The just war doctrine, while initially appealing, suffers from fundamental and insurmountable flaws. Its rules are overly vague, self-contradictory, and unrealistic. Also, it has unacceptable potential consequences: it sets the bar for just military intervention so high that not only would its firm application lead to an end to humanitarian intervention and other worthy ends, but such observation would be largely seen as unjust by the people of the world. I shall examine the various rules upon which Jus ad Bellum (determining whether the conditions for a just war are satisfied) and Jus in Bello (determining whether conduct within war is just) are based and demonstrate how they are flawed, incomplete, or inadequate.
The first major criticism of just war theory is based on the vagueness of the terms. What, for example, does it mean to be a ‘just authority?’ To quote The Economist: “The UN is what it is—a place where diplomatic horse-trading is conducted and states manoeuvre to secure their national interest. The position it takes on an American attack will probably be determined by whether or not the Mugabe-fêting president of France decides to wield his veto. That, surely, cannot be a measure of morality.” Likewise, the prohibition of violence carried out by “private individuals or groups” does not take into account matters of self defense. Here, the flaw is more of omission than of vagueness. Surely, there are conditions under which it is just to employ force unilaterally: when the alternative is horrific, for example. ‘Proportionality’ as a concept is also exceptionally vague. Using just enough force to win a war is a certain recipe for major casualties on both sides. By contrast, overwhelming force can reveal the hopelessness of a fight and lead to surrenders rather than combat and a reduction of bloodshed. In this sense, the idea of Proportionality is both vague and incomplete. Essentially every rule features a phrase open to wide interpretation: “a reasonable chance of success” could mean many thing to many people, likewise “last resort.” Should we respond to genocide by slowly escalating diplomatic pressure, then sanctions, then bilateral talks while thousands or millions are dying? The swiftness with which force can bring closure to an evil is a strong support not only for its use, but for its relatively rapid use once its effectiveness is determined to be likely.
It is also clear that the rules of just war can easily contradict one another. For example, how do we balance Proportionality with a “reasonable chance of success?” Do we consider the chance of success when using minimal force? When using maximum conventional forces? Or when considering even the use of nuclear or other weapons of mass destruction? The probability of a just peace is related to the strength of the attacking power, particularly in cases where superior numbers and technology will allow the sort of relatively ‘clean’ war now expected of the United States. Also, the Proportionality rule that you cannot destroy your enemy may make any just peace impossible. The complete removal of a regime may be vital to a sturdy peace. The recent American use of ‘shock and awe’ techniques reveal the contradiction, in some cases, between minimal force and discrimination. (Though the effectiveness of this tactic remains uncertain pending more complete examination of the conflict in Iraq.) A massive show of force against military targets can actually limit civilian casualties. A doctrine that contradicts itself can provide no useful model for behaviour. Likewise, one that gives different answers based on how vague terms are defined cannot be used to give definitive evidence of the justice of injustice of a particular action.
The just war doctrine, for all of these reasons, is an unrealistic mechanism for choosing to go to war or for conducting a war. While the ideas are generally appealing, close examination and case studies reveal them to fail the test of pragmatism. It must be acknowledged that no war is waged or considered from an ideal position. By definition, any situation where was is being considered is one where standard procedures have been suspended. To try and apply such high minded yet vague guidelines under such circumstances is both unrealistic and likely to bar the use of military force even when such use is justified or even urgently called for.
The final critique of the just war doctrine is that, given the modern situation, it sets too high of a threshold. Gone are the days of the Somme and a million casualties for fifty feet of captured land. Gone also are the days of indiscriminate carpet bombing like that of Dresden. Modern militaries have the capability to wage wars that, by historical standards, are remarkably clean. As such, they should not be subject to the same level of prohibition against military force. If they are willing to accept the burden of a higher expectation of care about avoiding civilian targets, and a higher level of accountability, those things should be accompanied by a lower threshold at which military force becomes and allowable, or even a preferred, option.
I would posit that no war in history has followed the just war doctrine to the nearest approximation of the letter as can be determined. Thus, if there has been a single just war in history, the satisfaction of these criteria is not a necessary condition for it being just. Further, I would say that the requirements of the just war theory do not, alone, serve to justify war. The vital condition is that overall welfare, and the welfare of the least advantaged, be boosted by the war above the level preceding the war. Namely, the war must lead to an improvement of the lives of those non-combatant members of the state or states it is being waged against. Thus, the just war doctrine is neither a necessary nor sufficient set of criteria to evaluate the justice or injustice of a war. Likewise, the contradictions of its varied axioms and their vagueness make it impossible for use as a yardstick of just conduct within war.
Finally, one point not explicitly made reference to by the just war doctrine is the state of the attacked country afterwards. Even after the 'cleanest' war, it is unlikely that the country will remain entirely stable and secure. Considerations of this nature, in terms of how the country will be both immediately after the war and in the long term, are also vital to establishing the justice or injustice of a conflict.