Killing in Self‐Defense

Abstract

Can we ever permissibly kill others in self-defense, and if we can, what is the moral principle that permits such lethal acts? Consider a Villainous Aggressor who wants to kill me simply because he hates me, and I see him coming at me with an axe. Can I permissibly kill him if this is the only way to save my own life? What about the case of an Innocent Aggressor? This is someone who has the intention to kill me, but they are not morally responsible for forming this intention: perhaps a villain slipped them a drug which temporarily caused them to have this intention. Finally consider an Innocent Threat—someone who threatens my life even though they have formed no intention to kill me and exercise no agency at all. An example would be someone who has been pushed off a cliff and will land on me and kill me unless I vaporize him with my trusty ray gun first (if I do not shoot he will survive the fall). Like Judith Jarvis Thomson, I think these are all cases where it is permissible to kill one person in order to save my own life. Jeff McMahan, Michael Otsuka, and several others, however, have offered a powerful argument against the permissibility of killing Inno-