For hundreds of years, intellectuals have been arguing about just war theory, attempting to determine how best to use it in thinking about contemporary war. But war is not what it used to be, and it is entirely unclear that scholars who wrote about the topic before the advent even of machine guns, much less airplanes, missiles, and nuclear, biological, and chemical weapons can offer us much guidance or enlightenment. Yet many scholars interested in war continue to frame their arguments in the terms of just war theory, nearly always paying what they regard as the customary deference to its early expositors, or “fathers,” as many writers fondly refer to them. In recent decades, Michael Walzer has made this practice seem incumbent on “serious” scholars of war; his Just and Unjust Wars has since its publication in 1977 (New York: Basic Books) largely shaped the contours of debate about war among philosophers and political scientists.