The Making of Christian Law in Late Medieval and Early Modern Japan: Theology, Casuistry, and Legal Adaptation (Session 1)

These presentations integrate Japanese scholarship, global legal history, and cultural studies to investigate the late sixteenth- and early seventeenth-century processes by which missionaries developed legal and moral norms for Japanese Christian communities. All presentations will be in English, but there will be interpretation available for the Q&A.

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The Making of Christian Law in Late Medieval and Early Modern Japan: Theology, Casuistry, and Legal Adaptation / 中近世日本におけるキリスト教法の形成：神学・決議論・法の適応

SESSION 1: TOKYO (SUNDAY 3.1.2026 | Keio University, Mita Campus | Orii Yoshimi)

Coordinator/Staff: Victor Laubenstein (PhD Student, TUFS)
Admission: Free (予約不要)
Contact: yorii(at)keio.jp (折井) / victorlaubenstein(at)gmail.com (Victor)

Schedule

16:00-16:10 | Welcome Remarks: Orii Yoshimi (Keio Univ.)

16:10-16:50 | “The Legal History of Slavery in the Kirishitan Period: The 1598 Episcopal Excommunications and the Legal Deconstruction of Slavery in Japan”

Speaker: Rômulo Ehalt (Max Planck Institute for Legal History and Legal Theory, Germany)

Abstract: This presentation examines a crucial text in the history of slavery in Japan: the De mancipiis Indicis (c. 1610), a treatise written by Gomes Vaz, a former Jesuit procurator in India. Discussing slavery across more than twenty regions under Jesuit mission in early modern Asia, Vaz details a project aimed at shifting the Jesuit approach to the Japanese slave trade at the beginning of the seventeenth, from the casuistic weighing of individual "cases of conscience" century toward a strategy of jurisdictional externalization. At the center of this transition are the letters of excommunication issued by the Bishops of Japan, which transformed the moral problem of slavery into an absolute, non-negotiable legal ban. The presentation centers on an analysis of Vaz’s treatise, which provides the only surviving record of Bishop Luís Cerqueira’s decree of September 4, 1598. Vaz deconstructs the legal standing of slavery, reframing it not as a fixed reality of the ius gentium or natural law, but as a fragile "artifice of human law" (relatio iure humano inventa) present across all different strands of law. By demonstrating that the excommunication letters all date from 1598 (rather than 1596 or 1597, as scholars previously believed), this presentation explores how Vaz harmonized three disparate legal acts—the 1570 Portuguese royal alvará, the 1598 episcopal excommunications, and Toyotomi Hideyoshi’s prohibitions, aiming at changing the way the Portuguese Empire related to Japan and seeking to legally dissolve the institution of slavery within the Japanese mission to secure the Portuguese presence in Asia.

16:50-17:30 | “On Omura Sumitada’s motivations for forcibly Christianizing his territories”

Speaker: James Fujitani (University of Nottingham)

Abstract: In 1569, about eleven years before he granted the port of Nagasaki to the Jesuits, Omura Sumitada decided to entirely Christianize his territories. All inhabitants either had to accept baptism or leave the land. It is not clear why he made this radical decision. Without any particular evidence, historians have assumed that he was either coerced into doing so by the Jesuits or that he was motivated by religious fanaticism. This paper offers an alternative explanation, arguing that he was in fact acting quite strategically. He was unifying his territories under a single rule, just like other Warring States’ daimyō of the time, such as Oda Nobunaga.

17:40-18:20 | “Made in Japan. Why and how probabilism emerged at the end of the Sengoku period?”

Speaker: José Luis Egío (Universidad Complutense de Madrid)

Abstract: In this presentation, I will show how the encounter between Portuguese Jesuit missionaries and Japanese pagans at the end of the Sengoku period came as a cultural shock to the European preachers. Surprised by the sophistication of a culture rich in ancient religious and philosophical traditions and by the Japanese people’s firmness in their native moral convictions, which were a source of resistance to the intense work of religious indoctrination, the Christian missionaries encountered a failure they had not experienced before among other non European Pagan peoples. Therefore, in order to convert a greater number of Japanese to Christianity, they had to adapt and relax some of the strict moral norms of theological foundation that regulated social and family life in Christian Europe at that time. We will see how this problematic arrival of Christianity in Japan, together with the theological doubts raised by the innovations in commercial practices that the global expansion of commercial networks during this same period made mandatory, ultimately gave rise to a new method for resolving philosophical and ethical doubts. We are referring to probabilism, or the doctrine according to which, in order to resolve an uncertain moral problem, any of the probable answers to it can be followed, even if it is not the most probable solution or answer. This is a major “invention” in the history of thought, in which Japan and the Japanese played a fundamental role.