It is sometimes described as "duty" or "obligation" based ethics, because deontologists believe that ethical rules "bind you to your duty". The term 'deontological' was first used in this way in 1930, in C. D. Broad's book, Five Types of Ethical Theory.
Deontological ethics is commonly contrasted with consequentialist or teleological ethical theories, according to which the rightness of an action is determined by its consequences. However, it is also important to note that there is a difference between deontological ethics and moral absolutism. Deontologists who are also moral absolutists believe that some actions are wrong no matter what consequences follow from them. Immanuel Kant, for example, famously argued that it is always wrong to lie – even if a murderer is asking for the location of a potential victim. Deontologists who are not moral absolutists, such as W.D. Ross, hold that the consequences of an action such as lying may sometimes make lying the right thing to do. Kant's and Ross's theories are discussed in more detail below.
[Theories] which hold that there is some special connexion between [Moral Obligation and Moral Value]....might take the following forms. The concepts of obligation are fundamental and the concepts of value are definable in terms of them. Thus it might be held that the notion of fittingness is fundamental, and that "X is intrinsically good" means that it is fitting for every rational being to desire X. Such theories might be called Deontological. The concepts of value are fundamental, and the concepts of obligation are definable in terms of them. Such theories may be called Teleological. E.g., it might be held that "X is a right action" means that X is likely to produce at least as good consequences as any action open to the agent at the time. (Bold print not in original)Thus, the term 'deontological' picked out the set of ethical theories that are based on the idea that an action's being right or wrong is basic, and whether a situation is good or bad depends on whether the action that brought it about was right or wrong. To illustrate, imagine that someone can bring it about that nobody in the world suffers from starvation. However, to do so they would have to act in a way that was morally wrong. Perhaps, they would have to kill everyone currently living on land that could not support agriculture. A deontologist would state that the way that the end to starvation was brought about would mean that the 'world without starvation' was a bad state of affairs.
A teleologist, on Broad's use of the term, explains the rightness of actions in terms of the goodness of the state of affairs that occurs because of that action. If some action genuinely brings about greater good in the world, then it is a right action, and this rightness is independent of the nature of the action or the intentions of the person carrying out the action. Broad points out that on this understanding of the distinction between 'deontological ethics' and 'teleological ethics', not all utilitarians are teleologists:
'Utilitarianism, in some of its forms, would be an example of [teleological ethics]. But [[Henry Sidgwick|[Henry] Sidgwick]], though a Utilitarian, definitely rejects the view that "right" means "conducive to good".'
The most famous deontological theory of ethics is that of the German philosopher Immanuel Kant. However, the Divine Command Theory, also known as 'theological volunterism', is a form of deontological ethics, and a number of modern philosophers have also developed deontological ethical theories.
Kant's argument that to act in the morally right way, one must act from duty, begins with an argument 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 '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 to not be good without qualification, because when people take pleasure in watching someone suffering, this seems to make the situation ethically worse. He concludes that there is only one thing that is truly good:
Nothing in the world—indeed nothing even beyond the world—can possibly be conceived which could be called good without qualification except a good will.Kant then argues that the consequences of an act of willing cannot be used to determine that the person has a good will; good consequences could arise by accident from an action that was motivated by a desire to cause harm to an innocent person, and bad consequences could arise from an action that was well-motivated. Instead, he claims, a person has a good will when he or she 'acts out of respect for the moral law'. People 'act out of respect for the moral law' when they act in some way because they have a duty to do so. So, the only thing that is truly good in itself is a good will, and a good will is only good when the willer chooses to do something because it is that person's duty. Thus, according to Kant, goodness depends on rightness.
Kant's three significant formulations of the categorical imperative are:
[Utilitarianism] seems to simplify unduly our relations to our fellows. It says, in effect, that the only morally significant relation in which my neighbours stand to me is that of being possible beneficiaries of my action. They do stand in this relation to me, and this relation is morally significant. But they may also stand to me in the relation of promisee to promisor, of creditor to debtor, of wife to husband, of fellow countryman to fellow countryman, and the like; and each of these relations is the foundation of a...duty....Ross's pluralism is also apparent in this quote. He argues that there are seven right making features of moral action:
He called these prima facie duties, because when a person tries to decide how to act, each of these duties need to be taken into consideration when deciding which duty should be acted upon. When more than one of these 'duties' applies to a person in some situation, only one should be acted upon. Assume, for example, that I promise to watch a movie with a friend. I now have a prima facie duty to go with her to watch the movie. However, on my way to pick my friend up, I see a car accident. The person who was clearly in the wrong insists that it is the innocent person's fault. I now have a prima facie duty of justice to wait for the police to arrive at the accident and report what I saw. What is my duty? Ross would probably say that the duty of justice trumped the duty of promise-keeping in this instance. I can, after all, explain the situation to my friend, and make it up to her somehow. In another situation, however, the duty of promise-keeping may be more significant than the duty of justice.
Frances Kamm's 'Principle of Permissible Harm' is an effort to derive a deontological constraint which coheres with our considered case judgments while also relying heavily on Kant's Categorical Imperative. The Principle states that one may harm in order to save more if and only if the harm is an effect or an aspect of the greater good itself. This principle is meant to address what Kamm feels are most people's considered case judgments, many of which involve deontological intuitions. For instance, Kamm argues that we believe it would be impermissible to kill one person to harvest his organs in order to save the lives of five others. Yet, we think it is morally permissible to divert a runaway trolley that would otherwise kill five innocent and immobile people onto a side track where one innocent and immobile person will be killed. Kamm believes the Principle of Permissible Harm explains the moral difference between these and other cases, and more importantly expresses a constraint telling us exactly when we may not act to bring about good ends—such as in the organ harvesting case.
In 2007, Kamm published a book that presents new theory that incorporates aspects of her 'Principle of Permissible Harm', the 'Doctrine of Productive Purity'. Like the 'Principle of Permissible Harm', the 'Doctrine of Productive Purity' is an attempt to provide a deontological prescription for determining the circumstances in which people are permitted to act in a way that harms others.
Many Act or Case utilitarians offer critiques of deontology as well as Rule Utilitarianism. Jeremy Bentham, an early utilitarian philosopher, criticized deontology on the grounds that it was essentially a dressed-up version of popular morality, and that the unchanging principles that deontologists attribute to natural law or universal reason are really a matter of subjective opinion. John Stuart Mill, who lived in 19th century Britain, argued that deontologists usually fail to specify which principles should take priority when rights and duties conflict, so that deontology cannot offer complete moral guidance.
Further, Mill argued in the opening pages of his book Utilitarianism that the Categorical Imperative that Kant had formulated to support the duties he had argued as categorical in fact used consequential logic; if the ends of a formulated maxim logically supported the maxim, that is, the maxim if universalised created a theoretical world that could exist and would be beneficial to society, then the maxim could be offered as a rule under which society should live. Mill criticised Kant for avoiding saying what the Imperative reduced to - the ends justify the means, a primary tenet of consequentialism - and thus using it to come to the opposite conclusion.
Shelly Kagan, notes in support of Mill and Bentham that under deontology, individuals are bound by constraints (such as the requirement not to murder), but are also given options (such as the right not to give money to charity, if they do not wish to). His line of attack on deontology is first to show that constraints are invariably immoral, and then to show that options are immoral without constraints.
Another, unrelated critique of deontological ethics comes from aretaic theories, which often maintain that neither consequences nor duties but "character" should be the focal point of ethical theory. The ancient Greek philosopher Aristotle, for example, sought to describe what characteristics a virtuous person would have, and then argued that people should act in accordance with these characteristics.