The Science of Conjecture: Evidence and Probability Before Pascal

by James Franklin

The famous inquisitor, Bernard Gui, explains in his Manual (c. 1323) why the inquisitor cannot afford to be squeamish about evidential difficulties: “It is, indeed, all too difficult to bring heretics to reveal themselves when, instead of frankly avowing their error they conceal it, or when there is not sure and sufficient testimony against them. Under these circumstances difficulties rise on all sides for the investigator. On the one hand his conscience will torment him if he punishes without having obtained a confession or conviction of heresy; on the other hand, all that repeated experience has taught him of the falseness, guile and malice of such people will cause him still greater anguish. If they escape punishment owing to their fox-like craftiness it is to the great harm of the faith, for they become even stronger, more numerous and more wily than before. Moreover, lay persons devoted to the faith find it scandalous that an inquisitorial case, once begun, should be abandoned more or less for lack of method.”