On Reciprocity, Revenge, and Replication: A Rejoinder to Walzer, McMahan, and Keohane

In their contributions to the symposium “Just War and Unjust Soldiers,” Michael Walzer, Jeff McMahan, and Robert O. Keohane add greatly to our understanding of how best to study and apply just war doctrine to real-world conflicts. We argue, however, that they underestimate both the degree to which the American public seeks revenge, rather than just reciprocity, and the extent of popular acceptance of violations of noncombatant immunity by soldiers perceived to be fighting for a just cause. We call on empirical political scientists, lawyers, psychologists, and historians to engage with moral philosophers and political theorists in debates about the influence of just war theory and the laws of armed conflict.

Legalism, Justice, and the War on Terrorism

Some standard norms of conduct in war are morally unsustainable. The “noncombatant immunity” principle that prohibits deliberate use of force against noncombatants represents one such norm. Standard noncombatant immunity is limited, its focus on intention, allowing, in effect, ordinary noncombatants to be harmed routinely through lawful attacks by combatants. These noncombatant casualties often are likely, foreseeable, and avoidable and thus not merely accidental. Apart from the moral problem of just war legalism, the practical problem is this: a military power cannot expect to win hearts and minds in foreign populations, as the war on terrorism requires, when its approach to fighting expresses relatively little concern for noncombatant lives. Greatly reducing noncombatant casualties is a pragmatic imperative that recommends fighting to a much higher standard—even when prevailing moral and legal norms allow collaterally harming noncombatants.

Revisiting Hiroshima in Iran: What Americans Really Think about Using Nuclear Weapons and Killing Noncombatants

Numerous polls demonstrate that U.S. public approval of President Harry Truman's decision to drop the atomic bombs on Hiroshima and Nagasaki has declined significantly since 1945. Many scholars and political figures argue that this decline constitutes compelling evidence of the emergence of a “nuclear taboo” or that the principle of noncombatant immunity has become a deeply held norm. An original survey experiment, recreating the situation that the United States faced in 1945 using a hypothetical U.S. war with Iran today, provides little support for the nuclear taboo thesis. In addition, it suggests that the U.S. public's support for the principle of noncombatant immunity is shallow and easily overcome by the pressures of war. When considering the use of nuclear weapons, the majority of Americans prioritize protecting U.S. troops and achieving American war aims, even when doing so would result in the deliberate killing of millions of foreign noncombatants. A number of individual-level traits—Republican Party identification, older age, and approval of the death penalty for convicted murderers—significantly increase support for using nuclear weapons against Iran. Women are no less willing (and, in some scenarios, more willing) than men to support nuclear weapons use. These findings highlight the limited extent to which the U.S. public has accepted the principles of just war doctrine and suggest that public opinion is unlikely to be a serious constraint on any president contemplating the use of nuclear weapons in the crucible of war.

War in Political Philosophy

We can distinguish between three moral approaches to war: pacifism, realism, and just war theory. There are various theoretical approaches to war within the just war tradition. One of the central disputes between these approaches concerns whether war is morally exceptional (as held by exceptionalists), or morally continuous with ordinary life (as held by reductive individualists). There are also significant debates concerning key substantive issues in the ethics of war, such as reductivist challenges to the thesis that combatants fighting an unjust war are the moral equals of those fighting a just war, and the challenge to reductivism that it undermines the principle of noncombatant immunity. There are also changing attitudes to wars of humanitarian intervention. One under-explored challenge to the permissibility of such wars lies in the better outcomes of alternative ways of alleviating suffering. The notion of unconventional warfare has also come to recent prominence, not least with respect to the moral status of human shields.

Evaluating the Revisionist Critique of Just War Theory

Modern analytical just war theory starts with Michael Walzer's defense of key tenets of the laws of war in his Just and Unjust Wars. Walzer advocates noncombatant immunity, proportionality, and combatant equality: combatants in war must target only combatants; unintentional harms that they inflict on noncombatants must be proportionate to the military objective secured; and combatants who abide by these principles fight permissibly, regardless of their aims. In recent years, the revisionist school of just war theory, led by Jeff McMahan, has radically undermined Walzer's defense of these principles. This essay situates Walzer's and the revisionists’ arguments, before illustrating the disturbing vision of the morality of war that results from revisionist premises. It concludes by showing how broadly Walzerian conclusions can be defended using more reliable foundations.