Natural Law and Christian Communities in Early Modern Europe: Reflections on a Colloquium

Writing in the 1610s, the great Jesuit scholar Francisco Suarez noted breezily that it was clear there was a natural law. All that was needed, he added, was to figure out what it was (De Legibus 2.5.1). Multiple chapters, pages, and precise distinctions later, his reader is left in no doubt that the answer is definitely complicated, but also that it is important, that how natural law is understood, analysed, and indeed imposed will make a difference here on earth, and perhaps also to people’s immortal souls. Suarez was writing a century after the great revival of natural law thinking in the early sixteenth century and by this time the language of natural law had become commonplace in intellectual, religious and political life. Scholars have long recognised this development, and yet the contours and consequences of early modern natural law thinking have yet to be fully understood, especially as they relate to new interpretations of Christianity and the Church. To explore these themes further, we (Reginald Lynch OP, Sam Head, and Sarah Mortimer) held a colloquium at Oxford in September 2025, generously supported by Christ Church, the Oxford CIH, and the Angelicum.

Recognising that the study of early modern natural law has often been highly fragmented, we wanted to begin a conversation that would bring a range of perspectives together. Recent research has often focused on particular elements of the natural law tradition, sometimes from the perspective of religious commitments, such as Reformed theology or Thomist Catholicism. Meanwhile, there has been continuing interest in the political implications of natural law, for theories of resistance or of contractualism, of toleration or absolutism.  But rarely do these approaches come together, and the boundary lines between them remain firm. It is our belief, however, that this modern fragmentation fails to capture some of the most important aspects of early modern natural law discourse, for it was exactly those lines of tension between the different models of natural law that exercised people - not only those engaged in scholarship, but those involved in the political and religious controversies of the time. 

A potrait of John Duns Scotus (1265/6-1308) by Justus van Gent (c.1476)

In particular, perhaps the most pressing intellectual question of this period concerned the relationship between natural law and Christianity, a relationship which shaped and at times defined new ideas about both politics and faith. Yet recent approaches have tended to obscure this, sometimes taking for granted a distinction between the theological and the political which was itself born out of the contestations of the early modern period. The premise of our colloquium, therefore, was that scholarly conversation would be enriched if we widened our gaze and stepped over some of those boundaries. To this end we invited scholars working on Catholic traditions, Scotist as well as Thomist, and on a variety of Protestant approaches, and we encouraged speakers to consider questions of genre and dissemination as well as the content of the works they were studying.

What was apparent from the papers was that natural law was a language shared across Europe, and this commonality could encourage conversation and cross-fertilisation across religious and political boundaries. It could be presented as, and even be understood as, neutral between different groups and confessions. But natural law could also be used to divide and exclude; it could be weaponised and used to condemn or persecute those people and actions deemed to be unnatural – as David Lantigua’s account of the debates between Bartholomeo de las Casas and Juan Gines de Sepùlveda made clear. It could be used to offer apparently universal principles for solving specific problems such as how to define incest or which relatives one could legitimately marry, as Hannah Dongsun Lee explained, or determining the scope and limits of toleration. But it could also be linked to a particular moment in human history, most obviously the arrangements to be found – or read out of – the book of Genesis, as Sam Head showed. Meanwhile, Anna Becker’s paper examined how the line between what was considered ‘natural’ and what ‘artificial’ or ‘contractual’ was itself contested, not least when it came to the limits and extent of maternal rights and duties towards children.

For me, three central themes arose from the papers and discussion. The first concerned the question of authority, of who controlled the interpretation of natural law or of the space which natural law left open for positive laws and for the particular decisions of any given community.  Several papers made reference to the ongoing battles between churchmen, magistrates, and lawyers as each sought to show the importance of a distinctive set of expertise or authority in translating natural law principles into specific laws and rules. By focusing our attention on the fluid and shifting lines between the natural and artificial, or the universal and particular, the speakers helped us to see how and why this boundary was policed. At the same time, the growing interest in this period in different kinds of positive law, particularly the distinction between divine and human positive law, generated tension between and among lawyers and theologians as they sought to determine the ongoing validity of the laws and commands in the Bible. This was especially true once Hugo Grotius’s work became known across the Protestant lands, for it encouraged Protestant writers to draw creatively on a taxonomy of law developed originally in Catholic circles.

The frontispiece to an early edition of Hugo Grotius' De jure belli ac pacis (1625)

The extent and limits of different kinds of community, both political and spiritual, proved to be a second theme. Ian Campbell noted the Roman origins of the distinction between ‘civil’ wars and those fought against outsiders, showing how both Franciscan and Dominican theologians problematised this separation as they examined the features of multiple or composite monarchy and, in the case of the Franciscans, were willing to avenge injuries committed well outside their own jurisdictional boundaries. Meanwhile, Reginald Lynch’s paper considered the formation of Catholic consciences on the Iberian peninsular, and the alignment between reason and revelation within academic communities committed to the importance of both. Several other papers also reflected on the creation and the policing of communities, especially as efforts were made in this period to encourage deeper commitment to a territorial ‘fatherland’ or to a particular visible church.

The third theme was limitations of natural law, especially as a set of universal rules and principles understood in juridical terms. The first panel paper drew our attention to the importance of experience and embeddedness in generating reflection on what it might mean to be human, especially as that experience took place in distinct places and spaces. Later on, the final panel considered how some of the canonical figures in the history of political thought sought to include qualities such as gratitude and mercy into their analyses of society. Tim Stuart-Buttle’s paper emphasised the importance for Hobbes of the virtue of gratitude, the cultivation of which was essential for the smooth and peaceful functioning of society and for sovereign authority. My own paper discussed the Dutch Remonstrants’ vision of a Christian magistrate committed to liberty and their connections to John Locke. But I also suggested that the Remonstrants were much more explicit than Locke ever was on the importance of Christ’s death as enabling reconciliation between God and humans, beyond the moral framework of law and right.

Across the sessions, therefore, there was a strong concern to show how natural law remained important as a tool of critique and criticism, challenging as well as enabling structures of power and authority. And there was also a recognition of the extent to which early modern people believed that natural law alone was not enough for a sustainable community. Indeed, throughout this period, ideas of natural law developed in tandem with interpretations of Christianity, history, and anthropology, as what was deemed to be ‘natural’ was shaped by the wider culture and context. Understanding and explaining some of these shifts remains a task for future scholarship, but even this one-day colloquium suggested how illuminating and powerful such scholarship might be.

Sarah Mortimer is a Professor of Early Modern History at Christ Church. The colloquium 'Natural Law and Christian Communities in Early Modern Europe' took place in Oxford on 29 September 2025