"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.

Demonstrating the vibrancy of an Early Modern Muslim society through a study of the natural sciences in seventeenth-century Morocco, Revealed Sciences examines how the natural sciences flourished during this period, without developing in a similar way to the natural sciences in Europe. Offering an innovative analysis of the relationship between religious thought and the natural sciences, Justin K. Stearns shows how nineteenth and twentieth-century European and Middle Eastern scholars jointly developed a narrative of the decline of post-formative Islamic thought, including the fate of the natural sciences in the Muslim world. Challenging these depictions of the natural sciences in the Muslim world, Stearns uses numerous close readings of works in the natural sciences to a detailed overview of the place of the natural sciences in scholarly and educational landscapes of the Early Modern Magreb, and considers non-teleological possibilities for understanding a persistent engagement with the natural sciences in Early Modern Morocco.