In this short essay I would try to sketch Kantian theory of morals which was presented by this famous German philosopher in "Groundwork of the Metaphysics of Morals". Kant's moral views could also be found in his other works ("Critique of Pure Reason", "Critique of Practical Reason" and "Critique of Judgement"), but the main thought is given by himself in the "Metaphysics of Morals".

Metaphysics, for Kant, is a system of pure knowledge: it is attained a priori and involves only a priori concepts. It is unpolluted by experience, which can easily mislead us. I think that here is a place for a short explanation: long before Kant terms 'a priori' and 'a posteriori' were known to the philosophers and fixed with - respectively - analytical and synthetical phrases. Kant was the first known thinker who introduced in his "Prologomena" the concept of synthetical a priori sentences. These sentences were formulated apart from experience, but, unlike their analytical counterparts, broaden our knowledge. Every metaphysical system should be founded on such sentences.

In Kantian perspective the subject of morals, at least as we ordinary understand it, has both pure and empirical parts. The pure part contains the a priori principles of morality; the empirical part, which is called "practical anthropology", is concerned with applying these principles to conditions that can arise in experience.

"The Metaphysics of Morals" has three chapters. In the first chapter Kant's chief purpose is to discover the "first principle" of our ordinary moral judgement. In second chapter Kant attempts to locate this principle (called "the moral law") by reference to deeper philosophical considerations. In the third chapter he tries to explain why this law is bidding us although we are imperfectly rational beings. (If we would be perfectly rational we would - after finding moral law - conform our actions to it).

1) The Notion of Good Will

In the beginning Kant argues that in the scope of ordinary moral conviction we find that there's only one thing good "in or out the world" without any qualification: the good will. We could find in the whole world many good things: intelligence, wit, judgement, courage, wealth and health are good examples. But they are good only because they lead us to some aims. It is good to be healthy, because then we are free of distress or pain; it is good to be intelligent, because we can easily solve the problems. As we can clearly see these goods are qualified by something. Unfortunately sometimes they are put to bad use. Courage could help a thief to rob a house; even health - as Kant remarks - can lead us to pride and arrogance. Author of "Groundwork of the Metaphysics of Morals" is here in opposition to classical utilitarianism, in which the chief moral value is happiness. But the moral value of the world as a whole lies not only in amount of happiness it accumulates, but also in distribution of this good. So happiness isn't either good without qualification.

The moral ideal would be then possible world in which each rational being is both supremely happy and, because he is morally perfect, worthy of being supremely happy. By the way the only one, who could be morally perfect is someone having perfectly good will. The only candidate for this position is - as anyone could expect - the God himself.

2) Duty and Moral Value

After introducing the notion of good will Kant remarks:
"An action has moral value just when it is done for the sake of duty."
For him an action, which lead to happiness in deserving persons, "deserve praise and encouragement", but it does not imply, that it has moral value. One can imagine absolutely vicious action which, by the miscalculation, could lead to acceptable consequences. The vicious will is morally abominable in any case.

In this extremely rational view person who does his duty only at he cost of the painful moral struggle could be count as morally valuable. Persons who do duty because of the fortunate natural disposition are not judged morally bad; their actions are classified as legal (which is not the oppositional to moral).
So we have three types of actions:

• moral: executed from the respect for the law and against natural dispositions,
• legal: executed from the natural dispositions and in agreement with law,
• immoral: executed against the moral law.

Kant writes it in this way: "The moral value of an action is owing to the maxim on which it is based rather to its success in realizing some desired end or purpose."

Coming back to the title of the paragraph I see that I haven't explained yet the term duty. In this moral construction duty is defined as the "necessity of an action executed from respect for the law", which means that every rational being, who understands the moral law, has some duties. If he has a duties he notifies that if he would not fulfil them, he would show no respect for the moral law. His will couldn't be classified as good, so he couldn't be called a good person.

3) Maxims, the Will and the Moral Law

The concept of maxim is crucial to Kant's theory. Maxims or subjective principles connect motives with decisions to act; they take the form of the conditional sentences, like "I will do A if p" (e.g. "I would sign a book if I buy it."). The will is simply the mental ability to decide and choose from different possibilities. The good will (good without qualification) is the will to obey moral laws or to do one's duty.

Maxims are different from universally valid moral law, because they express motives that are valid for some rational beings. The universal moral law, as the name implies, is necessarily acceptable to all rational beings. So directive for all sane beings, which was 'found' by Kant in his speculations, is formulated like that: "Act only on that maxim through which you can at the same time will that it should become [or be] universal law." and is called categorical imperative.

If someone would like to know if he doesn't act against moral law, he should try to generalize his own maxim and answer if he'd like it to be used by other people. For example: someone has a maxim - 'Kill wherever it please you'. If that maxim would become universal law he would be probably killed some day. Of course formulation concerning maxims and moral law has its weak points. Let's imagine sadomasochist wishing to beat other people and be beaten by others at the same time. His maxim would pass the test of universal validation. To exclude such situations Kant introduced the 'doctrine of virtue' which have a form of such sentence: "A rational being necessarily wills the happiness of others". Also in other formulation of categorical imperative Kant says: "Act in such a way that you always treat humanity, whether in your own person or in the person of any other, never simply as means but always at the same time as an end." These additions definitely exclude the cases similar to sadomasochist's.

Recapitulation

As I noted in the beginning of this essay it is nothing more than sketch of Immanuel Kant's theory of morality. There are many publications which present close scrutiny of Kantian works - in my work I make use of "Kant's Theory of Morals" written by Bruce Aune. Quotations were taken from this book and have mainly source in English translation of "Grundlegung zur Methaphisics der Sitten" ("Groundwork of the Metaphysics of Morals") by H. J. Patton (New York, 1964).