The question that leads us into the study of different ethical theories concerns the reasons we have to be honest and just in circumstances that invite dishonesty or injustice without risk of disrupting social peace, tarnishing one’s reputation, or losing the goodwill of others. One thought a person who was faced with such circumstances might have is that his happiness is best served in the long run by adhering to the standards of honesty and justice. “The cash is very tempting,” he might say to himself as he looked at the wad of bills in the purse he had just found, “but it would be stupid to take it. The costs and risks involved make it likely to be more trouble than it’s worth.” The ideal that a person who thought along these lines would affirm is that of wisdom in the pursuit of happiness. In ethics, the theory that affirms this ideal is egoism. The popularity of this theory among people unfamiliar with moral philosophy suggests that no other theory has more immediate intuitive appeal. The theory, in addition, has a secure and important place in the history of ethics. Arguably, it is the theory Plato worked out in the Republic to answer Thrasymachus’ challenge to the value of justice. In any case, it certainly had other champions in the ancient world. The most noteworthy of these is the great Hellenistic philosopher Epicurus (341–271 BCE). Its place in modern philosophy is no less prominent. In the early modern period its defenders included such major thinkers as Thomas Hobbes (1588–1679) and Benedict de Spinoza (1632–1677), and it continued to receive strong and important support in the eighteenth and nineteenth centuries. Only in the twentieth century did its vitality begin to wane, although even today it still has active and influential defenders.

Let us return to the problem to which our final criticism of existentialist ethics led. Recall that it concerned whether one’s never taking anyone else’s perspective but one’s own when deliberating about what to do is rationally defensible. If Sidgwick had been successful in his attempt to reconcile utilitarianism with egoism, then he would have shown that rationality required following the Principle of Utility. And because following the principle entails taking a general view of one’s circumstances when deliberating about what to do, he would have then shown that always omitting consideration of others’ perspectives when so deliberating would not be rationally defensible. One cannot, after all, follow it without sometimes considering directly how one’s actions will affect others for good or ill. Sidgwick’s failure to reconcile utilitarianism with egoism does not mean, of course, that always omitting consideration of others’ perspectives is rationally defensible, but it does mean that showing it to be rationally indefensible requires an account of deliberation free of the quandary that stymied Sidgwick’s attempt, namely, the dualism of practical reason. The problem, then, is to find an account of deliberation on which practical reason is unified and its exercise yields principles of right action that require one to consider the perspectives of others.

Teleological conceptions of morality originated in ancient Greek philosophy. The major systems of ethics among the ancient Greeks, those of Plato and Aristotle, in particular, were teleological. So too were those of Epicurus and other thinkers who founded important schools of philosophy in the period that came after Plato and Aristotle. Deontological conceptions, by contrast, have a different origin. They derive from an ideal of universal divine law that Christianity drew from the Judaic materials from which it sprang. Christianity, to be sure, drew from the ancient Greeks as well. Its identification of universal divine laws with the laws of nature, for instance, comes from the Stoics, chiefly through Cicero (106–43 BCE). But the ideas in Christianity that yielded deontological conceptions are found in its understanding of divine laws as the laws of a supreme ruler that bind his subjects to obey him in the way that a covenant with him would bind them. These juristic ideas, which originated in Mosaic law, are the original frame for deontological conceptions. The principal text that inspired them is Paul’s statement in Romans: “When Gentiles who have not the law do by nature what the law requires, they are a law to themselves even though they do not have the law. They show that what the law requires is written on their hearts, while their conscience also bears witness and their conflicting thoughts accuse and perhaps excuse them.”

Ethics, like other branches of philosophy, springs from seemingly simple questions. What makes honest actions right and dishonest ones wrong? Why is death a bad thing for the person who dies? Is there anything more to happiness than pleasure and freedom from pain? These are questions that naturally occur in the course of our lives, just as they naturally occurred in the lives of people who lived before us and in societies with different cultures and technologies from ours. They seem simple, yet they are ultimately perplexing. Every sensible answer one tries proves unsatisfactory upon reflection. This reflection is the beginning of philosophy. It turns seemingly simple questions into philosophical problems. And with further reflection, we plumb the depths of these problems.

What interest could rational agents have in acting lawfully if not for the order, stability, and other collective goods that law brings to society? Why should it otherwise matter to them that their actions are lawful? It would matter to them, of course, if acting unlawfully made them liable to punishment. But in that case their interest in acting lawfully would not come from seeing it as a good thing. It would come, rather, from seeing it as the surest way to avoid a bad thing, something they have an interest in escaping. Yet the challenge to an ethics like Kant’s that represents lawfulness as the essence of moral action is to explain what could interest rational agents in acting lawfully regardless of how the law is enforced, regardless, that is, of whether it is enforced by threats of punishment or incentives to obey. The question, then, that confronts a defender of Kant’s ethics is why a rational agent should regard an action’s being lawful as a condition of its being reasonable to do. If he cannot give an answer to this question, the charge of excessive formalism will stick.

Our discussion of Beauvoir’s theory introduced the possibility of a tyrant who valued dominating others, not as a means to realizing other values, but rather as an ultimate end. Such a figure, you might have thought, appears only in works of fiction as the personification of evil. Yet he is a model of nobility in Nietzsche’s philosophy. Indeed, Beauvoir, in remaking existentialist ethics into a teleological theory, took Nietzsche as an arch opponent whose glorification of man’s will to power, to use his famous trope, nudged existentialism into solipsism. But in this regard she was mistaken. Nietzsche’s extolling of powerful, masterful men as the highest specimens of humanity was neither grounded in nor a springboard for solipsism. Rather it was a distinct echo of Thrasymachus’ views in the first book of the Republic. Like Thrasymachus, Nietzsche separated mankind into the few who were strong and the many who were weak, and like Thrasymachus too Nietzsche had only contempt for the latter and for their appeal to justice as a leveler that raises their fortunes and lowers the fortunes of the former. But unlike Thrasymachus, Nietzsche did not give an argument for his belief that the truly admirable man lives free of the restraints of justice and the other requirements of morality that would keep his desires for self-advancement in check. Thrasymachus’ error was to yield to Socrates’ insistence that he explain his views and submit them to an examination. His error was to put himself on the plane of reason, so to speak, where he was outmaneuvered by Socrates. Nietzsche took a different tack.

Eudaimonism was the dominant theory in ancient Greek ethics. The name derives from the Greek word ‘eudaimonia’, which is often translated as ‘happiness’ but is sometimes translated as ‘flourishing.’ Many scholars in fact prefer the latter translation because they believe it better captures the concern of the ancient Greeks with the idea of living well. This preference suggests that a useful way of distinguishing between eudaimonism and egoism is to observe, when formulating their fundamental principles, the distinction between well-being and happiness that we drew in Chapter 2. Accordingly, the fundamental principle of eudaimonism is that the highest good for each person is his or her well-being; the fundamental principle of egoism remains, as before, that the highest good for a person is his or her happiness. Admittedly, this way of distinguishing between the two theories would be theoretically pointless if the determinants of how happy a person was were the same as the determinants of how high a level of well-being the person had achieved. Thus, in particular, when hedonism is the favored theory of well-being, this way of distinguishing between eudaimonism and egoism comes to nothing. It fails in this case to capture any real difference between them. For when hedonism is the favored theory of well-being, determinations of how happy a person is exactly match the determinations of how high a level of well-being a person has achieved.

Both egoism and eudaimonism share an outlook of self-concern. They both identify the perspective from which a person judges what ought to be done as that of someone concerned with how best to promote his own good. On either theory, then, the highest good for a person is that person’s own good, whether this be his own happiness or his own well-being. Hence, on either theory, ethical considerations are understood to have the backing of reason insofar as they help to advance this good.