Jean Buridan (; ; Latin: Johannes Buridanus; – ) was an influential 14thcentury French scholastic philosopher.
Buridan taught in the faculty of arts at the University of Paris for his entire career and focused in particular on logic and on the works of Aristotle. Buridan sowed the seeds of the Copernican Revolution in Europe. He developed the concept of impetus, the first step toward the modern concept of inertia and an important development in the history of medieval science. His name is most familiar through the thought experiment known as Buridan's ass, but the thought experiment does not appear in his extant writings.
Life
Education and career
thumb|right|14th-century manuscript of Buridan's Questions on Aristotle's .
Buridan was born sometime before 1301, perhaps at or near the town of Béthune in Picardy, France, or perhaps elsewhere in the diocese of Arras. He received his education in Paris, first at the Collège du Cardinal Lemoine and then at the University of Paris, receiving his Master of Arts degree and formal license to teach at the latter by the mid-1320s. As university statutes permitted only those educated in theology to teach or write on the subject, there are no writings from Buridan on either theological matters or commentary of Peter Lombard's Sentences. Most scholars think it is unlikely that he went unnoticed, given his philosophical talents. As well, it is unlikely that he could not afford to study theology, given that he received several bursaries and stipends. Indeed, he is listed in a document from 1350 as being among the teachers capable of supporting themselves without the need for financial assistance from the University.
The bishop Albert of Saxony, himself renowned as a logician, was among the most notable of his students.
An ordinance of Louis XI in 1473, directed against the nominalists, prohibited the reading of his works.
Apocryphal stories
Apocryphal stories abound about his reputed amorous affairs and adventures which are enough to show that he enjoyed a reputation as a glamorous and mysterious figure in Paris life. None of the stories can be confirmed, and most contradict known historical information.
Some rumors hold that he died when the King of France had him put in a sack and thrown into the River Seine after his affair with the Queen came to light. François Villon alludes to this in his famous poem Ballade des Dames du Temps Jadis. Others suggest that he was expelled from Paris due to his nominalist teachings and moved to Vienna to found the University of Vienna. Another story talks of him hitting Pope Clement VI with a shoe. Buridan was the first to name this motion-maintaining property impetus but the theory itself probably did not originate with him. A less sophisticated notion of impressed forced can be found in the commentary of John Philoponus on Aristoteilan physics. In this he was possibly influenced by John Philoponus who was developing the Stoic notion of hormé (impulse). The major difference between Buridan's theory and that of his predecessor is that he rejected the view that the impetus dissipated spontaneously, instead asserting that a body would be arrested by the forces of air resistance and gravity which might be 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. This is closely related to the modern concept of momentum. Buridan saw impetus as causing the motion of the object:
:...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 (Questions on Aristotle's Metaphysics XII.9: 73ra).
Buridan also contended that impetus is a variable quality whose force is determined by the speed and quantity of the matter in the subject. In this way, the acceleration of a falling body could be understood in terms of its gradual accumulation of units of impetus. and Anneliese Maier both saw Buridan as playing an important role in the demise of Aristotelian cosmology. Duhem even called Buridan the forerunner of Galileo. Zupko has disagreed, pointing out that Buridan did not use his theory to transform the science of mechanics, but instead remained a committed Aristotelian in thinking that motion and rest are contrary states and that the universe is finite in extent.