The Once and Future Liberal: After Identity Politics by Mark Lilla HarperCollins, 143 pp., $24.99

I owe my marriage to identity politics. In 1960, I was born into a world where openly homosexual Americans were legally banned from federal employment, informally banned from much private employment, terrorized on the streets, persecuted by police, pathologized by psychiatrists, reviled from the pulpit, and made to live a lie. Fifty years later, in 2010, I married a man. In order for me to stop being a criminal, a sinner, and mentally ill—and in order for same-sex marriage even to be conceivable—homosexuality first had to become an identity.

If you were asked to name twentieth-century America’s single most powerful force for social improvement, identity politics would be a good choice. Its success in transforming American society for the better has been breathtaking. In that respect, now seems an odd moment to launch a polemic against identity politics, as Mark Lilla has done, and to ask American liberals to move on to “after” it.

A reckoning with the politics of identity, however, seems inevitable. For all their social triumphs, liberals are in the political wilderness. Over the eight years of Barack Obama’s presidency, Democrats lost, on net, more than one thousand elected offices, including thirteen Senate seats, sixty-nine House seats, twelve governorships, and more than nine hundred state legislature seats. Republicans dominate Congress and state governments, and Donald Trump is president. The left’s embrace of identity politics is receiving some of the blame. Steve Bannon, Trump’s arch-nationalist former chief strategist, recently said of the Democrats (in an interview with The American Prospect, a liberal journal) that “the longer they talk about identity politics, I got ’em. I want them to talk about racism every day. If the left is focused on race and identity, and we go with economic nationalism, we can crush the Democrats.”

Although Lilla, a self-described liberal Democrat, may cringe to receive support from such a quarter, he thinks Bannon is basically right on this point. Lilla’s new book, The Once and Future Liberal: After Identity Politics, is an expansion of a widely noticed New York Times opinion piece published shortly after the election. The book is very short, very sharp, and, at least on the left, very controversial. (A New York Times reviewer called it “trolling disguised as erudition.”) Nonetheless, progressives would make a mistake in waving aside its two core arguments, which are challenging and powerful.

“Identity politics” is a hard term to pin down, but a reasonable working definition would be: political mobilization organized around group characteristics such as race, gender, and sexuality, as opposed to party, ideology, or pecuniary interest. In America, this sort of mobilization is not new, unusual, un-American, illegitimate, nefarious, or particularly left-wing. My parents’ and grandparents’ generations took it for granted. My mother used to reminisce about watching the St. Patrick’s Day parade in New York with…