‘Kammerhofer’s efforts to maintain theoretical consistency are impressive. He advocates a form of scholarship not afraid to carry its analysis through ‘to the bitter end’, and wants to oppose any form of pragmatism that would bow to what is convenient or realistic within the everyday ‘realities’ of international law.’ - Joshua Paine for Leiden Journal of International Law"Uncertainty in International Law is a rich and nuanced book from which any reader interested in international legal theory will benefit. Moreover, in respect of the main substantive questions it deals with – self-defence, customary international law and interpretation and modification of treaties – the book displays a wealth of rigorous thinking that facilitates navigation through the complexities of legal indeterminacy" - The European Journal of International Law, Mónica García-Salmones Rovira