The Perpendiculum: Presumptions and Legal Arguments in the 12th Century - (Medieval Law and Its Practice) by David de Concilio (Hardcover)

About the Book

This book presents the collection of brocards known as Perpendiculum, produced in Northern France c.1170, offering for the first time an in-depth study of the work and providing a Latin edition and an English translation of its text.

Book Synopsis

The Perpendiculum (or Summula de presumptionibus), produced in Northern France c.1170, is one of the earliest collections of brocards: a literary genre intended to provide legal arguments for disputation in the medieval schools of law. Its innovative use of dialectical techniques and its theorization of canon law presumptions have attracted the attention of legal historians, raising questions on its origin and milieu.
This book offers the first comprehensive study of this work, with a Latin edition and an English translation of its text, shedding new light on the significance of this collection for twelfth-century legal teaching and learning.

Review Quotes

"Overall, De Concilio has done legal historians a service by editing and translating this complex text in a clear and accessible manner and providing a lucid and concise discussion of its importance (though one should have copies of Gratian's Decretum and the Corpus Iuris Civilis at hand to make the most of it). The book offers a fascinating look into the twelfth-century legal classroom, especially the sorts of questions and problems that occupied canonists in this period and the methods they used to address them. It will be most useful to legal historians interested in the development of legal ideas and the ius commune at this critical moment in legal history, but those interested in scholasticism, the development of the universities, and, more generally, how ideas spread in the intellectual fervent of the twelfth century (especially outside the great schools of Paris and Bologna) will also find much to occupy them."
Patrick R. Morgan, California Institute of Technology, in The Medieval Review, 8 October 2025

About the Author

David De Concilio, Ph.D. (2022, University of St Andrews/Università degli Studi Roma Tre), is research fellow at the Università degli Studi di Padova. He has published articles on medieval Roman and canon law, with a specific interest in the interaction between law, theology, and liberal arts.