The Science of Conjecture: Evidence and Probability Before Pascal

by James Franklin

What passes for philosophy around 1400 combines either originality with stupidity, as with Wyclif, or learning with complete unoriginality, as with Pierre d’Ailly. Ailly repeats the phrases of the Ockhamists, among them, “The probable taken more widely is what is true, either necessarily or contingently, but is not evident” and “More probable in natural light than its opposite.”84 But the life has gone out of the exercise. The spirit of the age is represented better by Petrarch. His work of 1370, On His Own Ignorance and that of Many Others, was composed after he left Venice, stung by the remark of some young Averroists that he was a “good man, but a scholar of little merit.” Its tone may be gathered from its remarks on skepticism: “Socrates says: ‘This one thing I know, that I know nothing.’ This most humble confession of ignorance Arce-silas blames as still too bold. . . . The Academy is disproved and rebutted long since, and it is established that something can be known when God reveals it. Therefore, it may be sufficient to know as much as is necessary for salvation.”