Abstract

Wars are large-scale conflicts between organized groups of belligerents, which involve suffering, devastation, and brutality unlike almost anything else in human experience. Whatever one’s other beliefs about morality, all should agree that the horrors of war are all but unconscionable, and that warfare can be justified only if we have some compel- ling account of what is worth fighting for, which can justify contributing, as individu- als and as groups, to this calamitous endeavour. Although this question should obviously be central to both philosophical and politi- cal discussion about war, it is at the forefront of neither. In recent years, philosophical discussion of warfare has bloomed, but the debate has focused on whom we may kill, on the assumption that our aims are justified.1 Political debate, meanwhile, is more concerned with matters of prudence, international law, and public justification, than with reassessing what is worth fighting for. For wars of intervention to halt or prevent massive humanitarian crises, this gap is not so troubling. When warfare is the only means to prevent the mass killing or enslavement of the innocent, the purposes of military force are clear enough (though undoubtedly many other problems remain). The problem is more pressing, how- ever, for the justification of national defence.3 Although common-sense morality and international law view national defence as the paradigm case of justified warfare, grounding this consensus is surprisingly difficult.4 We typically believe that any state is justified in using lethal force to protect its territory against any form of uninvited military incursion by any other state. And yet we lack a good argument to explain why this should be so. In this chapter, I explain why one familiar and otherwise plausible approach to the justification of killing in war cannot adequately ground common-sense views of permissible national defence.5 Reductionists believe that justified warfare reduces to an aggregation of acts that are justified under ordinary principles of interpersonal morality.6 The standard form of reductionism focuses on the principles governing killing in ordinary life, specifically those that justify intentional killing in self- and other-defence, and unintended but foreseen (for short, collateral) killing as a lesser evil. Justified warfare, on this view, is no more than the coextension of multiple acts justified under these two principles. Reductionism is the default philosophical approach to thinking through the ethics of killing in war. It makes perfect sense to ask what principles govern permissible kill- ing in general, before applying them to the particular context of war. If it cannot deliver a plausible set of conclusions about when national defence is permitted, then we must either revise our beliefs about which conclusions count as plausible, or else face the significant challenge of developing a different theoretical model for justifying war- fare—an exceptionalist model, which views war as an exception to the regular moral landscape, to which principles apply which apply to nothing else but war.7 We must show, in other words, that there is something worth fighting for in wars of national defence, which is not engaged when we use force in any other context. The chapter proceeds as follows. Section 2.2 sets out the argument against reduc- tionism.8 Section 2.3 considers and rebuts one common response to the argument, which has often been thought sufficient grounds to disregard its conclusion. Section 2.4 then asks whether a modified reductionism would survive unscathed by the argu- ment. Finally, section 2.5 sets out some desiderata on a plausible exceptionalist alterna- tive. Section 2.6 concludes.