In 1625 Hugo Grotius argued, "War must be carried on with not less scrupulousness than judicial processes are wont to be." (1) Grotius's views form the basis for both modern just war theory and contemporary international legal theory. In this essay I will discuss one principle that has been a cornerstone of both of these theories, the principle of discrimination of distinction--namely, that war tactics must not be employed that fail to distinguish the group of combatants from that of noncombatants, refraining from attacking noncombatants but justifiably attacking combatants. I will offer various reasons to reject the traditional principle of discrimination, on both conceptual and moral grounds. At the end of the essay I will offer an amended principle. It is my contention that if we follow Grotius's injunction that this principle be followed with minute scrupulousness, fewer military tactics will be justified than is normally thought.
Just war theorists contend that tactics are illegitimate unless they can be used in such a way so as to distinguish combatants from noncombatants. Contemporary international legal theory also draws heavily on the principle of discrimination. The Geneva Convention (IV), as interpreted in the Second Protocol of 1977, says: "The civilian population as such, as well as individual civilians, shall not be the object of attack ... Indiscriminate attacks are prohibited." (2) The principle of discrimination also relies on the idea that it is possible to distinguish, in a morally significant way, those classes or groups of people who participate in wars from those who do not. (3) The categories of "soldier" of "civilian" "combatant" or "noncombatant," are thought to be stable. Yet there are serious conceptual and normative problems with identifying such social groups. In this essay, I argue that, because of these problems, the traditional principle of discrimination offers no clear guidance because it offers no clear, morally relevant line between those who fight and those who do not. Nonetheless, I argue that a distinction of this sort should be maintained, although one that will restrict tactics in war far more than is normally recognized.
When soldiers go into war, they are told quite explicitly not to attack civilians, but that they can kill combatants. In the Gulf War of 1990-91, for instance, all U.S. soldiers leaving for Kuwait were given the "Pocket Card on the Rules of Engagement." At the bottom of the card was the following summary of the rules governing the conduct of U.S. soldiers in this war:
1) Fight only combatants
2) Attack only military targets
3) Spare civilian persons and objects
4) Restrict destruction to what your mission requires (4)
These relatively simple rules reflect a longstanding principle of the moral and legal conduct of war, the principle of discrimination. And this principle is still interpreted traditionally. As one influential contemporary international law textbook puts it: "The principle of discrimination, about the selection and methods, weaponry, and targets ... includes the idea that non-combatants and those hors de combat should not be deliberately targeted" for attack. (5)
This essay proceeds as follows. I begin by spelling out the conceptual and normative problems with the principle of discrimination, as it is traditionally understood. I then consider the example of the naked soldier as a test case for thinking about how to draw the distinction between combatants and noncombatants. I then return to metaphysical issues, setting the stage for thinking that war should not be understood in a collectivist way. I explain why I think the principle of discrimination is nonetheless worth saving, and offer a beginning attempt to provide a new restricted principle. I address various objections to my revised principle, and end with a discussion of the very status of using collective procedures in identifying who can be killed. Despite my misgivings about the traditional principle, throughout I argue that there is a major benefit to be derived from the principle of discrimination, in that it makes soldiers stop and think, and hence makes them less likely to use violence.
The 1907 Hague Convention's Regulations (6) provided the basis for the Geneva Conventions of 1949, both of which require four conditions for someone to be regarded as a combatant: "1) that of being commanded by a person responsible for his subordinates; 2) that of having a fixed distinctive sign recognizable at a distance; 3) that of carrying arms openly; and 4) that of conducting their operations in accordance with the laws and customs of war." (7) More recently, Ingrid Detter offers this definition of combatants: "'combatant' is defined as someone who distinguishes himself from the civilian population, carries arms openly and is subject to an internal disciplinary system ... he must also act on behalf of a belligerent." (8) These definitions are useful, but it is unclear whether they provide the bright line we need for a morally relevant distinction.
There are many problems with this basis of the principle of discrimination, conceptual as well as moral. Not the least of the conceptual problems is that this basis fails to take into account "irregular" armed forces, such as guerrilla groups or terrorist groups, which are surely just as morally worthy of attack, if anyone is, as are regular soldiers. There have been significant attempts to try to capture the nature of modern war, which is often waged by even such irregular forces as suicide bombers. What the definitions by stipulation lack is a morally relevant basis for drawing distinctions among classes or groups of people during war. For we can form groups by stipulation in an infinite number of ways, but this will not tell us who should be morally distinguished from whom.
"Soldiers" is a group that is often hard to define conceptually and even harder to identify according to any morally relevant characteristics. Morally, the distinction between those who can be attacked and those who cannot is often thought to be better drawn in terms of the distinction between the innocent and the guilty, or at least between the innocent and the noninnocent, rather than between soldiers and civilians. (9) This distinction is suggested as a way to capture the obvious point that enthusiastic munitions workers participate more in war efforts than reluctant conscripts who sit in desk jobs far from the front. What is needed, rather, is a morally significant demarcation. The one that many have seized on is the distinction between those who have done something wrong, insofar as it jeopardizes the security of others, and those who have not. It is the former but not the latter group that is a legitimate target of attack. Some have thought that a morally relevant distinction is between those who participate and those who do not participate in a type of harm. We could try to distinguish combatants from noncombatants on this basis--namely, on the basis of whether the individuals in question do or do not participate in an unjust war. If they do participate, then they are legitimate targets of assault by enemy combatants. If they do not participate, then they retain their immunity from such attack, and if they are nonetheless attacked, then this would signal a basis for a charge of war crimes. But this basis for distinguishing is also fraught with problems, especially if the distinction is to have any moral relevance, as we will next see.
Francisco Suarez, reacting against a long tradition to the contrary, tried to demarcate the truly innocent and separate them from those who are "guilty" in war. Earlier theorists, such as Averroes, had said that it is justifiable to kill any males who might take up arms. (10) Suarez instead held to the general principle that "no one may be deprived of his life save …