Note (return) — Chapter XII

Now, if Logic is of any value as an instrument for the discovery of truth, the attainment of certitude, it must teach us not only how to deduce conclusions from premises, but it must certify to us the validity of the principles from whence we reason and this is attempted by Aristotle in the Posterior Analytic. This treatise opens with the following statement: All doctrine, and all intellectual discipline, arises from a prior or pre-existent knowledge. This is evident, if we survey them all; for both mathematical sciences, and also each of the arts, are obtained in this manner. The same holds true in the case of reasonings, whether through [deductive] Syllogism or through Induction, for both accomplish the instruction they afford from information previously known--the former (syllogistic reasoning) receiving it, as it were, from the traditions of the intelligent, the latter (inductive reasoning) manifesting the universal through the light of the singular. 694 Induction and Syllogism are thus the grand instruments of logic. 695