In The Lies That Bind (Norton, Aug.), the New York University philosophy professor analyzes how the politics of group identity can lead people astray.

We all adopt group identities defined by things like race or nationality. What’s wrong with that?

It’s only wrong if you get trapped in the labels and forget that there’s a lot of diversity among people who share labels—and commonality among people who don’t share labels. I’m an unusual combination of labels that isn’t very helpful in predicting what I’ll do. You’ll find my name in the English peerage as the descendant of a baron, but most people like that don’t also have half their ancestry in Africa. I’m a good example of why identity labels don’t necessarily tell you much.

You criticize the notion that group identities are “essentialist”—that they reflect immutable characteristics within individuals. What about gender? Aren’t there essential differences between men and women, like the propensity to commit violent crime?

Gendered social systems may have nothing to do with bodily differences. You don’t need gender essentialism to explain differences in crime rates. They could flow from social roles and expectations: violence in boys is not heavily discouraged; violence in girls is.

Some pundits argue that religious doctrine, especially in the Islamic world, shapes political behavior. How does that square with your criticism of “scriptural determinism?”

“Scriptural determinism” is the claim that what’s in scripture will determine how members of a religion behave. I disagree: just because there are passages in the Quran that are inconsistent with liberal democracy, it doesn’t follow that Muslims can’t adhere to liberal democracy. I can find in the Bible a commandment to stone adulterers, but Christian and Jewish society has not done so for a long time. In real life, people focus on some parts of scripture and not others.

Donald Trump’s election is an iconic case of identity politics, but you see it as also covert class politics. How so?

You could call working-class whites who voted for Trump “deplorables,” or you could try to figure out their thinking. They sensed that they were regarded with contempt by Republicans and Democrats who thought of them as racist and sexist, and that Trump didn’t share that contempt. There was a populist hostility to elites who had not just more money and social capital, but more respect. So when Trump doesn’t look down on you, and echoes your sentiments on immigration, race, and feminism, it doesn’t seem surprising that you would vote for him. That’s working-class white identity politics.

Why are identity labels so important to people?

We’re tribal animals. Humans mostly don’t get things by being stronger and cleverer, but by being in better organized groups of people who are equally strong and clever. As we evolved, the capacity to form groups was adaptive. Group identities help us do that.