Who and What Is Tearing the US Apart?

In Shanksville, Pennsylvania, on Saturday, former President George W. Bush's theme was national unity — and how it has been lost over these past 20 years.

"In the weeks and months following the 9/11 attacks," said Bush, "I was proud to lead an amazing, resilient, united people. When it comes to the unity of America, those days seem distant from our own. A malign force seems at work in our common life that turns every disagreement into an argument, and every argument into a clash of cultures."

Though he surely...