ABSTRACT The crux of this essay shall be an analytical expository of the deontological theory of ethics from a general perspective and from the purview of Immanuel Kant. Kant undoubtedly is one of the greatest philosophers of all time. His contribution to virtually all the spheres of philosophy is quite phenomenal. He opined that human understanding is the source of the general laws of nature that structure all our experience; and that human reason gives itself the moral law. More specifically, Kant argued that a moral action is one that is performed out of a “sense of duty”. This paper intends to take a shot at the basic premises of Kant’s ethical philosophy, the system of thought that he subscribes to in formulating his categorical imperative, some criticisms that attend his theory and finally make a critical appraisal of his approach to ethics. ETHICS AS A BRANCH OF PHILOSOPHY Ethics is also called moral philosophy. One can argue that this is the most practical and human aspect of philosophy. While one may be perplex as to the relevance of epistemological or metaphysical questions to everyday life, such perplexity does not arise in the ethical enterprise. This is because in philosophy, it is concerned with the familiar issue of morality 1. Ethics is concerned with the questions of right and wrong in human behavior. It deals with how man ought to behave in certain ways. In other words, ethics studies the reasons why certain actions are morally wrong and why other kinds of actions are morally right and commendable. Good and bad (or right and wrong) actions are known in classical moral philosophy as "virtues and vices". The British philosopher, Thomas Hobbes, define ethics or moral philosophy as "the science of virtue and vice". 2. Hence, central to ethics as a branch of philosophy is the justification of moral actions. In any discussion on ethics or society, ''man'' is central. Apart from being an individual, man is also essentially a social being. As an individual, each man is complete, independent and distinct from other men. As a social being he cannot fully live as man nor fully develop and actualize his potentials outside of fellowship with other man. It is this inability of man to, by himself, meet his existential needs and develop his potentials that led to the emergency of the state 3. Given the essence of society as a product of the cooperation between men, it is inevitable that men must interact with each other in the society. In the course of his interaction, questions about the right mode of conduct and how people ought to relate with each other arise. Attempts to answer these questions generate the primary concerns of morality and philosophy of moral (ethics) 4. In an attempt to offer a justificatory ground and moral principles for the appraisal and regulation of human action, philosophers of different epoch have postulated severally. They have developed principles and modules man ought to follow in regulating their actions and to know whether an action is right or wrong all in a bid to achieve an ideal society. These philosophers are referred to as moral philosophers. Among the moral philosophers, there exist contradictions in their beliefs and ideologies on how man ought to act and the nature of moral judgments in the society. Some argued that human action is good and just only if it brings about a desirable end regardless of the means. They are of little concern about the means; they pitch their tent on the consequence of an action. To them the end justifies the means. Those who subscribe to this school of thought are called the consequentialist and the theory is called the theory of consequentialism in ethics. Prominent in this school are J.S Mill and Jeremy Bentham with their theories of utilitarianism which is the paradigm case for consequentialism. The utilitarian philosophers would always think in terms of the consequence of any act in his/her moral judgment. There are act and rule utilitarianism but the thrust of their ideas is that moral act should produce the greatest happiness for the greatest number of people. Conversely, some philosophers opined that human action can only be appraised to either be good or bad if such act is based on duty and borne out of reason or not. Duty is what the law or rule command one to do. They are of the opinion that the consequence of an action shouldn’t takes precedence over the intention behind the action. Those in this school of thought are called the deontologist and the theory is referred to as the theory of deontologism in ethics. ETHICAL DEONTOLOGISM The term deontology comes from the Greek word deon, meaning duty. The theory of deontology states we are morally obligated to act in accordance with certain set of principles and rules regardless of outcome. In religious deontology, the principles derived from divine commandment so that under religious laws we are morally obligated not to steal, lie, or cheat. Thus deontological t