Where does Kant’s Categorical Imperative come from?

One of the most beautiful and famous sentences from Kant’s work is the following:

"Two things fill the mind with ever new and increasing admiration and awe, the more frequently and persistently it reflects upon them: the starry sky above me and the moral law within me."

When one reflects on this sentence, one may well notice that the moral law is not present within us in the same way as the starry sky is above us.

The starry sky is situated above us in our capacity as natural beings. As such, we are subject to the same laws as the stars and all other natural things, namely the laws of nature. A law is characterised by the fact that it determines the things that fall under it with necessity. If, for example, I let go of the ball I am holding in my hand, it will fall downwards, in accordance with the law of gravity and thus necessarily. As natural beings, the laws of nature apply to us in the same way as they do to all other natural phenomena, be they stars in the sky or balls in our hands. When we jump from the diving platform at the outdoor swimming pool, we fall downwards with exactly the same necessity as a ball would if we were to let it fall from up there.

The moral law, on the other hand, is not within us in the sense in which one might possibly say that our heart or our spine is us, but in the sense that we are consciously aware of it as a guiding principle in our actions. Just as the laws of nature govern things in nature, so the moral laws govern the members of the moral world. Only we, as acting and therefore rational beings, have the moral law within us and thus belong to the moral world. Stars or balls, on the other hand, cannot act. As such, they lie outside the moral world.

The categorical imperative constitutes the union of these two worlds, that is, the natural and the moral world. For it represents the manner in which, in our dual nature as natural beings on the one hand and rational beings on the other, we are subject to the moral law.

The moral law – just as, incidentally, positive law, which, according to Kant, in a certain sense also forms part of the moral law – relates to us as a commandment. A commandment determines what we must do. For example, Kant maintains that the moral law commands us to always tell the truth, which in turn means that, according to Kant, we must always tell the truth. The ‘must’ inherent in a command expresses the necessity of the moral law, which is inherent in its nature as a law. A command, in turn, is expressed in the linguistic form of the imperative. That is why the moral law appears to us in the form of an imperative. For example: “Tell the truth!”

However, the commanding nature of the moral law also expresses, for us, its fundamental difference from a law of nature. The fact that we must do what the moral law commands us to do also means that, whilst we can do it, we do not necessarily do so. Thus, whilst it is always possible for us to tell the truth (however unpleasant this may sometimes be), quite obviously we do not always do so and, in this sense, do not do so necessarily. That which is determined by a law of nature, on the other hand, happens necessarily in precisely that sense. Thus, we necessarily fall downwards when we jump from the diving platform. Precisely for this reason, however, it would be strange to say that we must fall down when we jump off the diving platform, or, to put it another way: this way of speaking is only coherent if we understand the ‘must’ here in a different way from the ‘must’ in the statement that we must always tell the truth. Similarly, strictly speaking, that which is determined by a law of nature is not something we do, but rather something that happens to us. Thus, whilst the jump from the diving platform is something we do, the subsequent fall merely happens to us.

The fact that it is possible for us to obey the moral law holds true because we are rational beings and thus belong to the moral world. The fact that we do not necessarily do so, on the other hand, holds true because we are at the same time natural beings and thus belong to nature. For this reason, the categorical imperative unites the two worlds to which we belong. For beings of pure reason – that is, for beings who do not belong to nature but exclusively to the moral world – the moral law would, on the other hand, also apply, but it would not be a commandment for them, since such beings would necessarily obey the moral law. To put it another way: for beings of pure reason, the moral law would, in a certain sense, be a law in the same way that the law of gravity is for us as natural beings.

Kant formulates the categorical imperative in various ways. The basic formulation is: "Act only according to that maxim through which you can at the same time will that it should become a universal law." For Kant, our "maxim" is the principle which we follow in our actions. An immoral maxim would be, for example: “I will only tell the truth if this does not have any unpleasant consequences for me.” The categorical imperative thus requires us to act only in accordance with those maxims which are simultaneously capable of becoming a law for all moral beings and are therefore necessary. This may sound abstract at first, but the idea is in fact very familiar to us. The rhetorical question we typically use to challenge the morality of an action – “What if everyone were to do this?” – suggests that we consider a person’s maxim of action to be precisely not generalisable. To stick with the example just given: “What if everyone were to tell the truth only when this had no unpleasant consequences for them?” In doing so, we are thus indirectly expressing nothing other than the demand that our actions must be fit to serve as a universal law – and therefore precisely the demand that the categorical imperative places upon us.

By demanding, as the way in which the moral law relates to us, that our actions be suitable as a universal law of the moral world, the categorical imperative makes us law-making members of the moral world. In a further formulation of the categorical imperative, Kant expresses precisely this idea: ‘Accordingly, every rational being must act as if, through its maxims, it were at all times a law-giving member of the universal realm of ends.’

By a ‘realm of ends’, Kant means nothing other than a community of rational beings governed by moral laws and thus within the moral world. For Kant, our dignity as human beings consists precisely in the fact that, in our actions, we are capable of this kind of law-making. To obey the categorical imperative and thus to act morally is therefore nothing other than living up to our own human dignity.

From Kant’s perspective, moral action is therefore, in the final analysis, a matter of self-respect. Since we act as law-givers in our moral actions, the categorical imperative demands both independent thought and action from us. This brings us full circle to another beautiful and famous sentence from Kant’s work: “Have the courage to use your own understanding!” Anything else would be beneath our dignity.