Jean Buridan (in Latin, Joannes Buridanus) (1300 – 1358) or John Buridan was a French philosopher, a nominalist, who wrote extensively on logic and natural philosophy. Although he was one of the most famous and influential logicians, philosophers and theologians of the later Middle Ages, he is today among the least well known. Many of his works are still available only in Latin.
Unlike other major philosophers in the fourteenth century, he did not become a faculty member of theology. He distinguished philosophy from theology and remained as a logician. While Buridan wrote extensive commentaries on almost all the works of Aristotle, he moved forward in a new direction, from Aristotelian speculative metaphysics to modern scientific explanation. Buridan developed the concept of impetus, the first step toward the modern concept of inertia. His name is most familiar through the thought experiment known as "Buridan's ass" (a thought experiment which does not appear in his extant writings).
Born, most probably, in Béthune, France, Buridan first attended the Collège Lemoine, and then the University of Paris where he studied under the scholastic philosopher William of Ockham. He received his Master of Arts degree and formal license to teach by the mid-1320s. He served as rector at the University of Paris in 1328 and 1340. Numerous unsubstantiated stories about his reputed amorous affairs and adventures are evidence that he enjoyed a reputation as a glamorous and mysterious figure in Paris. According to one story, he was sentenced to be tied in a sack and thrown into the river Seine for dallying with Queen Jeanne de Navarre, but was ultimately saved through the ingenuity of one of his students. (Francois Villon alludes to this episode in his poem Ballade des Dames du Temps Jadis.) Buridan was able to support himself with benefices and academic funding, which also suggests that he was a charismatic figure.
Buridan departed from tradition by spending his academic life in the faculty of arts, rather than obtaining the doctorate in theology that typically prepared the way for a career in philosophy. He further maintained his intellectual independence by remaining a secular cleric, rather than joining a religious order, and avoided involvement in church politics. For his students, he wrote literal commentaries and quaestiones (critical studies) on most of the major works of Aristotle; these became distributed throughout Europe and were used as textbooks at many universities. By 1340, his confidence had grown sufficiently for him to launch an attack on his mentor, William of Ockham. This incident has been interpreted as the beginning of religious skepticism and the dawn of the scientific revolution. Buridan prepared the way for Galileo Galilei through his development of the theory of impetus. Buridan also wrote on solutions to paradoxes such as the liar paradox. A posthumous campaign by Ockhamists succeeded in having Buridan's writings placed on the Index Librorum Prohibitorum from 1474 until 1481. Albert of Saxony, himself a renowned logician, was among the most notable of Buridan’s students.
Jean Buridan wrote commentaries on almost all of Aristotle’s major works, including entire Organon, Physics, On the Heavens, On Generation and Corruption, De Anima, Parva Naturalia, Metaphysics, Nicomachean Ethics, and Rhetoric. He also wrote treatises on several controversial topics of philosophy, such as the Tractatus de relationibus (Treatise on Relations), Tractatus de universalibus (Treatise on Universals), Tractatus de consequentiis (Treatise on Consequences), and Quaestio de puncto (Question on <the Nature of> Points). His greatest work was the Summulae de dialectica (Compendium of Dialectic), a comprehensive logic textbook, originally intended as a commentary on the Summulae logicales of the thirteenth-century dialectician, Peter of Spain. It became an original and independent work in which Buridan rephrased traditional medieval Aristotelian logic using newer, terminist logic; and was a popular textbook at Paris and in the universities of Heidelberg, Prague, and Vienna.
Jean Buridan was a terminist, or ‘modern’, regarding the semantic properties of terms (literally, the "ends" ("termini"), or subjects and predicates, of propositions) as the primary unit of logical analysis. He believed that accurate terminology and correct grammar were essential for the study of logic, in order for scholars to be able to communicate with each other. William Ockham and other nominalists of the time sought to create an ideal terminology, a written and spoken language that would perfectly define specific concepts; any proposition which was improperly phrased would therefore be false. Buridan, took a different view, regarding spoken language as a means of communicating concepts; a person, by choice or error, could use improper grammar or terminology and still be speaking the truth. The meaning of a proposition could be clarified if the parties involved in the discussion reached consensus on the terminology being used.
Like Aristotle, Buridan identified two purposes for the use of logic; pedagogical (logica docens), teaching students about structure and method, and how logic could be used, and the application of logic to practical questions (logica utens) to determine whether certain conclusions were accurate. Buridan believed that logic was ultimately a practical discipline, and demonstrated its use in his own scientific explorations.
During the thirteenth century numerous thinkers, including St. Albert the Great (1206-80), Peter of Maricourt (exact dates unknown), Robert Grosseteste (c.1175-1253) and Roger Bacon (c.1212-1292), had recognized the necessity of empirical scientific research. Although Aristotle had never exactly explained how knowledge of the “causes” could be acquired, Grosseteste and Bacon tried to respond these problems.
Christian philosophers of the fourteenth century began to address themselves seriously to explaining and defining the physical world, while still supporting the doctrine of the Creation. Buridan lived and worked during the beginning of the scientific movement associated with nominalism and the theories of William Ockham. Ockham himself was not a scientist, but his emphasis on factual information and empirical research was a stimulus to the study of science. Ockham did not consider himself anti-Aristotelian; instead he thought of himself as a genuine interpreter of Aristotle. Ockham’s theories created an intellectual atmosphere which encouraged the development of scientific method. Jean Buridan was one of the theologians and philosophers who took up physical and scientific study.
One of the puzzles which fourteenth century scholars began to examine scientifically was the nature of “motion.” The concept of inertia was alien to the physics of Aristotle. Aristotle and his peripatetic followers held that a body was only maintained in motion by the action of a continuous external force. Thus, in the Aristotelian view, a projectile moving through the air would owe its continuing motion to eddies or vibrations in the surrounding medium, a phenomenon known as "antiperistasis". In the absence of a proximate force, the body would come to rest almost immediately.
Jean Buridan, following in the footsteps of John Philoponus (c. 490- c.570 C.E.), proposed that motion was maintained by some property of the body, imparted when it was set in motion. Buridan named the motion-maintaining property "impetus." He rejected the view that the impetus dissipated spontaneously, asserting instead that a body’s movement would be arrested by the forces of air resistance and gravity opposing its impetus. Buridan further held that the impetus of a body increased with the speed with which it was set in motion, and with its quantity of matter. Clearly, Buridan's impetus is closely related to the modern concept of momentum. He saw impetus as "causing" the motion of the object. Buridan anticipated Isaac Newton when he wrote:
...after leaving the arm of the thrower, the projectile would be moved by an impetus given to it by the thrower 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.
Buridan used the theory of impetus to give an accurate qualitative account of the motion of projectiles, but he ultimately saw his theory as a correction to Aristotle, maintaining core peripatetic beliefs including a fundamental qualitative difference between motion and rest.
The theory of impetus was also adapted to explain celestial phenomena in terms of "circular impetus." Aristotelians thought that the celestial bodies were made up of a special “fifth element” which could only move with circular motion. Buridan suggested instead that this idea, and a second explanation which gave the celestial bodies their own “intelligences,” were unnecessary to explain the movement of celestial bodies. Instead, he said that celestial bodies were made up of the same elements as earthly objects, and had a similar quality of “impetus” which God had imparted to them when He created them. Heavenly bodies did not encounter air resistance or the force of gravity, and so continued in unending motion. This theory was adopted and further developed by Albert of Saxony, Marsilius of Inghen, and Nicholas Oresme.
Buridan's commentary on Aristotle's Nicomachean Ethics includes discussions of the structure of the will and its relation to the intellect, the nature of human freedom, the phenomenon of akrasia or weakness of will, practical reason, and the unity of the virtues. He apparently sided with Aristotle and Thomas Aquinas in saying that the will was always subordinate to the intellect. The will was unable to choose to do evil, but it relied on the intellect to interpret whether a particular action would be good or evil. If a person was ignorant or his intellect was in some way impaired, it might mistake evil for goodness and the will would act accordingly. If the intellect was not able to distinguish that one act was better than another, the will was able to defer choosing between the two acts by doing nothing at all. In the example known as Buridan's Ass, a donkey starves to death because it has no reason to choose between two equidistant and equally tempting piles of hay. This particular example is nowhere to be found in Buridan's writings, (although there are versions of it going back at least to Aristotle) and may have been promoted by his critics, who wished to demonstrate the absurdity of the concept of free will as inaction.
All links retrieved March 20, 2013.
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