A classic opposition in the history of political thought is between two types of nationalism: civic and ethnic. The first type, civic nationalism, is said to have developed in Western Europe and the United States. According to several historians of political thought, civic nationalism is the political force that led to democratic revolutions in France and the United States. It fosters the development of a horizontal solidarity of citizens, in theory, equal before the law, that identifies with the state and its constitutional legacy. It has strong roots in the political thought of the Enlightenment and liberalism.
Civic nationalism values the identification of all citizens with the state. It has also been a political force behind the unification of many states. The second type of nationalism developed in Central and Eastern Europe. It is often referred to as a cultural, ethnic or organic nationalism. While civic nationalism is often associated with the Enlightenment, cultural nationalism is more generally associated with the romantic reaction to the Enlightenment. It fosters identification of the members of the nation with a given language, cultural tradition, and often ethnoreligious symbols. Under its more extreme variants, ethnic nationalism can lead to policies of ethnic cleansing and genocide.