An open society is a dynamic and pluralistic society in which democratic institutions defend free thinking, universalism, humanitarianism, and social mobility. This is a society that prioritizes the rights and responsibilities of the individual over one’s traditional ties and affiliations as part of the collective. This concept was initially introduced by the French thinker Henri Bergson in 1932 and further developed by Karl Popper. Popper contrasts an open society with a closed society. The latter chooses the tribal collective over the individual and is rigidly structured based on traditions and taboos. An open society welcomes outside influence, whereas a closed society shuns it.

In The Open Society and Its Enemies, Popper traces the development of an open society as part of the theory of knowledge, rather than politics, by focusing on three key philosophers, Plato, Hegel, and Marx. First, he locates the movement toward such a society in the Athenian democracy during Plato’s lifetime embodied by intellectuals like Socrates as well as the Athenian maritime commerce and information exchange. Plato, however, viewed social and political change as decay that occurs when one moves further away from the ideal Forms.