With each conflagration in the ongoing conflict between Israel and the Hamas-dominated Gaza Strip, the question of the proportionality of Israel’s response to terrorist activities reemerges. Since proportionality is considered a necessary element in the justification of military action according to international humanitarian law, this question is important. Yet despite the countless commentators, experts, anchors, and analysts offering their impressions, the matter remains deeply perplexing, given that no one ever provides a reasonably clear criterion as to what proportionality entails or how it is to be identified. How then should we think about this in a way that would help to make sense of events?

Proportionality is essentially a mathematical concept. It is therefore intuitive to analyze the justness of military action mathematically too. This temptation, however, fails to produce valuable moral insight. If the enemy killed a hundred of yours, then presumably a proportionate retaliation would be to kill roughly a hundred of his; if instead you kill 500, you respond disproportionally. Judging by what one hears in news commentaries, this seems to be the widespread implicit assumption. But while this understanding of the proportionality of military action might sound initially plausible, it is in fact morally bankrupt. If you can fully achieve your military goals by killing only 10 enemy soldiers, then killing another 90 for the sake of proportionality would be pointless and morally wrong. Such an understanding of proportionality would be more like a reversion to a backward tribal mentality of score-settling than the product of an enlightened moral compass.

The intuitive mathematical idea of proportionality yields even worse results in the context of its core intention of protecting civilians. Mathematical proportionality is ideal when it is a precise one-for-one exchange, but it can become an abomination when the enemy targets and kills civilians. Since the Palestinian terrorist organizations in Gaza have indiscriminately fired tens of thousands of rockets and mortars at Israeli towns, precise proportionality would dictate that Israel retaliates by firing the same number indiscriminately at Palestinian neighborhoods. And since Hamas tortured and raped and burned and murdered some 1,200 Israelis on October 7th, a precisely proportional response would require Israel to respond in kind. Surprisingly, no one ever asks those commentators who simply count the dead and then lament the lack of proportionality if they would be satisfied with such exemplary proportional retaliation.

Since our common intuition fails to deliver helpful moral guidance, it may be wise to consult the experts. In a fascinating study, published in 2020 in the European Journal of International Law, Daniel Statman, professor of philosophy at Haifa University, and colleagues did just that. Their study sought to test the proportionality judgments of experts working on the ethics and/or the laws of armed conflict. Sampling almost 300 experts in 11 countries, the study examined whether they could provide reliable guidance for solving real-world dilemmas concerning the legitimacy of collateral harm that results from military attacks. The results (regarding, for example, the collateral harm produced by bombing an enemy’s headquarters) demonstrated the absence of reasonable convergence among experts. If experts cannot agree among themselves, this presumably means that there are no experts capable of issuing adequate moral prescriptions on proportionality. 

If laypeople’s judgments aren’t helpful and experts cannot offer assistance, how are we to proceed? Although the idea of proportionality encapsulates a valuable intuition, it seems unable to offer practical guidance, so it should be subordinated to a more fundamental moral principle. That principle demands that, in pursuing a just military goal, substantial efforts must be made to minimize civilian casualties. This principle has the advantage of being comprehensible, patently just, and an adequate ethical interpretation of the words of the Geneva Convention requiring that the civilian toll not be “excessive in relation to the concrete and direct military advantage anticipated.” This principle can be understood as a reinterpretation of proportionality itself—one that offers better objective practical guidance as well as a sensible basis for rational debate. 

How is this principle to be applied to the Israel-Hamas war? Once we recognize that the military goal of disarming Hamas is morally legitimate, then moral clarity will be gained by asking whether the Israeli Defense Forces (IDF) make “substantial efforts” to minimize civilian casualties. For this not to be an abstract question, answerable according to a respondent’s political leanings, but a question that experts can answer more or less objectively, it should be detailed into a question about best practices and a question about consequences. The first question asks how the techniques used by the IDF compare with techniques used by other militaries in comparable conflicts. The second question asks how the resulting civilian-to-combatant ratio of casualties compare.

These questions are empirical and comparative, not speculative. Since I am a moral philosopher, not a military historian or security analyst, I do not presume to provide an expert opinion. However, consulting the relevant experts, the general picture seems to be quite clear. Regarding the question of employing adequate measures to minimize civilian casualties, a recent essay published by the Lieber Institute of Law and Land Warfare at West Point, titled “Israel, Hamas, and the Duty to Warn,” summarizes thorough on-the-ground research: “What can be said with confidence is that the IDF regularly uses a wide variety of warnings [to civilians in the war zone in Gaza], almost certainly more than any other military.” It adds that “some worry that the Israeli Defense Forces (IDF) created an unrealistically high bar on when and how to provide warnings...”

Regarding the question of consequences, the responsible procedure would be to check the ratio of civilian-to-combatant casualties in Israel-Hamas military conflicts and compare it to parallel conflicts. In a meticulous study conducted by the Meir Amit Intelligence and Terrorism Information Center (ITIC) in 2021, researchers were able to trace the personal identity of the 236 Gazans killed during Operation Guardian of the Walls, the last large-scale round of violence before the current one. (The Palestinian Center for Human Rights estimated the death toll at 247, so even if we assume for argument’s sake that the Palestinian figure is the more accurate estimate, the ITIC sampled 95 percent of the dead.) At least 114 out of 236 casualties were confirmed as military operatives of terrorist groups. This amounts to 48.3 percent of combatants, at minimum.

This ratio then ought to be compared to ratios in other conflicts historically around the globe. The discussion of the global data is somewhat complicated and I cannot broach it here, but I would say that some expert evidence suggests a mean historical ratio of roughly 1:1 (a conservative estimation). If this is correct, then given that the density of the population in Gaza is extremely high, and given the intentional efforts by Hamas and Palestinian Islamic Jihad to embed themselves in the civilian population (including their efforts to prevent civilians from fleeing combat zones), the result of 1:1 ratio by the IDF is astonishingly low in comparative analysis. The tentative conclusion seems to be that Israel’s response is an exemplar of proportionality.

This kind of assessment of proportionality can sometimes be made by any thinking person who keeps track of the events. For instance, Israel currently estimates that its forces have dropped more than 10,000 munitions on Gaza. The Gaza authorities, meanwhile, report that more than 10,000 Gazans (fighters and civilians) have died during the current hostilities. In other words, fewer than one civilian in Gaza is killed on average by each bomb dropped from a jet fighter (sometimes weighing hundreds of kilos) or shot from a cannon. How is this possible in one of the most densely populated urban areas in the world? This is an astonishing feat of minimizing civilian casualties, indicating, again, that Israel’s operations should be judged as a model of proportionality. 

Judging a military goal to be just does not specify the reasonable scope of the operation intended to achieve that goal. Israel’s just military goal is the toppling of the Hamas terrorist regime, and this obviously requires a particularly wide scope of operations, since nothing less will force Hamas to end its death grip on the Gaza Strip or its jihad against the Jewish state established in what they see as the Abode of Islam. Since Hamas is committed to perpetual war against Israel, and since it had great success in attacking Israel on October 7th, severely damaging the deterrence that keeps Israel safe, it is vital to Israel’s security that the Hamas regime and military be demolished. Failure to achieve this goal would be a strategic catastrophe for Israel, and so toppling Hamas is part of Israel’s exercising its basic right to self-defense. It is a mark of cynical indecency to insist that Israel is acting “disproportionately” when its forces are doing the minimum required to secure their right to self-defense.

As far as the minimization of casualties is concerned, it is often unreasonable to look only at current hostilities; we should zoom out and look at the wider picture. This broader perspective would enhance our appreciation of the proportionality of the Israeli military actions. During an October 24th interview, Hamas leader Ghazi Hamad declared that the Al Aqsa Flood operation of October 7th “is just the first time, and there will be a second, a third, a fourth,” so not destroying Hamas now due to sensitivity to collateral civilian casualties will guarantee many more rounds of violence and a much greater toll of civilian casualties. The number of casualties incurred during the current hostilities must be evaluated against that combined future number. Since every round of violence that ends without defeating Hamas allows it to build up its military strength further in preparation for its next attack, each round of violence tends to be more lethal than the last. This forward-looking calculation also works retrospectively: had Israel toppled Hamas years ago, the combined number of casualties (on both sides of the border) would have been so much lower than the current count. Furthermore, if terrorists are rewarded for hiding behind their own civilian populations with pressure on their enemies to cease retaliation, the practice of using civilians as human shields will be incentivized. This, too, will guarantee many more civilian casualties worldwide. So, if we truly care about minimizing civilian casualties, we must not reward the Hamas ideology that glorifies a “nation of martyrs.”

Israel’s military activities in Gaza should be considered proportionate inasmuch as they minimize civilian casualties in the course of fighting for a just cause. But this is not how the morality of Israeli military conduct is assessed in mainstream commentary and discussion. Nor is any alternative understanding of proportionality ever properly evidenced or defended in a rational, non-impressionistic, non-biased manner. Since Israel’s critics consistently fail to provide their own account of how Israel could achieve its just goals with fewer casualties in Gaza, it seems safe to conclude that there is no such better alternative. Criticizing others for exercising their right for self-defense without being able to offer any responsible and viable alternative is morally inert at best. Rather more likely, it is positively cruel.