This article seeks to deal with morality or moral philosophy (ethics) as viewed by Kant, one of the greatest philosophers in the west. According to Kant, scientific natural science contains within itself a priori synthetic judgments without which it cannot be called "science". Synthetic a priori judgments are necessary and universal judgments upon which all sciences are based. Thus, morality (ethics) as a science contains in itself a priori synthetic judgments like 'we ought to tell the truth'. This 'ought to' dose not result from any particular facts we experience at a particular time. In other words, our judgments come from our reason, not from the objects we experience. Kant says that knowledge generally consists of a form and a substance. Substance, according to Kant, comes to our mind from the external world and form is something our minds impose upon the matter, so every human being inevitably thinks about things in accordance with the natural structure of the mind, and by virtue of these human beings can justify the necessary and universal laws in sciences.
In his view, rational knowledge is of two kinds: material and formal. Formal knowledge is what he calls formal or transcendental logic and material knowledge itself which deals with a subject is of two kinds: natural philosophy and moral philosophy (ethics). Both natural sciences and ethics have one empirical aspect and one a priori aspect. The a priori aspect of ethics is called pure ethics or moral philosophy. For Kant moral philosophy serves to justify or account for the necessity and universality of moral judgments. In other words, moral philosophy serves to make a distinction between the a priori elements and the objects of experience and to examine what accounts for the acceptance of a priori elements, i.e., how one can achieve certain binding rules or principles concerning human behavior (conduct). Kant offers certain rules and principles through which one can recognize the necessary and universal principles in ethics.