Narrow and Wide Necessity

There are two distinct perspectives one can take when considering the necessity constraint on defensive force: (1) which defensive option among those averting a threat would minimize harm to attackers (specifically, those potentially liable to defensive harm); and (2) which of these options would minimize harm to bystanders (specifically, those not liable to defensive harm)? This article introduces the concepts of narrow necessity for perspective (1) and wide necessity for perspective (2), following similar terminology for proportionality analysis. Currently, the ethics of defensive force literature lacks these concepts. Adopting them establishes a parallel structure for the proportionality and necessity constraints, so that both have narrow and wide perspectives. This proposal has the advantage of clarifying the scope of the necessity constraint, while also explaining paradigm violations of necessity that raise problems for competing proposals.