But it is at the level of electoral politics that identity liberalism has failed most spectacularly, as we have just seen. National politics in healthy periods is not about “difference,” it is about commonality. And it will be dominated by whoever best captures Americans’ imaginations about our shared destiny. Ronald Reagan did that very skillfully, whatever one may think of his vision. So did Bill Clinton, who took a page from Reagan’s playbook. He seized the Democratic Party away from its identity-conscious wing, concentrated his energies on domestic programs that would benefit everyone (like national health insurance) and defined America’s role in the post-1989 world. By remaining in office for two terms, he was then able to accomplish much for different groups in the Democratic coalition. Identity politics, by contrast, is largely expressive, not persuasive. Which is why it never wins elections — but can lose them.

The media’s newfound, almost anthropological, interest in the angry white male reveals as much about the state of our liberalism as it does about this much maligned, and previously ignored, figure. A convenient liberal interpretation of the recent presidential election would have it that Mr. Trump won in large part because he managed to transform economic disadvantage into racial rage — the “whitelash” thesis. This is convenient because it sanctions a conviction of moral superiority and allows liberals to ignore what those voters said were their overriding concerns. It also encourages the fantasy that the Republican right is doomed to demographic extinction in the long run — which means liberals have only to wait for the country to fall into their laps. The surprisingly high percentage of the Latino vote that went to Mr. Trump should remind us that the longer ethnic groups are here in this country, the more politically diverse they become.

Finally, the whitelash thesis is convenient because it absolves liberals of not recognizing how their own obsession with diversity has encouraged white, rural, religious Americans to think of themselves as a disadvantaged group whose identity is being threatened or ignored. Such people are not actually reacting against the reality of our diverse America (they tend, after all, to live in homogeneous areas of the country). But they are reacting against the omnipresent rhetoric of identity, which is what they mean by “political correctness.” Liberals should bear in mind that the first identity movement in American politics was the Ku Klux Klan, which still exists. Those who play the identity game should be prepared to lose it.

We need a post-identity liberalism, and it should draw from the past successes of pre-identity liberalism. Such a liberalism would concentrate on widening its base by appealing to Americans as Americans and emphasizing the issues that affect a vast majority of them. It would speak to the nation as a nation of citizens who are in this together and must help one another. As for narrower issues that are highly charged symbolically and can drive potential allies away, especially those touching on sexuality and religion, such a liberalism would work quietly, sensitively and with a proper sense of scale. (To paraphrase Bernie Sanders, America is sick and tired of hearing about liberals’ damn bathrooms.)

Teachers committed to such a liberalism would refocus attention on their main political responsibility in a democracy: to form committed citizens aware of their system of government and the major forces and events in our history. A post-identity liberalism would also emphasize that democracy is not only about rights; it also confers duties on its citizens, such as the duties to keep informed and vote. A post-identity liberal press would begin educating itself about parts of the country that have been ignored, and about what matters there, especially religion. And it would take seriously its responsibility to educate Americans about the major forces shaping world politics, especially their historical dimension.

Some years ago I was invited to a union convention in Florida to speak on a panel about Franklin D. Roosevelt’s famous Four Freedoms speech of 1941. The hall was full of representatives from local chapters — men, women, blacks, whites, Latinos. We began by singing the national anthem, and then sat down to listen to a recording of Roosevelt’s speech. As I looked out into the crowd, and saw the array of different faces, I was struck by how focused they were on what they shared. And listening to Roosevelt’s stirring voice as he invoked the freedom of speech, the freedom of worship, the freedom from want and the freedom from fear — freedoms that Roosevelt demanded for “everyone in the world” — I was reminded of what the real foundations of modern American liberalism are.