Why is the title father of international law considered incomplete or misleading for Hugo Grotius?

The title "father of international law" is considered misleading for Hugo Grotius because it overlooks the existence of diverse, historically coexisting regional normative systems that regulated relations between independent powers long before or alongside European developments.1

While Grotius’s work was foundational to the European tradition—which eventually expanded into a global framework following the subjugation of other civilizations by colonial powers—he was merely one of many contributors to this specific regional system. Other thinkers, such as Francisco de Vitoria, are also credited as founders of international law for their earlier efforts to apply moral principles to warfare and colonization. Furthermore, non-European civilizations had already established their own sophisticated norms and institutions, such as the siyar in Islamic civilization and the Sino-centric tributary system in East Asia. Therefore, labeling Grotius as the sole "father" ignores the broader, pluralistic history of international legal thought.12