Just War Theory: A primer

A member of a Kurdish special forces regiment watches from a hilltop as a U.S.-led coalition airstrike targets an Islamic State position while a large convoy of Kurdish peshmerga forces drives to Sinjar, Iraq, during a major offensive to expel Islamic State militants. (Alice Martins/For The Washington Post)

In a commencement address to West Point last year, President Obama outlined his foreign policy vision: “The United States will use military force, unilaterally if necessary, […] when our people are threatened; when our livelihoods are at stake; when the security of our allies is in danger […] In these circumstances, we still need to ask tough questions about whether our actions are proportional and effective and just.”

The president was invoking the tenets of just war theory, a longstanding ethical tradition studied by theologians, heads of state, philosophers and military leaders alike, dealing with how and why wars are fought and whether they are morally valid.

It’s doubtful that the president anticipated the Islamic State’s rapid rise, the Paris attacks and Russia’s growing involvement in Syria. Today, as conflicts multiply and the potential for American involvement increases, it’s worth now more than ever to discern how, if at all possible, to conduct ourselves morally in conflict.

Just war theory is seen as an outgrowth of classical Greco-Roman and Christian thought, though reflections are seen in other traditions as well. The Christian theologian Augustine of Hippo is credited with the assertion that war, though terrible, could be necessary in the face of certain dangers and lawful if conducted appropriately in the pursuit of peace. Later, Thomas Aquinas laid out the conditions under which a war could be considered just. Many of the rules developed by the just war tradition have been codified into contemporary international laws, such as the Geneva Conventions and the U.N. Charter.

Within just war theory, the moral issues surrounding war are traditionally divided into two main categories. Jus ad bellum concerns the justification for the resort to war in the first place, a question typically addressed to heads of state. Jus in bello is justice in war, referring to correct conduct in battle once the decision to go to war has been made, usually the concern of combatants, generals and soldiers. A third category has more recently entered discussion: Jus post bellum or justice after war, concerned with making a just peace and the responsibility and accountability of parties after war has ended.

To satisfy the principles of jus ad bellum, a war must be in the service of a just cause, must have been commissioned by a legitimate authority and must be waged for a right intention. War has to have been the last resort for keeping peace, should have a high probability of success and cannot cause harm disproportionate to the amount of good it is expected to achieve. The understanding of what each of those categories entails can be debated, but if even one of these conditions is not fulfilled — quite a high standard — any war embarked upon is unjust.

However, most recent conflicts have not been the sort to which just war theory normally applies — state-centric wars between sovereign nations deploying regular armies. As the nature of our conflicts continues to shift — and the potential for further hostility increases — it has become increasingly difficult to draw a clear line between what is justified and what is not.

World War II is seen as a quintessentially just war, and after 9/11, the attack on the Taliban regime in Afghanistan is also widely seen as justified. However, the ethics of continued U.S. engagement in the Middle East have become murkier over time, as our aims became more nebulous, our tactics more questionable and the “war on terror” seems less and less likely to end. The curtailment of civil liberties at home, mounting civilian casualties abroad and the resultant power vacuums in the Middle East have complicated the moral landscape.

Today, French President Francois Hollande has declared that the Islamic State’s attacks on Paris were an “act of war” against France, and presidential candidates have called for the United States to play a more active role in the Middle East. Is France justified in bombing Syria? Is involving the United States in the fight against the Islamic State necessary, and could it be considered just? Is it possible to fight terrorism within the confines of a just war framework? Our wars and conflicts have changed — do the old standards and theories still apply?

Over the next few days, we’ll hear from:

Jeff McMahan, professor and moral philosopher at Oxford University,

Marc Pierini, former EU ambassador to Turkey, Libya and Syria,

Thomas Donnelly, resident fellow and co-director of the Marilyn Ware Center for Studies at the American Enterprise Institute,

Neta C. Crawford, co-director of the Costs of War Project at Brown University and professor of political science at Boston University,

Aaron MacLean, combat marine veteran and managing editor of the Washington Free Beacon,

Thomas Madden, historian at St. Louis University,

Nolen Gertz, assistant professor of applied philosophy at the University of Twente,

Andrew Tabler, journalist, author, and fellow at the Washington Institute.