The Science of Conjecture: Evidence and Probability Before Pascal

by James Franklin

One of the more acute medieval historians is Bernard Gui, whose skills in evidence evaluation in history are close to those in his work as inquisitor. Occasionally even the actual evidence is the same; he has inquisitorial records sent to him under seal to assist his writing on history.83 His extensive researches in a wide variety of oral and written sources leave no doubt of the sincerity of his statement, “I have inquired (inquisivi) into the truth of what has gone before.”84 He is of course concerned with the lack of harmony in the sources, which he attributes to the errors of copyists and (being one of the first to do so) to the “diversity of authors’ opinions and positions.” In cases in which the authorities are equally trustworthy and the issue is minor, he is prepared to simply “present the contrary arguments and leave it to the reader to judge and choose.”