In moral philosophy, deontological ethics or deontology () is the normative ethical theory that the morality of an action should be based on whether that action itself is right or wrong under a series of rules and principles, rather than based on the consequences of the action. It is sometimes described as duty-, obligation-, or rule-based ethics. Deontological ethics is commonly contrasted to utilitarianism and other consequentialist theories, virtue ethics, and pragmatic ethics. In the deontological approach, the inherent rightfulness of actions is considered more important than their consequences.
The term deontological was first used to describe the current, specialised definition by C. D. Broad in his 1930 book, Five Types of Ethical Theory. Older usage of the term goes back to Jeremy Bentham, who coined it prior to 1816 as a synonym of dicastic or censorial ethics (i.e., ethics based on judgement). The more general sense of the word is retained in French, especially in the term code de déontologie (ethical code), in the context of professional ethics.
Depending on the system of deontological ethics under consideration, a moral obligation may arise from an external or internal source, such as a set of rules inherent to the universe (ethical naturalism), religious law, or a set of personal or cultural values (any of which may conflict with personal desires).
Deontological philosophies
There are numerous formulations of deontological ethics.
Kantianism
thumb|[[Immanuel Kant|right]]
Immanuel Kant's theory of ethics is considered deontological for several reasons. First, Kant argues that in order to act in the morally right way, people must act from duty (). Second, Kant argued that it was not the consequences of actions that make them right or wrong, but the motives of the person who carries out the action.
Kant's first argument begins with the premise that the highest good must be both good in itself and good without qualification. Something is "good in itself" when it is intrinsically good; and is "good without qualification" when the addition of that thing never makes a situation ethically worse. Kant then argues that those things that are usually thought to be good, such as intelligence, perseverance, and pleasure, fail to be either intrinsically good or good without qualification. Pleasure, for example, appears not to be good without qualification, because when people take pleasure in watching someone suffer, this seems to make the situation ethically worse. He concludes that there is only one thing that is truly good: