Jean Buridan (ca. 1300 – after 1358) was a French

French people

The French are a nation that share a common French culture and speak the French language as a mother tongue. Historically, the French population are descended from peoples of Celtic, Latin and Germanic origin, and are today a mixture of several ethnic groups...

 priest who sowed the seeds of the Copernican revolution

Copernican Revolution

The Copernican Revolution refers to the paradigm shift away from the Ptolemaic model of the heavens, which postulated the Earth at the center of the galaxy, towards the heliocentric model with the Sun at the center of our Solar System...

 in Europe. Although he was one of the most famous and influential philosophers of the late Middle Ages

Late Middle Ages

The Late Middle Ages was the period of European history generally comprising the 14th to the 16th century . The Late Middle Ages followed the High Middle Ages and preceded the onset of the early modern era ....

, he is today among the least well known. He developed the concept of impetus

Theory of impetus

The theory of impetus was an auxiliary or secondary theory of Aristotelian dynamics, put forth initially to explain projectile motion against gravity...

, the first step toward the modern concept of inertia

Inertia

Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

, and an important development in the history of medieval science. His name is most familiar through the thought experiment

Thought experiment

A thought experiment or Gedankenexperiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences...

 known as Buridan's ass

Buridan's ass

Buridan's ass is an illustration of a paradox in philosophy in the conception of free will.It refers to a hypothetical situation wherein an ass is placed precisely midway between a stack of hay and a pail of water...

 (a thought experiment which does not appear in his extant writings).

Career

Born, most probably, in Béthune

Béthune

Béthune is a city in northern France, sub-prefecture of the Pas-de-Calais department.-Geography:Béthune is located in the former province of Artois. It is situated South-East of Calais, West of Lille, and North of Paris.-Landmarks:...

, France, Buridan studied and later taught at the University of Paris

University of Paris

The University of Paris was a university located in Paris, France and one of the earliest to be established in Europe. It was founded in the mid 12th century, and officially recognized as a university probably between 1160 and 1250...

. 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. In particular, a rumour held that he was sentenced to be thrown in a sack into the River Seine

Seine

The Seine is a -long river and an important commercial waterway within the Paris Basin in the north of France. It rises at Saint-Seine near Dijon in northeastern France in the Langres plateau, flowing through Paris and into the English Channel at Le Havre . It is navigable by ocean-going vessels...

, but was ultimately saved through the ingenuity of a student. François Villon

François Villon

François Villon was a French poet, thief, and vagabond. He is perhaps best known for his Testaments and his Ballade des Pendus, written while in prison...

 alludes to this in his famous poem Ballade des Dames du Temps Jadis

Ballade des Dames du Temps Jadis

The Ballade des dames du temps jadis is a poem by François Villon which celebrates famous women in history and mythology, and a prominent example of the "Ubi Sunt ?" genre...

. Buridan also seems to have had an unusual facility for attracting academic funding which suggests that he was indeed a charismatic figure.

Unusually, he spent his academic life in the faculty of arts, rather than obtaining the doctorate in Theology

Theology

Theology is the systematic and rational study of religion and its influences and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university or school of divinity or seminary.-Definition:Augustine of Hippo...

 that typically prepared the way for a career in Philosophy

Philosophy

Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

. He further maintained his intellectual independence by remaining a secular cleric

Secular clergy

The term secular clergy refers to deacons and priests who are not monastics or members of a religious order.-Catholic Church:In the Catholic Church, the secular clergy are ministers, such as deacons and priests, who do not belong to a religious order...

, rather than joining a religious Order

Religious order

A religious order is a lineage of communities and organizations of people who live in some way set apart from society in accordance with their specific religious devotion, usually characterized by the principles of its founder's religious practice. The order is composed of initiates and, in some...

. By 1340, his confidence had grown sufficiently for him to launch an attack on his predecessor, William of Ockham

William of Ockham

William of Ockham was an English Franciscan friar and scholastic philosopher, who is believed to have been born in Ockham, a small village in Surrey. He is considered to be one of the major figures of medieval thought and was at the centre of the major intellectual and political controversies of...

. Buridan also wrote on solutions to paradox

Paradox

Similar to Circular reasoning, A paradox is a seemingly true statement or group of statements that lead to a contradiction or a situation which seems to defy logic or intuition...

es such as the liar paradox

Liar paradox

In philosophy and logic, the liar paradox or liar's paradox , is the statement "this sentence is false"...

. An ordinance of Louis XI., in 1473, directed against the nominalists

Nominalism

Nominalism is a metaphysical view in philosophy according to which general or abstract terms and predicates exist, while universals or abstract objects, which are sometimes thought to correspond to these terms, do not exist. Thus, there are at least two main versions of nominalism...

, prohibited the reading of his works.

The bishop

Bishop

A bishop is an ordained or consecrated member of the Christian clergy who is generally entrusted with a position of authority and oversight. Within the Catholic Church, Eastern Orthodox, Oriental Orthodox Churches, in the Assyrian Church of the East, in the Independent Catholic Churches, and in the...

 Albert of Saxony

Albert of Saxony (philosopher)

Albert of Saxony was a German philosopher known for his contributions to logic and physics...

, himself renowned as a logician, was among the most notable of his students.

Impetus Theory

The concept of inertia was alien to the physics of Aristotle

Aristotle

Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

. Aristotle, and his peripatetic followers, held that a body was only maintained in motion by the action of a continuous external force

Force

In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...

. 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

Antiperistasis

Antiperistasis, in philosophy, is a general term for various processes, real or contrived, in which one quality heightens the force of another, opposing, quality...

. In the absence of a proximate force, the body would come to rest almost immediately.

Jean Buridan, following in the footsteps of John Philoponus

John Philoponus

John Philoponus , also known as John the Grammarian or John of Alexandria, was a Christian and Aristotelian commentator and the author of a considerable number of philosophical treatises and theological works...

 and Avicenna

Avicenna

Abū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā , commonly known as Ibn Sīnā or by his Latinized name Avicenna, was a Persian polymath, who wrote almost 450 treatises on a wide range of subjects, of which around 240 have survived...

, 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. Moreover, he rejected the view that the impetus dissipated spontaneously (this is the big difference between Buridan's theory of impetus and his predecessors), 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. Clearly, Buridan's impetus is closely related to the modern concept of momentum

Momentum

In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...

. Buridan saw impetus as causing the motion of the object. Buridan anticipated Isaac Newton

Isaac Newton

Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

 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

Celestial mechanics

Celestial mechanics is the branch of astronomy that deals with the motions of celestial objects. The field applies principles of physics, historically classical mechanics, to astronomical objects such as stars and planets to produce ephemeris data. Orbital mechanics is a subfield which focuses on...

phenomena in terms of circular impetus.

Works by Buridan

• Hughes, G.E. (1982) John Buridan on Self-Reference: Chapter Eight of Buridan's Sophismata. An edition and translation with an introduction, and philosophical commentary. Cambridge/London/New York: Cambridge University Press, ISBN 0-521-28864-9.
• King, Peter (1985) John Buridan's Logic: The Treatise on Supposition; The Treatise on Consequences. Translation from the Latin with a Philosophical Introduction, Dordrecht: Reidel.
• Zupko, John Alexander, ed.&tr. (1989) 'John Buridan's Philosophy of Mind: An Edition and Translation of Book III of His ' Questions on Aristotle's De Anima (Third Redaction), with Commentary and Critical and Interpretative Essays.' Doctoral dissertation, Cornell University.
• Klima, Gyula, tr. (2001) John Buridan: 'Summulae de Dialectica'. Yale Library of Medieval Philosophy. New Haven, Conn./London: Yale University Press.

Works on Buridan

• Michael, Bernd (1985) Johannes Buridan: Studien zu seinem Leben, seinen Werken und zu Rezeption seiner Theorien im Europa des späten Mittelalters. 2 Vols. Doctoral dissertation, University of Berlin.
• Klima, Gyula (2008) John Buridan New York: Oxford University Press.
• Landi, Marcello, Un contributo allo studio della scienza nel Medio Evo. Il trattato Il cielo e il mondo di Giovanni Buridano e un confronto con alcune posizioni di Tommaso d'Aquino, in Divus Thomas 110/2 (2007) 151-185
• Thijssen, J. M. M. H., and Jack Zupko (ed.) (2001) The Metaphysics and Natural Philosophy of John Buridan. Leiden: Brill.
• Zupko, Jack (2003) John Buridan. Portrait of a Fourteenth-Century Arts Master. Notre Dame, Indiana: University of Notre Dame Press. (cf. pp. 258, 400n71)

External links

• Bibliography by Fabienne Pironet (up to 2001)
• Buridan's Logical Works. I. An Overview of the Summulae de dialectica a detailed summary of the nine treatises of the Summulae de dialectica
• Buridan's Logical Works. II. The Treatise on Consequences and other writings a summary of the other logical writings
• Buridan: Editions, Translations and Studies on the Manuscript Tradition Complete bibliography of the logical and metaphysical works
• Buridan's Logic and Metaphysics: an annotated bibliography (updates the bibliography of Fabienne Pironet to 2011)