Pour une histoire de la ‘double vérité’ (review)

Since the publication of the work of the Belgian medievalist Fernand Van Steenberghen, a solid consensus seems to have emerged in the community of historians of medieval philosophy: no scholar in the Middle Ages defended the so-called “doctrine of the double truth” that the Bishop of Paris, Stephen Tempier, had denounced in the prologue of his 1277 Condemnation. Moreover, how could a professional philosopher or theologian seriously contend that two contradictory statements are simultaneously true, one due to natural reason, and the other through the authority of faith? Therefore, the matter seemed settled and the file definitely closed: the double truth is nothing more than a “legend.” Yet the Italian medievalist Luca Bianchi’s in-depth critical analysis of the pseudo-historical evidence has now changed this. Without wanting to propose an entirely new interpretation of the historical ins and outs of this famous doctrine, Bianchi carries out a re-examination of the subject through a meticulous study of certain key texts that he has read in the light of a three-fold question: What impact did passages from Tempier’s decree on the “double truth” have on the medieval scholars themselves? Does the expression itself, ‘duplex veritas’, appear in some medieval documents? What were medieval thinkers’ attitudes in the face of philosophical arguments leading to conclusions contradicting the teachings of the Catholic faith?

Due to space constraints, I will limit my discussion to Bianchi’s most crucial results. The answer to the first question (ch. 1) leads us in a surprising fashion to the famous Disputatio of Luther (1539). In this text, the father of the Reformation opposes the principle according to which what is true in theology must also be true in philosophy—a thesis whose paternity he attributes to Parisian theologians. Wanting to ensure the pre-eminence of faith-based teachings over all forms of human rationalization, Luther came to subscribe to a certain form of the double truth, since he claimed that what is absolutely true according to faith can be false and impossible from the perspective of philosophy. This explains his radical opposition to the “Parisian” principle that Bianchi calls “the principle of the oneness of truth.” We learn that some theologians in fifteenth- century Paris, notably Jean Gerson and Guillaume Baudin, were actually inspired by Tempier’s decree to defend some form of this principle.

To respond to the second question (ch. 2), Bianchi first researched the electronic database Library of Latin Texts (CLCLT-6), and came up with “disappointing results”: no author uses the expression ‘duplex veritas’ in the relevant sense. Nevertheless, as imposing as it is, this database is not exhaustive, and Bianchi, well aware of this, extended his research by consulting other documents on paper, allowing him ultimately to reach a positive conclusion: the expression ‘duplex veritas’ appears in the course of a debate that took place around 1470 on the subject of the truth-value of statements about future contingents. This debate involved a master of arts from Louvain, Pierre de Rivo, who considered it essential to distinguish between the truth of philosophers and the “popular” truth upheld by the churchmen, and a Parisian theologian whom we have already encountered, Guillaume Baudin, who invoked the “principle of the oneness of truth” to denounce the “double truth” that his adversary was promoting.

From Bianchi’s multifaceted response to the third question (chs. 3–4), I can only present the groundswell. From the statutes promulgated by the Parisian Arts Faculty in 1272 up to the condemnation of Galileo in 1633, including the constitution Apostolici regiminis issued by the Fifth Lateran Council (1513), a significant evolution may be observed in the requirements academic and religious authorities imposed on professors of philosophy (as well as on scientists) in the western Christian world. Indeed, we may observe that these requirements correspond, first, to the obligation to counter, as far as possible, arguments that contradict faith, and then transform into the duty to commit to a strong...