More of a Cause?

Does a person's liability to attack during a war depend on the nature of their individual causal contribution to the (unjust) threat posed? If so, how? The recent literature on the ethics of war has become increasingly focused on questions of this kind. According to some views on these matters, your liability hinges on the extent of your causal contribution: the larger your contribution to an unjust threat, the larger the amount of harm that we can impose on you in order to avert the threat. Some philosophers have suggested that we can ground a quite general principle of civilian immunity on this basis. But, do causal contributions really come in degrees? Can we make sense of a graded notion of causal contribution that can be relevant to debates about liability in war? I argue there is good reason to be sceptical. The appearance that causal contributions come in degrees is just an illusion that can be explained away.