Themes & patterns

Moore argues that 'good' is a simple, indefinable quality and that attempts to define it in terms of natural properties (like pleasure or desire) commit the 'naturalistic fallacy,' which is the central error in most ethical systems.

The book rigorously distinguishes between things that are good in themselves (intrinsic value) and things that are good as means to an end (instrumental value), arguing that ethical inquiry must first identify what has intrinsic worth.

Moore explores what constitutes the 'Ideal' or 'Summum Bonum,' arguing that many different things (e.g., personal affection, aesthetic enjoyment) are good in themselves, and that the best state of affairs is a complex whole of such goods.

Moore separates ethical questions into two kinds: what is good in itself and what actions we ought to perform, asserting that right actions are those that produce the greatest amount of good, making duty a matter of causal consequences.

Moore systematically refutes the hedonistic principle that pleasure is the sole good, using the method of isolation to show that pleasure alone lacks intrinsic value and that valuable wholes often include other elements.

Moore criticizes metaphysical ethical theories (e.g., those of Kant or Hegel) that attempt to derive ethical truths from claims about the nature of reality, arguing that this also commits the naturalistic fallacy by confusing 'what is' with 'what ought to be.'

The book emphasizes the importance of clarifying questions before answering them, and establishes that fundamental ethical principles (about intrinsic good) are self-evident intuitions, while practical duties require empirical causal evidence.