During the early nineteenth century, several movements and ideologies developed in response to the Enlightenment and French Revolution. One of these was Romanticism. Rejecting Enlightenment rationalism as soulless and inhumane, Romantic artists valued individual imagination, spontaneous emotion, and the inner life. The Romantics also denounced the philosophes' mechanistic view of the universe, seeking instead mystical union with nature that was suffused with God's presence. Laying the foundations of modern historical scholarship, the Romantics saw history as composed of historical periods, each of which possessed its unique qualities and spirit. Romanticism made possible most of the major cultural trends of the later nineteenth and twentieth centuries, trends ranging from Romantic music to the extreme nationalism that culminated in fascism. Although Romanticism emphasized the limits of reason, it found philosophical expression in German Idealism. Reacting to Hume's radical empiricism, Kant stressed how the knowing subject organizes experience of the world; and Hegel proposed a universal Mind or Spirit that manifests itself through historical development and is knowable to the human mind. Young Hegelians such as Marx revised Hegel's philosophy of history into a tool for radical social change.

The major political ideologies of the period also reacted to the Enlightenment and revolutionary legacies. Rejecting Enlightenment critical reason and revolutionary violence, conservatism upheld the value of traditions and institutions that had evolved through historical experience. According to Burke, de Maistre, and de Bonald, the French Revolution destroyed the traditions-e.g. Christianity-that truly define human community, replacing those with abstract principles that distorted human nature and society. Maintaining confidence in Enlightenment rationalism, liberalism promoted the basic ideals of the American and French revolutions. Proclaiming the value of individual liberty, liberals attacked all authorities that sought to limit that liberty. This emphasis led most liberals to embrace laissez faire economics and reject reform efforts on behalf of the poor. Suspicious of the lower classes, moderate bourgeois liberals rejected the radical democratic strain of the French Revolution. Radicals such as Paine and Bentham embraced democratic ideals and sought to extend them to the common people, calling for universal manhood suffrage and other reforms. Early socialists including Saint-Simon, Fourier, and Owen rejected liberal individualism, envisioning society founded upon cooperation rather than inhumane competition. Later in the century, Marx would radicalize socialism by calling for violent class conflict that would overthrow the bourgeoisie.

During this period, nationalism emerged as a powerful cultural and political force. Tied to German Romanticism, early nationalism celebrated what Herder called the Volksgeist, the "spirit of the people" as revealed through their history, art, and folk traditions. Although German romantics tended to reject French revolutionary principles, many liberals embraced early nationalism, fighting for the liberation of subject peoples. Later in the century nationalism grew, especially in Germany, increasingly conservative and irrational, adopting racist and anti-Semitic ideas. This extreme nationalism culminated with the violent fascist movements of the twentieth century.