Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" and of the new book "Governing America."

(CNN) -- In a recent column for The New York Times, David Brooks argued that the nation has now entered into a "capitalism debate." Brooks wrote that President Obama, who he said is feeling defensive about the failure of his policies to revitalize economic growth, has launched an all-out assault on capitalism by depicting Mitt Romney as the embodiment of corrupt and vicious economic practices.

The president's decision to focus on Romney's work at Bain Capital, Brooks argues, has shifted the "focus of the race from being about big government, which Obama represents, to being about capitalism, which Romney represents." Romney responded in kind, "I'm convinced he wants Americans to be ashamed of success."

If this shift continues, the campaigns will spend the next four months presenting voters with a false impression about the the real contest.

While both parties have a strong incentive to ramp up the rhetoric to mobilize voters to turn out, this kind of campaign features a debate that has little to do with the governing that will actually take place after the election....