^[1] ‘John Buridan (c. 1300–c. 1361) was the most famous philosopher of his time, and probably the most influential, but we know very little about his life’. This is the opening sentence of Jack Zupko’s monograph on the thought of John Buridan, who had received his master’s degree by the 1320’s in the arts faculty at the university of Paris and was a teacher in the same faculty until his death. The opening is somewhat surprising—what about Duns Scotus or William Ockham, who were not only more widely known in their time but are in our days as well? Perhaps the implication is that these were theologians and Buridan was merely a master of arts, but were Scotus and Ockham less conscious in their philosophical thought of the difference between revelational theology and philosophy as an exercise of natural reason? Not at all. Being members of the Franciscan order they might have been more pious than Buridan was, but even Buridan’s making his readers believe that he is a good Catholic does not leave much to be desired. While Scotus was also a spiritual author, being officially beatified in 1993, Ockham was ascetic in this respect and, like Buridan, did not write directly religious works.

^[2] Zupko’s book is a work by one of the leading scholars on Buridan and a considerable contribution to Buridan studies. While Bernd Michael’s dissertation Johannes Buridan: Studien zu seinem Leben, seinen Werken und zur Rezeption seiner Theorien im Europa des späten Mittelalters 1–2 (Berlin 1985) is an important historical study on Buridan’s life, works and influence, Zupko’s book is the first full-length monograph on his philosophical thought. It is divided into two parts, which are called ‘Method’ and ‘Practice’. ‘Method’ is about logic and the theory of science and ‘Practice’ is about natural philosophy, metaphysics and ethics, i.e., about the areas in which Buridan applies his logical and methodological ideas. This plan corresponds to how teaching was organized in medieval universities.

^[3] Because of the prestige of logic, all arts students spent much time in logic courses. Logic and semantics were the areas in which medieval scholars developed new and original theories in the twelfth century. The next century was not as remarkable, but there was a new logic boom in the early fourteenth century, which developed earlier theories further and introduced new systematic insights into consequences, modalities, insolubilia and some other matters. In the thirteenth century, the arts curriculum was arranged to correspond mainly to Aristotle’s works, with the intention that students should become familiar with their contents. Teaching took place by commenting on these or dealing with questions more or less directly relevant to Aristotle’s works and some other basic texts. Because of medieval developments, Aristotle’s works did not provide a sufficient basis for teaching logic in the universities. In Buridan’s case this is shown by his using Peter of Spain’s Summulae logicales as the text which he comments on in his introductory course Summulae de dialectica.

^[4] In the first part, Zupko first describes Buridan’s view of grammar and logic as arts and then describes his teaching of logic following the disposition of the Summulae, which has recently been translated by Gyula Klima. There is a chapter on propositions, predicables and categories and one chapter for each of suppositions, syllogisms, topics, fallacies, demonstrations, and insoluble propositions. These themes of medieval logic are extensively researched by contemporary historians, and Buridan’s views are often compared with other medieval approaches and evaluated as contributions to philosophical logic. Zupko concentrates on describing the main lines of the historical background and doctrinal content of the Summulae as well as some particular subjects which are thought to shed light on the general interpretation of Buridan’s thought.

^[5] While the first part of the book makes for useful and illuminating reading, it is strongly influenced by Zupko’s interpretation of Buridan’s conception of logic ‘as a way of doing philosophy, i. e., as a something that has meaning only when it is learned and applied in practice’. This is said to be ‘completely alien to the modern understanding of logic as a self-contained theory of inference’ (135). Scholars on the history of logic who regard Buridan as a remarkable logician hardly agree with the thesis that what he was doing is ‘completely alien’. There certainly are differences between medieval and modern logic, but the main point is not that medieval logic is not formal and theoretical. Buridan’s remarks on modal syllogistic and modal consequences, to mention one example, are hardly understandable without considering their elaborated theoretical background, very different from that of Aristotle’s modal logic and to some extent also from that of Ockham. Some scholars consider fourteenth century modal logic as the most impressive theoretical achievement of medieval logic and Buridan as one of its architects. Evaluations of this kind are based on analyzing theoretical insights which did not necessarily have any direct practical application. Perhaps Zupko would not deny this, though one might think so from his somewhat ambiguous description of Buridan’s conception of logic as having ‘meaning only when it is learned and applied in practice’.

^[6] The second part includes chapters on metaphysics as a discipline (10), the soul-body relation (11), human knowledge and the possibility of natural philosophy or science (12), the natural science of psychology (13), virtue (14) and freedom (15). Chapters 11, 12, 13 and part of 15 appeared in various journals in the nineties. In many chapters Zupko discusses Buridan’s application of logical analysis and his ideas of the principles of inductive and deductive knowledge. Chapter 10 begins with some remarks on theology and philosophy and moves on to the mereological discussion of wholes and parts. This theme in continued in the next chapter’s discussion of Buridan’s view of how souls inhere in their bodies. Some readers might have been interested in a more extensive discussion of metaphysics as natural theology. Chapter 12 on knowledge is mainly concentrated on Buridan’s conception of the nature and source of the certainty of natural knowledge and his response to the scepticism of some contemporaries, such as Nicholas of Autrecourt. An interesting question is Buridan’s medieval ‘reliabisim’ and the role of the doctrine of the intellect’s natural inclination to truth. In chapter 13 the author compares Thomas Aquinas, Buridan and Nicole Oresme in terms of their conceptions of psychology as a science and their explanations of intellectual memory. In Zupko’s view Buridan exhibits a tendency to regard psychology as an empirical science, less akin to metaphysics than in Aquinas. Zupko associates Buridan’s view of impetus with his accounts of intellectual dispositions and virtues (pp. 222, 241–2). An analysis of the impetus theory and some other influential physical conceptions might have added suitable features to this philosophical portrait.

^[7] Chapter 14 on virtues and 15 on free act are related to ethics. Many authors have recently dealt with Buridan’s view of the freedom of the will, which seems to be some kind of compromise between Thomist intellectualism and the Franciscan approach where this freedom is associated with the conception of real alternative options. In Buridan this alternativeness is associated with the possibility of deferring a choice in situations of uncertainty as human situations of choice often are. Zupko argues that Buridan’s main interest was an attempt to provide a doctrinally acceptable formulation of the Aristotelian and Thomist view after the Condemnation of 1277. Buridan does not explicate the details of the idea that in order to be more sure one can voluntarily postpone the choice of what the intellect regards as probably good. According to Zupko, the famous example of Buridan’s ass, which is not found in Buridan, probably originated as a parody of his account of the freedom of the will as its ability to defer for further consideration any practical judgement which is not absolutely certain (p. 400).

^[8] Most of Buridan’s works are commentaries or more independent questions on Aristotle’s treatises. There are some Renaissance editions of these; the work on modern critical editions has made slow progress (pp. 275–7). It is probable that new editions will stimulate the discussion of Buridan’s philosophy and its influence on late medieval and early modern thought. Zupko’s book will be useful in this context. While shedding light on some inspiring philosophical insights, it is also a reminder of the scholastic aspects of Buridan’s work which are easily neglected by philosophical readers with less patience and less taste for purely medieval matters.