The principle of discrimination (or distinction, as it is sometimes called in legal circles) requires that soldiers treat civilians differently from fellow soldiers, generally not attacking the former except in extreme situations. The Geneva Conventions call for a clear separation of people into two camps: those who are protected from assault, including army medical personnel, injured soldiers, prisoners of war, and civilians on the one hand, and soldiers actively engaged in hostilities on the other hand. Since the Middle Ages, it has been common to differentiate these people into two large groups, although there has not been wide agreement about which of the following groups were the most salient: civilians versus soldiers; noncombatants versus combatants; or the innocent versus the non-innocent (the guilty). In this chapter, I will argue that the principle of discrimination or distinction is most plausibly defended as an extension of the principle of humane treatment, and only on that basis is it to be seen as providing a nonutilitarian basis for deciding how to act during war.

As I explained in Chapter 5, the principle of discrimination is often defended as itself a basis for rough-grained treatment, where there is an absolute ban on certain forms of violence against civilians, noncombatants, or the innocent, but where these forms of violence can appropriately be used against soldiers, combatants, or the non-innocent (guilty).