Americans don’t have a common ancestry. Therefore, we have to work hard to build national solidarity. We go in for more overt displays of patriotism than in most other countries: politicians wearing flag lapel pins, everybody singing the national anthem before games, saying the Pledge of Allegiance at big meetings, revering sacred creedal statements, like the Gettysburg Address.

We need to do this because national solidarity is essential to the health of the country. This feeling of solidarity means that we do pull together and not apart in times of crisis, like after the attacks on 9/11. Despite all our polarization, we do accept the election results, even when the other party wins. People in New York do uncomplainingly send tax dollars to help people in New Mexico. We are able to assimilate waves of immigration.

National solidarity is especially important for the national defense. Men and women serve in the armed forces for a variety of reasons, but one of them is the awareness that it is an extraordinary privilege to be an American, that it is a debt that needs to be repaid with service.

Soldiers in combat not only protect their buddies, they show amazing devotion to anyone in the uniform, without asking about state or ethnicity. This is the cohesion that makes armies effective.