Burali-Forte paradox See SET -THEORETIC PARA -. DOXES , SET THEOR. Buridan, Jean (c.1300–after 1358), French philosopher. He was born in Béthune and educated at the University of Paris. Unlike most philosophers of his time, Buridan spent his academic career as a master in the faculty of arts, without seeking an advanced degree in theology. He was also unusual in being a secular cleric rather than a member of a religious order. Buridan wrote extensively on logic and natural philosophy, although only a few of his works have appeared in modern editions. The most important on logic are the Summulae de dialectica (‘Sum of Dialectic’), an introduction to logic conceived as a revision of, and extended commentary on, the Summulae logicales of Peter of Spain, a widely used logic textbook of the period; and the Tractatus de consequentiis, a treatise on modes of inference. Most of Buridan’s other writings are short literal commentaries (expositiones) and longer critical studies (quaestiones) of Aristotle’s works.
Like most medieval nominalists, Buridan argued that universals have no real existence, except as concepts by which the mind ‘conceives of many things indifferently.’ Likewise, he included only particular substances and qualities in his basic ontology. But his nominalist program is distinctive in its implementation. He differs, e.g., from Ockham in his accounts of motion, time, and quantity (appealing, in the latter case, to quantitative forms to explain the impenetrability of bodies). In natural philosophy, Buridan is best known for introducing to the West the non-Aristotelian concept of impetus, or impressed force, to explain projectile motion. Although asses appear often in his examples, the particular example that has come (via Spinoza and others) to be known as ‘Buridan’s ass,’ an ass starving to death between two equidistant and equally tempting piles of hay, is unknown in Buridan’s writings. It may, however, have originated as a caricature of Buridan’s theory of action, which attempts to find a middle ground between Aristotelian intellectualism and Franciscan voluntarism by arguing that the will’s freedom to act consists primarily in its ability to defer choice in the absence of a compelling reason to act one way or the other.
Buridan’s intellectual legacy was considerable. His works continued to be read and discussed in universities for centuries after his death. Three of his students and disciples, Albert of Saxony, Marsilius of Inghen, and Nicole Oresme, went on to become distinguished philosophers in their own right.
See also METAPHYSICS , OCKHAM. J.A.Z.