As I understand, Kant says moral laws are liberty so there is not any "condition" for it.

But it's very dangerous for me because that's to say human must act according to something we cannot ask for why, so they are not rational.

  • It is rational that a chain of why's must stop somewhere, and not just when it comes to morality. For Kant, all moral imperatives are "hypothetical", to advance some end, except one, the categorical imperative, which is to be done for no end other than itself.
    – Conifold
    Jan 14, 2020 at 20:07
  • He wrote two books on why a good will (moral intentions) follows the categorical imperative and the later one also (kind of) explains what exactly the end of such a will is. What exactly is the question here? If one wants to act morally or autonomous (which can be used interchangeably in Kant), one has to act according to the categorical imperative. That's true (for Kant) because the very concepts of true freedom and morality (doing what is good, not what is good for me), if analysed, lead to the insight that this is true. We cannot ask why what?
    – Philip Klöcking
    Jan 14, 2020 at 21:00

1 Answer 1



You put Kant on his head here. Probably you think that sentences like "Thou shalt not lie" were unquestionable for Kant. But that's not what the categorical imperative is. For Kant, the categorical imperative is a single, abstract principle that is the core of all "imperatives" like the one mentioned.

The categorical imperative is:

[A]ct according to the maxim that can make itself at the same time a universal law (GMM, 4:436)

How does it work like?

Kant's categorical imperative tells us whether whatever we want is reconcilable with how good will or a perfect being would want to act like. We always bring the material and the question with us already:

The situation we find ourselves in is that we want to do something, say, lie to our partner because we messed up and don't want them to know. And now we ask ourselves (our rational side) whether this is the right or moral thing to do.

What Kant argues is that this question can be answered by asking whether the maxim of our will could be a general law, ie. if it was possible that every rational being could act accordingly in the same situation (I answered the question what exactly a maxim is elsewhere here).

In our case, the question would be whether, if everyone would always lie to cover up their mistakes, that would work. Kant's answer would be "no" since in such a world, noone would trust the word of each other since they know the other one would definitely lie if it only was to their advantage and we could not possibly know whether this is such a case. Consequently, we know that the moral/good thing to do is telling the truth.

Why using this as a principle, then?

The complicated thing to understand here is that when we do something because of any reason but wanting to do the good/moral thing, ie. because of it being according to the categorical imperative, the action becomes selfish and immoral. As he tries to show, it is in the very concept or idea of morality and goodness that its principle is the categorical imperative.

So why using this quite monstrous principle? It is quite easy, if you are intelligent, to figure out what to do if you want to reach some goal...it is immeasurably harder to figure out what to do if you only want to do stuff that is also right to do.

What the categorical imperative does is carving out those things that are immoral from all the things you want do do anyway. Thus, the question "why" is, in a sense, already answered: Because I want it and it is not immoral. And let's face it: if we are rational, we do not want to do what is immoral "just because".

For Kant, what happens when we start to be rational, ie. reason about whether what we want to do is right or wrong, we implicitly or explicitly use the categorical imperative. The only thing he did is showing us that this, indeed, is the principle of rational morality spelled out.

Long story short: Why should I act according to the categorical imperative? Because that is a) what I, qua being rational, want to do anyway since b) that's what is the good/moral thing to do.

((This answer tries to break it down as far as possible without becoming a caricature of Kant. It intentionally omits scholarly referencing in favour of simplicity and readability. The content is built upon the Groundwork of the Metaphysics of Morals (1785) and the Critique of Practical Reason (1787/88).))

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