Journal of Controversial Ideas

I have published three articles in academic journals on the Gaza war, the first of which is criticized in the article by Simon Lucas in this issue of the Journal of Controversial Ideas.1 Responding to these criticisms provides an opportunity for me to fill some gaps in my earlier arguments.

Lucas begins his critical discussion of my arguments with an examination of my views about the requirement of proportionality. “There is,” he writes, “an ongoing debate … about whether proportionality is a useful criterion for assessing the justice of war.” I am, however, unaware of any such debate. The only two instances of skepticism about whether there is a requirement of proportionality in war of which I am aware appear in two defenses of Israel’s war in Gaza. One, by Michael Walzer, asserts that assessments of proportionality are either mere expressions of emotion or propaganda (Walzer, 2023). The other, by Daniel Statman, contends that it is unrealistic and unfair to expect a state to refrain from causing “disproportionate harm to its enemy,” including all those members of the enemy population, such as children, who bear no individual moral responsibility for anything their state has done (Statman, 2025, p. 192). I have replied to Walzer at length in my original article and more briefly to Statman in another article and will not rehearse my arguments here (McMahan, 2024a, pp. 390–392; 2025a, pp. 220–222).

In at least five places, mainly with reference to my arguments about the requirement of necessity, but also in response to my claims about proportionality, Lucas objects to my appealing to “hypothetical counterfactuals” and engaging in “counterfactual speculation” – that is, to my making claims about what would have happened if some agent had acted differently. This kind of speculation is, however, no more uncertain than prospective assessments of what would happen if one were to act in a certain way. And both are unavoidable in the moral assessment of action, whether prospective or retrospective, and both are essential to the assessment of necessity and proportionality in war.

To determine whether a war or act of war would be necessary in the relevant sense, one must speculate not only about what would happen if it were to occur, but also about what would happen if various alternative courses of action were to be followed instead. And to determine whether some war or act of war was necessary, one must speculate about what would have happened had various alternative courses of action been followed instead. To determine whether a war or act of war would be proportionate, one must speculate about what would happen if it were to occur and about what would happen were it not to occur. And to determine whether a war or act of war was proportionate, one must speculate about what would have happened if it had not been done.

To reject my arguments about proportionality and necessity, moreover, Lucas and others must also engage in counterfactual speculation – which is of course what Lucas does, for example when he comments briefly on certain measures I suggested that Israel could have taken instead of pursuing a large-scale war. He writes that “implementing such measures in the aftermath of the October 7 attacks – whether alone or in conjunction with other proposals McMahan advances – appears at least somewhat unlikely to succeed; such actions could just as easily be interpreted as signs of weakness, potentially inviting further escalation by Israel’s adversaries.”

Lucas engages in further counterfactual speculation in criticizing my claims about the proportionality of Israel’s war that concentrate on only one type of bad effect: death, and one type of good effect: the prevention of death. He says, for example, that I “pay insufficient attention to broader and longer-term goods – such as regional stability and the prevention of future atrocities.”

I do not, however, have the “constricted conception of benefit” that he attributes to me. There are, of course, good effects other than saving the lives of innocent people that a war might produce that are relevant to proportionality, as well as bad effects other than causing the deaths of innocent people. I should have made it clearer that I concentrated on the causation and prevention of the deaths of innocent people because these effects are of such obvious importance and because the killing of innocent people by Israel has been such a salient feature of this war. The challenge for defenders of the war is to identify good effects it has had that morally outweigh the killing of 68,229 people (as of October 2025), the great majority of whom have been children, women, elderly people, and men in no way associated with Hamas (Polgreen, 2025). It is, for example, highly unlikely that other alleged good effects, such as strengthening regional stability and the prevention of atrocities, morally outweigh the innumerable atrocities committed by Israeli forces in Gaza, which have resulted in so many deaths and have been neither “hypothetical” nor “counterfactual.” It is, moreover, worth emphasizing that claims about the good effects that I have not considered generally depend on “counterfactual speculation” – for example, that there would be less regional stability and more atrocities, now and in the future, if the war had not occurred.

One possible good effect of war that Lucas says is “especially salient in the context of the present conflict” is “the preservation [by Israel] of state sovereignty.” It is, however, deeply implausible to suppose that Hamas or any other Palestinian organization could now or at any time in the foreseeable future threaten Israeli sovereignty, even by “occup[ying] a portion of Israeli territory.” It is, moreover, instructive in this case and, as we will see, in many others, to consider the implications of Lucas’s claims for Palestinians as well as for Israelis. Palestinians and Israelis are both national groups with interests in and rights to national self-determination though sovereign statehood. And there is no reason to suppose that preserving state sovereignty for Israeli Jews is more important morally than establishing state sovereignty for Palestinians, who have been ruthlessly denied it by Israel for decades. Readers who doubt this claim should consult their beliefs about the moral importance prior to 1948 of creating a sovereign state for Jews around the world who had been forced to live, and were persecuted, in enclaves and ghettos, effectively under occupation, in states ruled by non-Jews. So anyone who believes that seeking to reduce even further the already negligible threat to Israeli sovereignty posed by Hamas can weigh against and justify the killing of tens of thousands of innocent Palestinian civilians must accept that finally compelling Israel to allow Palestinians to have a sovereign state in territories to which Israel has no moral or legal claim should, on Lucas’s view, justify the killing of a vastly larger number of innocent Israeli civilians. This seems to me a reductio ad absurdum of Lucas’s view.

Another important good effect that Lucas claims that Israel’s war has had is strengthened deterrence, not only of Hamas but also of other enemies of Israel, such as Hezbollah and Iran. This, he says, is a consideration I dismiss, claiming also that I “fail to consider a substantial body of scholarship on deterrence,” citing only one document and without indicating any of the important points that I have missed. One consideration that he fails to consider is that the strength of deterrence inevitably changes over time, so that the achievement of a high level of deterrence at a certain time is likely to be only temporary, possibly even evanescent. It may be, for example, that the current Israeli government has sufficiently demonstrated its willingness to slaughter civilians that enemies will be deterred from attacking Israel while this government remains in power. But this government will sooner or later be succeeded by a different one whose members may be detectably more willing to respect at least some moral constraints on state action, as some Israeli governments have been in the past. In that case, enemies will reassess their options, no matter how strongly they may be deterred at the moment.

Incidentally, nothing Lucas says refutes, or even addresses, my claim, which he cites, that if the large-scale killing of civilians, even as a side effect of attacks on military targets, is welcomed as a means of strengthening the deterrence of others, it is terrorism. And it is obvious enough by now that Israel has on many occasions killed civilians intentionally (McMahan, 2025b, section on “Necessity and Intentionality”).

Given Lucas’s repeated expressions of skepticism about “counterfactual speculation,” it is noteworthy that the various claims he makes about the good effects of Israel’s war – enhanced regional stability, the prevention of atrocities, strengthened deterrence, preservation of sovereignty, etc. – are all based on counterfactual speculation. And so, indeed, are claims about how many Israeli civilians’ lives the war has saved. But many of the bad effects of the war other than the many tens of thousands of deaths of innocent people are not speculative but have actually occurred. These include the infliction of severe wounds on approximately 170,000 people, the great majority of whom are innocent civilians; permanent disabilities caused by these woundings; widespread bereavement; lasting health problems caused by widespread malnutrition, particularly among children; the destruction of innocent people’s homes, possessions, and places of work; and so on. The vast majority of Gaza’s pre-war population of over two million people have suffered at least one of these very serious harms. And these same Gazans – again the vast majority of whom are innocent civilians – are virtually certain to continue to suffer other grave harms in the future. Many or most of them will be forced, either by Israel or by the conditions of life in what Israel has reduced to an uninhabitable wasteland, to become impoverished refugees in foreign lands. The war has also ensured that there is virtually no possibility in the foreseeable future that these people will be able to achieve freedom and self-determination as a nation in the lands where they and their ancestors have lived. All of these bad effects of the war were also excluded from my assessment of proportionality solely in terms of the number of innocent people who have been killed and the number whose lives it is reasonable to believe have been saved by the war. But they reinforce the conclusion in my earlier article that Israel’s war has been vastly disproportionate. It is highly implausible to suppose that these many terribly bad effects on more than two million Palestinians are somehow morally outweighed by such speculative and vaguely specified good effects as increased regional stability and the strengthening of deterrence. What other good effects have there been? One might cite the release of 168 of the 251 hostages taken on October 7. But I and many of the relatives of the hostages believe that more of the hostages could have been released, and much sooner, had Israel not fought this war but had instead implemented effective defensive measures and negotiated for the hostages’ release shortly after October 7. But suppose we credit the war as the cause of the good effect of the release of 168 innocent hostages. Even so, in the assessment of proportionality, this good effect can morally offset only a tiny fraction of the harm that the war has caused in killing at least 50,000 innocent people and severely wounding at least 140,000 others (out of the total 170,000).

In criticizing my arguments about proportionality, Lucas contends not only that I consider only a narrow range of good and bad effects but also that I work with an impoverished account of the moral significance of special relations among the members of a political community. On his view, these relations can justify people in giving very substantial priority to the interests of other members of their political community over those of people who are not members. This view is closely connected with his understanding of war as “a confrontation between collective entities, not isolated individuals,” that “gives rise to collective moral identification, where pride, shame, and moral responsibility are borne by association, not personal involvement.” Lucas cites with approval “similar views in Jewish military ethics [that] emphasize obligations rooted in a shared collective fate, arguing that one must prioritize one’s own citizens and soldiers over those bound to a different destiny.” These views of political communities and war do not, he writes, distinguish individuals who are liable to attack from those who are not, but instead acknowledge “the political reality that citizens, like children with respect to their parents, inevitably share in the consequences of their leaders’ choices.” With the application of these views to Israel clearly in mind, Lucas writes further that they place “the emphasis on protecting one’s own people – and especially on bringing abducted citizens and soldiers home by all means available to the state.” This last phrase, which I have italicized, is, in effect, a rejection of all or virtually all moral constraints on the practice of war.

We should again notice the implications of Lucas’s claim for what Palestinians, who because of Israel certainly have a “shared collective fate,” might permissibly do. Over many years, but particularly during the last two years, Israel has abducted and indefinitely imprisoned thousands of innocent Palestinian civilians, including doctors and other professionals – far more than Hamas abducted as hostages on October 7; though because Israel’s abductions were conducted by soldiers or police, they are called “arrests,” and the victims are called “detainees” rather than “hostages.” As has recently emerged quite vividly in photographs, examination of returned corpses, and testimonies of Palestinians released alive in exchange for the 20 remaining Israeli hostages, Palestinians imprisoned at sites such as Sde Teiman have been tortured, sexually abused, kept in cages, humiliated in grotesque ways, and executed (Tondo & Tantesh, 2025). According to Lucas’s view, applied impartially, it has all along been permissible for Palestinians, including members of Hamas, to use “all means available,” no matter how violent or who among Israelis the victims might be, to “bring home” any of these thousands of detainees.

The view that Lucas defends, according to which moral responsibility is derived through “association, not personal involvement,” offers little or no basis for the moral significance of traditional distinctions such as those between combatants and noncombatants, between people who are morally liable to attack and those who are morally immune, and even between adults and children. Children are, apparently, morally responsible by association for the acts of their political leaders and are thus morally vulnerable to having to “share in the consequences of their leaders’ choices” – for example, in the case of Palestinian children, by being killed by Israeli bombs because of what members of Hamas chose on October 7.

Lucas writes at length about “reciprocity” as the critical moral notion in understanding the morality of war, though he never offers a clear elucidation of this protean notion as it appears repeatedly in his article. He claims that “McMahan’s account of reciprocity appears to elide important distinctions,” though I have no account of reciprocity, either in war or in other matters, and do not believe that ordinary notions of reciprocity have any application to the practice of war. Lucas does offer four closely related views that he bundles together under the label “reciprocity.” We can consider them in the order in which he presents them.

One, which he attributes to Uwe Steinhoff and apparently accepts himself, is that “certain morally relevant conditions governing the justified use of force depend on reciprocal recognition: under specific circumstances, these conditions may be relaxed or suspended in light of shared expectations and established practices.” As written, this makes little sense; for it is difficult to understand how moral constraints could be relaxed or suspended because of “shared expectations and established practices.” My best guess is that Lucas means that the violation of moral constraints on the practice of war by one side weakens or nullifies those constraints in their application to the other side. If, for example, they kill our civilians, that makes it permissible for us to kill theirs (though why this additional source of permissibility is needed is a mystery given that we, on Lucas’s view, are already entitled to give substantial priority to our people over theirs, who are collectively morally vulnerable because of the acts of their leaders, and especially given that we are permitted to use “all means available” to protect our own people).

A second view “appeals to reciprocal agreement: … parties who strategically exploit … a principle [prioritizing the protection of one’s own civilians] may forfeit their standing to object – or, at the very least, weaken their claim – when the principle of extraordinary regard for civilian life is invoked in ways that place them at a disadvantage.”

I will refrain from commenting on the suggestion that Israel operates on the basis of a “principle of extraordinary regard for civilian life.” Lucas does, however, cite evidence that it operates on the basis of a principle of “extraordinary regard” for the lives of Jewish Israeli civilians – namely, the asymmetry in the numbers of prisoners released when prisoner exchanges are negotiated – for example, in the case of Galid Shalit, which Lucas cites.2 This extraordinary regard was not always evident, however, to the families of the dead hostages who pleaded with the government throughout the war to negotiate for the hostages’ release. The members of these families must surely suspect that some of the hostages who died while in captivity were killed inadvertently by the Israel Defense Forces (IDF) during the prosecution of the war; for, while hostage-takers sometimes publicly kill a hostage as a means of increasing pressure on those they are trying to manipulate, in general it makes no sense for captors to kill hostages, as only living hostages are useful for purposes of coercion, which, by definition, is what hostages are for.

I should acknowledge, if only parenthetically, that Lucas does offer one piece of evidence for the claim that Israel has an extraordinary regard for civilian life in general – namely, that late in the war, in June 2025, Israel sealed a tunnel under the European Hospital, “rather than destroying [it] with explosives, as is common practice elsewhere in Gaza.” This was, however, a matter of Israeli self-interest. At that point, Israel had already destroyed most of the hospitals in Gaza, for which it was much criticized throughout the world. The European Hospital had been founded by the United Nations Relief and Works Agency for Palestine Refugees with funding from the European Union, and it would have provoked further criticism if Israel had caused it to collapse by detonating explosives beneath it – particularly since it had already, in the preceding month, been the target of Israeli airstrikes that killed 26 people and wounded a great many more. What is more revealing of the Israelis’ attitude to civilian life, or at least Palestinian civilian life, is Lucas’s admission that in the many other instances in which Israel destroyed underground tunnels, it blew them up, killing and injuring the people in the buildings above them when it could have sealed them with concrete instead.

This second view, which appeals to some sort of largely imaginary “reciprocal agreement,” has implications that are morally implausible. First, suppose a man who is very upset vents his anger by hitting a randomly chosen stranger in the face. The next day, a different stranger hits the first man in the face for no reason. The first man has been wronged, and has a justified complaint about being hit arbitrarily, even though he did the same thing to another just the day before.

Second, and more importantly, this view, as applied by Lucas to the Gaza war, takes a collectivist form. “If,” he writes, “one regards belligerents as collective agents defending themselves as if they were individuals, even high casualty numbers could, at least in principle, be morally justified … even at the cost of innocent lives.” On October 7, members of Hamas murdered innocent Israeli children. According to this second view, they thereby exploited, and violated, some sort of reciprocal agreement with Israel, thus weakening or altogether nullifying the moral constraint that would otherwise have prohibited Israel from killing Palestinian children. Hamas, then, “can hardly object when Israel, in turn, invokes” the principle that “places high value on the lives of its citizens … in ways that may disadvantage others.” In short, Hamas’s having killed Israeli children justifies Israel’s killing of Palestinian children.

What is most deeply mistaken here is the collectivism. The idea that a child’s right not to be killed could be weakened or eliminated just because that child happens involuntarily to be a member of a national group, some of whose other members have engaged in terrorism, is – to me at least – morally odious. Lucas says that Hamas can hardly object if Israel does what Hamas has done. But what Hamas has a right to object to is irrelevant. It is the individually innocent victims of Israeli violence who have a fully justified objection.

Again, it may help to show how mistaken this view is to apply it consistently to both Palestinians and Israelis. For many years, and particularly over the past two years, Israeli settlers, often protected by the military and the police, have been entering the West Bank and then beating, robbing, and sometimes killing innocent, unoffending Palestinians living there, virtually always without being punished through the Israeli courts. Lucas’s collectivist view seems to imply that this makes it permissible now for Palestinians, even those who have never been harmed by settlers, to enter Israel and beat, rob, and occasionally kill Israelis who have never harmed a Palestinian. I doubt that Lucas accepts this implication.

Further on, Lucas states a third, “thicker conception of reciprocity – one that ties the respect of individual rights, including the right to life, to reciprocal recognition, which can be forfeited through failure to uphold it.” As far as I can tell, this “thicker conception” is no different in substance from the collectivist view I have just criticized, except in making more explicit the appalling claim that wholly morally innocent civilians, who lack the power of “reciprocation,” can lose their right not to be killed solely because of what their unelected, authoritarian “leaders” have done.

Finally, Lucas cites a fourth articulation of “a principle of reciprocity” in a quotation from Steinhoff. As Steinhoff understands it, this principle takes the form of a negative version of the Golden Rule that says, in effect, that one may do unto another what that person has wrongly done unto others. This is certainly not the way the principle was understood by Jesus, who urged victims of wrongdoing to turn the other cheek. Nor is it plausible in the collectivist form in which, according to Steinhoff, it “shifts proportionality restrictions in a way that give [sic] more moral latitude to the Israel Defense Forces.” For that again implies is that it is permissible to inflict harm on innocent people that would be disproportionate if other members of those people’s collective had not done wrong. While this may not be an espousal of guilt by association, it is an acceptance of responsibility and loss of rights or moral status by association only – which I believe to be paradigmatically unjust.

Steinhoff might reply that he explicitly refers to “civilians applauding the slaughter of women and children,” a comment that is echoed by Lucas’s claim that “civilians who endorse or tolerate indiscriminate violence, or who express indifference toward the suffering of noncombatants, may bear a different kind of moral burden than those who oppose such actions.” These claims have some plausibility, but that is because they are not collectivist but are claims about the ways in which the acts of individuals can affect their own individual moral liabilities. But the civilians to whom Steinhoff refers were only a handful of people in a population of more than two million, almost half of whom are children. So even if these people’s loathsome behavior might have compromised their individual moral immunity, it could not possibly have affected the proportionality of Israel’s war in Gaza, or even of any of Israel’s individual acts of war.

I accept that people who ought to oppose their leaders’ unjust and harmful action but do not do so may thereby become liable to small harms, such as effects of economic sanction, if their suffering those harms could limit or prevent the wrongful action of their leaders (McMahan, 2024b, section 4, “Liability to Harm in War”). Again, however, these claims must be applied equally to both Palestinians and Israelis. In May of 2025, between 53 and 82 percent of Israelis expressed support for Netanyahu’s plan to transfer the entire population of Gaza to some other land (Shulman, 2025). And in August of 2025, when there was widespread famine in Gaza as a result of the Israeli blockade, 79 percent of Israelis said that they were “not so troubled” or “not troubled at all” about it (Issacharoff, 2025). Consistency requires, I believe, that Lucas should accept that these people could permissibly have been compelled to “bear a different kind of moral burden” if that could have disrupted the plans for the transfer of the population or diminished the suffering and saved the lives of starving Palestinians.

Before concluding, I want to rectify a couple of misrepresentations of my views in Lucas’s article. First, concerning my view of civilian liability, Lucas writes that “McMahan’s narrow emphasis on electoral behavior seems to be insufficient for assessing degrees of civilian complicity and the moral permissibility of collateral harm.” Here and in other passages, he suggests that I assume that Palestinian civilians might be liable to be harmed only if they voted for Hamas in 2006 or later gave it their support when its leadership was challenged. As the comments in the preceding paragraph indicate, this is not my view. I believe that civilians can make themselves liable to be harmed, and even to be killed, if they would otherwise contribute in significant ways to the achievement of unjust goals in an unjust war. On this view, if harming certain individual Gazans would prevent them from collaborating in effective ways with Hamas in harming innocent Israelis, they could be liable to suffer those harms. But immediately after briefly discussing the relevance of “voting behavior” to liability, I cited various reasons – including polls that show that before October 7th the great majority of Gazans did not support Hamas and felt helpless to control its action – for rejecting the idea that significant numbers of Gazan civilians were collaborating in these ways with Hamas. The great majority of civilians in Gaza bear little or no moral or causal responsibility for what Hamas does. Harming them is thus causally inefficacious in preventing terrorist acts by Hamas. They are therefore not liable to be harmed by Israel.

Second, Lucas writes that my “engagement with the principle of necessity is comparatively short, receiving only cursory attention in the concluding section of his article,” after which he comments at length on my one-paragraph discussion of the retrospective dimension of the requirement of necessity. In the preceding paragraphs of my section on necessity, however, I gave reasons for thinking that there were far more effective means than large-scale war of achieving Israel’s just aim of protecting its citizens from terrorist violence by Hamas. In doing so, I explicitly referred back to my earlier section on proportionality in which I listed nine measures that Israel could have implemented rather than fighting a large-scale war. The substance of my main case for the claim that Israel’s war has violated the requirement of necessity is in that material, which Lucas discusses in only a few sentences. Those sentences, perhaps predictably, reject my claims on the ground that they are “largely speculative judgments” that are “framed as counterfactuals.” But, as I noted in Section 1 above, the assessment of necessity, whether in advance or after the fact, requires counterfactual reasoning as a matter of logical necessity.3

Finally, in seeking to refute my brief and admittedly underdeveloped comments about the relevance of past action to the present application of the principle of necessity, Lucas appeals mainly to examples involving merely imprudent past action – for example, a case in which one has facilitated the theft of one’s possessions by leaving one’s door unlocked. But it has not been through mere imprudence that Israel has repeatedly refused to do what would have made terrorist attacks by Palestinians far less likely. As I emphasized in the article Lucas discusses, the many courses of action that Israel could have pursued that would have diminished the threat of terrorist attacks are in general ones that it was morally required to pursue, including courses of action that would have involved not acting in ways that were wrong. Thus, a more apt analogy is a case in which one steals a number of another person’s possessions and takes them home. It seems that one’s defensive rights are indeed compromised if the person whose possessions one has stolen breaks violently into one’s house to recover them.