The rubble of the Yassin Mosque. Is Israel’s action in Gaza in accordance with "just war" principles? Associated Press / Alamy Stock Photo

Is Israel waging a just war?

It is almost impossible to apply abstract moral principles to the horrific situation on the ground. But we have to try
December 6, 2023

Amid the maelstrom of outrage and despair unleashed by the war in the Middle East, there has been tremendous global pressure to call out the greater evil and take a side. Arguments about whether the horrifying toll on Palestinian civilians is proportionate to Israel’s legitimate goal of self-defence spark outrage—many find the very question inhumane. How can the mass killing of innocents possibly be justified? 

This question points to a central tenet of pacifism: that there can be no justification for the killing of non-combatants. Because war unavoidably involves such killing, many pacifists argue that war is morally unacceptable in all cases, even when waged with restraint in self-defence, or to avert a greater evil. From this perspective, there can be no moral debate about civilian death in Gaza. The killing and destruction on both sides must end. 

The problem with this pacifist stance, though, is that no matter how right it may sound in the abstract, when something truly existential is at stake—for example, a people’s right to safety and self-determination in their homeland—we sometimes think it is legitimate, even morally necessary, to fight for the cause.

Enter “just war” theory. Contrary to pacifism, this theory accepts the legitimacy of war in some cases and insists that war can be waged in more or less morally acceptable ways and for more or less morally acceptable reasons. 

Once we concede this much, then difficult debates about the permissibility of the aims and methods involved in specific wars become not just tolerable, but necessary. This will include gut-wrenching judgements about exactly how much “collateral damage” may be acceptable or proportionate in a given context. How does just war theory go about determining these things?

Drawing heavily on Thomas Aquinas’s master work, the Summa ­Theologiae, as well as Greco-Roman sources, proponents of just war theory offer several familiar criteria, many of which are codified in the Geneva conventions or elsewhere in international humanitarian law. To wit: war must be waged by a legitimate authority, as a tool of last resort and in the service of a just cause. It must be motivated by a “right intention”, such as establishing a just peace, and it must have a high probability of success. War must not cause harm disproportionate to the amount of good it is expected to bring about and civilians must never be treated as targets, nor disproportionately harmed by the fighting. These principles are taken to bind all parties categorically, regardless of whether the other side acknowledges or respects them.

Israel was subject to unconscionable atrocities on 7th October, and believes the safety of its people, as well as its national survival, to be at stake. But while self-defence is certainly a just cause, its war aimed at Hamas’s destruction has drawn moral outrage by appearing to run afoul of other just war principles, particularly the proportionality of harm to civilians.

Just war theory seeks to extend morality into the most brutal, abysmal corners of human life

Arguments about ceasefires often appeal to these principles, but the issue is inevitably contentious and complex. This is because applying just war principles is hard, especially when there is radical asymmetry between combatants, and jointly fulfilling all or most of these principles might not be possible. For instance, whether Israel can provide its citizens with the defence to which they are morally entitled without causing disproportionate death and suffering to civilians in Gaza is a question with no obvious answer. That Israel’s historical actions may have helped create the tragic situation in which it finds itself does not make the moral dilemma any less genuine.

Despite the difficulties involved in applying just war principles and in getting warring parties to live up to them, this intellectual tradition takes on the vital task of extending morality into the most brutal, abysmal corners of human life, rather than ceding that territory to our animality. When the other side are perceived as savages who show no restraint, it is easy to believe they are owed no restraint in return. The bloody free-for-all that follows from this logic is the ultimate abasement of our humanity and makes no one safer in the long run. Just war theory stands against such a prospect by insisting that nothing licenses the waging of war without restraint. 

The horror of war and the slaughter of innocents can lead us to throw up our hands and cry out for a maximalist, pacifist solution. But embracing just war theory does not have to mean rejecting the pacifist’s dream of peace. Instead, it can empower us to advocate for the lesser evil in cases where, tragically, peace remains elusive. 

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