For decades, politicians in Washington have paid lip service to “fiscal responsibility” as they practice fiscal irresponsibility on a scale unprecedented in American history. The national debt of the United States has now climbed beyond $35 trillion, a number so large that it has ceased to register emotionally with most citizens. Yet numbers do not lose their consequences simply because they become difficult to imagine. A trillion dollars is a thousand billion dollars. Thirty-five trillion dollars represents obligations so enormous that future generations may spend much of their lives paying for promises made long before they were old enough to...