Probably no name has more weight in the history of European philosophy than Kant’s. With this venerable name, the concept of the categorical imperative immediately dawns: “Only act according to that maxim through which one can also want it to become a general law”. But what does that mean?
The basics of Kant’s ethics
Understanding Immanuel Kant’s (1724-1804) ideas is much like climbing a heavy mountain for most philosophy students. It really takes a lot of practice and effort. With this introduction to Kant’s ethics I will at most just skim the surface, at best I will be able to provide some pointers to strengthen understanding.
In order to be able to start right away, we should consider some key data on Kant’s ethics, which will already anticipate and facilitate some things for later discussion. Kant is a strict advocate of a so-called ethical or moral rationalism. That basically means nothing else than that for him all ethical truths must always be general truths of reason.
In normative ethics, he only wants to allow claims that can be recognized and substantiated as correct through pure reason. They thus become general laws – a fundamental concept in Kant’s entire philosophy. In addition, Kant sets himself apart from his predecessors with his ethics.
Before Kant there were essentially two other theoretical structures of ethics, namely the virtue ethics of antiquity – mainly represented and spread by Aristotle – and English utilitarianism , which, however, only really emerged in the 18th century. Kant’s ethics is called the opposite of these two currents as deontology , ie as duty ethics . The differences become clear in the course.
One last point should be mentioned briefly before we really get into the analysis. Kant’s ethics are absolutely unpsychological, which means that he is not interested in what might, for example, motivate people, what drives them or makes them happy. After all, these are all empirical facts that must not play a role in a rational morality. A short summary of his approach could look like this:
1) Starting point: what is absolutely good? We have to examine intentions to act!
2) Against his (subjective) inclinations, man must obey the (objective) duty of morality.
3) Categorical imperative: The moral law is an unconditionally valid law of reason.
basis on the metaphysics of ethics
This is the title of one of Kant’s writings in which he organizes his thoughts on ethics. The main aim of the foundation for the metaphysics of morals is the establishment of a moral principle with the help of which actions can be judged morally [1, p.203]. Right at the beginning, Kant therefore asks himself what is to be understood as being morally unreservedly good. [ibid.]
This is the basis of the much-quoted and famous first sentence of the Foundation for the Metaphysics of Morals , which gives a concise answer to it: There is nothing in the world, and indeed at all possible to think apart from it, that could be considered good without restriction other than alone a good will  .
Right at the beginning of the first paragraph, the good will marks the deontological element in Kant’s ethics. In contrast to utilitarian ethics, which are based on consequences – that is, teleological, that is, goal-oriented – and to eudaimonistic ethics, which consider happiness to be inherently good and valuable, Kant has something else in mind with his ethics.
Neither the consequences of an action nor the resulting happiness for the actor should play a role in judging an action as moral or immoral. Kant is thus committed to ethics through and through. His basic thesis can be summarized as follows:
Goodwill is the intentional action of a reflective subject who must wrestle with desires in order to do what is morally right. Because the human being, as an imperfect, rational being, because a sensual and rational being, does not always act as reason dictates, the moral law represents an imperative for human beings which he must obey out of duty. [1, p.203f.]
Important terms: will, maxim and law
For Kant, the first important term ‘will’ is synonymous with the rational faculty in the form of so-called practical reason , which means “the ability of man to act independently of sensual determinants, ie drives, needs and passions, sensations of the pleasant and the unpleasant to be selected “[4, p.12].
Why is this term so important? Kant just wants to show that a good will, i.e. what we find unreservedly good and moral, is present exactly where someone acts out of duty. The good will thus includes the concept of duty and enables Kant to transition to it.
The two terms maxim and law are opposite poles that come under the umbrella of will and duty. Whenever we act, according to Kant, we raise a so-called maxim as a subjective principle of action that expresses our will. These are mostly determined by inclinations and by no means by reasonable consideration.
On the other hand, there is the law as an objective principle of practical reason, which tells people how they should actually act and not just – as all maxims do – how they want to act out of subjective motivation. Kant himself summarizes it as follows:
The maxim is the subjective principle of action and must be distinguished from the objective principle, namely the practical law. The former contains the practical rule which reason determines according to the conditions of the subject (often ignorance or the inclinations of the same), and is therefore the principle according to which the subject acts; But the law is the objective principle, valid for every rational being, and the principle according to which it should act, that is, an imperative. 
The moral law
The big question is how such imperatives should be concretely according to Kant. First of all, there is a category of imperatives that are intuitively very plausible, and we even use them every day.
An example would be: ‘If you want to get on the train, you have to hurry up’. In this imperative there is a condition that precedes the instruction.
Kant calls this form of imperatives hypothetical, i.e. dependent on goals that can be pursued or not. However, these hypothetical imperatives can never be a general law, because they are based precisely on empirical facts and are not absolute truths of reason. After all, I might not want to go to the train either – what then?
Let us consider the following case: I have a maxim X. This could be, for example: I always buy red cars because I like the color red. What are the characteristics of this maxim? The most important thing is that I have to understand exactly this maxim with others. Now that means if someone else buys a red car because they like the color red, I can’t suddenly say, ‘That doesn’t make any sense’.
Our maxims are context-transcendent!
In this regard, the Kant expert Prof. Tim Henning has formulated a reconstruction of Kant’s argument that connects exactly what we have already heard about good will and duty. From this requirement and the above example alone, it can be concluded that the mandatory content can only be a very specific one, namely that of the moral law:
At the beginning we already got to know this premise of Kant: We can only imagine moral value where the agents show a certain kind of motivation, which Kant calls “good will” [3, p.17]. Building on this, the following argument arises:
(2) Such a good will exists (at least in the case of us humans) exactly where we act “out of duty”.
(3) If we act “out of duty” in this way, then this duty can only have a very specific content – precisely the content of the moral law. [3, p.17]
Categorical and Hypothetical Imperatives
We have already seen in the introduction what this famous categorical imperative should be: Act only according to the maxim through which one can at the same time want it to become a general law. This is exactly what we basically assume for every one of our actions, just not consistently. Kant explains it as follows:
If I even think of a hypothetical imperative, I don’t know in advance what it will contain: until the condition is given to me. But if I think of a categorical imperative, I immediately know what it contains.
For since the imperative contains, besides the law, only the necessity of the maxim to be in accordance with this law, but the law contains no condition to which it was restricted, nothing remains but the generality of a law at all, to which the maxim allows the enjoyment of brought to the present moment.