When President Barack Obama is trying to persuade Americans not to do something, he has a go-to line: 'That's not who we are.' Whether the issue involves discrimination, immigration, torture, criminal violence or health care, he invokes the nation's very identity.

Donald Trump may not speak explicitly of 'who we are,' but with his promise to make America great again, he engages in his own kind of identity politics, signaling that the nation has lost its sense of self. That gets to people.

Every human being has an assortment of diverse identities, and it greatly matters which one is triggered by social situations, which hold up different kinds of mirrors. The same is true for nations.

Cass Sunstein Quotes