Shortly after the 2015 general election, Jonathan Wheatley, a political scientist at the University of Zurich, published an analysis of voters’ attitudes which overturned conventional Westminster wisdom. Labour had suffered a crushing defeat, the story went, because the British people refused to be led towards Ed Miliband’s left-wing “Marxist universe”. David Cameron’s victory was a common-or-garden win for traditional, stolidly English economic conservatism. Nothing to see here.

Wheatley’s research confounded such complacency. On a conventional left-right spectrum he located Ukip voters slightly to the left of the Liberal Democrats, with both joining Labour and the Greens inside the left hemisphere. Not only that, but considerable numbers of Tory voters, too, were economically left of centre (the converse of which could not be said of Labour voters); the clear inference being that there was a “progressive majority” for centre-left economics. Far from being an electoral albatross, Ed Miliband’s cost-of-living platform should have romped home.

Unfortunately, as Wheatley pointed out, people don’t vote along economic lines only. There is a cultural dimension to politics, and in this sphere he found Labour voters – along with their Lib Dem and Green counterparts – to be nearly as far away from the British centre ground as Ukip. Tory voters stood alone between the “cosmopolitan” and “communitarian” polarities. Wheatley never expanded this into a hypothesis about Labour’s defeat, but it barely needed saying. The centre ground still mattered and the ­Tories still held it – just not in the way any of us usually thought about our politics.

In 2016, from Rome to London to Washington, liberalism’s annus horribilis bore Wheatley out, and then some. True, referendums always accentuate social divisions. Nevertheless, there is ample evidence that this cultural dimension could be reshaping Western political affiliation at a deeper level. On pressing matters of trade, national security, immigration and social cohesion, the cosmopolitan and communitarian axis already says far more about the contest of ideas than a conventional left-right divide.

More importantly, the Brexit moment has created powerful new political identities that speak to this cleavage and are now uncomfortably overlaid on long-established partisan loyalties. The question now is whether these divisions, as in Scotland, calcify into a moment of genuine realignment. The “Brexit by-elections” in Witney and Richmond Park may be a foretaste of the political battle to come. A battle fought, as Marine Le Pen, the leader of France’s Front National puts it, between “globalists” and nationalist “patriots”.

If this is the battle of the moment, then it’s a bloodbath. More painful still, at least as far as the left is concerned, is that the bedrock of support for such parties, as with Trump and Brexit, lies overwhelmingly on the traditional working-class left. This speaks to the broader failure of mainstream social-democratic parties to tame neoliberalism and temper globalisation. In the 1990s, with social democrats in the ascendant, the historian David Marquand warned that unless we could provide effective “shelter from the neo-capitalist storm” social democracy would collapse. If the shelter was “illusory”, he argued, then “religious fundamentalism, ethnic cleansing, xenophobic nationalism, moral authoritarianism and the scapegoating of minorities” would offer “seductive escape routes” from “the insecurity, injustices and tensions that untamed capitalism brings”. It is fair to say that in 2016 Marquand’s nightmarish vision became real.

Yet to escape it we will need more than economic radicalism. Economic injustice is only half the story – and even then, as Wheatley’s research underlines, it frequently finds a cultural expression. No: to regain an audience for its economic platform the modern left must also respond to the deep-seated cultural dislocation between itself and its former supporters.

This entails nurturing a progressive sense of patriotism to contest the national story. It remains a mystery how Labour activists can go dewy-eyed about Danny Boyle’s Olympic opening ceremony or Sadiq Khan’s inclusive “One London” campaign yet still recoil from other patriotic accounts of nationhood. Any hope of reconnecting with the heartlands will also require a level of empathy and sensitivity that the left has abandoned in recent years. It will require, in short, a strong dose of liberalism.

That this might seem paradoxical only shows how far liberalism has been contorted. We are familiar now with the war on free speech and dissent on our university campuses; with the culture of “safe spaces” and the “no-platforming” of reactionaries such as Peter Tatchell for insufficiently intersectional views.

Yet this is just the thin end of a wedge that John Gray, writing in this magazine, has argued has mutated modern liberalism. The founding principles of liberalism were always tolerance and the belief that individuals should be free to choose their idea of the good life. More than that, there was a recognition that this freedom and tolerance must be extended to those who pursue socially conservative or communitarian ideals.

Modern “liberals” spend immeasurable time proscribing the rules of political combat and nowhere near enough time understanding the emotional conditions that cause people to “transgress” them. Think how frequently and easily voters – and often socially disadvantaged voters at that – are dismissed as “racist” or, to quote Hillary Clinton, “deplorable”.

As J D Vance, the former marine-turned-academic author of Hillbilly Elegy, puts it: “If you’re an elite white professional, working-class whites are an easy target: you don’t have to feel guilty for being a racist or a xenophobe. By looking down on the hillbilly, you can get that high of self-righteousness and superiority without violating any of the moral norms of your own tribe. So your own prejudice is never revealed for what it is.” Now, when liberals encounter people who depart from their moral and ­political standards they condescendingly seek to “educate” rather than empathise. The result is a “liberalism” shorn of its ideological history – a “liberalism” that is a proxy for an uncompromising, cosmopolitan form of identity politics.

The backlash has been ferocious and, for the time being, we must live with the consequences. Not only has it riven our old electoral coalition, but it has united our political enemies against us.

The social psychologist Jonathan Haidt has demonstrated how attempting to de­legitimise concerns about such issues as immigration and national security can activate a “normative threat” in the human mind that encourages “status quo conservatives” to align with those more “predisposed to authoritarianism”.

Therefore, for social cohesion and the maintenance of a broadly liberal society, the left (and Labour in particular) must resist and reconcile this emerging cultural cleavage. Technological headwinds mitigate against it – namely a post-internet ethos that views all expressive actions as assertions of identity – but we must turn our back on cosmopolitan identity politics.

As a party of racial and gender equality, we must allow legitimate campaigns for positive discrimination to continue. But we must learn again to walk in the shoes of those who do not naturally share our ‘‘liberal’’ values, and deliver a politics that can reconcile competing cultural ideals in pursuit of the broader national interest.

With patriotism and liberal tolerance, the open society will always beat a closed one – that belief must endure. But at the moment we are contesting our opponents’ “closed” politics with a closed politics of our own. And it is not working.

Tristram Hunt is the MP for Stoke-on-Trent Central (Labour)