First imagine a case in which a person uses violence in self-defense; then imagine a case in which two people engage in self-defense against a threat they jointly face. Continue to imagine further cases in which increasing numbers of people act with increasing coordination to defend both themselves and each other against a common threat, or a range of threats they face together. What you are imagining is a spectrum of cases that begins with acts of individual self-defense and, as the threats become more complex and extensive, the threatened individuals more numerous, and their defensive action more integrated, eventually reaches cases involving a scale of violence that is constitutive of war. But if war, at least in some instances, lies on a continuum with individual self- and other-defense, and if acts of individual self- and other-defense can sometimes be morally justified, then war can in principle be morally justified as well. It follows that the only coherent forms of pacifism are those that reject the permissibility of individual self- or other-defense—for example, those based on an absolute prohibition of violence or killing.