This contribution to the history of philosophy provides a guide to modern natural law theory, sets out the background to liberal ideas of rights and contractarianism, and offers a study of the Scottish Enlightenment. This major contribution to the history of philosophy provides the most comprehensive guide to modern natural law theory available, sets out the full background to liberal ideas of rights and contractarianism, and offers an extensive study of the Scottish Enlightenment. The time span covered is considerable: from the natural law theories of Grotius and Suarez in the early seventeenth century to the American Revolution and the beginnings of utilitarianism. After a detailed survey of modern natural law theory, the book focuses on the Scottish Enlightenment and its European and American connections. Knud Haakonssen explains the relationship between natural law and civic humanist republicanism, and he shows the relevance of these ideas for the understanding of David Hume and Adam Smith. The result is a completely revised background to modern ideas of liberalism and communitarianism.