Joseph Parent and Joseph Bafumi make a worthy contribution to the ongoing debate over the sources of U.S. grand strategy. Although their critique of our article misfires, it does provide us a welcome opportunity to reinforce our central claim that the erosion of bipartisanship and liberal internationalism in the United States stems from both international and domestic developments.1
Parent and Bafumi contend that a monocausal account suffices. They argue that geopolitical conditions—the end of the Cold War and the onset of unipolarity—adequately explain the collapse of political discipline and the awakening of the “long suppressed domestic cleavages” that undermined the bipartisan consensus on U.S. grand strategy. We fully accept that the international setting had a significant impact on the domestic sources of American statecraft. Indeed, we describe in detail how changes in polarity and the threat environment affected U.S. politics and policy from WorldWar II through the current Iraq War (see pp. 15–16, 20–31).
Although we welcome parsimony, geopolitics alone cannot explain the trajectory of U.S. statecraft. Domestic conditions are at least as important as the international setting in shaping U.S. foreign policy. America soundly rejected liberal internationalism after World War I but embraced it enthusiastically after World War II—despite the similar geopolitical opportunities afforded by military victory. The main difference was the domestic landscape; Woodrow Wilson and the League of Nations were attacked from the left and the right, whereas Franklin Roosevelt and the United Nations enjoyed the support of the bipartisan center Roosevelt had assembled in wartime.