G. E. Moore

Key ideas

1. Good is indefinable. Moore argued in Principia Ethica that good is a simple notion, like yellow, and cannot be defined in terms of anything else. For any proposed definition, such as pleasure, it remains an open question whether the thing defined is good.
2. The naturalistic fallacy. His name for the mistake of identifying the simple notion good with some other notion. He found it in hedonism and in appeals to evolution, and held that it leaves ethical principles without any valid reason behind them.
3. Intrinsic value and organic unities. Some things are good in themselves, and the value of a whole need not equal the sum of the values of its parts. Consciousness of a beautiful object is of great value, though the object unobserved has comparatively little.
4. Ideal consequentialism. An act is right when it produces no less good than any alternative. Moore named personal affection and aesthetic enjoyment as the greatest goods we can imagine.
5. Refuting idealism. In 1903 Moore attacked the thesis that to be is to be perceived, insisting that an experience of blue is distinct from the blue it is an experience of.
6. Common sense and the external world. Moore claimed to know with certainty a list of common-sense truisms, and in 1939 offered a proof that external things exist: here is one hand, and here is another.
7. Moore's paradox. It is absurd to assert that it is raining and add that one does not believe it, although the sentence could be true. The puzzle concerns what an assertion expresses and requires of the speaker.

George Edward Moore (1873–1958) was an English philosopher at Cambridge who, with Bertrand Russell, led the revolt against British idealism that gave rise to analytic philosophy. He is remembered for three things: the argument that good cannot be defined, the defence of common sense against philosophical doubt, and a puzzle about belief now called Moore’s paradox.

Born in Upper Norwood, south London, he studied classics and then philosophy at Trinity College, Cambridge, from 1892. He was a Cambridge Apostle from 1894 to 1901 and a friend of the Bloomsbury circle, though he never joined it. He edited Mind from 1921, held the chair of Mental Philosophy and Logic from 1925 until 1939, when Ludwig Wittgenstein succeeded him, and died in Cambridge in 1958.

Why did Moore say that good cannot be defined?

In Principia Ethica (1903) Moore asked what good means and gave a deliberately disappointing answer: “good is good, and that is the end of the matter.” It is, he said, a simple notion, like yellow, which cannot be explained to anyone who does not already know it.

His main argument is the open question argument. Take any proposed definition, for example that good is what we desire to desire, and ask whether what we desire to desire is good. Moore held that the question stays intelligible and open, which it could not if the two phrases meant the same. He called the mistake of identifying good with some other notion the naturalistic fallacy, and found it in the hedonism of Bentham and in appeals to evolution.

The best-known reply is that two terms can pick out one property without meaning the same, so a question can stay open even when an identity is true. Even so, the argument shaped metaethics: non-naturalist moral realists built on it, and the emotivism of A. J. Ayer grew partly from the same dissatisfaction with naturalism. Moore’s own view was a version of intuitionism: the basic judgements of what is good are self-evident, though he said he was not an Intuitionist “in the ordinary sense”.

What did Moore think is valuable?

Moore was a consequentialist: an act is right when it produces no less good than any alternative. What is good in itself? “Personal affections and aesthetic enjoyments”, he wrote, “include all the greatest, and by far the greatest, goods we can imagine.” He added that “The value of a whole must not be assumed to be the same as the sum of the values of its parts”: to be conscious of a beautiful object is of great value, while the same object with no one aware of it has comparatively little.

How did Moore answer the sceptic?

Moore began by rejecting idealism. In “The Refutation of Idealism” (1903) he attacked the doctrine that to be is to be perceived, and insisted that an experience of blue differs from the blue it is an experience of.

In “A Defence of Common Sense” (1925) he listed truisms that he claimed to know with certainty, among them that a living human body exists which is his own. In “Proof of an External World” (1939) he held up his hands and said, “Here is one hand”, and then, gesturing with the other, “and here is another”. Hands are external things, so external things exist. The argument is valid, he held, and its premise is known more surely than any premise a sceptic could offer against it.

Critics ask whether the proof begs the question, and the debate continues in epistemology. Wittgenstein’s last notebooks, published as On Certainty (1969), start from Moore’s claims to know such things.

What is Moore’s paradox?

It is the oddity of asserting something like “It is raining, but I do not believe that it is raining.” The sentence could be true, since it can rain while the speaker does not believe it, yet it is absurd to say. Moore was the first to note this, and it bears on what an assertion expresses and requires of the speaker, a question taken up in debates about the knowledge norm of assertion.

What was his influence?

His influence came through arguments more than doctrine. With Russell he began to de-emphasise the idealism then prevalent in Britain, and in Principia Ethica he named his teacher Henry Sidgwick as the only ethical writer who, so far as he knew, had clearly recognised that good is indefinable. Lectures of 1910–11, published as Some Main Problems of Philosophy (1953), introduced the term sense-datum. Wittgenstein and analytic philosophy took the argument on from there.

UGC NET Unit 6 names his refutation of idealism, defence of common sense and proof of an external world, and UPSC Philosophy Paper I groups him with Russell and the early Wittgenstein; see the UGC NET guide and the UPSC guide.

Reading Moore

Begin with Principia Ethica, free at Project Gutenberg: Chapter I sets out the argument about good, and the Preface argues that philosophers go wrong by answering questions before discovering exactly what question they are asking. Then read “The Refutation of Idealism”, the first essay in Philosophical Studies, also free. “A Defence of Common Sense” and “Proof of an External World” are in neither volume; look for them in a university library.