Seth Lazar’s “Associative Duties and the Ethics of Killing in War” is an original, rich, challenging, and intricately argued contribution to our understanding of the ethics of war. Its main aim is to explain how fighting in a war can be permissible when warfare inevitably involves the killing of people who are not liable to be killed—a problem that is more extensive than it may seem.
Civilians are almost inevitably killed in war and Lazar accepts that few if any civilians are liable to be killed in war. In principle, of course, a war could be fought without killing civilians, and certainly without killing them intentionally. Yet it is scarcely possible to fight a war, or at least a war in the familiar sense, without intending to kill enemy combatants. Lazar believes, however, that many combatants are not liable to be killed. As I and others have argued, those who fight for a just cause in a just war (“just combatants”), and by permissible means, do nothing to make themselves morally liable to be killed—that is, they do nothing to forfeit or lose their right not to be killed. And Lazar himself has argued, in previous work, that many combatants who fight in wars that lack a just cause (“unjust combatants”) are also not liable to be killed. This is because the harm that, as individuals, they threaten to cause is insufficiently great or because the degree to which they are responsible for the harm they threaten is too low. I think he is right about this, though I think the proportion of unjust combatants who are not liable to be killed is in most cases lower than he thinks it is.