During the mid-nineteenth century, the Enlightenment tradition expanded as artists and thinkers sought to examine society with scientific objectivity. In the arts this effort took the forms of realism and naturalism. Reacting against the Romantic emphasis on emotion and the inner life, realist painters such as Courbet represent the empirical world accurately and dispassionately, favoring subjects drawn from everyday life. Preferring prose fiction and drama to lyric, realist writers across Europe-from Gaskell in Britain and Flaubert in France to Tolsoy and Chekov in Russia-scrutinized social relations, often exposing the hypocrisies and abuses that caused suffering. Pioneered by Zola, naturalism extended realism by examining the structures of cause and effect that determined human behavior. Both movements reflected the increasingly scientific, secular outlook of Western civilization.

Philosophy and science also exemplified this trend. Founded by Comte and developed by Durkheim and Buckle, positivism rejected abstract metaphysics, using the methods of scientific inquiry to study history and society. Scientists including Dalton, von Helmholtz, Mendeleev, and Pasteur made important contributions to physics, chemistry, and biology. Darwin's theory of evolution presented a comprehensive biological account of the organic world that challenged traditional Christianity. Rejecting Enlightenment humanism and Christian humanity, the Social Darwinists applied this theory to society, using them to justify racism, imperialism, ruthless economic competition, and militarism. Equally challenging to orthodox Christianity were the critical biblical scholarship of Strauss, the philosophies of Feuerbach and Kierkegaard, and the liberal theology of the catholic modernists.

During this period political thought, both radical and moderate, concerned itself with the abuses of industrial-capitalist society. Marx's materialist revision of Hegel owed much to the Enlightenment scientific outlook. However, his account of the economic foundation of history, and his prophetic vision of the downfall of bourgeois capitalism constituted a secular faith. Similarly hostile to capitalism, anarchism envisioned a stateless society of peasants and artisans emerging from the violent overthrow of all government. During this period, liberalism gradually gave up its commitment to extreme laissez-faire economics and sought to address the abuses of industrialism. British liberals such as Mill and the circle of Thomas Green argued that the state must intervene in society to ensure that all citizens can truly enjoy the fruits of liberty. Consequently, these thinkers called for the expansion of suffrage, tolerance of all viewpoints, and social legislation on behalf of the poor. Spencer vigorously argued against such state action, advocating extreme laissez faire and liberal individualism.

Feminism emerged during these decades as a significant movement. Building upon the earlier ideas of de Gouges, Wollstonecraft, and Marinteau, feminists of this period, including the Grimkés and Taylor, called for the extension of liberal rights and freedoms to women. Although these activists faced deep-seeded male prejudices, they did gain the support of some prominent men, such as Bentham, Thompson, and Mill. The feminist struggle continued in several countries through the nineteenth century and into the twentieth.