It might surprise you to meet the idealist in the race

American foreign policy has often been described as oscillating between realist and idealist poles. The U.S. presidential election campaign offers an excellent opportunity to subject the presumptive Democratic and Republican nominees to a realist-idealist test.

Realists see the world through gray and melancholy lenses: humans are selfish and aggressive by nature, and conflict between political entities is inevitable. Diplomacy, backed by military force, can at best moderate state behavior, if favorable balances of power are maintained by coalitions of the privileged and the satisfied. Henry Kissinger and George H.W. Bush are typically cited as realists.

Idealists argue that global society is not condemned to perpetual conflict because humans possess the capacity to escape from primeval aggressive instincts with the help of rational education, economic abundance and democratic institutions. They point especially to post-World War II Europe, which managed to shed a centuries-old pattern of interstate and civil wars, nationalism, genocides and the Holocaust and create the European Union. Woodrow Wilson and Jimmy Carter are usually placed in the idealist camp.

At first blush, one would be tempted to classify Republican Sen. John McCain as a realist and Democratic Sen. Barack Obama as an idealist. We argue here that McCain is the idealist, and Obama the realist.

McCain's idealist rhetoric emerges most clearly when he proposes a new "League of Democracies . . . that can harness the great power of the more than 100 democratic nations around the world to advance our values and defend our shared interests."

McCain sees staying in Iraq as necessary to finish what was started, because "the best way to secure long-term peace and security is to establish a stable, prosperous, and democratic state in Iraq that poses no threat to its neighbors and contributes to the defeat of terrorists."

One can imagine archetypal realist George Kennan, were he still alive, counseling that "one contains one's adversaries, rather than forcing regime change through military intervention."

During the primaries, Obama promised to withdraw from Iraq in a short period of time, avoid an additional front in Iran, and replace preemptive war with preemptive diplomacy.

For Obama, containment and deliberations (even with one's adversaries) and a return to multilateralism backed by force are all realist recipes for managing a quasi-anarchic international system.

The only obvious idealist trait in Obama's positions is his objective of reconciliation within America and between America and the rest of the world.

The Obama rhetoric now reflects a shift toward the general election and away from the primaries.

Before his Iraq visit, he asserted that: "I've always said that the pace of withdrawal would be dictated by the safety and security of our troops and the need to maintain stability. That assessment has not changed."

Following the visit to Iraq, Obama emphasized that: "My goal is to no longer have U.S. troops engaged in combat operations in Iraq" but left open their continued presence for training and counter-terrorism.

At the same time, he implied that he would not hesitate to use U.S. troops withdrawn from Iraq in the "perilous and urgent" anti-terrorism effort in Afghanistan. Obama has also hardened his line on Iran, which, as he warned after its missile tests, "now poses the greatest strategic challenge to the United States in the region in a generation."

While skeptical of political rhetoric in general, we believe that the world views of the presumptive presidential candidates do reflect the fundamental idealist-realist split, and suggest the broader outlines of the policies either would follow if elected.