Most modern aspects of just war theory found in the West can be traced to Saint Augustine of Hippo, and later specified by Saint Thomas Aquinas. The basic purpose of this theory was to teach Christians, and other just rulers, that waging war in general was not sinful if war was waged under certain circumstances for certain moral purposes. This theory is broken down into two parts. First is the right to go to war, and second is how states are to act during war. The principles of just war theory have been the underlying justifications for many modern conflicts, even if not acknowledged explicitly.
This examination of just war theory is not meant to oppose violent conflict in its entirety, or to necessarily oppose the ideals set out by just war theory. Instead, it is meant to demonstrate how just war theory has become a scapegoat for state actors as they seek to gain approval. Rather than ensuring that governments only participate in just conflicts, it has given governments a green light to participate in any war, as long as they can make the public believe that the conflict falls roughly into the requirements set by the just war theory. The requirements for how combatants act during the conflict may be an exception to this, as the public is often either unaware of the actions taking place or is aware via photos and video clips. However, warring governments are usually able to point to the necessity or morality of the war to justify any violations during the war itself.
The competent authority requirement seems to be one of the more subjective points in the theory. Aquinas in Summa theologiae II-II focused on the legitimacy behind the declaration of war itself. As an example, a sovereign must declare war, not a private individual. It is important to note that sovereigns during Aquinas’s time acted similarly to private persons in that they had authority over their realm if their subjects and noblemen were happy, rather than a system where a government has power indefinitely, with regular elections providing the illusion of choice. Additionally, sovereigns at the time were directly responsible for their realm as it was their property; thus, wars declared had the potential to greatly affect the sovereign’s personal finances. The point however is problematic due to differing definitions and theories of individual and natural rights that would supersede the rights of sovereigns in modern-day states.
Because of tricky definitions, this requirement may mean that a group is never justified in violent resistance. After all, what defines a nation? Surely Kosovo is a nation at this point, even though the United Nations has not awarded it with this status. What about groups that existed before the United Nations? Hungary was surely a nation, even when it was dominated by the Austrian Habsburgs. Did a nation only exist if they had a king? An argument can surely be made that the Jews resisting during World War II made up a nation of sorts, but with no sovereign. The Czechs and Poles had fighting regiments, but their states were overtaken by the Axis and Soviet powers. Their governments in exile existed out of necessity, not with a popular vote or regular elections. The British assisting the Czechs and Poles may have been fighting a just war, but were the resisting Czechs and Poles? Wars of resistance must be admissible if violent force in general is, but they find no room in just war theory.
A possible update to this point could change it to require that wars must be fought not by dictators, but by elected leaders. This is easy for a state to ignore, unfortunately, as almost every state has policies that allow for increased power for the executive during times of emergency or war. This starts a pattern of the state ignoring requirements when convenient.
The probability of success requirement is a tricky point as well. First, one must measure it morally. Should any state that will certainly lose resist going to war to regain lost territory or to rescue hostages? What of purely defensive struggles? Should a state give up as soon as it is clear that it has no chance against an invading enemy? Surely a defense cannot be labeled as unjust simply because it is a lost cause. When looking at this through a modern lens, this requirement may be extremely outdated and useless. All an executive must do is make a legislature believe that winning a war is possible, even if it is not.
Additionally, war prospects often change or can fool military officials. The first Arab-Israeli war in 1948 certainly had the potential for a strong win from the Arab coalition. Fighters from seven Arab countries had a great shot at defeating Israel during this conflict. However, foreign arms shipments, among other factors, resulted in a largely favorable outcome for Israel. Similarly, in Vietnam, the United States Congress was assured that this conflict would be an easy win for the American-led coalition in South Vietnam. Predictably, however, intelligence reports were faulty, and Congress was misled. Both historically and logically, this requirement of just war theory has been less than useful.
The last resort requirement is perhaps the most problematic point as there could always be another “last” resort after other options are tried. As states and elected officials usually need to look outwardly strong, they are less likely to offer satisfactory terms during negotiations if there is no threat of violence, or continued violence. A realist must understand that the threat of violence is the ultimate diplomatic tool, to be used often before serious nonviolent routes have been exhausted. This is of course not what is claimed by either side during conflict. Both sides are quick to point to supposed attempts at peace before a conflict is started. Additionally, states that are painted as the aggressor will never have truly exhausted diplomatic routes according to opposing state actors and major media outlets. This requirement of last resort will always be viewed, or painted, as respected by both sides, but it rarely is. It is, by definition, subjective, completely reliant on the strategic goals of each actor.
The final requirement of this first part—the right to go to war—states that a just war must be fought over a just cause. The just cause point is easily manipulated by warmongers and the media that serve them. Saddam Hussein using chemical weapons or killing babies in hospitals was an easy story to tell, harder to prove, but it was hypothetically possible in the minds of Americans and thus did not have to be proven true. Similarly, Vladimir Putin attacking the virtuous Ukraine in a completely unprovoked fashion is easy to claim, but only when ignoring recent historical events. Even if the truth comes out, as has largely been the case for the Iraq War, consequences rarely come for the fabricators. As with all the previous requirements, organizations such as the United Nations in theory can ensure that state actors adhere to the just cause requirement. The unfortunate reality is that the UN is made of state actors who represent the strategic interests of their sender nations. The UN also has few enforcement mechanisms, and the permanent members of the Security Council can veto meaningful resolutions.
The second part of the just war theory lists requirements on how states must act during the war and are all related. The distinction between combatants and civilians, the proportionality between civilian and military targets, the necessity of attacking militarily strategic targets, the fair treatment of prisoners of war, and the necessity to resist using methods that are considered evil are all principles that are easy to forget during the fog of war. Both sides are rarely equally accountable for infractions, with the winning side being almost always absolved from most of its infractions. This occurrence means that a side may violate the just war theory as long as it sufficiently increases the odds of winning.
Rather than critiquing all the moral ideals found within just war theory, this observation was meant to point out how unrealistic, and historically ignored, these principles are. State actors will always justify conflict for their own benefit. Instead of giving such allowances to state actors, it would be wise to restrict their use of force to something much more measurable. One can look to Murray Rothbard for this:
A just war exists when a people tries to ward off the threat of coercive domination by another people, or to overthrow an already-existing domination. A war is unjust, on the other hand, when a people try to impose domination on another people or try to retain an already-existing coercive rule over them.