A citizen, according to Aristotle's famous definition which has shaped western political thinking, is one who shares both in ruling and in being ruled. Citizens as rulers exercise collectively the political prerogatives of authoritative power over the polity, while the self-same body of individuals are the subjects of such rule. This ideal was severely limited in practice for Aristotle and other ancient thinkers, because they thought that most people lacked either the qualities necessary for participating in political life or the privileged circumstances of a leisured life that would enable cultivation of such qualities and make political participation feasible.

The democratisation of politics in modern times has entailed a fundamental reaffirmation of the ancient ideal of citizenship. Democracy entails free and equal individuals forming themselves into a political community in which they, the people, have final authority to rule and in which they constitute government accordingly. As Rousseau expressed it succinctly, the individual is equally a member of the sovereign body that makes fundamental law and a member of the subject body that obeys it. This virtuous circle of citizenship links both sides of the political equation, restraining and civilising political authority on the one hand and on the other ennobling civil obedience because the citizen is obeying the will of a larger collective of which she or he is an active member.