Robert Alexy’s theory of legal argumentation is among the notable contributions made to mainstream jurisprudence in the last three decades. Remaining true to its rational discursive mission, it engages with both analytical positivism and natural law theories. A recent collection of essays edited by George Pavlakos explores Alexy’s theory from a number of philosophical standpoints, revealing its theoretical potential and flaws. By doing so, this volume helps us to gain a better understanding of the implications of Alexy’s theory of legal (...) argumentation, but also to identify new areas of research within the discourse theory of law. Although this collection is concerned with a critical examination of various aspects of Alexy’s work, it nonetheless draws attention to the dual characteristics of positive law, that is, the problematic separation of facts from values, law from morality, legal certainty from justice, which continue to preoccupy legal theory. In what follows I shall attempt to examine the debate between Alexy and the contributors to Pavlakos’s volume in order to gain a deeper understanding of the role of dichotomies in legal theory. Part 1 starts by explaining the theoretical background against which I have read the debate on Alexy’s theory of legal argumentation. I have explored the role of dichotomies in socio-legal research elsewhere. However, in the following pages, I shall use Alan Norrie’s critical examination of antinomies to throw light on some of the shortcomings of Alexy’s theory and also to discuss the concerns of mainstream jurisprudence. In that sense, this essay presents both Norrie’s and Alexy’s works, using the former to critically assess the latter. In Part 2, I briefly sketch the layout of Pavlakos’s collection to provide an overview of the type of questions that are discussed by the various contributors. Parts 3 and 4 bring into focus two issues that loom large in the collection. The first issue is Alexy’s central thesis on law’s claim to correctness, while the second concerns the duality of law exemplified by the attempts of mainstream jurisprudence to cope with the tension between the positivist notion of law and the idea of justice. In Part 5, I conclude the essay by reflecting on some of the implications of Alexy’s thesis. (shrink)