backing of a small cohort. The franchise, or vote, if there was one, extended only to a very small group of land-owning males. Societies were hierarchical, with great wealth disparities. The idea of a republic, a bottom-up government ruled by the will of the people rather than by a king, was a revolutionary idea. The universal franchise—or one man (and in its more radical form, one man or woman), one vote—was another revolutionary concept that many feared would lead to "mob" rule.

Ideas such as John Locke's of the natural rights of man to liberty, property, and equality, and his idea of the right to resist tyranny, however, began to take hold. By early 1848, Marx and Engels had published The Communist Manfesto, telling workers they had nothing to lose but their chains, and various socialist ideas were in the air.

During this period of rapid industrialization, social change, war, and economic fluctuations, many people were thrown out of normal patterns of agrarian life that had existed for centuries. The growth of newspapers spread ideas, even to the illiterate who heard about them through friends who could read. Discontent with colonialism, slavery, lack of a voice in government, corruption, and wealth inequality led to revolt. People had seen great changes, had suffered under tyrannous monarchical governments, and believed more change was possible that could spread power and wealth more equitably.

The social and political changes of the eighteenth and early nineteenth centuries have their roots in the devastating religious wars that wracked Europe in the seventeenth century. With the rise of Protestantism and the fracturing of the old uniformity of religion, in which the Catholic Church allied with Christian monarchs to create a ubiquitous system of power, Protestant countries began to clash with Catholic ones and people within countries with official religions began to emigrate or demand the right to follow the dictates of their own consciences. This was expressed by John Locke in his  "A Letter Concerning Toleration: Humbly Submitted" as follows:

No peace and security among mankind—let alone common friendship — can ever exist as long as people think that governments get their authority from God and that religion is to be propagated by force of arms.

The demand for religious freedom was tied to the concept of political liberty. If the king was not an agent of God, part of an alliance of throne and altar, then the legitimacy of rulers was increasingly seen as a sort of contract with the citizens of a country. This notion of a contractual relationship between ruler and ruled, in which the ruler becomes an administrator who maintains order and other public goods in response to the wishes of the people, mandates mechanisms by which the ruler is constrained by the people's will in the form of elections to select parliaments or assemblies that express the people's will. 

These liberal political and religious ideas were the essence of a movement called the Enlightenment, which called for political and religious liberty and toleration of diverse views. The Enlightenment was a fundamentally optimistic movement that believed that reason and science could cure social ills and help construct a fair and just society. The major British thinkers of the Enlightenment included John Locke, David Hume, and Adam Smith. Among the notable thinkers of the French Enlightenment were Voltaire, Denis Diderot, and Jean-Jacques Rousseau. The "Founding Fathers" of the United States were also part of the Enlightenment. 

Political reform in Britain during this period was gradual. Although Britain was the earliest and perhaps most dramatic exemplar of the Industrial Revolution, and its ensuing economic changes and urbanization, rather than undergoing a revolution, it gradually passed a series of Reform Bills extending the voting franchise and a series of acts that allowed increasing religious freedom.

In France, the Ancien Régime remained allied with the Roman Catholic Church, and social change came in the form of the French Revolution of 1789 to 1799, which overthrew the king and established the foundations of a secular, liberal democracy. In the United States, the change to a modern, secular democracy occurred in concert with separation from British rule.