Just War Theory outlines conditions under which the use of force by a state actor can be morally justified. Philosophical traditions have addressed the moral justification for war since ancient times, all over the world. The problem can be easily framed. Morality in general forbids harming another being due to a simple reciprocity of duty and obligation. Moral duties derive from universal principles, commands that are applicable in all situations no matter the participants. A moral duty against causing harm can be readily derived from this configuration of shared desire and the universality of moral duty.
All moral agents, indeed all sentient beings, desire to avoid pain and therefore violence and harm that can cause pain. Given this shared desire, an agent avoids being the cause of harm to others because they want others to avoid being the cause of harm to them. An agent who desires to harm others but not to be harmed themselves must embrace an inconsistency that explains why they are permitted to harm while others are not. The two desires are considered inconsistent because, with respect to a desire to avoid harm, the agent who wants to harm is the same as other agents. One must articulate a reason that they would be permitted to harm while others do not share the same privilege.
A successful Just War Theory must provide an account of circumstances that suspend a general moral duty to some extent. A Just War Theorist must argue against the grain of morality and identify a configuration of conditions or events that render immoral acts morally permissible. In fairness to Just War Theorists, the circumstances identified are generally fairly narrow. When facing an invading force, when other paths to resolution are exhausted, and when violence now will not preclude a peaceful resolution later, Just War Theorists will generally agree that the use of force can be morally justifiable.
When one compares those conditions to the causes of war over the last two hundred years, one labors to find a “just war.” World War II often enjoys the status of a morally justifiable war, but the designation becomes more fragile in light of the atrocities committed by all parties, the imperialist motivations that motivated war in Europe, and the Iron Curtain that divided erstwhile allies in the aftermath. For the most part wars prosecuted by so-called “great powers” find their justification in greed, in power, and in revenge.
The wars familiar to a 21st century person are the wars of empire, of colonization, of hegemony. An examination of the Roosevelt Corollary and the Bush Doctrine readily shows motivation to assert sovereignty beyond national boundaries. While the overt reasoning includes preserving security or preventing worse consequences, the actions that follow from those foreign policy frameworks reinforce the dominance of one group by the subjugation of others. Just War Theory serves only to identify heroes and villains in propaganda in service of imperialist ends.
In the clash of empires the proper protagonists are the people trapped between clashing villains. Imperial governments act out of disregard for people other than their own, and even then often only their own wealthy and privileged citizens. The interests of the owner class become the interest of the imperial state. If a foreign country is not a peer considered either ally or enemy, it is merely a collection of resources and territory, both prize and battlefield of proxy wars. For all the good intentions of scholars, Just War Theory fails to safeguard against improper violence. Instead, it advances a contradiction to support imperialist interests and transmute violence into a noble duty.