A philosophical tradition is not merely a historical sequence of ideas; rather, it contains analytical continuities as well as discontinuities. For example, the concept of an ideal state (prominent in ancient Greek political philosophy) was replaced by that of a social contract at the turn of modernity, around the sixteenth century. And yet, some degree of continuity has been preserved since political philosophers today continue to ask questions that have to do with the nature of political
community, the justification of political authority, and the legitimacy of civil disobedience.