These comments address three themes concerning Oona A Hathaway’s and Scott J Shapiro’s The Internationalists (Hathaway and Shapiro 2017), a great contribution to scholarship about international relations, international law and international legal theory. I first explore further some game theoretical themes, how the Peace Pact arguably contributed to avoid war by creating institutions – such as international courts – that helped stabilise an assurance game among states by providing trustworthy information and commitments, in turn influencing practices and beliefs concerning mutual non-aggression. Second, I suggest that the authors should not claim more than that the Peace Pact was one cause of the massive shift in reduced warfare. Further arguments are needed to show that this treaty was the trigger that ‘began a cascade’. Third, I suggest that the lessons for the future are limited, as we explore how to preserve and improve on the New World Order of the Pact, rather than backsliding into the Old World Order.

In this contribution, the key elements of the book’s progress narrative will be discussed. The focus will be set on the ‘backbone’ of the book, which consists of three ideas or elements: the periodisation decision (II), the claim of a specific conception of social change (III), and a specific understanding of international law (IV). In regard to each of those elements it will be asked how they are justified, what insights they provide and whether there are blind spots.