Julian E. Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter," published by Times Books, and editor of a book assessing former President George W. Bush's administration, published by Princeton University Press.

With all the talk about the ideological and strategic divisions within the GOP, the real choice that primary voters will have to make next year is a simple one.

Republicans have to decide whether to pick a candidate who appeals to their hearts or to their minds. The field is still fluid, but so far Texas Gov. Rick Perry appears to be the candidate who appeals most strongly to the ideological passion of conservatives, even though he stumbled in last week's debate.

Former Massachusetts Gov. Mitt Romney, who doesn't inspire that passion seems to be the right man at the right time to defeat a struggling incumbent president. In recent weeks, at least based on the polls, logic seems to be a stronger pull.

Traditionally, voters tend to go for the candidate who appeals to their hearts, even if the choice may be less likely to win. The primary process favors candidates who play to the base of the party and voters want someone they can believe in.

The outcome of making this choice has been mixed. When voters selected the unknown former Georgia Gov. Jimmy Carter over establishment Democrats like Henry "Scoop" Jackson and Birch Bayh in 1976, going for the person who promised to rebuild trust in American politics, their candidate defeated President Gerald Ford....