One of the most colorful and fascinating figures of the Middle Ages was Peter Abelard. Many who know little about the technicalities of medieval logic still know about his life and loves. Some mystery and much romance surround the events of his life, and beneath this fascination the fact that Abelard was undoubtedly one of the more skilled philosophers of the era is sometimes forgotten. For one thing, much less of his work has been translated than that of others from the same period who are, consequently, now better known. Furthermore, his particular doctrines have not gained the fame that came to others. No matter how important Glosses on Porphyry may be in a medieval setting, the idea of practicing philosophy through such commentary is not a currently accepted form. However, few were more responsible than Porphyry for the problems that dominated the Middle Ages, and Abelard’s glosses concern crucial issues.
This work belongs to the branch of philosophy that Abelard, following the Roman philosopher Boethius, called “rational” (the other divisions being the “speculative” and the “moral”). It corresponds most nearly to what is called logic, although it comprehends a wider area of problems than formal logic does. Porphyry prepared an introduction for the Categories (in Organon, second Athenian period, 335-323 b.c.e.; English translation, 1812) of the Greek philosopher Aristotle, and it is this work upon which Abelard comments. Abelard’s treatment of the problem of the status of universals really ended the argument in its all-absorbing attraction; from then on it was only one among a series of problems. Abelard, however, was condemned by his church because his doctrines seemed to lead to paganism.
Definition, division, and classification are the central logical problems to be considered first. Essential definition is the main issue, and consequently all these logical problems basically involve metaphysical issues. In Porphyry’s mind, and Abelard’s as well, logical division is division according to real structures actually present in nature. How are the creatures of the natural order divided? This question concerns the way of things as much as it does the ways of logical procedure, for in the medieval mind, the two are to be worked on until they become the same. The mind adjusts its classifications to the divisions it finds in nature. Logical investigation is ontological inquiry, and through it the structure of the world is grasped.