Book Review of the Groundwork of the Metaphysics of Morals

Immanuel Kant wrote the book as the introduction to his metaphysics of morals: “the search for and establishment of the supreme principle of morality” that is responsible for popularity and common understanding. The book follows vigorous and relatively simple logic – the importance of the metaphysics of morals, the deduction of his supreme principle of morality, and elevation to the metaphysics of people’s interaction with the world – to ensure that readers well understand the basis of his theory, and the critique of pure practical reason would not only be clearly explained but also explicitly understood.

The book is divided into three sections, from common rational and empirical morality to pure metaphysics of morals and finally to the critique of pure reason. In the first section, Kant argues against virtue ethics and utilitarianism that virtue ethics, of moderation in affects and passions, can become extremely evil without the basic principle of a good will while utilitarianism disregards that a good will is not good for its effects, but its volition as good in itself. By elaborating the basic principle of a good will over affects, he states the importance of creating a universal law of nature instead of empirical judgements. Besides, he also argues the significance of conforming ones’ duties from “a self-seeking purpose” because a good will is presented through fulfilling their duties. 

The second section further emphasizes why the universal law of nature comes first: practical rule “expresses more generally, but they can never justify setting aside their true original, which lies in reason, and guiding oneself by examples.” Once the practical rules cannot evade from their own conditions to fit into the whole universe, the whole world, then an a priori rule of morals should be established first. Besides unfeasible practical rules, it is also inefficient to have a mixed doctrine of morals because it cannot accurately lead to what is good and what is evil – making “the mind waver between motives that cannot be brought under any principle.” He also introduces important concepts in the second section. He suggests that the universal law of nature is a categorical imperative, representing “an action as objectively necessary of itself” without reference to other conditions. Thus, by contraction with hypothetical imperative (with reference to other actions to set up its own necessity), the categorical imperative is called the imperative of morality which represents in the necessitation of will. Therefore, to make sure there is only a single universal law of nature, there is only a categorical imperative that “act only in accordance with that maxim through which you can at the same time will that it become a universal law.” Similarly, the universal imperative of duty can go as follows: act as if the maxim of your action were to become by your will a universal law of nature.” In other words, act only upon your maxim which can be a universal law for everyone (every rational being) in the world to follow. These two propositions are of the most important thoughts in the book. Rational beings, being an end in itself, should also be treated as an end instead of a means. So, under a supreme practical ground, “act that you use humanity… always at the same time as an end, never merely as a means”; otherwise, the maxim of your action cannot be seen as universal law of nature for its opposition to humanity, the necessity in rational being itself. Every rational being must be lawgiving and at the same time accepting others’ laws (pay full participation and efforts to achieve full effect) to be thought as an end in itself. The categorical imperative, unconditional in giving laws, is the principle of the autonomy of the will. Autonomy is “the ground of the dignity of human nature and of every rational nature” since people give laws and accept laws according to their freedom, marking their capacity of reasoning. “Morality is thus the relation of actions to the autonomy of the will” as people will their maxim of actions to be universal law of nature, the universal doctrine of morality.

Section three turns from metaphysics of morals to the critique of pure reason. Kant has already elaborately stated why there should be a universal law of nature combined with a prior knowledge in above two sections. Freedom is under special law – the categorical imperative of morality – so, a free will is equivalent to a will under moral laws. Freedom is a property of all rational beings: it must be presupposed because a will of rational being must be regarded of itself as free to guarantee reason is the author of its principles. As freedom makes people rational beings in societies, there are two worlds metaphysically where these people belong to: a world of sense and a world of understanding. People who cognize themselves through sense, the appearance of their nature, belong to the world of sense where they are unable to perceive things in themselves. Wiser people who belong to the world of understanding cognize themselves through pure activity in them (“(what reaches consciousness immediately and not through affection of the senses”). The categorical imperative represents a synthetic proposition a priori due to the conglomeration of a will affected by sensible desires and a will pure and practical in itself. Freedom is only an idea of reason, whereas nature is a concept of understanding that brings the universal law into practice. In order to think reason itself as practical, it is necessary to be in the two worlds at the same time, or to say, be in the world of reason (combination of pure understanding and sensible desires).

Groundwork of the Metaphysics of Morals is the first philosophy book that I have read thoroughly. It impresses me for its prudent logical analysis of the deduction of Kant’s metaphysics of morals. Regardless of the difficulty of reading for me, I find no fallacy and no disagreement to his theory, because I do not know where I can get into to make an objection. Simply as the introduction of Kant’s metaphysics, the content the book contains has already obsessed me. I can hardly imagine how much information would contain in his critique of pure reason. Hopefully the pain of reading this book brings experience and preparation for next reading assignments.