Likelihood of Success, the Science of War, and the False Security of a Technical Principle

Abstract

I argue that it may be time to abandon the likelihood of success principle, a relative newcomer to the just war tradition. First, I am unconvinced of the normative value of the concept, especially when applied to states participating in defensive wars. Second, and more pragmatically, our lack of knowledge about what determines the outcomes and durations of wars, the application of a scientific-sounding concept to what is essentially a judgment of art may distort our moral reasoning. Estimating the chance that a particular war (or use of force) will generate the outcomes one hopes for is fiendishly difficult, and to be accurate, requires a knowledge of military and political science that few theorists possess. In its current form, the likelihood of success principle serves to reify existing power disparities and to render defensive wars apparently illegitimate.