The term ethics may refer to the philosophical study of the concepts of moral right and wrong and moral good and bad, to any philosophical theory of what is morally right and wrong or morally good and bad, and to any system or code of moral rules, principles, or values. The last may be associated with particular religions, cultures, professions, or virtually any other group that is at least partly characterized by its moral outlook.

Traditionally, ethics referred to the philosophical study of morality, the latter being a more or less systematic set of beliefs, usually held in common by a group, about how people should live. Ethics also referred to particular philosophical theories of morality. Later the term was applied to particular (and narrower) moral codes or value systems. Ethics and morality are now used almost interchangeably in many contexts, but the name of the philosophical study remains ethics.

Ethics matters because

1. it is part of how many groups define themselves and thus part of the identity of their individual members,
2. other-regarding values in most ethical systems both reflect and foster close human relationships and mutual respect and trust, and
3. it could be “rational” for a self-interested person to be moral, because his or her self-interest is arguably best served in the long run by reciprocating the moral behavior of others.

Ethics, the discipline concerned with what is morally good and bad and morally right and wrong. The term is also applied to any system or theory of moral values or principles.

The origins of ethics

Mythical accounts

Introduction of moral codes

When did ethics begin and how did it originate? If one has in mind ethics proper—i.e., the systematic study of what is morally right and wrong—it is clear that ethics could have come into existence only when human beings started to reflect on the best way to live. This reflective stage emerged long after human societies had developed some kind of morality, usually in the form of customary standards of right and wrong conduct. The process of reflection tended to arise from such customs, even if in the end it may have found them wanting. Accordingly, ethics began with the introduction of the first moral codes.

Virtually every human society has some form of myth to explain the origin of morality. In the Louvre in Paris there is a black Babylonian column with a relief showing the sun god Shamash presenting the code of laws to Hammurabi (died c. 1750 BCE), known as the Code of Hammurabi. The Hebrew Bible (Old Testament) account of God’s giving the Ten Commandments to Moses (flourished 14th–13th century BCE) on Mount Sinai might be considered another example. In the dialogue Protagoras by Plato (428/427–348/347 BCE), there is an avowedly mythical account of how Zeus took pity on the hapless humans, who were physically no match for the other beasts. To make up for these deficiencies, Zeus gave humans a moral sense and the capacity for law and justice, so that they could live in larger communities and cooperate with one another.

That morality should be invested with all the mystery and power of divine origin is not surprising. Nothing else could provide such strong reasons for accepting the moral law. By attributing a divine origin to morality, the priesthood became its interpreter and guardian and thereby secured for itself a power that it would not readily relinquish. This link between morality and religion has been so firmly forged that it is still sometimes asserted that there can be no morality without religion. According to this view, ethics is not an independent field of study but rather a branch of theology (see moral theology).

There is some difficulty, already known to Plato, with the view that morality was created by a divine power. In his dialogue Euthyphro, Plato considered the suggestion that it is divine approval that makes an action good. Plato pointed out that, if this were the case, one could not say that the gods approve of such actions because they are good. Why then do they approve of them? Is their approval entirely arbitrary? Plato considered this impossible and so held that there must be some standards of right or wrong that are independent of the likes and dislikes of the gods. Modern philosophers have generally accepted Plato’s argument, because the alternative implies that if, for example, the gods had happened to approve of torturing children and to disapprove of helping one’s neighbors, then torture would have been good and neighborliness bad.

Problems of divine origin

A modern theist (see theism) might say that, since God is good, God could not possibly approve of torturing children nor disapprove of helping neighbors. In saying this, however, the theist would have tacitly admitted that there is a standard of goodness that is independent of God. Without an independent standard, it would be pointless to say that God is good; this could mean only that God is approved of by God. It seems therefore that, even for those who believe in the existence of God, it is impossible to give a satisfactory account of the origin of morality in terms of divine creation. A different account is needed.

There are other possible connections between religion and morality. It has been said that, even if standards of good and evil exist independently of God or the gods, divine revelation is the only reliable means of finding out what these standards are. An obvious problem with this view is that those who receive divine revelations, or who consider themselves qualified to interpret them, do not always agree on what is good and what is evil. Without an accepted criterion for the authenticity of a revelation or an interpretation, people are no better off, so far as reaching moral agreement is concerned, than they would be if they were to decide on good and evil themselves, with no assistance from religion.

Traditionally, a more important link between religion and ethics was that religious teachings were thought to provide a reason for doing what is right. In its crudest form, the reason was that those who obey the moral law will be rewarded by an eternity of bliss while everyone else roasts in hell. In more sophisticated versions, the motivation provided by religion was more inspirational and less blatantly self-interested. Whether in its crude or its sophisticated version, or something in between, religion does provide an answer to one of the great questions of ethics: “Why should I be moral?” (See below Ethics and reasons for action.) As will be seen in the course of this article, however, the answer provided by religion is not the only one available.

Prehuman ethics

Nonhuman behavior

Because, for obvious reasons, there is no historical record of a human society in the period before it had any standards of right and wrong, history cannot reveal the origins of morality. Nor is anthropology of any help, because all the human societies that have been studied so far had their own forms of morality (except perhaps in the most extreme circumstances). Fortunately, another mode of inquiry is available. Because living in social groups is a characteristic that humans share with many other animal species—including their closest relatives, the apes—presumably the common ancestor of humans and apes also lived in social groups. Here, then, in the social behavior of nonhuman animals and in the theory of evolution that explains such behavior may be found the origins of human morality.

Social life, even for nonhuman animals, requires constraints on behavior. No group can stay together if its members make frequent, unrestrained attacks on each other. With some exceptions, social animals generally either refrain altogether from attacking other members of the social group or, if an attack does take place, do not make the ensuing struggle a fight to the death—it is over when the weaker animal shows submissive behavior. It is not difficult to see analogies here with human moral codes. The parallels, however, go much further than this. Like humans, social animals may behave in ways that benefit other members of the group at some cost or risk to themselves. Male baboons threaten predators and cover the rear as the troop retreats. Wolves and wild dogs take meat back to members of the pack not present at the kill. Gibbons and chimpanzees with food will, in response to a gesture, share their food with other members of the group. Dolphins support other sick or injured dolphins, swimming under them for hours at a time and pushing them to the surface so they can breathe.

It may be thought that the existence of such apparently altruistic behavior is odd, for evolutionary theory states that those who do not struggle to survive and reproduce will be eliminated through natural selection. Research in evolutionary theory applied to social behavior, however, has shown that evolution need not be so ruthless. Some of this altruistic behavior is explained by kin selection. The most obvious examples are those in which parents make sacrifices for their offspring. If wolves help their cubs to survive, it is more likely that genetic characteristics, including the characteristic of helping their own cubs, will spread through further generations of wolves.

Kinship and reciprocity

Less obviously, the principle also holds for assistance to other close relatives, even if they are not descendants. A child shares 50 percent of the genes of each of its parents, but full siblings too, on the average, have 50 percent of their genes in common. Thus, a tendency to sacrifice one’s life for two or more of one’s siblings could spread from one generation to the next. Between cousins, where only 12.5 percent of the genes are shared, the benefit-to-sacrifice ratio would have to be correspondingly increased.

When apparent altruism is not between kin, it may be based on reciprocity. A monkey will present its back to another monkey, which will pick out parasites; after a time the roles will be reversed. Reciprocity may also be a factor in food sharing among unrelated animals. Such reciprocity will pay off, in evolutionary terms, as long as the costs of helping are less than the benefits of being helped and as long as animals will not gain in the long run by “cheating”—that is to say, by receiving favors without returning them. It would seem that the best way to ensure that those that cheat do not prosper is for animals to be able to recognize cheats and refuse them the benefits of cooperation the next time around. This is possible only among intelligent animals living in small, stable groups over a long period of time. Evidence supports this conclusion: reciprocal behavior has been observed in birds and mammals, the clearest cases occurring among wolves, wild dogs, dolphins, monkeys, and apes.

In short, kin altruism and reciprocity do exist, at least in some nonhuman animals living in groups. Could these forms of behavior be the basis of human ethics? There are good reasons for believing that they could. Kinship is a source of obligation in every human society. A mother’s duty to look after her children is recognized in every known society, and the duty of a father to support and protect his family is almost as widely maintained. Duties to close relatives take priority over duties to more distant relatives, but in most societies even distant relatives are still treated better than strangers.

If kinship is the most basic and universal tie between human beings, the bond of reciprocity is not far behind. It would be difficult to find a society that did not recognize, at least under some circumstances, an obligation to return favors. In many cultures this is taken to extraordinary lengths, and there are elaborate rituals of gift giving. Often the repayment must be superior to the original gift, and this escalation can reach extremes that eventually threaten the economic security of the donor. The huge “potlatch” feasts of certain Native American tribes are a well-known example of this type of situation. Many Melanesian societies also place great importance on giving and receiving very substantial amounts of valuable items.

Many features of human morality could have grown out of simple reciprocal practices such as the mutual removal of parasites from awkward places. Suppose a person wanted to have the lice in his hair picked out and was willing in return to remove lice from someone else’s hair. The person must choose his partner carefully. If he helps everyone indiscriminately, he will find himself delousing others without getting his own lice removed. To avoid this, he must learn to distinguish between those who return favors and those who do not. In making this distinction, he would be separating reciprocators from no reciprocators and, in the process, developing crude notions of fairness and of cheating. He will naturally strengthen his ties to those who reciprocate, and bonds of friendship and loyalty, with a consequent sense of obligation to assist, will result.

This is not all. The reciprocators are likely to react in a hostile and angry way to those who do not reciprocate. Perhaps they will regard reciprocity as good and “right” and cheating as bad and “wrong.” From here it is a small step to concluding that the worst of the no reciprocators should be driven out of society or else punished in some way so that they will not take advantage of others again. Thus, a system of punishment and a notion of just desert constitute the other side of reciprocal altruism.

Although kinship and reciprocity loom large in human morality, they do not cover the entire field. Typically, there are obligations to other members of the village, tribe, or nation, even when they are strangers. There may also be a loyalty to the group as a whole that is distinct from loyalty to individual members of the group. It may be at this point that human culture intervenes. Each society has a clear interest in promoting devotion to the group and can be expected to develop cultural influences that exalt those who make sacrifices for the sake of the group and revile those who put their own interests too far ahead. More tangible rewards and punishments may supplement the persuasive effect of social opinion. This is the start of a process of cultural development of moral codes.

Research in psychology and the neurosciences has thrown light on the role of specific parts of the brain in moral judgment and behavior, suggesting that emotions are strongly involved in moral judgments, particularly those that are formed rapidly and intuitively. These emotions could be the result of social and cultural influences, or they could have a biological basis in the evolutionary history of the human species; such a basis would continue to exert some influence even if social and cultural forces pulled in different directions. Some of this research, however, also indicates that people sometimes use reasoning processes to reach moral judgments that contradict their usual intuitive responses.

Anthropology and ethics

Many people believe that there are no moral universals—i.e., that there is so much variation from one culture to another that no single moral principle or judgment is generally accepted. It has already been shown that this is not the case. Of course, there are immense differences in the way in which the broad principles so far discussed are applied. The duty of children to their parents meant one thing in traditional Chinese society and means something quite different in contemporary Western societies. Yet, concern for kin and reciprocity are considered good in virtually all human societies. Also, all societies have, for obvious reasons, some constraints on killing and wounding other members of the group.

Herodotus Statue of seated man said to be Herodotus; in the Louvre, Paris.

Beyond this common ground, the variations in moral attitudes soon become more striking than the similarities. Man’s fascination with such variations goes back a long way. The Greek historian Herodotus (died 430–420 BCE) relates that the Persian king Darius I (550–486 BCE) once summoned some Greeks before him and asked them how much he would have to pay them to eat their fathers’ dead bodies. They refused to do it at any price. Then he summoned some Indians who by custom ate the bodies of their parents and asked them what would make them willing to burn their fathers’ bodies. The Indians cried out that he should not mention so horrid an act. Herodotus drew the obvious moral: each nation thinks its own customs best.

Variations in morals were not systematically studied until the 19th century, when Western knowledge of the more remote parts of the globe began to increase. In The Origin and Development of the Moral Ideas (1906–08), the Finnish anthropologist Edward Westermarck (1862–1939) compared differences between societies in matters such as the wrongness of killing (including killing in warfare, euthanasia, suicide, infanticide, abortion, human sacrifice, and dueling); the duty to support children, the aged, or the poor; forms of permissible sexual relationship; the status of women; the right to property and what constitutes theft; the holding of slaves; the duty to tell the truth; dietary restrictions; concern for nonhuman animals; duties to the dead; and duties to the gods. Westermarck had no difficulty in demonstrating tremendous diversity in what different societies considered good conduct in all these areas. More recent, though less comprehensive, studies have confirmed that human societies can and do flourish while holding radically different views about all such matters—though of course various groups within a society may do less well under some sets of beliefs than others.

As noted above, ethics itself is not primarily concerned with the description of the moral systems of different societies. That task, which remains on the level of description, is one for anthropology or sociology. In contrast, ethics deals with the justification of moral principles (or with the impossibility of such a justification). Nevertheless, ethics must take note of the variations in moral systems, because it has often been claimed that this variety shows that morality is simply a matter of what is customary and that it thus is always relative to particular societies. According to this view, no moral principle can be valid except in the societies in which it is held. Words such as good and bad just mean, it is claimed, “approved in my society” or “disapproved in my society,” and so to search for an objective, or rationally justifiable, ethics is to search for what is in fact an illusion.

One way of replying to this position would be to stress the fact that there are some features common to virtually all human moralities. It might be thought that these common features must be the universally valid and objective core of morality. This argument would, however, involve a fallacy. If the explanation for the common features is simply that they are advantageous in terms of evolutionary theory, that does not make them right. Evolution is a blind force incapable of conferring a moral imprimatur on human behavior. It may be a fact that concern for kin is in accord with evolutionary theory, but to say that concern for kin is therefore right would be to attempt to deduce values from facts (see below The climax of moral sense theory: Hutcheson and Hume). In any case, the fact that something is universally approved does not make it right. If all human societies enslaved any tribe they could conquer, and some freethinking moralists nevertheless insisted that slavery is wrong, they could not be said to be talking nonsense merely because they had few supporters. Similarly, then, universal support for principles of kinship and reciprocity cannot prove that these principles are in some way objectively justified.

This example illustrates the way in which ethics differs from the descriptive sciences. From the standpoint of ethics, whether human moral codes closely parallel one another or are extraordinarily diverse, the question of how an individual should act remains open. People who are uncertain about what they should do will not be helped by being told what their society thinks they should do in the circumstances in which they find themselves. Even if they are told that virtually all other human societies agree and that this agreement stems from evolved human nature, they may still reasonably choose to act otherwise. If they are told that there is great variation between human societies regarding what people should do in such circumstances, they may wonder whether there can be any objective answer, but their dilemma still would not be resolved. In fact, this diversity does not rule out the possibility of an objective answer: conceivably, most societies simply got it wrong. This too is something that will be taken up later in this article, for the possibility of an objective morality is one of the constant themes of ethics.