I am very much honoured to have been asked to make the closing speech at this Conference. Since this is the first time for over fifty years that a philosophical congress of this scope has been held in England, I hope that you will think it suitable for me to devote my lecture to the revival of the empiricist tradition in British philosophy during this century. I shall begin by examining the contribution of the Cambridge philosopher G. E. Moore. Though he first owed his fame to his book Principia Ethica (Moore, 1903) regarded as a work of genius by the Cambridge Apostles and their associates in Bloomsbury, who did not venture to question Moore's mistaken view of ‘good’ as an unanalysable non-natural quality, his reputation now chiefly rests on his subsequent defence of common sense.