This special issue grew out of a small conference The Known & the Unknown: Exploring Twelfth-Century Philosophy, which was funded by the Carlsberg Foundation, hosted by the Saxo Institute, and held at the University of Copenhagen in April 2018. Its central topic was the many, mostly unexplored, commentaries on Aristotle, Boethius, and Porphyry that constitute the key textual evidence for a fascinating phenomenon that, although it played a pivotal role in the philosophical revival of Western Europe, remains frustratingly underexplored to (...) this day: the logical schools of the twelfth century. The present introduction has two parts. In the first part, John Marenbon lays out the background to this special issue of Vivarium as a whole, explaining both what the philosophical project pursued by twelfth-century logicians was and how, and how far, the historical project of understanding it has progressed over the last two hundred years. In the second part, Heine Hansen briefly presents the issue and its contents. (shrink)

Medieval philosophers had a predilection for using the correlative pair father and son as an illustrative example in their discussions of relations. The use of this example has sometimes led to charges of confusion on the grounds that fatherhood and sonship are not proper converses. The present article shows how a group of twelfth-century philosophers from the milieu around the logician Alberic of Paris handled the problems arising from the use of this illustrative example which they had inherited from their (...) ancient and late-ancient predecessors. (shrink)