So the credit-rating agencies that helped to create the financial crisis that led to a deep recession are now warning that the U.S. could lose the AAA rating it has had since 1917. As painfully ironic as this is, there's no benefit in shooting the messengers. The real culprit is the U.S. political class, especially the President who has presided over this historic collapse of fiscal credibility.

Moody's and the boys are citing the risk of a default on August 2 as the proximate reason for their warning. But Americans should...