It's tempting to view the European debt crisis as a simple morality tale. Hard-working, fiscally responsible northern Europeans such as the Germans and the Dutch are being forced to pick up the tab for their profligate southern neighbors—the Greeks, the Italians and the Spanish.

Germans tend to see the problem this way and, increasingly, so do many U.S. commentators. Unfortunately, that attractively simple story doesn't always stack up—most notably in the case of Spain.

In...