The thesis investigates the deep conceptual structure of the distinction between creation and application of law. Legal philosophers either take the distinction for granted (and so do the vast majority of legal scholars in general) or, when they address it directly, it is so for the only purpose of criticising it as just another upshot of legal formalism. The latter approach suggests the distinction is either unsound or, at the very least, useless. The thesis argues that supporters of this stance do not realise the implications of their positions – which transcend legal-theoretical discourse and raise serious problems in both political and constitutional theory. The thesis’s first chapter purports to show that our models of constitutional democracy – as a complex set of institutional power-constraining mechanisms - are ultimately grounded on the distinction between creation and application of law. Hence the theoretical unsoundness of the distinction would undermine the very foundations of such democracies. The thesis argues that if judges are always creating the law, it follows that nothing like the ‘application of law’ is possible and, as a result, there is little or no justification for the practice of having statutes and other institutionalised forms of law. In this regard, Chapter 2 argues that realist theories of adjudication cannot make sense of one of law’s most important features, namely its normativity. More generally, undergirding a certain conception of our current adjudicative practices is the idea of (judicial) discretion, which is an essentially legal concept. In Chapter 3 I discuss this idea, comparing how it is conceived and used in both jurisprudence and administrative law (where such notion has been originally developed, at least in civil-law jurisdictions). The chapter aims at showing that an appropriate conception of discretion plays a pivotal role in grounding an analytical distinction between creation and application of law. Chapter 4 fleshes out the deeper philosophical assumptions of such distinction and, more specifically, it puts forward a conception of ‘law as communication’ which highlights the inescapable relation between law and language, and the parallel relation between philosophy of law and philosophy of language. In this chapter, I also argue that philosophy of language can and should play a role in understanding what law is, but that, at the same time, law is a unique communicative phenomenon, whose characteristics call for an original theoretical analysis. Finally, Chapter 5 brings together the several threads of the argument and presents the analytical model of the distinction between creation and application of law. The conclusion is that the creation/application distinction, thus conceived, is necessary not just in order to defend our liberal political practices - but more fundamentally, to account for law’s own raison d'être as a power-constraining device.

Qu’est-ce que la rationalité pratique ? Répondre à cette interrogation, c’est déterminer la nature du raisonnement pratique qu’un acteur se trouvant dans une situation concrète doit entreprendre ; comment, autrement dit, il doit délibérer, juger et agir. Afin de mener à bien ce projet, les philosophes contemporains mobilisent des héritages philosophiques distincts. Dans chacune des trois grandes traditions de la philosophie occidentale – les traditions française, allemande et anglo-américaine – des philosophes se revendiquant d’Aristote ou de Kant ont ainsi récemment débattu de la possibilité de fonder en raison des principes normatifs généraux, du rôle que de tels principes peuvent jouer au sein du raisonnement pratique et des liens que l’on doit tisser entre la rationalité pratique et les vertus. L’objectif général de notre recherche est de démontrer la fécondité des débats entre kantiens et aristotéliciens tout en défendant l’existence d’un kantisme transformé par l’aristotélisme qui nous permet aujourd’hui de mieux cerner les ressorts du raisonnement pratique. Un tel parcours nous fournira l’occasion de contribuer à la réception de travaux qui n’ont pas encore fait couler beaucoup d’encre en France, notamment ceux de Christine Korsgaard, d’Onora O’Neill, de Barbara Herman et de Nancy Sherman. / What is practical rationality? To answer this question, one must determine how an agent facing a specific challenge in a given situation should reason and determine how to act. In order to carry out this project, contemporary philosophers build on different historical perspectives. In each of the three main tradition of Western philosophy – the Anglo-American, German and French traditions – philosophers are thus rereading Aristotle and Kant to answer questions such as “Is it possible to ground general normative principles?”, “What role must principles play in our practical reasonings?” and “What is the relationship between practical rationality and virtue?”. My overall objective is to shed light on these debates, and then to defend a form of Kantianism infused with Aristotelian ideas that can help us paint a more satisfying picture of practical rationality. By doing so, I also contribute to the French reception of contemporary philosophical works such as the ones of Christine Korsgaard, Onora O’Neill, Barbara Herman and Nancy Sherman.