Our Most Challenging Issue – Five

A frequent refrain in media, in social networking memes and posts, in political rhetoric and in classrooms is that the United States is the greatest nation on Earth. It has also been called a grand experiment and a melting pot.

It is exactly that peculiar nature of our country—that it was founded by immigrants and sought to welcome and include yet more immigrants of diverse tribes—that makes it unique. Comedian Jon Stewart commented in a recent interview that, in setting up this ”one nation”...