Historical Introduction

Abstract

Although many of the details of the development of logic in the Middle Ages remain to be filled in, it is well known that between the time of Peter of Spain (d. 1277) and Paul of Venice (d. 1429), a high level of sophistication and formalism was reached. The theory of consequences or valid inference forms, which involved a recognition of the place and value of propositional logic, was of particular importance, but supposition theory, which included an analysis of meaning and reference, as well as complicated quantificational inferences, and the study of logical paradoxes under the title of insolubilia, were also significant. Perhaps the most outstanding figures in these departures from the syllogistic logic of Aristotle were Ockham, Buridan and Burleigh, who all worked in the first half of the fourteenth century, but such followers as Albert of Saxony and Marsilius of Inghen, and such lesser figures as Strode and Heytesbury, should not be overlooked. An encyclopedic account of his predecessors’ work was given by Paul of Venice in his Logica Magna, showing that formal logic was alive and well at the beginning of the fifteenth century, but hitherto no one has been able to give a clear answer to the question of what happened next. Many opinions have been offered, of course. Typical is that of Father Boehner, who claimed that at the end of the fifteenth century logic entered upon a period of unchecked regression, during which it became an insignificant preparatory study, diluted with extra-logical elements; and the insights of such men as Burleigh into the crucial importance of propositional logic as a foundation for logic as a whole were lost.1 His judgement is supported by studies of humanism and of Ramism, which, by concentrating upon schools little interested in formal logic, reinforce the impression that formal logic was very sick, if not dead. Nor has the focusing of attention upon isolated figures helped. John of St. Thomas, Joachim Jungius, and the authors of the Port-Royal logic have all been the subjects of discussion and study in recent years;2 yet someone who is acquainted only with the works of these men will have a very poor grasp of what actually happened in the post-medieval period.