An argument against Kant's categorical imperative is the "hiding Jews from the Nazis" example: "Per the categorical imperative, you should never lie. Therefore if you are hiding Jews in the basement during WWII, and Nazis knock on your door asking if there are any Jews in the house, your duty is to answer truthfully. But this would lead to the death of innocent people - hence the categorical imperative doesn't work"

Fair enough, but can't we amend the rule regarding lying to be:

"Don't ever lie, unless by doing so you are saving the life of an innocent person."

This formulation is still universal, in the sense that it can be applied in any conceivable situation to determine whether lying is acceptable or not - and so it conforms to Kant's principle that: "Act only according to that maxim whereby you can at the same time will that it should become a universal law."

Moreover, this actually seems closer to the Kant's rule that Humanity should be the deciding factor in all our moral decisions:

"Act in such a way that you treat humanity, whether in your own person or in the person of any other, never merely as a means to an end, but always at the same time as an end." - in the Nazi example, the humanity of the people being hidden in the basement overrides whatever obligations I have to be truthful to the authorities, and hence lying is the best course of action.

Is this reasoning valid? Are imperatives still considered "categorical" if they contain unambiguous universally applicable "unless-then" clauses?

  • Conditions are not categorical, but that is just a matter of language. If the condition really is unambiguous and universally applicable, you can almost always turn this into an adjective instead of a condition. The problem is not as much with the if/then construction as with bringing in non-categorical constructs like 'innocent' and 'saving' -- is anyone truly innocent? how sure can you really be that they would die?... The tests needed to apply the maxim cannot be relativistic like that unless the duty itself is not absolute.
    – user9166
    Jul 13, 2017 at 20:58
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    And, for the nth time this example has been raised here, there is no imperative to comply with an order. No one would want to live in a world where we could just order each other around at whim. So you have no duty to answer truthfully, because you have no duty to answer. What you should do is fight the Nazis and deprive them of the right to make such demands.
    – user9166
    Jul 13, 2017 at 21:42
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    Just to clarify: Kantian may be understood ambiguously - do you aim at in accordance with Kant's own thinking or brought about in kantian style thinking? Kant himself has some nice answers on that, some kantian philosophers argue the way the question does.
    – Philip Klöcking
    Jul 15, 2017 at 15:09
  • @Jobermark " What you should do..." by what measure? 'Should' if you want to comply with Kant's advice, or 'Should' if you want to achieve the objective of helping the innocent against unjustified aggression? It's not clear from your comment which you mean and each would have a very different impact on the OP's question "Is this reasoning valid?"
    – user22791
    Jul 17, 2017 at 9:47
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    @PhilipKlöcking In so far as there is a difference, I was originally using the word here in the same way that people say that "philosopher X is using a Kantian framework" or "philosopher Y is a neo-Kantian" , my understanding was that Kant himself was categorical about the categorical - see here - however you indicate otherwise, so now I am curious as to which answers of Kant you are referring to. Jul 17, 2017 at 19:52

5 Answers 5


What does it mean to categorize? It means to put things in piles which are distinct, where every thing goes in the right pile, and the definitions of the piles actually separates the things logically, with an absolute true/false distinction.

And what does it mean to categorically assert or deny something -- it means that there is absolute truth, or no truth to it -- that the assertion or denial has an absolute truth value.

So categorical means "having the form of a distinct property with a binary truth value".

(One meaning of the root /agoreuein/ is 'to predicate', but this is less than fully compelling because another is 'to harangue'. From the examples above, we have to take it that Aristotle meant the former, and that is the use that has come down to German and English usage, and into Kant's hands and ours.)

For something to be universal and categorical at the same time, absolutely everyone would give it the same binary truth value.

If we can lie 'for good reason' then there should be a meaning of 'good reason' that all of us can agree on. All of us -- even Nazis or deranged murderers seeking their next victim -- should have our status as real actors respected. You cannot have your person-hood revoked just by being the wrong person.

If you can prove a stronger result, with Kant, you have to accept it over the weaker result. Period. If there is a deduction that makes for an absolute duty, and one that makes for a contingent duty, you have an absolute duty. Choice needs to be preserve within each deduction, not between them.

Trying to avoid violence by lying is putting the contingent duty to defend people from violence up against the absolute duty to maintain the ability to decide what is true.


To resolve this moral dilemma, one might have to posit a second, supplementary and/or contradictory categorical imperative to "always tell the truth" such as " protect innocent lives when possible" or "treat others as you would wish to be treated". The underlying philosophical problems with this are that a) Kant's theory doesn't tell us what to do when moral values conflict and b) Kant's theory doesn't necessarily admit the idea that moral values conflict and c) even if Kant's theory of morality is compatible with the idea of incompatible/conflicting values, the theory itself doesn't provide a clear rationale for how to resolve these conflicts. Perhaps other philosophies could shed light on the issue of conflicting values, but they would have to step outside the Kantian framework of ethics and in doing so may not remain within its starting points. I think it would be hard to argue for the moral validity of anything stronger than evasion or silence (or perhaps in some circumstances fighting back) as a morally justifiable response to this quandary. But it would seem, within the framework of the categorical imperative, that situations in which values conflict are not easily resolvable, particularly if one clear categorical imperative (such as truth-telling) will obviously come into conflict with another and/or lead to a disastrous result. In other words, this might be a situation in which common sense and philosophy (or Kant's philosophy at least) are truly at odds. Another problem with applying ideas of C.I. to this situation is that the imperative should be the same regardless of to whom it is being applied, which is both a strength and a weakness - in that you must act the same to innocent people with benevolent motivations as you would to evildoers with clear malicious intent.

  • If you have references they would help support your answer and give the reader a place to go for more information. Welcome to Philosophy! Jan 16, 2019 at 21:52
  • I don't think the categorical imperative is meant to be a "framework" of preemptive rules. Maybe we can ask @PhilipKlöcking for some guidance here, and you can edit accordingly.
    – christo183
    Jan 17, 2019 at 5:37
  • I think the "rules" if we're calling them that imposed by the categorical imperative are absolute...hence the term "categorical", which by definition doesn't allow for analysis of context.
    – Leah
    Feb 11, 2019 at 1:04
  • from Oxford encyclopedia: "What the Humanity Formula rules out is engaging in this pervasive use of humanity in such a way that we treat it as a mere means to our ends. Thus, the difference between a horse and a taxi driver is not that we may use one but not the other as a means of transportation. Unlike a horse, the taxi driver’s humanity must at the same time be treated as an end in itself. "
    – Leah
    Feb 11, 2019 at 23:44

It's not entirely clear here exactly what you're asking it sounds like a moral question as to how to apply Kant's ethics, which is how I've answered, but it could be a question about how far one can manipulate Kant's ethics without it no longer being 'Kant's', which seems an entirely trivial question which I won't engage with, so my apologies If I've missed the point.

Fair enough, but can't we amend the rule regarding lying to be: "Don't ever lie, unless by doing so you are saving the life of an innocent person."

Yes, but only if you already believe that saving the Jews is the right thing to do and that telling the truth to the Nazis about where they are hiding is not going to bring that objective about. You have, in formulating such a maxim, already done the ethical work the maxim is pretending to help you do. You've already decided what outcome you think would be morally right (saving the lives of the Jews) and you've already decided what course of action will best bring about that outcome (not telling the Nazi's where they are). The point of the maxim is not to help you make such a decision, it is to help you justify it to yourself so you can live with the choices you make, as Bertrand Russell put it "without being paralysed by hesitation"

You could just as easily justify the decision (that you've already made) by utilitarian ethics (the most good will come about by saving the innocent from oppression), by virtue ethics of any kind (it is a virtue to defend the oppressed against violence), even by hedonism (standing up to such a powerful group as the Nazis to save innocents makes me feel like a hero which gives me a lot of pleasure). You make the ethical system fit your preferences, they will all require some manipulation of their inherent ambiguities to make them fit.

Are imperatives still considered "categorical" if they contain unambiguous universally applicable "unless-then" clauses?

Considered by whom? Surely this will depend entirely on a completely subjective interpretation of "unambiguous". As Jobermark points out "innocent" and "saving" can be considered ambiguous, but so can "universal law", which is, I think, the crux of the question. How detailed do you make the law? Is it lying to anyone, lying to authority, lying to Nazis, or lying to these particular Nazis on this particular day that you are universalizing? These ambiguities are a necessary component of any ethical system, not a flaw, they are there because if an ethical system actually did tell us how to act in every situation, it would undoubtedly be so over-simplistic and prescriptive as to be completely unworkable within days of everyone following it. But perhaps more importantly, what kind of idolatrous zealot would dismiss millions of years of cultural evolution to follow the prescriptions of one random 18th century German?

If, when faced with actual Nazis (or the modern-day equivalent) asking about the whereabouts of your neighbours, intending to do them real harm, anyone really wishes to rely on the advice of just one person against all their instincts and culturally learned values and judgements, then good luck to them. For the rest of us the philosophy is post hoc, so if makes sense, then it can be considered valid and a justification for what you already think is right of no greater or lesser value than any other equally valid justification.


Yes, I think the reasoning is valid.

More generally we can say that lying is justified by the categorical imperative so long as it's for a noble reason, since everyone agrees that noble reasons are noble. It's lying for ignoble reasons that aren't justified. Of course this then puts the burden of understanding on what are noble purposes, but in the example you quote this is straight-forward and this comes under the categorical imperative.

  • So if the CI tells us that lying is justified so long as it is for a reason which we think is noble, then how does Kant's philosophy differ from "do what you already think is right"?
    – user22791
    Jul 17, 2017 at 9:39
  • Clearly the Nazi himself does not consider the evader 'noble', he considers him at odds with the general will of his people. Again, 'noble' is not a category, it is a sentiment -- looked at closely, it does not have a binary truth value.
    – user9166
    Jul 17, 2017 at 20:50

Tying into jobamark's answer, Kant posits that morality is a priori, and so is known before observations come into play. Conditions like whether a choice would result in the deaths of innocent people can have no impact, because, under Kantian epistemology, you can't actually know whether a certain outcome is the result of a certain choice. Unless-then clauses are not Kantian.

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