Public order: limit and condition of tolerance: research on legal pluralism.

Summary Public policy is the name of 104 legal concepts (Part 1). In private international law, it is one of the 39 great problems, paradoxes, vicious circles, petitions of principle (qualification, referral, electio juris, etc.) of this subject (part 2). A problem is an incompatibility between the two answers successively given to a question at two different moments of a reasoning. The 39 problè́mes have as their common cause the entanglement of two incompatible theories (and thus the entanglement of the two incompatible reasonings they respectively underlie): that of legal monism and that of legal pluralism. The problems are problems because of this entanglement. They cease to be problems as soon as this entanglement ceases. The arguments of positive law (Perelman) concerning the passage from what is different but tolerated to what is too different to be tolerated show that the public policy exception is a pluralist technique (Santi Romano) that cannot be presented in monist terms (Hans Kelsen).