This article understands Antonio Cassese's Realizing Utopia as an invitation to reflect about idealist international law scholarship and its method. In Realizing Utopia and Five Masters of International Law Cassese proposed critical positivism as the adequate method for the international lawyer to interpret international law and to suggest legal reform in order to bring international law better in line with the values of the international community. While I agree that critical positivism allows the practitioner of international law to pursue his utopian vision when interpreting and applying the law, I argue that legal scholarship that engages in proposals on what the law is or should be needs to go beyond critical positivism. On the one hand, it has to venture into other disciplines, such as moral philosophy, political theory, or economics, to justify its choices. On the other hand, it must take account of other subdisciplines of law, in particular private law and "law & society" studies, in order to benefit from their insights into the relationship between law, markets, and society. These reflections, to me, do not diminish the value of Realizing Utopia, but rather suggest that it should be read as an instance of utopian international law practice.