LAST week I promised a series of columns making deliberately unrealistic policy proposals, on the theory that the Trump era has overturned a lot of basic political assumptions (my own included), making it a reasonable time to entertain unusual ideas.

This week’s proposal is directly related to one of those overturned assumptions: the theory, beloved of liberals but accepted as well by many conservatives, that a multiracial society requires both parties to compete across lines of ethnicity and color, and that white-identity politics is a path to the political wilderness.

Not so. Instead, the demographic transformation of America has given us a Democratic Party more attuned to racial injustice or committed to ethnic patronage (depending on your point of view) than ever, and a Republican Party that has exploited white racism or ridden a white backlash against ethnic patronage (again, depending on your perspective) on its way to control of the House, the Senate and the White House.

At one end of this polarized political landscape, you have the liberal acclaim that greeted Ta-Nehisi Coates’s case for reparations, his argument that the debt owed by “the people who believe themselves to be white” to the descendants of African slaves is vast and essentially unpaid.