I have long admired and learned from Anne-Marie Slaughter, and the Princeton Project report, "Forging a World of Liberty under Law," which she coauthored with another leading scholar I admire, John Ikenberry, is a major contribution to the debate over post-Bush foreign policy that I encourage everyone to read. As I have said before, I consider my differences with them to be part of a debate within the family of liberal internationalists in the Wilson-Roosevelt tradition, so my focus on limited areas of disagreement should not obscure the consensus on most values and subjects that we share, such as a favorable view of international law and multinational institutions that distinguishes liberal internationalists from neoconservatives.

We do disagree, to be sure, about some aspects of history and present-day policy. First, history. Anne-Marie writes: "In the first place, the liberal internationalism of Roosevelt and Truman believed both in having a concert of great powers (the UN Security Council) and of democracies (NATO, the Marshall Plan, and ultimately the EU)." This is not inaccurate as a description of the long span from World War II until the end of the Cold War, but I think it is important to distinguish Cold War institutions like NATO, the Marshall Plan, and the EU from the earlier, postwar global architecture planned by American liberal internationalists between the outbreak of World War II and the Cold War, with the Korean War serving as the hinge between the two eras of liberal internationalism. Although they contemplated regional groupings like the Organization of American States (OAS) as part of the UN system, neither the Roosevelt administration nor the early Truman administration had any plans for a "concert of democracies" or a European union excluding the dictatorial Soviet Union before the Cold War intensified. Indeed, the U.S. offered Marshall Plan aid to the Soviet Union, which rejected it and forced its satellites in Eastern Europe to reject it. NATO was founded only in 1949, and the European Common Market, which became the EU, was founded much later in 1957 by the Treaty of Rome.

In other words, history between 1939 and 1989 offers contemporary American liberal internationalists two visions or models of world order, not one: the post-1945 global system that the Roosevelt and early Truman administrations planned but only partly achieved, and the Cold War American alliance system that the later Truman administration and its successors hastily improvised during the long emergency. The U.S. since the fall of the Berlin Wall has tried to create a new international system by incrementally expanding the Cold War system (for example, by expanding NATO) when in my view we should have gone back to the drawing board and updated America's never-implemented post-1945 plans, with appropriate modifications for our era. I wouldn't object to the incremental expansion approach, however, if it allowed Russia and China to join security alliances to which the U.S. belongs now, not in the remote future after some ill-defined probation.

Anne-Marie argues that a "responsibility to protect" is an idea that "grows directly out of" the Preamble to the UN Charter and the Universal Declaration of Human Rights. That's true if the question is the moral legitimacy of states. Of course states should protect their inhabitants, rather than oppress, torture and murder them. My concern is with legal reasons for war, inasmuch as liberal internationalism, before it is anything else, is a system for limiting war. There are many things that states should do which other states cannot force them to do. Article 51 of the UN Charter permits wars of self-defense, with the help of allies if necessary, and Article 42 permits wars that have been authorized by the Security Council. Until the members of the United Nations formally amend the UN Charter to provide for a third kind of legal warfare, wars by the U.S. or other countries to enforce a "responsibility to protect" on the part of evil regimes will be illegal under international law, unless authorized by the Security Council. How can liberal internationalists criticize the Bush administration for claiming that the U.S. has the right unilaterally to adopt its own eccentric interpretation of the Geneva Conventions governing torture, and yet support equally far-fetched readings by the US or other democratic countries of the black letter law of the UN Charter governing war?

In "Forging a World of Liberty Under Law," Anne-Marie and John Ikenberry also proposed another de facto amendment of the rules of the UN Charter that govern war, by suggesting that a majority of the world's democracies could authorize military interventions consistent with the purposes of the UN, if the UN did not undertake reforms they sought and if one or more Security Council members blocked a war that most democracies wanted to wage. If I have understood their proposal correctly (and I apologize if I have not), it would be relevant only in cases of "wars of choice" like Iraq and Kosovo, not defensive wars under Article 51 that don't need Security Council authorization. An "Iraq Syndrome" or US public backlash against further interventions may render this debate academic.

I'm pleased to be able to end on a note of harmony. Yes, I think that Americans, privately as well as officially where appropriate, should encourage groups working for democracy and human rights in Asia and elsewhere -- by means that do not include bombing, invasion, sabotage and U.S. funding for foreign political parties. And I share Anne-Marie's enthusiasm for turning the G-20, which has a majority of democracies but is not limited to them, into an informal global concert. As I said, this is a debate among people who share the same premises, even if sometimes we arrive at different conclusions.