Although many people now think differently about the connection between morality and self-interest, Plato’s attempt to argue that those who are just are in the long run happier than those who are unjust has had an enormous influence on Western ethics. Like Plato’s views on the objectivity of goodness, the claim that justice and personal happiness are linked has helped to frame the agenda for a debate that continues even today. Aristotle
Plato founded a school of philosophy in Athens known as the Academy. There Aristotle, Plato’s younger contemporary and only rival in terms of influence on the course of Western philosophy, went to study. Aristotle was often fiercely critical of Plato, and his writing is very different in style and content, but the time they spent together is reflected in a considerable amount of common ground. Thus, Aristotle holds with Plato that the life of virtue is rewarding for the virtuous as well as beneficial for the community. Aristotle also agrees that the highest and most satisfying form of human existence involves the exercise of one’s rational faculties to the fullest extent. One major point of disagreement concerns Plato’s doctrine of Forms, which Aristotle rejected. Thus, Aristotle does not argue that in order to be good one must have knowledge of the Form of the Good.
Detail of a Roman copy (2nd century bce) of a Greek alabaster portrait bust of Aristotle, c. 325 bce; in the collection of the Roman National Museum.A. Dagli Orti/©De Agostini Editore/age fotostock
Aristotle conceived of the universe as a hierarchy in which everything has a function. The highest form of existence is the life of the rational being, and the function of lower beings is to serve this form of life. From this perspective Aristotle defended slavery—because he considered barbarians less rational than Greeks and by nature suited to be “living tools”—and the killing of nonhuman animals for food and clothing. From this perspective also came a view of human nature and an ethical theory derived from it. All living things, Aristotle held, have inherent potentialities, which it is their nature to develop. This is the form of life properly suited to them and constitutes their goal. What, however, is the potentiality of human beings? For Aristotle this question turns out to be equivalent to asking what is distinctive about human beings; and this, of course, is the capacity to reason. The ultimate goal of humans, therefore, is to develop their reasoning powers. When they do this, they are living well, in accordance with their true nature, and they will find this the most rewarding existence possible.
Aristotle thus ends up agreeing with Plato that the life of the intellect is the most rewarding existence, though he was more realistic than Plato in suggesting that such a life would also contain the goods of material prosperity and close friendships. Aristotle’s argument for regarding the life of the intellect so highly, however, is different from Plato’s, and the difference is significant because Aristotle committed a fallacy that has often been repeated. The fallacy is to assume that whatever capacity distinguishes humans from other beings is, for that very reason, the highest and best of their capacities. Perhaps the ability to reason is the best human capacity, but one cannot be compelled to draw this conclusion from the fact that it is what is most distinctive of the human species.
A broader and still more pervasive fallacy underlies Aristotle’s ethics. It is the idea that an investigation of human nature can reveal what one ought to do. For Aristotle, an examination of a knife would reveal that its distinctive capacity is to cut, and from this one could conclude that a good knife is a knife that cuts well. In the same way, an examination of human nature should reveal the distinctive capacity of human beings, and from this one should be able to infer what it is to be a good human being. This line of thought makes sense if one thinks, as Aristotle did, that the universe as a whole has a purpose and that human beings exist as part of such a goal-directed scheme of things, but its error becomes glaring if this view is rejected and human existence is seen as the result of a blind process of evolution. Whereas the distinctive capacity of a knife is a result of the fact that knives are made for a specific purpose—and a good knife is thus one that fulfills this purpose well—human beings, according to modern biology, were not made with any particular purpose in mind. Their nature is the result of random forces of natural selection. Thus, human nature cannot, without further moral premises, determine how human beings ought to live.
Aristotle is also responsible for much later thinking about the virtues one should cultivate. In his most important ethical treatise, the Nicomachean Ethics, he sorts through the virtues as they were popularly understood in his day, specifying in each case what is truly virtuous and what is mistakenly thought to be so. Here he applies an idea that later came to be known as the Golden Mean; it is essentially the same as the Buddha’s middle path between self-indulgence and self-renunciation. Thus, courage, for example, is the mean between two extremes: one can have a deficiency of it, which is cowardice, or one can have an excess of it, which is foolhardiness. The virtue of friendliness, to give another example, is the mean between obsequiousness and surliness.
Aristotle does not intend the idea of the mean to be applied mechanically in every instance: he says that in the case of the virtue of temperance, or self-restraint, it is easy to find the excess of self-indulgence in the physical pleasures, but the opposite error, insufficient concern for such pleasures, scarcely exists. (The Buddha, who had experienced the ascetic life of renunciation, would not have agreed.) This caution in the application of the idea is just as well, for while it may be a useful device for moral education, the notion of a mean cannot help one to discover new truths about virtue. One can determine the mean only if one already has a notion of what is an excess and what is a defect of the trait in question. But this is not something that can be discovered by a morally neutral inspection of the trait itself: one needs a prior conception of the virtue in order to decide what is excessive and what is defective. Thus, to attempt to use the doctrine of the mean to define the particular virtues would be to travel in a circle.
Aristotle’s list of the virtues and vices differs from lists compiled by later Christian thinkers. Although courage, temperance, and liberality are recognized as virtues in both periods, Aristotle also includes a virtue whose Greek name, megalopsyche, is sometimes translated as “pride,” though it literally means “greatness of soul.” This is the characteristic of holding a justified high opinion of oneself. For Christians the corresponding excess, vanity, was a vice, but the corresponding deficiency, humility, was a virtue.
Aristotle’s discussion of the virtue of justice has been the starting point of almost all Western accounts. He distinguishes between justice in the distribution of wealth or other goods and justice in reparation, as, for example, in punishing someone for a wrong he has done. The key element of justice, according to Aristotle, is treating like cases alike—an idea that set for later thinkers the task of working out which kinds of similarities (e.g., need, desert, talent) should be relevant. As with the notion of virtue as a mean, Aristotle’s conception of justice provides a framework that requires fleshing out before it can be put to use.
Aristotle distinguished between theoretical and practical wisdom. His conception of practical wisdom is significant, for it involves more than merely choosing the best means to whatever ends or goals one may have. The practically wise person also has the right ends. This implies that one’s ends are not purely a matter of brute desire or feeling; the right ends are something that can be known and reasoned about. It also gives rise to the problem that faced Socrates: How is it that people can know the difference between good and bad and still choose what is bad? As mentioned earlier, Socrates simply denied that this could happen, saying that those who did not choose the good must, appearances notwithstanding, be ignorant of what the good is. Aristotle said that this view was “plainly at variance with the observed facts,” and he offered instead a detailed account of the ways in which one can fail to act on one’s knowledge of the good, including the failure that results from lack of self-control and the failure caused by weakness of will. Later Greek and Roman ethics