G. E. Moore

Moore was born in a London suburb to a physician, read classics at Trinity College, Cambridge, turned to philosophy at Russell's urging, and was elected a fellow in 1898. That year The Nature of Judgment attacked Bradley's idealism, holding that propositions and their objects are independent of any mind; Russell said Moore led the revolt against Hegelianism. The Refutation of Idealism (1903) analysed 'to be is to be perceived' and showed that it confused the act of sensing with the object sensed.

Principia Ethica of the same year argues that 'good' is a simple, unanalysable quality, like yellow, and that any definition of it as pleasure, the desired or the evolved commits the 'naturalistic fallacy'; the test is the 'open question argument': of any definition one can meaningfully ask 'but is it good?'. What is good in itself can be judged only by intuition, and his answer was friendship and the enjoyment of beauty. Keynes, Woolf and Strachey treated the book as scripture, and the ethics of Bloomsbury came from it.

In 1904 a shrinking inheritance took him from Cambridge, and he worked independently in Edinburgh and London for seven years, returning as lecturer in 1911, professor from 1925 to 1939, and editor of Mind from 1921 to 1947. He would stop mid-lecture to puzzle over a question again and again; students said he was the only man who really thought at the lectern. When Wittgenstein returned to Cambridge they argued often, and Moore said Wittgenstein made him feel he should not be doing philosophy.

His method was the defence of common sense. A Defence of Common Sense lists propositions he knows to be true: I have a body, it was born some years ago, the earth existed long before, and other people know such things too. Any philosophical argument against these has premises less certain than the propositions themselves. Proof of an External World (1939) raised his hands: 'here is one hand, and here is another, so at least two external things exist'; Wittgenstein's On Certainty is a meditation on that proof. Almost without ambition, he shaped the whole style of British philosophy.