Medieval Formal Logic

Central topics in medieval logic are here treated in a way that is congenial to the modern reader, without compromising historical reliability. The achievements of medieval logic are made available to a wider philosophical public then the medievalists themselves. The three genres of logica moderna arising in a later Middle Ages are covered: obligations, insolubles and consequences - the first time these have been treated in such a unified way. The articles on obligations look at the role of logical consistence in medieval disputation techniques. Those on insolubles concentrate on medieval solutions to the Liar Paradox. There is also a systematic account of how medieval authors described the logical content of an inference, and how they thought that the validity of an inference could be guaranteed.

Keckermann remarked of the sixteenth century, "never from the begin ning of the world was there a period so keen on logic, or in which more books on logic were produced and studies oflogic flourished more abun dantly than the period-in which we live. " 1 But despite the great profusion of books to which he refers, and despite the dominant position occupied by logic in the educational system of the fifteenth, sixteenth and seven teenth centuries, very little work has been done on the logic of the post medieval period. The only complete study is that of Risse, whose account, while historically exhaustive, pays little attention to the actual logical 2 doctrines discussed. Otherwise, one can tum to Vasoli for a study of humanism, to Munoz Delgado for scholastic logic in Spain, and to Gilbert and Randall for scientific method, but this still leaves vast areas untouched. In this book I cannot hope to remedy all the deficiencies of previous studies, for to survey the literature alone would take a life-time. As a result I have limited myself in various ways. In the first place, I con centrate only on those matters which are of particular interest to me, namely theories of meaning and reference, and formal logic.

Originally published in 1972, Medieval Logic and Metaphysics shows how formal logic can be used in the clarification of philosophical problems. An elementary exposition of Leśniewski’s Onotology, an important system of contemporary logic, is followed by studies of central philosophical themes such as Negation and Non-being, Essence and Existence, Meaning and Reference, Part and Whole. Philosophers and theologians discussed include St Anselm, St Thomas Aquinas, Abelard, Ockham, Scotus, Hume and Russell.

Is medieval logic formal? And if yes, in what sense? There are striking affinities between medieval and contemporary theories of language. Authors from the two periods share formal ambitions and maintain complex, and at time uneasy, relations with natural language. However, modern scholars became careful not to overlook the specificities of theories developed more than five hundred years apart, in particular with respect to their 'formal' character. In 1972, Alfonso Maieru noted that the efforts of medieval logicians to identify logical structures in language formal enough to become objects of scientific consideration. He also stressed that the language investigated is a historical one, Latin, so that one can legitimately wonder to which extent ... one is allowed to speak of 'formal logic' in the middle ages. In other words, medieval logic is characterized by a tension between 'formalist ambitions' and constraints proper to natural language. Today, our knowledge of the field has considerably expanded, calling for a new assessment of the question.

This book presents formalizations of three important medieval logical theories: supposition, consequence and obligations. These are based on innovative vantage points: supposition theories as algorithmic hermeneutics, theories of consequence analyzed with tools borrowed from model-theory and two-dimensional semantics, and obligations as logical games. The analysis of medieval logic is relevant for the modern philosopher and logician. This is the first book to render medieval logical theories accessible to the modern philosopher.

The scholastic literature on dialectic is vast, but scholars have not yet taken full advantage of its riches. In this work, Eleonore Stump traces one strand of the history of formal logic from its source in antiquity through the fourteenth century.