The major political changes in European monarchies during the Age of Enlightenment were largely catalyzed by the rise of rationalism and the challenge to traditional authority. Enlightenment thinkers like Voltaire and John Locke advocated for reason, liberty, and the social contract, influencing political thought and governance. These ideas laid the groundwork for revolutions, such as the American Revolution and the French Revolution, promoting notions of democracy over absolute monarchy. As a result, many monarchies were compelled to adapt or cede power, leading to constitutional governments and the spread of political liberalism.