This chapter has a twofold purpose. First, we examine Luhmann's writings on politics and law in terms of their contribution to the theoretical development of modern sociology and legal and political theory. We shall offer an account of the conceptual foundations of Luhmann's thought, and in this we emphasize the importance of his criticisms of the theoretical assumptions concerning politics, law and society that are widely accepted within contemporary philosophy and sociology. In so doing, we seek to place Luhmann's thought within a broad theoretical perspective, and to stimulate the reflection that his work represents a ground-breaking response to the mainstream of post-Enlightenment legal and political thought. Second, we also seek to reconstruct the specific debates which shaped the development of Luhmann's theoretical ideas. The reconstructive sections included here will focus in part on the obvious influences on his work, such as Parsons, Weber and Arnold Gehlen. However, we shall also discuss his dialogues with other theorists — for instance, with Kant and Habermas — through which he cemented his theoretical observations of the social system. In addition, we shall examine some of the rather less obvious debates in which he engages, such as, for instance, those with Martin Heidegger and Michel Foucault, whose work might not obviously or immediately be connected with legal and political theory.