How, according to Kant, ought we respond when the categorical imperative obliges us to take two mutually-exclusive courses of action?

For instance if two people are being lowered into a pit of lava. I can pull one lever and save one, or pull the other lever and save the other, but if both levers are pulled, both die.

I have an obligation to keep others from peril and an obligation not to hurt people. So I'm obligated to try and save one of them, but in doing so, I ensure the death of the other. This seems to be fundamentally different than the trolley problem. Saving one person does not entail dooming another, previously uninvolved party---and yet it means the person I did not save is certainly doomed.

What ought I do?

  • I have an obligation to keep others from peril and an obligation not to hurt people. These are two different obligations. The first is not to be found in Kant. The second is absolute but does not relate to your example.
    – virmaior
    Commented Oct 12, 2016 at 4:45
  • How broadly should we construe hurt? "Ensure the death of" seems like a fair extension to me.
    – Canyon
    Commented Oct 12, 2016 at 4:54
  • I don't understand how you're jumping from (A) I have an obligation not to harm others to (B) I have an obligation to ensure others are not harmed (I'm doing my best to decipher your most recently "Ensure the death of" comment but don't really get it).
    – virmaior
    Commented Oct 12, 2016 at 5:04
  • 1
    Every doctor chooses whom to treat, knowing others will die. I think you have to pull all the way back to not choosing whom to kill, where killing is a definite act.
    – user9166
    Commented Oct 12, 2016 at 5:11
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    But the doctor's action is the choice. Betting on other's probable actions, is, itself not unversalizable -- if you all do it, the 'most probable' action never happens. Kant does not measure utility or play odds, (to do so is arrogant in a certain way -- it ties morality to a skill) even in a contingent duty, the final decision may just as well be random as tied to likelihood or utility.
    – user9166
    Commented Oct 12, 2016 at 5:15

2 Answers 2


Two thoughts.

First, for Kant himself, it is never the case that the categorical imperative comes in conflict with itself. In other words, Kant rejects the idea that there are conflicting moral principles and we must choose among them.

Second, the problem you pose does not even demonstrate conflicting moral principles or a situation where the categorical imperative obliges us to take two mutually-exclusive courses of action. You seem to be misunderstanding the categorical imperative when you equate it with the imperfect duty to help others.

In the situation, you describe the moral self has a choice between two courses of action both of which are possibly moral if performed in accordance with the categorical imperative. The wording in the preceding sentence is obtuse but important -- For Kant, actions do not necessarily qualify as moral even if the end agrees with morality. Instead, they only qualify as moral when the maxim of my action corresponds with a law that could be universalized or that treats humanity (rational nature) as an end rather than a means or as a possible law in a kingdom of ends.

Stated another way, helping either person for the right reason would qualify as moral as a fulfillment of the imperfect duty to help others. BUT it does not follow that you have failed in this duty because you did not help all others at all occasions. (Kant explains this in more detail in the Metaphysics of Morals: Doctrine of Virtue and Critique of Practical Reason).

One major reason for this is that Kant is not concerned primarily with the consequences of our actions. Thus, for Kant, that one person died because I saved someone else does not ever impute a moral wrong to me. In fact, it is possible to act morally in ways that lead to the deaths of others on the Kantian picture. Specifically, because my duty is to pursue a maxim that treats others as ends -- and these others can include those with immoral goals. (Cf. Why shouldn't you lie to the future murderer of your children?)

To answer one formulation of your question towards the end, you ought to save one of the lives because each life is an end of infinite worth rather than price. You need not feel any guilt that saving one meant you couldn't save the other.

  • To say that the CI cannot come into conflict with itself seems to be begging the question. Why do we only have an imperfect duty to keep others from harm? (A better wording of my original "obligation to help people".
    – Canyon
    Commented Oct 12, 2016 at 4:43
  • (1) Kant himself states the CI can never come into conflict with itself... (2) Kant specifies two imperfect duties (i) to help others and (ii) to improve ourselves. Not sure why you're altering the list.
    – virmaior
    Commented Oct 12, 2016 at 4:44
  • Sorry, ought to have put a harder delineator between the first and second sentences. We must prove the consistency of any axiomatic system. Simply stating that it cannot come into conflict with itself is not nerely enough.
    – Canyon
    Commented Oct 12, 2016 at 4:51
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    Consider the meaning of universal. If there were a conflict, the source of the conflict is probably the will of an individual. If we have universalized the rule over their expected objection, we have done the deduction incorrectly. So this is not a fiat, it is a theorem.
    – user9166
    Commented Oct 12, 2016 at 4:53
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    @canyon maybe Kant is completely wrong. That's completely possible, but (1) the scenario you've manufactured poses not problem for his account or his claim and (2) many of the things you're claiming with respect to Kant are things that do not appear in any of his texts (at best they represent a flawed reading of Groundwork)
    – virmaior
    Commented Oct 12, 2016 at 5:05

Contrived, specific examples are not going to have categorical maxims. You cannot universalize choosing either person you might kill with the levers -- if you were the one not saved, you would not agree to the rule. So the maxim says nothing on the subject. It suggests you not go out of your way to kill them both, but, not surprisingly, it does not give you a way of solving an unsolvable problem.

Kant's rules, in general, don't take the full detail of any situation under consideration, they only consider categorical rules. If the specifics of a situation cause a difficulty applying the rule, the rule is probably wrong -- it is supposed to be universal, after all, and the person presenting the difficulty would reject universalizing the rule. In such a case, there probably is not a most moral way to act, and that is fine. Duty does not dictate every action in complete detail. It leaves as much leeway to your own autonomy as you would universally accept.

But it needs enough specificity to be generalized. You are not obligated to help people. There are situations in which you do not need help, would not appreciate it, and it might make you dependent or less efficient. You are not obligated not to hurt people. There are situations when hurting people is necessary -- Kant would not refuse to perform surgery. Whatever rules should guide you in these situations are going to rely more on what kind of help or harm is in question.

You are enjoined not to kill, as deciding whom to kill could never be universalized -- everyone would say 'not me'. On the other hand you are not required not to let anyone die -- otherwise we would be keeping people on respirators for centuries. There is some tipping point where your inaction is culpable, but it clearly can't extend to the point where you should never choose one life over another, no matter what, or no one could ever be a physician.

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