The Science of Conjecture: Evidence and Probability Before Pascal

by James Franklin

Innocent III again had a part to play, in enunciating another of the general maxims so favored by medieval lawyers: “In doubtful matters the safer path is to be chosen” (In dubiis via est tutior eligenda).13 This much-discussed axiom, sane enough on the surface, stands in need of some interpretation. What does safer mean? Does it mean more probable? Or morally safer? Can these two meanings conflict? The more natural interpretation is morally safer, as explained by Peter the Chanter: in doubtful cases in which doctors disagree and no decision can be found in scripture or in papal decrees, “it is safer to incline to that part in which it is certain there is no sin.”