In 1918 prominent American philosopher James H. Tufts asked, ‘Is there, can there be, any ethics of international relations? ^[1]’ In the turbulent century since, that question has inspired many attempts at an answer. Contemporary events press the issue again.

Tufts was a collaborator of John Dewey ^[2], who also turned to the issue in 1923. Dewey saw ‘the extraordinary confusion that is found in current moral ideas as they are reflected in the ethics of international relations’. He asked why it is that ‘morals have so little effect in regulating the attitude of nations to one another’. To cut through the confusion, Dewey was left promoting an idea suggested by Salmon Levinson in his monograph Outlawry of war ^[3] (1921).

The questions posed by Tufts and Dewey remain unanswered as a century marked by almost continuous war and conflict followed their formulation. But Dewey’s simple response became a principle in law if not in strategic practice. Developments in international law ^[4] have ‘not only outlawed war as a legitimate means of settlement of international disputes but also banned most uses of military force short of war and even threats to use force in international relations’.

Nevertheless, those engaging in aggressive war itself, often accompanied by frequent heinous acts which are self-evidently morally unjustified and often criminal by domestic norms, are rarely held to account. An exception was the German ^[5] and Japanese ^[6] war crimes trials following World War II.

At the time, these trials seemed to cement into international law ^[7] the offences of engaging in a conspiracy to commit crimes against the peace, war crimes and crimes against humanity; planning and waging war; mistreating enemy combatants and prisoners of war; deliberately causing death or injury to civilian populations outside of military necessity; and murdering, exterminating, enslaving, deporting or persecuting an individual on political, racial or religious grounds.

The long, convoluted and uncertain path ^[8] that the advocates of outlawing war followed throughout the first half of the 20th century finally seemed to end in the United Nations Charter ^[9]. But of course international practice, even the conduct of the nations that were responsible for shaping international law on aggressive war, has fallen far short of the ideal.

The gap between ethics and international relations has only widened since Tufts and Dewey pondered the relationship. They could have had no premonition of the incomprehensible and horrific moral catastrophe perpetrated by the National Socialists in Europe or the cruelty of the Japanese imperialist war in East Asia. But parties on all sides of the postwar conflicts in Vietnam, Algeria, Palestine, Iraq, Afghanistan and Syria, among others, have perpetrated the crimes that were identified in the Nuremburg trials and entrenched in the UN Charter.

History appears to demonstrate the rightness of the sceptical opinions of the political realists ^[10] about the relevance of ethics in relations between states. Realists like Reinhold Niebuhr ^[11] and Hans Morgenthau ^[12] were critical of moralism, objecting to the ‘abstract moral discourse that does not take into account political realities’. George Kennan ^[13] noted that ‘there are no internationally accepted standards of morality’. Other realists in what might be termed the more-or-less Machiavellian tradition, such as E.H. Carr ^[14], considered that the ‘standards by which policies are judged are the products of circumstances and interests’ and that ‘morality can only be relative, not universal’.

More optimistically, the major contributors to the debate over the conduct of international relations have felt impelled to confront the issue of ethics. Among philosophers of ethics the position of the political realists is highly contestable. The response to the appearance of Michael Walzer’s Just and unjust wars ^[15] (1977) highlights the intensity of the debate.

Opposition ^[16] appeared to Walzer’s argument that foreign military intervention is always morally wrong, irrespective of how despotic, tyrannical or oppressive the domestic government. Walzer’s only exceptions were when a state was massacring or enslaving its own citizens or when a legitimate secession was being forcibly prevented. Gerard Doppelt ^[16] criticised ‘a rhetoric of morality in international relations which places the rights of de facto states above those of individuals’. Walzer’s ethical framework boiled down to just one substantive unethical act; as Brian Orend summarised it ^[17], ‘the only just cause for resorting to war is to resist aggression’. Like Dewey and Levinson 50 years earlier, Walzer was left with outlawing aggressive war.

Dewey would be even more confounded by the general contemporary confusion in ethical theory, let alone its application to international affairs (for example, in peer-reviewed journals like Ethics & International Affairs and Philosophy & Public Affairs). Moreover, the world’s challenges have been made far more complex through technology, globalisation, decolonialisation and shifting geopolitical power—even more than the problems World War I raised for him.

Still, war remains a great scourge and rationally should be thought of as a last resort, if it is contemplated at all. To generalise, perhaps unjustly, it seems that even in the muddle still enveloping the Tufts question, the one thing nearly all contributors to the debate agree on is that aggressive war is the action that attracts the greatest anathema.

Tufts finished on a somewhat hopeful note, arguing that ‘the give and take of scholarship in pursuit of truth bespeak a democratic value that is real’. He put his trust in ‘the appeal of the finer institutions which man is building’. More pessimistically, Dewey concluded that, while ‘the first move in improving international morality is to outlaw war’, that didn’t mean ‘that wars would necessarily cease’.