Just War, Jihad, And the Study of Comparative Ethics. - Over the past three decades discussions of the ethics of war have been enriched by a number of historical studies. In this, the work of James Turner Johnson stands out, although books by Frederick Russell, Philip Bobbitt, and others also deserve mention. Interest in comparison, particularly of the cross-cultural type, is more recent. And for some scholars, the comparative study of the ethics of war seems to raise problems different from (and more difficult than) historical works: linguistic issues, differences in worldview, and diverse social settings somehow loom larger when one compares, say, Christian and Muslim judgments regarding the resort to and conduct of war. Are such scholars right? Does comparison need justification? Does progress in comparison require special theories or models? In this essay, I argue that the answer to each of these questions is no. Comparative evaluation is always a part of historical study. While linguistic and other types of variation require attention, scholars engaged in historical work need no special models or justifications. This is also the case with studies involving comparison across cultures. While there are difficulties related to translation and other matters, the issues are no different than those raised by more "strictly" historical accounts. The most important questions in any comparative or historical project have to do with purpose: that is, scholars must be able to answer the question, why does this matter? In the case in which I am most interested--a comparison of the just war and jihad traditions--I argue that the payoff is considerable, not least with respect to understanding the encounter we have learned to call the war on terror.