It is difficult to think of an issue today as contentious as identity politics. Long criticised by the right as divisive and polarising, it has begun to be questioned by some on the left as well – from thinkers such as Mark Lilla and Jonathan Haidt. Writing from a liberal perspective in the Guardian, Columbia University professor Sheri Berman cited a host of psychological surveys showing that many white voters are supporting right-wing populists like Trump in a “defensive reaction” against perceived “group-based threats” that have been provoked, in part, by left-wing identity politics. Berman’s article – “Why identity politics benefits the right more than the left” – insisted that liberalism’s goal must be “winning elections,” which means “not helping Trump rile up his base by activating their sense of ‘threat’ and inflaming the grievances and anger that lead them to rally around him.” In her view, this requires “avoiding the type of ‘identity politics’ that stresses differences and creates a sense of ‘zero-sum’ competition between groups and instead emphasizing common values and interests.” Like Mark Lilla, …