Abstract

In the XVIIth century the conflict which opposed the jansenists to the jesuits involved the problem of the due process in theological matter. The jesuits heralded the thesis that the infallibility of the Church has to be extended from dogmatics (‘quaestio iuris’) to the historical facts (‘quaestio facti’). On the opposite side Arnauld maintained that such an opinion was ‘monstruous’: also in religious matters the ‘fact’ has to be proved according to the principles of a due process, and not by authority. In this article the thesis pleaded by the jansenists is considered in connection with the model of argumentative procedure offered by the Port-Royal logic.The Logique ou Art de penser (1622) by Antoine Arnauld and Pierre Nicole seems to have rediscovered the classical principles of the theory of argumentation: from the burden of proof to the idea of probable truth. But really a new model of adversary-system has been introduced into the modern mind, which is very different in concept from the topical tradition. The basic metaphor of combat, implying that the truth will prevail in the fight, is compatible with the epistemological premises of the modern logic (as the separation between ‘fact’ and ‘value’). Therefore the problem of the fact-finding seems to be attracted into the area of the logic of information, and not of the theory of argumentation