A presidential campaign might not be the best forum to have a serious discussion about the future of American foreign policy. But the likely nominees, Republican Sen. John McCain and Democratic Sen. Barack Obama, went at it last week. The debate was over if, when and how the United States should negotiate with hostile nations such as Iran.

McCain says that Obama's plan to have direct talks with the leader of Iran is dangerous and foolhardy. The leader of the Republican party, President George W. Bush — you remember him — speaking in Israel this month, said such a proposal was analogous to the appeasement toward Hitler in the 1930s. Obama shot back that there was a need for tough-minded diplomacy that has too often been missing from the Bush administration's approach to foreign matters.

There are two different levels to this debate, one political and one substantive, and they do not always overlap. Politically, McCain and Bush are trying to highlight Obama's inexperience in the national security arena. Their underlying message is: He's not ready to be president.

Obama is trying to differentiate himself from Bush's eight years of hard-line, bellicose foreign policy and emphasize his theme of change. His position has also been criticized by Sen. Hillary Clinton.

But there's also a serious point here that reflects real differences between Obama and McCain. As Michael Mandelbaum of the Johns Hopkins School of Advanced International Study has pointed out, you talk with your enemies when you believe it will further your national security interests. That is, this is a practical, not an ideological issue. Or at least it should be.

What's troubling about McCain's stance is that it smacks of the same ideological approach to foreign affairs that has marked too much of the Bush administration. The demonization of nations with whom we have conflicting interests is counterproductive. The Hitler analogies are used too often, too easily.

The reality is that even hard-line administrations have used diplomacy with declared enemies — sometimes through secret back channels, sometimes through elaborate summit meetings. Henry Kissinger's secret trip to China to set up the Nixon opening to Beijing is one example. Both Jimmy Carter and Ronald Reagan tried back channels to Iran. Israel has often had back channels to Arab leaders.

At the same time, Obama made a rookie mistake by seeming to say he would talk with the likes of Iranian President Mahmoud Ahmadinejad when he took office. It might have played well with Iowa Democrats, but it sticks with him now. Diplomacy is about timing and leverage, and Obama didn't make that clear. And diplomacy doesn't always work. President Bill Clinton tried to force a peace agreement between Israel and the Palestinians in 2000, when the Palestinian leadership wasn't prepared to accept a deal. Eight years of fighting has been the result.

Despite some of his early campaign rhetoric, Obama has it more right than McCain. He seems to be more of a foreign-policy realist, while McCain is more of an idealist. McCain seems to have come closer to the neoconservatives over the years. Opening a dialogue with nations that the United States has fundamental disagreements with is usually a worthwhile exercise. Iran, for instance, is a large, complex nation with different political currents. Treating any nation as an implacable foe runs the risk of creating a self-fulfilling prophecy.

Diplomacy is about carrots and sticks. And nobody should doubt that Washington has plenty of sticks. But sometimes using the carrots is more effective. The question we should all be asking ourselves in this campaign is which candidate would be more adroit at using those carrots and sticks to repair the United States' position in the world and further our vital interests. But we're going to have to see through the fog of campaign bluster to make that decision.

James Klurfeld is a professor of journalism at Stony Brook University. Reach him at james.klurfeld@stonybrook.edu. He wrote this commentary for Newsday.