At the same time as the modern idea of the state was taking shape, Hugo Grotius (1583-1645), Thomas Hobbes (1588-1679) and Samuel Pufendorf (1632-94) formulated three distinctive foundational approaches to international order and law beyond the state. They differed in their views of obligation in the state of nature (where ex hypothesi there was no state), in the extent to which they regarded these sovereign states as analogous to individuals in the state of nature, and in the effects they attributed to commerce as a driver of sociability and of norm-structured interactions not dependent on an overarching state. Each built on shared Roman and sixteenth-century foundations (section I). Section II argues: 1) that Grotius's natural law was not simply an anti-skeptical construction based on self-preservation (pace Richard Tuck), but continued a Roman legal tradition; 2) that Hobbes's account of natural law beyond the state was essentially prudential, not moral (pace Noel Malcolm); and 3) that commerce as a driver of social and moral order (Istvan Hont's interpretation of Pufendorf and Adam Smith) had a substantial and under-appreciated impact on international legal order. Each contributed to the thought of later writers (section III) such as Emer de Vattel (1714-67), David Hume (1711-76), and Adam Smith (1723-90), and eventually to the empirical legal methodologies of Jeremy Bentham (1748-1832) and Georg Friedrich von Martens (1756-1821).