“All that which, in the history of philosophy, can be traced back to non-philosophical causes is itself irrelevant to philosophy as such.” Because this judgment of an eminent historian is true, the historian of philosophy must needs be a philosopher in order to be a faithful historian, and the philosopher must needs scan the record of history for philosophical lessons which are as permanent as is the philosophy which he professes. It is inevitable, therefore, that the philosophical continuity between the history of philosophy and philosophy itself should be an increasingly important meeting-ground between the philosopher and the historian. It is equally inevitable that those who are not only disciples of scholasticism as a philosophy but also students of its history during the Middle Ages should confront these two experiences with one another and seek in history itself some understanding of the meaning of scholasticism as a philosophy. This is particularly true in our day when the traditional notion of a universal medieval scholastic synthesis is being replaced by the notion that there were several and mutually irreducible such syntheses; though it may still be true that even in their irreducibilities some of these syntheses betray the influence of common causes.
Such a state of affairs is bound to raise the question as to the unity, the truth and meaning of scholasticism. What sort of unity has it as a philosophy if it is the heir of rival and conflicting syntheses? And since this question is raised under the supposition of a philosophical continuity between medieval and modern scholasticism, nothing less than the very significance and coherence of scholasticism is at stake. More than this, since medieval philosophy ended in exhaustion and decline by the middle of the fourteenth century, and since with Professor Gilson we are driven to seek philosophical causes for this decline, the philosophical continuity between medieval philosophy and present-day scholasticism raises the further question of the philosophical health and purity of the heir of a movement which ended in failure. So long as Ockhamism remains a strange and distant phenomenon, somehow outside the pale of the golden successes of the thirteenth century, questions of meaning, of unity and of truth within scholasticism might not appear with all the acuity that they really possess. But just as soon as there are any reasons for thinking that the thirteenth century laid the foundation for th fourteenth, then the present-day scholastic cannot scan his medieval predecessors too closely or too critically.
[From “The Dilemma of Being and Unity” by Anton C. Pegis]