Infectious Ideas: Contagion in Premodern Islamic and Christian Thought in the Western Mediterranean

Publication Year



Infectious Ideas is a comparative analysis of how Muslim and Christian scholars explained the transmission of disease in the premodern Mediterranean world.

How did religious communities respond to and make sense of epidemic disease? To answer this, historian Justin K. Stearns looks at how Muslim and Christian communities conceived of contagion, focusing especially on the Iberian Peninsula in the aftermath of the Black Death. What Stearns discovers calls into question recent scholarship on Muslim and Christian reactions to the plague and leprosy.

Stearns shows that rather than universally reject the concept of contagion, as most scholars have affirmed, Muslim scholars engaged in creative and rational attempts to understand it. He explores how Christian scholars used the metaphor of contagion to define proper and safe interactions with heretics, Jews, and Muslims, and how contagion itself denoted phenomena as distinct as the evil eye and the effects of corrupted air. Stearns argues that at the heart of the work of both Muslims and Christians, although their approaches differed, was a desire to protect the physical and spiritual health of their respective communities.

Based on Stearns's analysis of Muslim and Christian legal, theological, historical, and medical texts in Arabic, Medieval Castilian, and Latin, Infectious Ideas is the first book to offer a comparative discussion of concepts of contagion in the premodern Mediterranean world.

Table of Contents

Chronological List of Relevant Muslim and Christian Scholars Who Wrote on Contagion in the Premodern Period
Introduction: Contagion and Causality in the Study of Premodern Muslim and Christian Societies
1. Contagion in the Commentaries on Prophetic Tradition
2. Contagion as Metaphor in Iberian Christian Scholarship
3. Contagion Contested: Greek Medical Thought, Prophetic Medicine, and the First Plague Treatises
4. Situating Scholastic Contagion between Miasmaand the Evil Eye
5. Contagion between Islamic Law and Theology
6. Contagion Revisited: Early Modern Maghribi Plague Treatises
Conclusion: Reframing Muslim and Christian Views on Contagion
Appendix A: Contagion in the Christian Exegetical Tradition
Appendix B: The Presence of Ash'arism in the Maghrib


"A welcome addition to the growing literature on plague—and medical thought—in the premodern Islamic world. Stearns's translations add new voices to those already known, and approach known figures with subtlety and nuance, challenging or at least refining the conclusions of the established scholarship... Stearns has provided future students commanding the requisite skills and depth of vision both a model and a solid target."

— Joseph P. Byrne - American Historical Review

"Provides readers not only with a fascinating, beautifully researched account of contagion and plague in the premodern Western Mediterranean, but also with a series of thought-provoking new approaches to religious exegesis, legal interpretation, and literary production, and a set of methodological models that should serve scholars in the fields far beyond the realm of fourteenth- and fifteenth-century studies of illness and health in the Maghrib. The book is a fascinating read."

— Ruth A. Miller - Journal of the American Oriental Society

Johns Hopkins University Press