A soldier is about to execute 20 prisoners. He tells you that if you kill one of them, he'll let the other 19 go. This classic standoff between Kantian ethics and utilitarianism is discussed @ "Jim and the Indians" and killing someone to harvest organs, is it equivalent?

Now imagine a vaguely similar situation involving two nations.

Nation A declares war on Nation B, threatening to destroy a city with a population of one million people. To protect itself, Nation B must destroy Nation A's capital, with a population of 200,000.

So either one million people die or 200,000 die.

Of course, this situation is vastly more complicated because we're talking about self-defense as well as political functions - a leader must protect his or her country.

What would a Kantian and a Utilitarian do in this particular situation?


Just for clarification, the soldier in this example is not a liar. We know he's telling the truth. So the exercise boils down to a really simple question: Would you kill one person so that the others could live, or would you stand by and watch the entire group murdered?

Regarding Bread's comment about cities not being the problem, that's literally true - but it misses the point of my question. In my example, there really is no choice but destroy an entire city. If we have to make up a reason, we could say that Nation A has a constitutional clause stating it surrender if it's leader is killed, and it's known that he runs from one hideout to another in the capital city. So the only way to be sure he's eliminated is to destroy the entire city.

  • I think Kant allowed self-defence (when you are treated as means), so your problem is easy.
    – rus9384
    Feb 2 '19 at 7:51
  • 1. a) Never make deals with murderers, because murderers are always liars, too. b) Never sacrifice or compromise your own values in any situation. c) Killing is only moral when strictly for self-defense or to defend other innocent victims of violence. 2. Parasitism between humans is never 'noble'. 3. You don't have to destroy an entire capital city, just to eliminate or punish their leadership. Cities aren't leaders. Cities aren't people. Cities aren't the problem.
    – Bread
    Feb 2 '19 at 11:43
  • Points 1a and 2 miss the whole point of the question. I edited my question to clarify. Regarding 1b, suppose the soldier offered to free everyone if you tell a lie. Would you then compromise your values? Feb 3 '19 at 5:54

Rule utilitarianism

A rule utilitarian could have a rule against war on the grounds that human welfare is better served by such a rule, which could include pacifism or passive resistance, than one which licenses war and the enormous catastrophes which modern warfare entails or makes probable.

Act utilitarianism

An act utilitarian would calculate the probable consequences of war, a particular war in a particular situation. The outcome of the calculation cannot be predicted at this level of abstraction.


As Philip Klöcking reminds me:

Kant is clear in Towards Perpetual Peace that the categorical imperative is the supreme principle of political action as well, so here, there is no difference between individual moral concerns and political obligations against the community as a whole.

This ties in exactly with what I want to say about the CI. In the language of the CI, maxims that license war involve (in commentators' language) a contradiction in the will. No rational person could prefer a world in which war is resorted to over a world in which it is repudiated and abstained from.

Our 'asocial sociability' may in practice lead us to war - this is an anthropological point - but Kant believes that war belongs to 'the lawless state of savages' and is an avoidable human evil. However, while he believes that this is evident to reason, precisely because of humankind's 'asocial sociability', the lesson is likely to be learnt only through experience.

Kant confidently asserts that ... "quarrelsomeness, in this case that of the great societies and states," serves to bring about "through the very antagonism" the necessary "condition of quiet and security." Triumphantly, he proclaims that "wars, the excessive and never-ending preparation for wars, and the want which every state even in the midst of peace must feel - all these are means by which nature instigates attempts, which at first are inadequate, but which, after many devastations, reversals, and a very general exhaustion of the states' resources, **may accomplish what reason could have suggested to them without so much sad experience, namely to leave the lawless state of savages and enter into a union of nations (foedus amphyctyonum)**. (Carl J. Friedrich, 'Erasmus and Kant : on War and Peace', World Affairs, Vol. 133, No. 1 (June 1970), pp. 1-12: 9; Kant, "Idee zu einer allgemeinen Geschichte in weltbürgerlicher Absicht," in Werke, ed. Cassirer, vol. IV, 149ff.)

  • Since this is an aspect of the question: Kant is clear in Towards Perpetual Peace that the categorical imperative is the supreme principle of political action as well, so here, there is no difference between individual moral concerns and political obligations against the community as a whole. Act Utilitarianism cannot be coherently considered here, since indeed the outcome of the calculus depends on not only incalculable empirical factors (mere theory about the future) but also on e.g. the weighing of the value of lives of one's own people compared to the lives of other people.
    – Philip Klöcking
    Feb 3 '19 at 18:12
  • @Philip Klöcking. Thank you as always. I did invoke the CI in my original text - ref. to 'contradiction in the will'. I have, and I hope this is OK, included your Perpetual Peace remark with acknowledgement in my revised text. There are enormous difficulties with act-utilitarianism across the board. I included it only as an analytic possibility in the relation of utilitarianism to war. Best - Geoffrey
    – Geoffrey Thomas
    Feb 3 '19 at 19:42
  • @PhilipKlöcking Act utilitarianism could be considered from the neutral side, I think. Regarding the calculation of outcomes, it's indeed is transcomputational problem, but heuristics are always available.
    – rus9384
    Feb 3 '19 at 19:51

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