Why do we have a right to self-defense? Over the years, this seemingly simple question has proved difficult to answer. The right to self-defense arises in situations that involve culpable, non-culpable or non-agent aggressors. The difficulty is to find an explanation that justifies self-preference in each of these instances and maintains the moral distinction between the permitted killing of aggressors and the prohibited killing of innocent bystanders.
This Essay examines three lines of justifications that have been developed over the past three decades: lesser harmful results, forced choice and the rights theory. The “lesser harmful result” argument maintains that the killing of the aggressor is a lesser harm than the death of the defender. The “forced choice” argument says that self-defense is either justified because the defender is uniquely forced to choose between his life and the life of the aggressor, or excused because the he lacks real choice. Finally, the “rights theory” justifies self-defense by the prevailing right of the defender not to be killed over that of the aggressor.
This Essay argues that all three explanations fall short of the comprehensive justification needed to answer this question. It develops a new justification based on a theory of forced consequences. This justification combines two principles: the commonly recognized civil-law principle of fault-based selection and the principle according to which—in situations where either A or B must pay the costs for A’s “bad luck”—A must be the one to pay these costs and may not transfer the burden onto B.