A closed society is traditional, tribalist, and collectivist, with a rigid social structure. It opposes change and does not tolerate external ideas. Popper contrasts this type of society with his ideal open society.

Democracy is a system of government within the framework of the ideology of liberalism. In a democracy, citizens are able to choose their leaders through a system of voting, and their rights are protected by the means of laws and institutions. Democracy is universalist, humanist, and egalitarian. Popper views democracy as the optimal form of government because the checks and balances of a democratic system are designed to prevent a poor leader from causing too much damage. The author also considers democracy necessary for his ideal open society.

Egalitarianism is the doctrine that holds equality of all citizens before the law as the highest value. Popper uses the related term “equalitarianism.” Contemporary democratic societies seek this ideal by pursuing equal access to political decisions, through democratic institutions such as voting, and social equality through the equal treatment of all, among others.