 “Contractarianism” names both a political theory of the legitimacy of political authority and a moral theory about the origin or legitimate content of moral norms. The political theory of authority claims that legitimate authority of government must derive from the consent of the governed, where the form and content of this consent derives from the idea of contract or mutual agreement. The moral theory of contractarianism claims that moral norms derive their normative force from the idea of contract or mutual agreement. Contractarians are skeptical of the possibility of grounding morality or political authority in either divine will or some perfectionist ideal of the nature of humanity. Social contract theorists from the history of political thought include Hobbes, Locke, Kant, and Rousseau. The most important contemporary political social contract theorist is John Rawls, who effectively resurrected social contract theory in the second half of the 20th century, along with David Gauthier, who is primarily a moral contractarian. There is no necessity for a contractarian about political theory to be a contractarian about moral theory, although most contemporary contractarians are both. It has been more recently recognized that there are two distinct strains of social contract thought, which now typically go by the names contractarianism and  contractualism.