Ius Gentium et Naturae: The Human Conscience and Early Modern International Law

This chapter examines how various early modern conceptions of conscientia relate to the emergence of ius gentium et naturae in the so-called Age of Conscience. It starts with the Thomist conception of conscience as ‘forum internum’ and analyses the role it played in the work of Spanish Scholastic Francisco de Vitoria when he reconceives ius gentium et naturae as a body of law applicable to Christian and non-Christian peoples. Ius gentium et naturae was thus entangled with ‘the power of the pastorate’ as Michiel Foucault coined it. At its core lies a discussion of how Grotius’ conception of the human conscience, which drew on both Thomism and Erasmian humanism, in turn led to a ius gentium et naturae disentangled from Roman Catholic moral theology, doctrine, and practice. For Grotius reason and conscience underpinned a universal law of nature, backed up by a decentralised - internal - court system (‘forum internum’ or ‘forum conscientia’), which was equally operated by Christian, Catholic and Protestant, Gewissener and non-Christian sovereigns and peoples alike. Today, ‘conscience’ is uncritically assumed and used in international law. As we have seen time and again, while human conscience is the space for humans to apply moral knowledge, it is also the space to err profoundly. The politics that come with the interpretations of the court of conscience, like with any court, requires our unwaning scrutiny.