Buridan, John (c. 1300–1361)

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(c. 13001361)

John Buridan, or Johannes Buridanus, was a philosopher and arts master at the University of Paris. Little is known about his early life other than that he hailed from Picardy in the north of France, most likely from the town of Béthune. As a young man he studied at the Collège Lemoine in Paris, where he was awarded a benefice or stipend for needy students, and then at the University of Paris, where he earned the degree of master of arts and received his license to teach in the 1320s. He spent his entire academic career at the University of Paris, twice serving as its rector. He was a respected figure who was often asked to settle jurisdictional disputes and assist in other matters of academic governance.

Two features of Buridan's career are distinctive. The first is that he remained a teaching master in the faculty of arts without ever moving on to take a higher, doctoral degree in theology, which was the more typical career track for philosophers at the time. Why he decided not to join the more prestigious ranks of the theologians he does not say, but given his philosophical talent and stature at the University, it is safe to assume that he had his reasons for remaining where he was. One possibility, which is suggested by some of his remarks about the relation between philosophy and theology, is that he believed philosophy to be an essentially secular enterprise, which he would have to abandon if he became a theologian. Whether this represents an important first step in the direction of modernity awaits further investigation, but at the very least, Buridan was passionately committed to the autonomy of philosophy as a discipline proper to the faculty of arts, not theology.

The other distinctive feature of Buridan's academic career is that he remained a secular cleric rather than joining a religious order such as the Dominicans or Franciscans. The popularity of these orders in the thirteenth century had revitalized the study of theology, raising it to speculative heights it has not seen since. But as the larger orders began to institutionalize the training of their novices outside the university and develop their own intellectual traditionswith Thomas Aquinas being championed by the Dominicans and Bonaventure and John Duns Scotus by the Franciscansserious disputes arose not only within religious orders but between them, a phenomenon that led to the development of different schools of philosophy: Thomistic, Scotistic, and so on (hence the term Schoolmen ). As a secular cleric, Buridan could safely ride above these disputes, without being obliged to defend or explain the authorities of any particular tradition. This theoretical independence can be seen in the occasionally eclectic character of his remarks.

Most of Buridan's writings are in the form of commentaries on Aristotle, whose texts were the primary subject of study in the medieval arts curriculum. These commentaries survive in two forms: expositiones or literal commentaries and quaestiones or question commentaries, both of which have their origins in the way Buridan actually taught. He would begin by giving his students a line-by-line exposition of a portion of Aristotle's text and follow this up with a problem or question raised by the passage although not explicitly discussed in it, such as whether the intellect has the capacity to recall previous thoughts, analogous to the power of memory in the sensitive part of the soul (see Aristotle, De Anima III.5, 430a24). Arguments for and against would be inventoried, after which Buridan would give his ownsometimes lengthyresolution of the question, with responses to arguments on the opposite side. A similar method was used by Thomas Aquinas in composing the Summa Theologiae.

Buridan wrote commentaries on all of the major works of Aristotle. But because he lectured more than once on a given text over the course of his long career, some commentaries exist in more than one version, and the evolution in his thinking about a particular issue can occasionally be seen in these different versions. In addition to the commentaries, he wrote a massive logic textbook, the Summulae de Dialectica (Compendia of dialectics), as well as a number of shorter, independent treatises on controversial topics such as the Tractatus de relationibus (Treatise on relations)], Tractatus de universalibus (Treatise on universals), and Tractatus de consequentiis (Treatise on consequences). He was by any measure a prolific author.

Buridan's influence is immediately evident in the work of his younger contemporaries at Paris: Albert of Saxony, Marsilius of Inghen, and Nicole Oresme. But his commentaries and his Summulae de Dialectica continued to be read and commented on for several generations. Manuscripts and early printed editions of his writings were carried by his students and followers to the new universities in Heidelberg, Kraków, Prague, and Vienna, where they served as primary texts in courses on logic and Aristotelian philosophy. In this way, the via Buridani continued to influence European thought well into the early modern period.


Buridan's view of logic is best conveyed by the opening line of Peter of Spain's Summulae Logicales (Compendia of logics), the thirteenth-century textbook on the basis of which Buridan prepared his logical masterwork, the Summulae de Dialectica : "Dialectica est ars artium, ad omnium methodorum principia viam habens (Dialectic is the art of arts, having access to the principles of all other inquiries)." More than just a method, logic is the grammar of philosophical discourse, the discipline whose procedures govern rational inquiry in virtually every field investigated by the arts master, from metaphysics and cosmology to natural philosophy and ethics. Buridan composed the nine treatises of his Summulae so that they exhibit an orderly progression of teachings based on the proposition, beginning with propositions themselves (I), moving down to the significance and referential function of their component terms (IIIV), then back up to propositions again, considered as parts of more complex patterns of reasoning: syllogisms (V), topics (VI), fallacies (VII), and demonstrations (VIII). The work closes with a series of logical exercises (IX). The order of the Summulae reflects Buridan's assumptions about the semantic character of human understanding, which is in turn a reflection of the metaphysical structure of creation.

Buridan is usually classed as a terminist logician. The terminists (sometimes referred to as the moderni or moderns ) were a diverse group of thirteenth- and fourteenth-century philosophers who regarded the semantic properties of terms (literally, the "ends [termini ]," or subjects and predicates, of propositions) as the primary unit of logical analysis. His main contribution was to modernize and systematize the old logic of Aristotle and Boethius using the newer techniques of the terminists, though in the process he offered innovative solutions to traditional problems in the philosophy of logic. His solutions to logical paradoxes such as the liar are still being discussed today. Consider, for example, the sentence, "Every proposition is false," assuming "that all true propositions are annihilated while the false ones remain, and then Socrates propounds only this: 'Every proposition is false' " (Summulae 9.8, seventh sophism). Is Socrate' proposition true or false? Buridan argues that it is false, and his reasoning shows his mastery of the semantic nuances of the question. "Every proposition," he says, "virtually implies another proposition in which the predicate 'true' is affirmed of the subject that supposits for [the original proposition]" (Summulae 9.8, seventh sophism). Thus, for the truth of any proposition P, it is required not only (1) that the subject and predicate terms of P stand for the same thing or things, but also (2) that P imply another proposition, "P is true," which must also be trueotherwise there would be a true antecedent and a false consequent. Accordingly, the constituent terms in the proposition uttered by Socrates"Every proposition" and "false"stand for the same things, since in the posited case, "all true propositions are annihilated and the false ones remain, and then Socrates propounds only this: 'Every proposition is false'." So the first condition is satisfied. But the implied proposition, "P is true" (where P is the name of "Every proposition is false"), is false because its constituent terms, "Every proposition is false" and "true," do not stand for the same thing, since ex hypothesi, P stands for the antecedent proposition "Every proposition is false," not for things that are true. But this gives us a true antecedent and a false consequent, and so the consequence does not hold. Therefore, the sophism is false.


Buridan viewed metaphysics as the highest form of philosophical inquiry, yet his Questions on Aristotle's Metaphysics is among the shortest of his commentaries. There appear to be two reasons for this. First, he is not optimistic about the possibility of humans coming to know the ultimate nature of reality in this life because he doubts whether people are ever in a position to be acquainted with the natures or essences of things as such. Most of the time one must make do with inferences based on sense, memory, and experience, and the latter experience shows that even the firmest empirical conviction is subject to revision. Second, Buridan is adamant that metaphysics belongs to philosophy, not to theology, and hence that it cannot take its principles or starting points from Scripture or religious doctrine: "metaphysics differs from theology in the fact that although each considers God and things that pertain to divinity, metaphysics considers them only as regards what can be proved and implied, or inductively inferred, by demonstrative reason. But theology has for its principles articles [of faith], which are believed quite apart from their evidentness, and further, considers whatever can be deduced from articles of this kind" (Questions on Aristotle's Metaphysics, I.2). This leads him to assert the autonomy of philosophersand implicitly of the arts masters as wellin a rather striking way: metaphysics, or philosophical wisdom, cannot be ordained by theology because its methods, which are rooted in its principles, are different. Philosophy is accordingly not inferior to theology, just different. This was an important step toward the modern view of philosophy as a secular enterprise.

Buridan was also a nominalist, though it is better to think of late-medieval nominalism as a parsimonious way of doing philosophy than as a commitment to denying the existence of real or Platonic universals. The method in Buridan's metaphysics is his logic. He tries wherever possible to apply the Summulae 's analytical techniques to the interpretation of Aristotle, and his approach is critical in that it tends to view traditional questions in metaphysics as based on confusions of logic or language. Thus, when asked whether universals really exist outside the soul, he replies by clarifying the meaning of the common term universal with respect to its correlative terms, individual, particular, and singular. His rejection of realism is expressed in the same fashion: universal terms have no ultimate significate, nothing outside the soul they can make known as such. What such terms mean is other terms: the primary signification of universal is "predicable of many," which makes it a term of second intention, or a term of terms, since only terms are predicable. Likewise, when the term universal occurs in a proposition, it signifies not a what but a how, that is, how one conceives of somethingin this case, that the term so designated is "indifferent to many supposits," or individuals.

Clearly, Buridan thinks that the careful and systematic analysis of language is the best way of dealing with such metaphysical problems. The trouble usually begins with untutored persons who think that each and every substantive term must correspond to a thing, or that true predication must involve the real inherence of attributes in subjects rather than making the more modest assumption that the subject and predicate terms simply stand for the same thing(s).

Natural Philosophy and Ethics

Buridan's natural philosophy and ethics are also shaped by the methods of the Summulae. Thus, his treatment of infinite magnitudes in his Questions on Aristotle's Physics focuses on clarifying the different senses of the term infinite : nothing is infinite if by that one means an actually existing infinite magnitude, although one can always imagine a magnitude greater than the one being considered, and do so without limit. The concept of infinity is thereby redeemed for natural science as a mode, or way of thinking.

Buridan also played a key role in the demise of the Aristotelian picture of the cosmos in the later Middle Ages. His major contribution was to develop and popularize the theory of impetus, or impressed force, to explain projectile motion. Rejecting the Aristotelian idea of antiperistasis according to which the tendency of a moving projectile to continue moving (think of a ball after it has left the hand of a thrower) is due to a proximate but external moving cause (the air surrounding it, in this case)Buridan argued that only an internal motive force, transmitted from the mover to the projectile, could explain its continued motion. The theory did not originate with Buridan, but he is perhaps the first to have seen that a force of this kind need not be self-dissipating: "[A]fter leaving the arm of the thrower, the projectile would be moved by an impetus given to it by the thrower," he says, "and would continue to be moved as long as the impetus remained stronger than the resistance, and would be of infinite duration were it not diminished and corrupted by a contrary force resisting it or by something inclining it to a contrary motion" (Questions on Aristotle's Metaphysics, XII.9). This is a long way from Aristotle, and not all that far from Galileo.

Despite its revolutionary implications, Buridan did not use impetus to transform the science of mechanics. He remained unapologetically Aristotelian in other respects, continuing to hold, for example, that motion and rest are contrary states of bodies. He should instead be thought of as someone who tried hard to reshape Aristotelian physics in the face of an increasingly mechanistic worldview.

Buridan's method in natural science is empirical in the sense that it emphasizes the evidentness of appearances, the reliability of a posteriori modes of reasoning, and the application of naturalistic models of explanationsuch as the concept of impetusto natural phenomena. Purely theological considerations are dismissed as irrelevant: "[O]ne might assume that there are many more separate substances than there are celestial spheres and celestial motions, viz., great legions of angels [magnae legiones angelorum ], but this cannot be proved by demonstrative arguments originating from sense perception" (Questions on Aristotle's Metaphysics, II.9). Buridan concedes that an omnipotent God could deceive people in ways they could never detect, but this is tempered by his confidence, for which he cites empirical evidence, that people's ordinary powers of perception and inference are sufficiently reliable to make "the comprehension of truth with certitude possible for us" (Questions on Aristotle's Metaphysics, II.1). He had little patience for skeptical arguments (such as those he believed were advanced by his Parisian contemporary, Nicholas of Autrecourt), objecting that it is absurd to demand that all knowledge be demonstrable by reduction to the principle of noncontradiction. Natural philosophy is about what happens for the most part, assuming the common course of nature.

Despite Buridan's prolific output, stellar reputation, and profound influence on later thinkers, most philosophers know of him only in connection with Buridan's Ass, the traditional example in which a donkey starves to death because it has no reason to choose between two equidistant and equally tempting piles of hay. This is doubly unfortunate because this example is nowhere to be found in Buridan's writings, though there are versions of it going back at least to Aristotle (see De Caelo 295b32). The best explanation of its association with Buridan is that it began as a parody of his account of free choice by later critics, who found absurd his idea that the will's freedom could consist in inaction, or more specifically, in its ability to defer or send back for further consideration any practical judgment that is not absolutely certain. But Buridan's Ass, which is apparently possessed of reason, would have surely seen the good in ceasing to deliberate once his hunger or thirst became too acute, and would have permitted his sensory appetite to lead him to whichever appeared first.

See also Impetus; Logic, History of: Medieval (European) Logic; Universals, a Historical Survey.


works by john buridan

Iohannis Buridani Tractatus de consequentiis. Edited by Hubert Hubien. Louvain, Belgium: Publications universitaires, 1976.

John Buridan on Self-Reference: Chapter Eight of Buridan's Sophismata: An Edition and Translation with an Introduction and Philosophical Commentary. Edited and translated by G. E. Hughes. Cambridge, U.K.: Cambridge University Press, 1982.

Iohannes Buridanus Quaestiones in Praedicamenta. Edited by Johannes Schneider. Munich, Germany: Beck, 1983.

"Jan Buridan, Kommentarz do Isagogi Porfiriusza." Edited by Ryszard Tatarzyňski. Przeglad Tomistyczny 2 (1986): 111195.

"Johannis Buridani, Tractatus de differentia universalis ad individuum." Edited by Sławomir Szyller. Przeglad Tomistyczny 3 (1987): 137178.

John Buridan's "Tractatus de Infinito". Edited by J. M. M. H. Thijssen. Nijmegen, Netherlands: Ingenium, 1991.

Le traité de l'âme de Jean Buridan [De prima lectura]. Edited by Benoît Patar. Louvain-la-Neuve, Belgium: Editions de l'Institut supérieur de philosophie; Longueuil, Quebec: Editions du Préambule, 1991.

Johannes Buridanus, Questiones Elencorum. Edited by Ria van der Lecq and H. A. G. Braakhuis. Nijmegen, Netherlands: Ingenium, 1994.

"Buridan, On Aristotle's Ethics, Book X." Edited by R. J. Kilcullen. Edition available online at: http://www.humanities.mq.edu.au/Ockham/ (1996).

Ioannis Buridani, Expositio et Quaestiones in Aristotelis "De Caelo". Edited by Benoît Patar. Louvain-la-Neuve, Belgium: Éditions de l'Institut supérieur de philosophie; Paris: Peeters, 1996.

Summulae de Dialectica. Translated by Gyula Klima. New Haven, CT: Yale University Press, 2001.

works about john buridan

Biard, Joël. Logique et théorie du signe au XIVe siècle. Paris: Vrin, 1989.

Klima, Gyula. "Buridan's Logic and the Ontology of Modes." In Medieval Analyses in Language and Cognition, edited by Sten Ebbesen and Russell L. Friedman, 473495. Copenhagen: Royal Danish Academy of Sciences and LettersC. A. Reitzels Forlag, 1999.

Thijssen, J. M. M. H., and Jack Zupko, eds. The Metaphysics and Natural Philosophy of John Buridan. Leiden-Boston-Köln: Brill, 2001.

Walsh, James J. "Buridan on the Connection of the Virtues." Journal of the History of Philosophy 24 (1986): 453482.

Willing, A. "Buridan and Ockham: The Logic of Knowing." Franciscan Studies 45 (1985): 4756.

Zupko, Jack. "John Buridan." In The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta. Winter 2003 Edition. Available from http://plato.stanford.edu/.

Zupko, Jack. John Buridan: Portrait of a Fourteenth-Century Arts Master. Notre Dame, IN: University of Notre Dame Press, 2003.

Zupko, Jack. "Substance and Soul: The Late Medieval Origins of Early Modern Psychology." In Meeting of the Minds: The Relations between Medieval and Classical Modern European Philosophy, edited by Stephen F. Brown, 121139. Turnhout, Belgium: Brepols, 1999.

Jack Zupko (2005)