The Enlightenment, a philosophical movement that dominated in Europe in the 18th century, was centered around the idea that reason is the primary source of authority and legitimacy and advocated such ideals as liberty, progress, tolerance, fraternity, constitutional government, and separation of church and state.
Rationalism, or a belief that we come to knowledge through the use of logic and thus independently of sensory experience, was critical to the debates of the Enlightenment period when most philosophers lauded the power of reason but insisted that knowledge comes from experience.
Natural rights, understood as those that are not dependent on the laws, customs, or beliefs of any particular culture or government, and therefore universal and inalienable, were central to the Enlightenment debates on the relation between the individual and the government.