IN THE book After Virtue, the moral philosopher Alasdair MacIntyre examines the way in which we debate issues such as just war, abortion, or equal opportunities. Those arguing from opposing sides, he suggests, can never agree, because they begin from different premises. On war, one side prioritises justice, the other, survival. On abortion, one side begins with rights, the other with universality. On opportunity, one side gives primacy to equality, the other to liberty. A dialogue of the deaf is therefore inevitable.

The Brexit debate has become like that. Remainers focus mainly on the economy. They cite government and OECD predictions that Brexit will reduce GDP between six and nine per cent over the next 15 years, and may plunge us into recession. No deal would be bad for the European Union, which does ten per cent of its trade with us; but it would be catastrophic for the UK, which does 49 per cent of its trade with the EU. Every new development only deepens the gloom.

The result has made a few Leavers, like the prominent Tory Eurosceptic Peter Oborne this week, change their minds. But most remain fixed. They either reject the detailed analysis — with little more than bold assertions — or change the subject. Leavers seem little concerned with economics: for them, Brexit is about cultural issues such as sovereignty, immigration, and identity. We must take back control, even if we end up poorer.

This enables Leavers to ignore the fact that they were peddled a lot of untruths in the referendum campaign. Michael Gove told them that we would “hold all the cards” in the negotiations. David Davis insisted that he would be able to negotiate “the exact same benefits” as staying in the single market. The Germans would be more concerned with preserving frictionless trade to sell us their BMWs than with maintaining the integrity of the EU. None of this was true, but that seems less important to Leavers than their indignation over Parliament’s insistence on scrutinising the detail rather than swiftly endorsing no deal or a bad deal.

Analysis of the latest polling, by academics such as Matthew Goodwin, Tom Simpson, and the former Labour minister John Denham, suggests that the social and cultural factors are increasingly overwhelming economic ones in the public perception of Brexit. Public perceptions are, of course, not always accurate. (On immigration, the British public think that 30 per cent of the population were born foreigners, whereas the actual statistic is only 13 per cent.) But it is not so much the accuracy of the facts which is revealing here, as the subjects on which the two sides focus.

This may herald a significant realignment in British politics. The traditional Left-Right/Labour-Tory division seems to be being replaced by a Leave-Remain/cosmopolitan-provincial rift, in which economics takes a back seat to identity. This divide may turn out to be more be deep-rooted than the old disagreements about taxation and public spending.

If so, that only underlines how foolish Theresa May was, three years ago, to embark on a Brexit strategy that delivered for the 17 million and alienated the 16 million. If identity is the issue rather than economics, what was needed was a healing approach to bring together a divided nation. That division feels deeper now than ever.