Socialism is one of the three great ideologies of modern times, along with liberalism and conservatism. All three demand that politics should not be founded on tradition, authority, or religion but on reason. However, liberals, socialists, and conservatives have disagreed for two centuries about what can be derived from reason. To put it simply, liberalism is the view that reason is found in the individual human, who should be emancipated so he or she can carry out his or her own reasonably chosen activities. Socialism is a development of this thought, since it is the view that the human should be emancipated, although collectively rather than individually, for the reason that each human is constituted by his existence in society. And conservatism – odd as it may sound – is a further development of this thought, since it is the view that emancipation is impossible either individually or collectively without a reasoned recovery of the very traditions, authorities, and religions from which reason seems to have emancipated us. Socialists tend not to take conservatives seriously: they were, and are, concerned more to criticise liberals. Either they extend liberalism until it includes socialist recognitions or they dismiss liberalism because it excludes them. These two different attitudes constitute the ambivalence of socialism, which has half the time been for reform and half the time been for revolution. They also constitute the ambivalence of Shaw's socialism.

Shaw is perhaps the greatest socialist that England (or Ireland) has ever produced. Henry Mayers Hyndman and William Morris, the founders of two of the great socialist parties in England, considered him their equal; and he was responsible, along with Sidney Webb, for much of the success of the third, the Fabian Society. He edited the first classic work of socialism in English, Fabian Essays in Socialism, in 1889. His telegraphic address in the 1890s was simply ‘Socialist, London’. He argued for more than sixty-five years that a socialist sensibility was fundamental. Until at least the 1960s there is no question that he was the most read socialist in the English language. He was far more influential than Marx. Yet he was not an originator. He was not of the First International, which under Marx had attempted to establish socialism as a cause, but of the Second International, which expected it to triumph in the modern state.