Abstract

What one is ultimately interested in with regard to ‘just cause’ is whether a specific war, actual or potential, is justified. I call this ‘the applied question’. Answering this question requires knowing the empirical facts on the ground. However, an answer to the applied question regarding a specific war requires a prior answer to some more general questions, both descriptive and normative. These questions are: What kind of thing is a ‘just cause’ for war (an aim, an injury or wrong suffered, or something different altogether)? I call this ‘the formal question’. Then there is what I call the ‘the general substantive question’. Depending on the previous answer to the formal question, the general substantive question can be formulated as: ‘Which causes are just?’ or as ‘Under what conditions is there a just cause?’ A final question, which has recently elicited increased interest, is what I call ‘the question of timing’: does the ‘just cause’ criterion only apply to the initiation of a war or also to the continuation of a war, that is, can a war that had a just cause at the beginning lose it at some point in its course (and vice versa)? I argue that a just cause is a state of affairs. Moreover, the criterion of just cause is not independent of proportionality and other valid jus ad bellum criteria. One cannot know whether there is a just cause without knowing whether the other (valid) criteria (apart from ‘right intention’) are satisfied; and this account has certain theoretical and practical advantages. As regards the general substantive question, I argue that all kinds of aims can, in principle, be legitimately pursued by means of war, even aims that might sound dubious at first, like vengeance or the search for glory. Thus, the pursuit of such aims does not make the war disproportionate or deprive it of just cause. As regards the question of timing, I argue that the criteria of jus ad bellum apply throughout the war, not only at the point of its initiation. While starting a war at t1 might be justified, continuing it at time t2 might be unjustified (and vice versa), and this insight does not require an addition to jus ad bellum but is already contained in it.