G.E. Moore Quote on the Naturalistic Fallacy: The Good Is Indefinable

Quote

"The question, 'What is good?' is the most fundamental question in all ethics, and the good is indefinable." — G.E. Moore, Principia Ethica (1903)

Author

G.E. Moore (1873–1958) was a British philosopher and a founder of analytic philosophy and of metaethics. Principia Ethica is his most famous work and a landmark of twentieth-century ethics.

Source

The quotation is drawn from the opening chapters of Principia Ethica, where Moore states that "good" is the fundamental notion of ethics and that it is simple, unanalyzable, and indefinable.

Context

Moore begins Principia Ethica by asking what "good" means. He argues that "good" is a simple, non-natural property — like "yellow" in the sense that it cannot be defined by analysis, though unlike yellow it is not a natural property. Anyone who tries to define good in terms of a natural property — pleasure, say, or the satisfaction of desire — commits the naturalistic fallacy. Moore's open question argument exposes the fallacy: for any proposed definition of good, we can meaningfully ask whether the thing so defined is itself good, and so the definition fails to capture the term. This defense of the irreducibility of the good is a cornerstone of moral realism.

Meaning

The quotation carries Moore's central thesis: the good is indefinable, and the question of what is good is the most fundamental question of ethics. The point is not that we cannot recognize good things — Moore thinks we know goodness by intuition — but that "good" cannot be reduced to or explained by anything else. The naturalistic fallacy is the mistake of confusing the good with whatever natural property it is supposed to accompany. The quotation matters because it reshaped ethics into a discipline concerned with the very meaning of moral terms, and it grounds a moral realism that takes the good to be an objective fact. This makes it a key reference point in the Ethics & Wisdom collection.

Related Wisdom

The quotation grounds Moore's metaethical account of ethics and morality, and it connects to the wider wisdom tradition's question of what makes a good life genuinely good.