Principia Ethica — A Reader’s Guide

The Naturalistic Fallacy and the Indefinability of Good

Moore devotes the opening chapters to establishing that 'good' is a simple, non-natural property that cannot be analyzed or defined in terms of any natural object or property. He argues that any attempt to equate 'good' with pleasure, desire, or any empirical quality commits the naturalistic fallacy. This fallacy, he contends, underlies the errors of hedonism, utilitarianism, and evolutionary ethics. Moore illustrates his point by insisting that even if we could identify what things are good, the question 'Is this thing good?' remains open and distinct from any factual description. The property of goodness, he maintains, is known only through intuition—a direct, self-evident apprehension that cannot be proved or disproved by empirical evidence.

Hedonism and Its Internal Contradictions

In Chapter III, Moore subjects hedonism—the view that pleasure is the sole good—to rigorous criticism. He distinguishes between egoistic hedonism (my own greatest pleasure is the sole good) and universalistic hedonism or utilitarianism (the greatest pleasure of all is the sole good), arguing that these two positions are not merely different but strictly contradictory. If hedonism is true, egoism cannot be, and vice versa. Moore points out that Sidgwick, a leading exponent of hedonism, fails to recognize this contradiction. Moreover, Moore argues that even if hedonism were true, the utilitarian end would not be the best conceivable, but only the best possible for us to promote. He concludes that the refutation of hedonism follows from the more fundamental error of trying to define 'good' in terms of pleasure.

Metaphysical Ethics and the Reality of Non-Natural Objects

Chapter IV addresses metaphysical ethics—theories that derive ethical conclusions from metaphysical premises, as seen in the works of the Stoics, Spinoza, Kant, and Hegelian writers. Moore credits metaphysicians with recognizing that not everything that exists is a natural object; they have drawn attention to entities such as numbers and truths that do not exist in time. However, he argues that they mistakenly treat 'good' as if it were a metaphysical entity that can be inferred from metaphysical truths. Moore insists that goodness itself does not exist in time, but the things that are good can exist. He uses the example of arithmetic truths—'Two and two are four'—to illustrate that such truths do not exist yet are meaningful. This distinction, he claims, is essential for understanding the unique status of ethical propositions.

Readers approaching Principia Ethica will benefit from attending closely to Moore's repeated insistence on clear question-asking. The book is structured as a series of critical examinations of rival theories, each evaluated against the standard of whether it respects the indefinability of 'good.' Moore's prose is precise and argumentative, often proceeding by careful distinctions and refutations. The work rewards patience with its analytical rigor, even as it challenges many common assumptions about the foundations of morality.