The Art of Reasoning

The Art of Reasoning: Techniques of Scientific Argumentation in the Medieval Latin West (400-1400)’ is a project designed by Mariken Teeuwen and Irene van Renswoude for the 2015 scheme, ‘Vrije Competitie’, of the Netherlands Organisation of Scientific Research. The project, which started in 2016 and ended in June 2020, discussed the practices of argumentation and reasoning from the early Middle Ages up to the period of the medieval universities. The research team consisted of Mariken Teeuwen, Irene van Renswoude and Irene O’Daly. In the last year Renée Schilling was added to the team for assistance in matters of content, creativity and practical organisation.

In the current grand narrative of the intellectual history of the Middle Ages, scholars only started to question received knowledge and think critically in the twelfth century, when the age of scholasticism created a new intellectual climate and universities were born. Yet the tools for thinking critically and challenging authorities have always been part of the intellectual world of the Middle Ages (and before). The misunderstanding is, we argue, not only caused by lingering prejudices about the ‘Dark Ages’, but also by the hidden nature of the evidence. Whereas the tools of scientific argumentation of the twelfth and thirteenth centuries manifested themselves in the production of texts and new textual genres (sententiae, disputationes), in earlier ages they often took the shape of paratexts: commentaries, marginal annotations, diagrams.

Plate 1: Paris, BnF, Latin 11127, f. 49v (detail): diagrams added to a commentary of Boethius on Aristotle, 10th century, manuscript from the circle of Gerbert of Aurillac. Source:

It is only in the last years that these paratexts have become visible to a larger audience of researchers. Before 2000, they were largely hidden in manuscript margins, now many of them are on free display in hundreds of online collections of digitized manuscripts, ready, for the first time, to be explored. From late Antiquity to the late Middle Ages, these voices in the margin are testimonies to a critical and scientific way of dealing with texts: versions are compared, passages that seem to be corrupt are marked, contrasting opinions are highlighted, confronted and discussed. In other words: the annotations offer a perspective on the intellectual culture of the Middle Ages that is much richer than previously assumed.

In our project these new sources were explored from the perspective of the history of scholarly thinking. By studying both the period before the birth of the first universities and thereafter, we attempted to offer a new view on the evolution of argumentation in the medieval Latin West. The annotations of both well-known medieval scholars and anonymous ones, of monks, masters, students and readers, were our guide. To see some of the results of our research, you can visit our virtual exhibition The Art of Reasoning in Medieval Manuscripts (online since December 2020).

Plate 2: Some edges of the leaves of Leiden, UB, BPL 144, Boethius and Martianus Capella. Netherlands, 12th century. Source: UB Leiden.

Now discover the hidden side of the medieval book! This video introduces the virtual exhibition The Art of Reasoning in Medieval Manuscripts, in which medieval manuscripts are investigated from a new angle: through the annotations in the margins. The video was made by 3D Animation Studio Colorbleed.