Did Immanuel Kant intend for the Categorical Imperatives to be used together, or separately, when trying to determine an actions ethicality or morality

If you answer yes, individually, then how does one determine which categorical imperative is to be applied to questions, situations or actions

  • 2
    Groundwork, 4:435. All versions are equal, all but the general one may be 'closer to intuition' and work better for some people because of that. Pretty sure about the reference, though off the top of my head. Could extend to 436, though.
    – Philip Klöcking
    Commented Feb 21, 2018 at 22:29
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    There is only one categorical imperative according to Kant, "Act only according to that maxim whereby you can at the same time will that it should become a universal law", other formulations derive from it. This may be disputed but this is what he held.
    – Conifold
    Commented Feb 22, 2018 at 19:02
  • @Conifold In the Metaphysics of Morality by Kant, I counted at least 3 Separate ones. Are they all a progression to the “only one”???
    – user31089
    Commented Feb 22, 2018 at 19:17
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    @TonySnow According to Kant, yes. The fuller quote is "There is therefore only a single categorical imperative, and it is this: act only according to that maxim through which you can at the same time will that it become a universal law", see Philip's post Why is there only one Categorical Imperative? Modern philosophers are skeptical of his unicity claim, see What are some examples of categorical imperatives/universalizable maxims relevant to modern ethics?, but Kant is Kant.
    – Conifold
    Commented Feb 22, 2018 at 20:31
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    Possible duplicate of Why is there only one Categorical Imperative?
    – Conifold
    Commented Feb 23, 2018 at 20:11

1 Answer 1


Kant writes in his Groundwork of the Metaphysics of Morals:

The above three ways of representing the principle of morality are fundamentally only so many formulae of the selfsame law, one of which of itself unites the other two within it. However, there is yet a dissimilarity among them, which is indeed subjectively rather than objectively practical, namely to bring an idea of reason closer to intuition (according to a certain analogy) and thereby to feeling. (4:436)

The three mentioned ways are the Formula of the Law of Nature (4:421), The Formula of Humanity (4:429) and the Formula of the autonomous will in a Kingdom of Ends (4:434), the last one containing the other two (see Timmermann's Kant’s Groundwork of the Metaphysics of Morals: A Commentary, Cambridge UP, 2007, pp. 105-6, 109-11).

All of these three are "closer to intuition (according to a certain analogy)", which is paraphrasing that while a will governed only by morality is "an idea of reason" (which has no correspondence in experience, strictly speaking), i.e. we do not have a concept of it, we can use analogies like "law of nature", "end in itself" and "autonomy in a kingdom of ends" to get an idea of what this could actually mean.

This, Kant states, does not imply an "objectively practical" difference, but only a "subjectively" one. In short: They are objectively the same, they just have a different "feeling" to them.

But in the end, there is only one categorical imperative, which is the reason why he is able to state:

But in moral judging it is better always to proceed by the strict method, and make the foundation the universal formula of the categorical imperative: act according to the maxim that can make itself at the same time a universal law. If,l however, one wants at the same time to obtain access for the moral law, it is very useful to lead one and the same action through the said three concepts and thereby, as far as can be done, bring it closer to intuition. (4:436-7, bolded PK)


Kant's answer is that if it helps you, you may use all versions as they are objectively the same. But strictly speaking, there is only one single categorical imperative and applying this is always the "best" (most rational) way to judge morality.

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