Book: Principia Ethica

Overview
Principia Ethica (1903) by George Edward Moore is a foundational work in modern moral philosophy that reshaped debates about the nature of value and the method of ethical inquiry. Moore insists that "good" is a simple, unanalyzable property that cannot be reduced to or identified with natural characteristics such as pleasure, desire satisfaction, or biological facts. The book combines careful conceptual analysis, appeals to common moral intuitions, and a defense of a form of utilitarianism that treats multiple kinds of intrinsic value as morally relevant.

Good as a Simple, Non-Natural Property
Moore's central claim is that the term "good" denotes a non-natural, simple quality that resists definition in natural terms. He warns against what he dubs the "naturalistic fallacy": the mistake of equating goodness with any natural property. According to Moore, every attempted naturalistic definition of "good", for example, "good is pleasure" or "good is what people desire", fails because it overlooks the distinctive, indefinable character of value. This conclusion rests on an insistence that philosophical analysis must respect the logical form of evaluative language, and that some predicates do not permit reduction to empirical descriptions.

The Open-Question Argument
Moore advances the open-question argument to show that naturalistic definitions of goodness are inadequate. For any proposed naturalistic analysis N of "good," one can meaningfully and sensibly ask, "Is N good?" If the identification were correct, the question would be tautological or closed; instead the question remains open and informative. This argumentative move aims to demonstrate that no empirical or descriptive account can capture the essence of "good," because the evaluative concept carries a normative import that eludes naturalistic paraphrase.

Ideal Utilitarianism and Value Pluralism
Although Moore rejects simple hedonism, he favors a form of utilitarianism, often called "ideal utilitarianism", that treats the right action as that which produces the best overall state of affairs. He argues that multiple things can be intrinsically good, including elements like aesthetic experience, intellectual achievement, and personal relationships, alongside pleasure. Moral judgment therefore requires balancing these intrinsic goods rather than reducing them to a single natural measure. This pluralistic view preserves a consequentialist structure while recognizing the richness of what might count as intrinsically valuable.

Intuitionism and Moral Knowledge
Moore defends an epistemology of moral intuition: certain moral truths are known directly through intellectual perception rather than by empirical investigation or inference from natural facts. These "intuitions" provide immediate, non-inferential awareness of value that grounds ethical theorizing. Moore's appeal to intuition aims to secure ethical knowledge while respecting the non-natural character of goodness. He acknowledges that intuitions require cultivation and careful reflection, but treats them as a legitimate and central source of moral insight.

Influence and Legacy
Principia Ethica profoundly influenced 20th-century meta-ethics by introducing the language and problems, non-naturalism, the naturalistic fallacy, and the open-question argument, that dominated later debates. It helped precipitate analytic philosophy's focus on conceptual clarification and inspired both defenders of non-natural value and critics who sought naturalist alternatives or emotivist readings of ethics. While Moore's intuitionism and non-naturalism have been contested, his insistence on careful analysis of evaluative language and his pluralistic account of intrinsic goods continue to shape contemporary discussions about the nature of value and the methods appropriate to ethical theory.