The Tools of Philosophy

In the firsts centuries of the Middle Ages all philosophers, no matter what the language was they were writing in, used ancient logic as a tool for grounding their arguments: above all, Aristotelian logic, but also Stoic logic. The Latins, though, did not have at their disposal all the texts that formed the Organon of Aristotle until the 12th c.; up to that time they only had access to the part of it called the Logica vetus (or Ancient Logic), namely those works translated by Boethius: the Categories, the De interpretatione, and the Introduction (or Isagoge) of Porphyry. Through some of Boethius’ own writings, but also through Augustine, they came to know the principal trends of Stoic logic, the doctrine of signs and of the hypothetical syllogism. It is only starting in the 12th c. that translations from Arabic and Greek reintroduced to the West not only Aristotle’s writings on the syllogism and on the method of science (the Prior and Posterior Analytics), but also Greek, late-antique, and Byzantine commentaries on Aristotelian logic. The 12th c. is a crucial period for the development of logic in the West. In fact, even before the recovery of the entire Organon, an original way of analyzing the logic and linguistics had appeared inside the schools, arising from the study of two of the liberal arts, dialectics and grammar. In the meantime some Islamic thinkers, besides carrying on the tradition of commentating on Aristotle, had started to create a different logic, capable of answering the new needs induced by the philosophical use of their own language. Only one of these texts was translated into Latin, the Logic of al-Ghazali, and later it was used by Ramon Lull to create an original method of demonstration, different from the Aristotelian one.