From Natural Law To Moral Law

In Kant’s moral philosophy, the moral law is one of most important concepts. Being the highest principle in the moral world, it is the key to understand Kant’s moral philosophy and even the foundation of his whole practical philosophy. As a research on "the individualist natural law in its final, highest form" this thesis includes two main sections, it starts with the origin of natural Jaw and its development with its impact on Kant. The second section is mainly a research on Kant’s moral law based on his works. The first main section starts with the Sophists’debates between physis and nomos and the logos of Heraclitus which originate the natural law theory, then theories of the naturalistic natural law in Ancient Greek and Ancient Rome, of theological natural law in Medieval Ages, of modern rationalism natural law display the development from natural law to moral law. which has its impact on Kant. The second main section have three parts. The first part starts with the distinction between norm and law, and the necessity of law in universal morality. And to understand the concept of moral law in two books, namely. Foundations of the Metaphysics of Morals is mainly through the concept of duty and the categorical imperative and its three expressions and Critique of Practical Reason is through the reasoning and property of moral law. The second part is about how the moral law could be possible, which mainly refers to the relation between moral law and freedom. Freedom, as an idea of reason, is the premise of the existence of moral law; while it is through moral law that we realize freedom. The awareness of Kant’s preparation for his moral philosophy in his first Critique is also necessary. This part also includes the duality theory as a solution to the circular reasoning. And in autonomy, which is the highest law in morality, combines moral law and freedom. The third part is about how the moral law could be practiced, in reality. It includes moral law and the moral feeling caused by the former function as motivation of practical reason, moral postulations, the good will and steps in Methodology, to make person as the subject of practical reason keep the endeavor in real world, which is trying to make the norm to which he conducts can also become universal law.