A period inaugurated by Karl Marx's Das Kapital (1867), Charles Darwin's The Descent of Man (1871), Clerk Maxwell's Electricity and Magnetism (1873) and Friedrich Nietzsche's The Birth of Tragedy (1872) was unlikely to be devoid of intellectual ferment. The men who exerted the largest influence on social, political and religious thought during the last three decades of the nineteenth century were Marx and Darwin: but the nature of this influence was greatly affected by the changing character of scientific and social thought in general, and by the repercussions of scientific ideas upon social thought. It was also profoundly affected by the rapidly changing condition of society and government, a condition brought about by scientific inventions, industrial expansion and new forms of social and political organisation. In no other period is intellectual history more inseparable from economic and political history—an inevitable consequence of the conquests of science in both thought and action. Under the impact of Marxism and Darwinism on the one hand, of unusually fast-moving social change on the other, adherents of older political philosophies and social faiths had to modify their arguments and outlooks. Utilitarianism, idealism and positivism continued as operative schools of thought. But they survived within a new context of philosophical and religious beliefs, amid a new ethos and new material conditions: and this context coloured their whole development.

Marx's analysis of economic forces in Das Kapital was designed to be the massive underpinning of the political doctrines which he and his collaborator, Friedrich Engels, had propounded since they issued the Communist Manifesto in 1848. As the avowed ‘continuation’ of Marx's Critique of Political Economy (1859), Das Kapital presented detailed evidence of the working of the laws of dialectical materialism.