Kant states (38,) “act as if the maxim of thy action were to become by thy will a universal law of nature”. This “categorical imperative” forms the basis of his book, Fundamental Principles of the Metaphysics of Morals. Though at times his writing is confusing Kant lays out his logic as to what a categorical imperative is. Kant divides the book into three sections. The first explains the transition from everyday moral beliefs to the philosophy of those morals. The transition from popular moral philosophy to the metaphysics of morals is explained in Section II.
Kant ends the book explaining how the metaphysics of morals is seen in everyday moral beliefs. In essence he forms a circle of reason, from common morals to philosophy, philosophy to metaphysics and metaphysics back to common morals. In the Introduction Marvin Fox explains three things to pay attention to when reading The Metaphysics of Morals. First, the book is Kant’s second major ethical work and to fully understand it you need to read The Critique of Pure Reason. Next, Metaphysics is not a guide for a complete moral philosophy; it provides the foundation for a moral philosophy.
Third, Kant creates many of his own technical terms, which can be confusing. Kant has two purposes in the Preface. First, he explains where the idea of morality fits into the three sciences, Physics, Ethics and Logic, of Greek philosophy. Morality the “laws by which everything out to happen”(Kant, 3) is the rational part of ethics. Kant is also careful to differentiate between rational and empirical laws. To Kant, morality can never be based on experience; it is always a priori. Morality exsisted before any event took place.
Kant, next, asks the question “Whether it is not of the utmost necessity to construct a pure moral philosophy” (5). Kant provides two reasons to study the metaphysics of morals. First, to understand a priori morals we must investigate their course. Second, morals may be corrupted if we fail to understand and estimate them correctly. Section 1 begins with the idea that “the only thing absolutely good is a good will”(11). According to Kant acts of courage and perseverance can be negative if a dubious idea is driving them. Kant uses “Duty” as an example of good will but provides three qualifications.
For an action to have moral worth it must be done from duty. He is careful to distinguish “three forms of duty; “from duty”, “conforming to duty” and “as duty requires” (15). A morally good action is not based on anything or done out of want for any object or inclination. It is performed simply because it is. For example, a man rescues a cat from a tree because he knows there is a reward offered. The man performs the act for a monetary purpose. An act driven by any possible reaction can not be based on “good will”. Good will is “good in itself” (12).
In Section II Kant provides an in-depth explanation of what a “categorical imperative” is. He first defines an imperative as a “command that is obligatory for a will” (30). In other words it is something we ought to do. He goes on to differentiate the two kinds of imperatives, hypothetical and imperative. An action based on a hypothetical imperative is done for the result while a categorical action is performed for itself. There are also three principles that make up the imperatives. The hypothetical imperative is made up of the “rules of human skills” and the “counsels of prudence” (34).
Both principles are subjective because they are based on a purpose, be it a job or happiness. The “Law of Morality”, or the laws that ought to govern human behavior, is the categorical imperative’s only principle and according to Kant the only theorem that deserves an explanation. Though Kant uses Duty as an example the categorical imperative has no real example. The categorical imperative is carried out for it’s own sake and any example would be tainted. Kant even goes on to state that any “empirical evidence of a moral law is highly prejudice to the purity of the moral law” (43)
Kant next introduces the idea of the “Kingdom of Ends” (50) Stated simply, humans are members of a kingdom that is governed by one law which encourages them to treat themselves and others as “ends in themselves” (50). In the kingdom everything either has value or dignity (51). Something with value can be replaced by anything else while something of dignity has an intrinsic value that can not be replaced. Humans, as rational creatures, are priviledeged to be members of the Kingdom of Ends and should strive to find the dignity of the Kingdom. This is the only reason Kant provides for people to follow the categorical imperative.