The Methods of Ethics: Summary & Key Insights

In the first book, I sought to define the boundaries of ethical inquiry. Ethics, I argued, must be concerned with what ought to be done—an imperative question distinct from the descriptive sciences of psychology or sociology. It is not enough to record how people act or why they feel certain impulses; we must ask whether they act rightly. Thus, ethics aims at the rational determination of duty. It searches for principles that can guide choices whenever our desires conflict.

The term 'method' in my title signifies a systematic procedure of reasoning about right and wrong. I distinguished ethics from mere casuistry or moral rhetoric; its task is to achieve cognitive clarity. To say that one ‘ought’ to act thus and so presupposes that reason can deliver genuine justification, not simply emotional conviction. Against moral skepticism, I contended that such reasoning is possible. But against uncritical moralism, I insisted that it must be subject to philosophical scrutiny.

This opening section lays the groundwork for all that follows. I argued that moral science can be approached under three leading methods—all claiming rational status yet differing profoundly in the principles they adopt. The egoistic method appeals to self-interest; the intuitionistic relies upon self-evident moral truths; and the utilitarian measures actions by their tendency to promote general happiness. My mission was not to dismiss any prematurely but to examine each in turn as impartially as possible. By doing so, ethics itself could be clarified, for only through comparison can we understand what moral reason truly requires.

The first of these methods, egoism, begins from a seemingly undeniable truth—that each person naturally seeks his own happiness. To follow reason, it might seem we should pursue it wisely, preferring long-term satisfaction to short-lived pleasure. I called this 'rational egoism': the view that the rational end of conduct is one's own greatest good. Many thinkers, from Hobbes to Bentham, assumed that self-interest could be the bedrock of morality. Yet when I examined the matter carefully, the picture proved more complex.

Rational egoism may guide individuals effectively through life, but when two egoists conflict—each pursuing personal happiness according to reason—reason itself cannot settle the dispute without appeal to something higher. A purely egoistic basis for morality cannot generate duties toward others except insofar as helping them serves one’s own interest. Though self-love is a fact of human nature, it neither explains nor justifies the moral idea that others’ welfare has intrinsic significance. This limitation pointed to the need for another method of ethics.

Nonetheless, egoism has truth in it. The moral value of prudence, the recognition that a life of self-control and foresight leads to greater well-being than impulsive indulgence, reflects rational insight. Yet the more thoroughly we reason about self-interest, the more we encounter situations where personal benefit conflicts with the happiness of others. Here rational egoism meets its boundary: reason cannot prove that it is always best for me to act benevolently, though moral sentiment urges it. This tension between private and public good lies at the heart of ethical theory and ultimately reappears at the end of the book as the 'dualism of practical reason.'