The Science of Conjecture: Evidence and Probability Before Pascal

by James Franklin

Hobbes, though inclined to follow Bacon and Descartes in exalting deductive reasoning, does insist on the fallibility of induction, while allowing that it is a good bet. He even assigns a number to the degree of reasonableness of an inductive argument, “for the signs are but conjectural, and according as they have often or seldom failed, so their assurance is more or less; but never full and evident: for though a man have always seen the day and night to follow one another hitherto; yet can he not thence conclude they shall do so, or that they have done so eternally: experience concludeth nothing universally. If the signs hit twenty times for one missing, a man may lay a wager of twenty to one on the event; but may not conclude it for a truth.”