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c. 1320-1360 CEPrimary source · 2 sourcesWell documented

Medieval Scholars Break With Aristotle on Motion

A Paris philosopher invents impetus and an Oxford theorem proves how falling bodies really accelerate

On the timeline · around c. 1320-1360 CE · Ancient and Classical FoundationsAncient and Classical FoundationsThe Scientific RevolutionMedieval Scholars Break With Aristotle on Motion800 CE100012001400

Quick facts

Key figures
Jean Buridan, Nicole Oresme
Buridan's concept
Impetus, an impressed quantity of motion
Oresme's proof
Merton College mean speed theorem
Institutions
University of Paris; Merton College, Oxford

What happened

In 14th-century Paris, the philosopher Jean Buridan proposed that a thrown object keeps moving not because it needs a continuous outside mover, as Aristotle held, but because the thrower impresses on it a quantity he called impetus, which the object retains until air resistance and its own weight wear it down. The MacTutor History of Mathematics archive credits Buridan with adding to Aristotle's theory of motion by recognizing that motion was retarded by resistance from the air, a genuine break from strict Aristotelian doctrine. Buridan's student Nicole Oresme went further mathematically: he became the first to prove the Merton College mean speed theorem, that a body moving under uniform acceleration for a fixed time covers the same distance as a body moving at a constant speed equal to its velocity at the midpoint of that time, a rule first stated by Oxford's Merton College scholars and later central to Galileo's own law of falling bodies.

Why it matters

Impetus theory and the mean speed theorem show that the break with Aristotelian physics did not begin with Galileo. Medieval scholars in Paris and Oxford had already found real cracks in Aristotle's account of motion and had proved, in Oresme's case, the same mathematical relationship for accelerated motion that Galileo would rediscover experimentally nearly three centuries later.

How we know

Buridan's and Oresme's arguments survive in their own written commentaries on Aristotle's Physics, transmitted through the medieval university manuscript tradition and studied directly by modern historians of science such as those at the MacTutor History of Mathematics archive.

Sources

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Medieval Scholars Break With Aristotle on Motion · History of Physics · SourcedStory