Commentators were right to point out that Mitt Romney committed a flagrant gaffe last week. Unfortunately, they were only half-correct in identifying the offense. Yes, Romney was impressively inartful in announcing that he was “not concerned about the very poor” because “we have a safety net there,” managing to upset both liberals (for his apparent insensitivity) and conservatives (for his apparent satisfaction with a welfare state they believe promotes dependency). But another objectionable part of Romney’s statement went mostly unremarked upon—namely, his declaration that his paramount concern was the economic circumstances of the middle class.

The idea that 90 or 95 percent of Americans are struggling may have achieved the status of...