election result is a triumph for Boris Johnson, the Conservative prime minister. After years of shaky government, the country has a leader who can lead. But although Johnson has secured the largest Conservative majority since the Thatcher era, he is the anti-Thatcher. The Iron Lady stood for principles: a smaller state, a refusal to prop up flailing industries. Johnson, in contrast, is breathtakingly unprincipled. He lies. He contradicts himself. His deliberate, comedic bumbling sends the message: I don’t hold myself to standards, so neither should you resent me if I ignore life’s tedious rules.

This is why the meaning of Johnson’s landslide is murky. On the pressing issue of Brexit, Johnson will deliver on his one clear promise — to take Britain out of the European Union by the end of January. But that merely begs the question: What sort of post-Brexit relationship with Europe will Johnson seek? On the wider matter of Johnson’s vision for his country, almost any guess is plausible. He might govern as a pragmatic, unifying centrist, as he promised in his victory speech Friday. Or he might govern as a clownish Trump clone, contemptuous of truth, legality and constitutional constraint.

Consider, first, the Brexit question. After leaving the European Union, Britain enters a transition phase during which it will continue to pay into E.U. coffers, enjoy membership of the E.U.’s Single Market and be bound by E.U. rules. This transition allows time for negotiations on everything from the future trading relationship to scientific cooperation, student exchanges, security collaboration and much more. Simpler negotiations between the E.U. and Japan, Canada or other countries have taken years. But Britain’s transition runs only to the end of 2020, allowing negotiators less than 12 months.

British voters seem to have swallowed Johnson’s slogan that he will “get Brexit done.” Likewise, financial traders have sent the British pound soaring on the theory that economic uncertainty has passed. But the danger that Britain might crash out of the Single Market without a deal to preserve export access remains very much alive. Johnson has studiously avoided saying whether he will seek regulatory alignment with the E.U., and therefore generous trade access; or whether he will embrace divergence, implying less trade with Europe but more regulatory freedom. Equally, his election manifesto pledged not to seek an extension of the end-of-2020 deadline, but he might forget that promise as he has forgotten others. In short, and contrary to what voters and speculators imagine, it is unclear when or how Johnson will really get Brexit done.

Next, consider Johnson’s wider vision. He was a good, pragmatic mayor of London, although the city’s prosperity owed much, ironically, to its position as the commercial capital of Europe. Reassuringly, Johnson has talked up his London record, glossing over his lazy, gaffe-prone spell as foreign minister. When he promises to revive his party’s tradition of unifying “One Nation” conservatism, he might actually mean it. His landslide frees him to ignore the cranks on the right of his party. It will also force him to attend to traditional Labour voters who, in this election, supported the Conservatives for the first time.

Yet it is not clear how these instincts will translate into a governing program. The formerly Labour industrial constituencies welcome Johnson’s expedient pledge to prop up flailing manufacturers, but delivering on this pledge would involve diverging from E.U. regulations that limit state aid. Those same industrial constituencies favor a trade deal that protects car exporters, but delivering on that would push Johnson’s Brexit strategy in the opposite direction. Meanwhile, the prime minister promises to keep everyone happy with lavish public spending. He will have to find the cash.

But the real worry about Johnson’s one-nation promise goes deeper. Before the election, the prime minister showed worrying signs of favoring a populist, authoritarian centrism rather than the pragmatic, democratic sort. To silence critics in his own party, he purged them. To overcome resistance from Parliament, he suspended it — and was then overturned by the courts. He evaded media scrutiny by refusing to appear with a prominent TV interviewer and reacted to questions from a journalist by seizing his phone. During a televised debate, his party renamed its Twitter feed “factcheckUK,” presenting its propaganda as the work of independent analysts. Ominously, Johnson’s manifesto promises that in future the courts will not be allowed “to create needless delays.”

Far from being punished for this conduct, Johnson has been rewarded. With a large majority in Parliament, he can now pass almost any law he likes. Will victory permit him to listen to the better angels of his nature? Or will it encourage his high-handedness? After this election, Britain knows the name of its prime minister. It does not know much else.

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