 In the modern era, the Dutch natural lawyer Hugo Grotius is credited with laying the foundations for the rise of international law as a genuine system of positive law, rather than simply a source of universal moral or “natural law” principles. By insisting that his system of law would be justifiable even if it were assumed that God does not exist, i.e., the “etiamsi daremus” argument in the Prolegomena to his De Jure Belli ac Pacis (1625: para. XI), Grotius paved the way for a more genuinely universalist conception of international law, independent of Christian beliefs and thus more ideologically inclusive (Nussbaum 2019: 97–140). Subsequently, important contributions were made by other major philosophers, including Pufendorf, Kant, Hegel, Bentham. Although the two leading legal philosophers of the twentieth century—Hans Kelsen and H.L.A. Hart—devoted attention to international law, and extensively so in the case of the former (Bernstorff 2010), international law was neglected by the Anglophone legal and political philosophers who followed them, and important works by international law scholars with potential significance to philosophical debate—e.g., Brierly (1928) or Lauterpacht (1933)—seldom resonated outside the field of international law. By the end of the last century, however, there was a surge in philosophical engagement with international law. This change is reflected in the publication of The Law of Peoples, the last book written by John Rawls (1999), and also in the more philosophically inclined works of prominent international lawyers, such as Thomas Franck (1995).