Abstract
This chapter discusses central strands of the modern social contract tradition. Distinguishing between moral and political theories on the one hand and contractualist and contractarian theories on the other, it presents one example of each of the ensuing categories: Gauthier’s moral contractarianism, Buchanan’s political contractarianism, Scanlon’s moral contractualism, and Rawls’ political contractualism. In the conclusion, strengths and weaknesses of social contract theories are discussed.