Periodically policy wonks will explain to young people why they’re wrong to feel aggrieved, because they’ve never had it so good. Most recently, the Resolution Foundation showed that millennials will inherit more than anyone before them. The fact that 35% of them will inherit nothing, and the average age for this windfall will be 61 – an excellent time to start a family, if you’re Charlie Chaplin – was neither here nor there.

Millennials set to reap huge rewards of inheritance boom Read more

As if this unearned wealth wasn’t enough, they are also nihilists. “When it comes to politics,” asked an article in the Atlantic, “do millennials care about anything?” It was written pre-Brexit and Trump, before 2015 was out, when all the disasters seemed natural and faraway, either literally (tsunamis, earthquakes) or atmospherically (wars, banking crises). The conclusion was that they didn’t: a bit of flim-flam survey data suggested US youth were in favour of volunteering, but their voting record was clear. Only 10 million of a possible 46 million young Americans had voted in the 2014 midterms, ergo they no longer took pride in their democratic agency.

Similar assumptions held in the UK, right up until the results of the 2017 election: the young didn’t vote, and couldn’t be persuaded to; if your manifesto had any money kicking around for vote-winning promises, they should be made to the old, who would at least be listening. “Pitch to the pensioners” had the status of a physical law of politics; like the weather, one could remark upon it and even complain about it, but to question it on ethical grounds was senseless.

In the turmoil after June this year, commentators scrambled to discover why the polls had turned out wrong. One explanation was that young people didn’t answer their doors because they were never in – so the feedback from canvassers was partial and dated.

Yet the wellspring of so many failed predictions was the widespread acceptance of a nonsensical precept: the young don’t vote because they’re different from the rest of us. Blame the internet, consumer culture, sausage-factory secondary education, celebrities, the marketisation of tertiary education, private debt, pornography, whatever – they’re just a different breed. Their hearts don’t swell at the same things; they’re not ambitious or pro-social in the same way. Had this been rejected at the outset for making no human sense, other explanations for their “inertia” might have been sought: maybe they weren’t voting because nothing on offer inspired them. Maybe the problem was not that they had given up on government, but that their hopes for it were so high they couldn’t be contained by the narrow limits of the post-crash consensus on “realism”.

Labour is identifying itself as the movement that embraces youth – as the party of the future, not the past

No need for these speculations now, of course, that the young have found their electoral expression: 60% of the 18- to 24-year-olds who voted did so for Jeremy Corbyn, on a turnout that was up 16 percentage points on the 2015 election, and accounted for most of the boost in numbers. Corbyn’s call for the voting age to be lowered to 16 is both sincere and expedient: no minimum voting age will ever be purely logical, there being as great a variance in maturity between 16-year-olds as there is between, say, members of the Conservative cabinet. But if you need to make a rule on the understanding of its arbitrariness, that rule must surely be: no responsibilities without rights. Any state that will let you join its army or compel you to pay its tax must give you representation. However, the rectitude of this demand is not why Corbyn’s making it: there is no chance in hell of a Conservative government allowing in an unnecessary horde of young voices when its purchase is failing even among the middle-aged. Labour is merely identifying itself as the movement that embraces youth and doesn’t fear it – as the party of modernity not stasis, the future, not the past.

Having raised his Glastonbury singing army, Corbyn will probably not be enough to contain its energy, and nor would he want to be. If there’s an election in 2018 – I find it impossible to imagine Theresa May staggering on for another 12 months – party-political campaigning may be occupation enough. But if it’s too slow coming, we should expect broad-based direct action: sit-ins and strikes, unions and students cooperating in the (French) spirit of 68, protests, vigils, UK Uncut-style happenings. Young voters this year found more than a political receptacle for a soup of opinions: mobilising around a defined project lit up their solidarity, coherence and enthusiasm, brought together disparate but like-minded movements, generating networks and structures. If the loss of her majority seemed the worst consequence of May’s ill-conceived election, the new composition of her opponents will be the more lasting effect.

The school of cliodynamics, which attempts to study history according to scientific principles, posits a theory of the “cycle of violence”: episodes of civic unrest explode every 50 years. The “secular cycle” describes the economic pattern where jobs and workers start off aligned, population growth leads to job shortages and wage stagnation, wealth concentrates in fewer hands, inequality drives corruption and political breakdown, and revolution ensues. Alongside it is the “father and son cycle”, where one generation sees an injustice and fights it; their children, conflict-weary, back off; and not until the next generation comes of age can the protest resume. These two cycles have intersected regularly – running up to 1870, 1920 and 1970 – across the developed world.

It’s appealing because it’s neat. And, probably for the same reason, it is rejected by many historians. Yet if 2018 begins to resemble 1968 in its sense of radical possibility, the explanation that history is repeating itself is too comfortable. Inertia cursed not the younger generation but everyone else: in the failure to make any plan for housing the future; the casual waving through of life-changing student debt; the blind eye turned to insecurity, exploitation and hyper-surveillance in the workplace. In all this torpor, politics has forgotten the only principle that gives it meaning: that of progress, of each generation using its energy to build for the next. Those conditions don’t so much predict a riot as incite one.

• Zoe Williams is a Guardian columnist