the philosophical study of morality. The word is also commonly used interchangeably with ‘morality’ to mean the subject matter of this study; and sometimes it is used more narrowly to mean the moral principles of a particular tradition, group, or individual. Christian ethics and Albert Schweitzer’s ethics are examples. In this article the word will be used exclusively to mean the philosophical study. Ethics, along with logic, metaphysics, and epistemology, is one of the main branches of philosophy. It corresponds, in the traditional division of the field into formal, natural, and moral philosophy, to the last of these disciplines. It can in turn be divided into the general study of goodness, the general study of right action, applied ethics, metaethics, moral psychology, and the metaphysics of moral responsibility. These divisions are not sharp, and many important studies in ethics, particularly those that examine or develop whole systems of ethics, are interdivisional. Nonetheless, they facilitate the identification of different problems, movements, and schools within the discipline.
The first two, the general study of goodness and the general study of right action, constitute the main business of ethics. Correlatively, its principal substantive questions are what ends we ought, as fully rational human beings, to choose and pursue and what moral principles should govern our choices and pursuits. How these questions are related is the discipline’s principal structural question, and structural differences among systems of ethics reflect different answers to this question. In contemporary ethics, the study of structure has come increasingly to the fore, especially as a preliminary to the general study of right action. In the natural order of exposition, however, the substantive questions come first.
Goodness and the question of ends. Philosophers have typically treated the question of the ends we ought to pursue in one of two ways: either as a question about the components of a good life or as a question about what sorts of things are good in themselves. On the first way of treating the question, it is assumed that we naturally seek a good life; hence, determining its components amounts to determining, relative to our desire for such a life, what ends we ought to pursue. On the second way, no such assumption about human nature is made; rather it is assumed that whatever is good in itself is worth choosing or pursuing. The first way of treating the question leads directly to the theory of human well-being. The second way leads directly to the theory of intrinsic value.
The first theory originated in ancient ethics, and eudaimonia was the Greek word for its subject, a word usually translated ‘happiness,’ but sometimes translated ‘flourishing’ in order to make the question of human well-being seem more a matter of how well a person is doing than how good he is feeling. These alternatives reflect the different conceptions of human well-being that inform the two major views within the theory: the view that feeling good or pleasure is the essence of human well-being and the view that doing well or excelling at things worth doing is its essence. The first view is hedonism in its classical form. Its most famous exponent among the ancients was Epicurus. The second view is perfectionism, a view that is common to several schools of ancient ethics. Its adherents include Plato, Aristotle, and the Stoics. Among the moderns, the best-known defenders of classical hedonism and perfectionism are respectively J. S. Mill and Nietzsche.
Although these two views differ on the question of what human well-being essentially consists in, neither thereby denies that the other’s answer has a place in a good human life. Indeed, mature statements of each typically assign the other’s answer an ancillary place. Thus, hedonism, as expounded by Epicurus, takes excelling at things worth doing – exercising one’s intellectual powers and moral virtues in exemplary and fruitful ways, e.g. – as the tried and true means to experiencing life’s most satisfying pleasures. And perfectionism, as developed in Aristotle’s ethics, underscores the importance of pleasure – the deep satisfaction that comes from doing an important job well, e.g. – as a natural concomitant of achieving excellence in things that matter. The two views, as expressed in these mature statements, differ not so much in the kinds of activities they take to be central to a good life as in the ways they explain the goodness of such a life. The chief difference between them, then, is philosophical rather than prescriptive. The second theory, the theory of intrinsic value, also has roots in ancient ethics, specifically, Plato’s theory of Forms. But unlike Plato’s theory, the basic tenets of which include certain doctrines about the reality and transcendence of value, the theory of intrinsic value neither contains nor presupposes any metaphysical theses. At issue in the theory is what things are good in themselves, and one can take a position on this issue without committing oneself to any thesis about the reality or unreality of goodness or about its transcendence or immanence. A list of the different things philosophers have considered good in themselves would include life, happiness, pleasure, knowledge, virtue, friendship, beauty, and harmony. The list could easily be extended. An interest in what constitutes the goodness of the various items on the list has brought philosophers to focus primarily on the question of whether something unites them. The opposing views on this question are monism and pluralism. Monists affirm the list’s unity; pluralists deny it. Plato, for instance, was a monist. He held that the goodness of everything good in itself consisted in harmony and therefore each such thing owed its goodness to its being harmonious. Alternatively, some philosophers have proposed pleasure as the sole constituent of goodness. Indeed, conceiving of pleasure as a particular kind of experience or state of consciousness, they have proposed this kind of experience as the only thing good in itself and characterized all other good things as instrumentally good, as owing their goodness to their being sources of pleasure. Thus, hedonism too can be a species of monism.
In this case, though, one must distinguish between the view that it is one’s own experiences of pleasure that are intrinsically good and the view that anyone’s experiences of pleasure, indeed, any sentient being’s experiences of pleasure, are intrinsically good. The former is called (by Sidgwick) egoistic hedonism, the latter universal hedonism. This distinction can be made general, as a distinction between egoistic and universal views of what is good in itself or, as philosophers now commonly say, between agent-relative and agent-neutral value. As such, it indicates a significant point of disagreement in the theory of intrinsic value, a disagreement in which the seeming arbitrariness and blindness of egoism make it harder to defend. In drawing this conclusion, however, one must be careful not to mistake these egoistic views for views in the theory of human well-being, for each set of views represents a set of alternative answers to a different question. One must be careful, in other words, not to infer from the greater defensibility of universalism vis-à-vis egoism that universalism is the predominant view in the general study of goodness.
Right action. The general study of right action concerns the principles of right and wrong that govern our choices and pursuits. In modern ethics these principles are typically given a jural conception. Accordingly, they are understood to constitute a moral code that defines the duties of men and women who live together in fellowship. This conception of moral principles is chiefly due to the influence of Christianity in the West, though some of its elements were already present in Stoic ethics. Its ascendancy in the general study of right action puts the theory of duty at the center of that study.
The theory has two parts: the systematic exposition of the moral code that defines our duties; and its justification. The first part, when fully developed, presents complete formulations of the fundamental principles of right and wrong and shows how they yield all moral duties. The standard model is an axiomatic system in mathematics, though some philosophers have proposed a technical system of an applied science, such as medicine or strategy, as an alternative. The second part, if successful, establishes the authority of the principles and so validates the code. Various methods and criteria of justification are commonly used; no single one is canonical. Success in establishing the principles’ authority depends on the soundness of the argument that proceeds from whatever method or criterion is used. One traditional criterion is implicit in the idea of an axiomatic system. On this criterion, the fundamental principles of right and wrong are authoritative in virtue of being self-evident truths. That is, they are regarded as comparable to axioms not only in being the first principles of a deductive system but also in being principles whose truth can be seen immediately upon reflection. Use of this criterion to establish the principles’ authority is the hallmark of intuitionism. Once one of the dominant views in ethics, its position in the discipline has now been seriously eroded by a strong, twentieth-century tide of skepticism about all claims of self-evidence. Currently, the most influential method of justification consistent with using the model of an axiomatic system to expound the morality of right and wrong draws on the jural conception of its principles. On this method, the principles are interpreted as expressions of a legislative will, and accordingly their authority derives from the sovereignty of the person or collective whose will they are taken to express. The oldest example of the method’s use is the divine command theory. On this theory,