The war had reinforced for Butler that the legalization of international relations was on the rise and the role of war was in decline, tamed by its subjection to law. However, Butler added that the development and use of what today we call the practice of “public diplomacy” was also required. In addition, Butler sought binding arbitration and defended a robust system of collective security. Yet all these institutional mechanisms rested on a more fundamental necessity—the creation of what he called “the international mind.” Engendered by liberal values, the international mind is best conceived as a cooperative and generous attitude in the settling of international disagreement. Enlightened world public opinion at work within the nation states of international society would be the carrier of international mind, its diplomacy working to bolster international law through compelling the compliance of nation states.