Medieval Europe · c. 1300–c. 1360
Jean Buridan
Paris arts master, logician and natural philosopher
A thrown body keeps moving because of an impressed force, “impetus”, rather than the surrounding air, a step toward the idea of inertia. The paradox of the ass starving between two equal haystacks is named after him, though it is not in his writings.
Life and thought
John Buridan was born around 1300 in or near Béthune in Picardy and spent his whole career in the arts faculty at Paris, twice serving as rector of the university. Unusually, he never joined a religious order or took a higher degree in theology: he remained a teacher of logic and natural philosophy for some forty years, and died around 1360.
He was a nominalist in Ockham’s spirit, and his textbook of logic, the Summulae, was used for generations. In physics he asked why a thrown stone keeps moving after it leaves the hand. Aristotelians said the air pushes it, but that seemed absurd. Buridan proposed that the thrower impresses on the stone a quantity of “impetus”, proportional to its speed and its quantity of matter, which lasts until air resistance and weight wear it away; in the heavens, with no resistance, it could last forever. This was not yet the law of inertia, but it was a step toward it. The famous ass between two haystacks is a later parody, not his.
Works
Shaped by
c. 1287–1347William of OckhamEnglish Franciscan logician who defied the pope384–322 BCEAristotlePlato’s student, Alexander’s tutor, founder of the LyceumMeanwhile, in other traditions
1238–1317 (some sources: 1199–1278)MadhvaFounder of Dvaita, the dualist school of Vedāntafl. 14th c., MithilāGaṅgeśa UpādhyāyaFounder of Navya-Nyāya, the ‘new logic’1332–1406Ibn KhaldūnNorth African historian and judge, founder of a science of societyOn the record
Buridan lived c. 1301–c. 1360.
He was born around 1300 in or near Béthune in Picardy. He last appears alive in a document of 1358 and was dead by 1361, when one of his benefices passed to someone else. His Summulae and his questions on the Physics went through several lectures and versions and cannot be dated exactly; the edition of the Physics questions follows his “final lecture”. The ass between two haystacks is nowhere in his writings.
Sources: Stanford Encyclopedia of Philosophy, “John Buridan”