The cumulative impact of a decade of austerity measures and of Labour shifting the political center of gravity leftward on economic policy means that Mr. Johnson has been forced to promise more public spending if he wins the election. But make no mistake: In the long term his administration remains committed, as one Conservative-aligned think tank put it recently, to “rampant individualism” and “a small state.”

In the stark difference between the potential futures it could deliver, the 2019 election is truly a product of its time. This vote was forced into existence by the pandemonium that has ripped through governing institutions in recent years — a deadlocked Parliament , the Brexit impasse, constitutional confusion. Its contours are now being molded by the deeper dynamics underlying all that turmoil, in particular the slow-motion implosion of “Third Way” market liberalism that has roiled politics across the global north since the 2008 financial crisis, and the ensuing struggle over what will replace it.

A decade on from the crash, Britain is still mired in the longest period of wage stagnation since the Napoleonic Wars, while productivity growth slows. Unsecured household debt is at a record high, and more than eight million people in working households live below the poverty line. Among the young especially, for whom unaffordable housing and job insecurity are the new normal, the aspirational story that gently moderated capitalism once told about itself has smashed against the rocks of reality.

The days when governments could promise perpetual economic growth, with a bit of skimming off the top for redistribution, are over. For many of those heading to polling stations on Dec. 12, this will be the first time in their adult lives that some form of centrist managerialism, offered by a party that could plausibly win power, is absent from the ballot.

Given that the next government must oversee some kind of resolution to the Brexit imbroglio, and will have the job of repairing both a dysfunctional democratic infrastructure and a tattered social fabric, the choices it makes will be far more consequential than those usually faced by incoming governments. Throw in the fact that the next prime minister will be in charge for half of the decade identified by the Intergovernmental Panel on Climate Change as the final one in which full-scale climate catastrophe could be averted, and it is no exaggeration to conclude that the victor will set Britain’s course for a generation and beyond.