The Authority of communis opinio doctorum in the Medieval and Early Modern Ius commune (13th-16th centuries)

The intellectual climate of scholasticism is founded, in a natural way, on the idea of community of knowledge, collected cumulatively in the slow process of assimilating and commenting on the tradition. If, on the one hand, a dialectical method permits to forge and test each opinion in the fire of opposites, contributing through the process of intricate dialectical subdistinctions to the final refinement of the argument discussed, the formal corroboration of an opinion, on the other hand, is only possible through the assessment of its coherence with the 'auctoritates'. In no other discipline of scholastic knowledge, the embedment of an argument in the community of scholars past and modern, through an endless sequence of quotations, is felt as being of such paramount importance than in medieval jurisprudence. Scholastic disputation stands not only as a sort of cognitive compass, but also as a decisional touchstone in the process of a practical application of the rule.

'The opinions of the learned', remarks Calderinus in his Repertorium at the beginning of the fourteenth century, 'bring doubt and obscurity into the law.'¹ The proliferation of often incompatible opinions in legal scholarship, painstakingly collected and diffused in 'margaritae', 'repertoria', 'singularia', and early legal dictionaries of the time, did not cease after the eventual triumph of the Accursian Gloss to the Corpus iuris civilis. Medieval jurisprudence needed plausible methodology to navigate through the forest of dicta found in the 'allegationes'. The rise of 'communis opinio doctorum' as an argument, with its claim to universality, may be regarded as development of an internal technique of legal discourse that purported to diminish the intrinsic vagueness and elusiveness of Ius commune.

The subject has enjoyed mixed fortunes in modern historiography. The most extensive studies were published in the thirties by Emilio Bussi in a preliminary study on the concept of Ius commune, Charles Lefebvre in a historical introduction to the can. 20 of the Pio-Benedictine Code, and Woldemar Engelmann in his 'opus magnum' on the reception.² While Bussi's account in a largely appreciative tone stressed the importance of the doctrine, attributing to it a decisive place in shaping the system of sources of late Ius commune, Franceso Calasso famously compared it to 'a plague that began to infect healthy tissues of both legal science and judicature'.³ Calasso's critique (and a scathing attack on Bussi's work) seemed to have halted serious interest for the concept for a while.⁴

Held in disdain and synonymous with epigonism of the late medieval legal jurisprudence the idea was nevertheless reclaimed by Luigi Lombardi in his vast essay on jurists as law-shapers.⁵ His study stands out as advancing the strongest thesis on the vital role of 'communis opinio', along with the rise of consilia literature, in what he describes as 'jurisprudentiality' of the Ius commune at the threshold of modernity. The main thrust of his argument was to regard the phenomenon as lawyers' projection of the idea of codification, making it a distinctive instance of legal positivism, crafted by jurists themselves.⁶ Consequently, the phenomenon was dubbed 'a jurisprudential version of the statute'.⁷

While Lombardi's controversial but thought-provoking claim was somewhat narrowed to the late fifteenth- and sixteenth-century Ius commune, focusing mainly on the views expressed by the late treatise writers, the doctrine covers much larger period of time and can be traced back to the middle of the thirteenth century. There are considerable challenges in disentangling the early form of argument.⁸ Though by no means scant, the reflections as to what makes an opinion common and what are its effects are scattered in the sources. Sometimes the remarks are perfunctory, articulated as an aside to the main thread. Other times the argument is intricately interwoven with substantive treatment of a question at hand so that it can hardly be studied separately. As a result, the study of the doctrine proves to be largely non-linear, as no fixed set of pertinent 'loci' can be satisfactorily determined, though quite understandably, the bulk...