Buridan's Ass
A donkey caught between equal bales of hay becomes a philosopher’s nightmare: if reasons are perfectly balanced, what moves the will at all?
Quick Facts
- Period
- 1301 – 1400
- Region
- Europe
- Key Figures
- Albert of Saxony, Jean Buridan, John Duns Scotus +2 more
Key Figures
Albert of Saxony
Successor
Parisian scholasticismAlbert of Saxony matters here not because he was the origin point of a famous paradox, but because he was one of the men...
Jean Buridan
Originator
University of Paris, scholastic AristotelianismBuridan stands at the point where medieval psychology became an exacting theory of agency. He is remembered today for th...
John Duns Scotus
Interlocutor
Franciscan scholasticismJohn Duns Scotus stands among the most exacting minds of the medieval world, a thinker whose reputation has often been r...
Martin Luther
Critic
Reformation theologyMartin Luther belongs to Augustine’s story not as a mere admirer but as one of his most consequential rereaders. An Augu...
Thomas Aquinas
Interlocutor
Dominican scholasticismThomas Aquinas stands as the most influential Christian interpreter of Aristotle, but that description only begins to ca...
The Story
This narrative combines documented history with dramatized scenes for storytelling purposes.
The World That Made It
Jean Buridan did not invent the medieval fascination with choice under constraint, but he lived at a moment when the problem sharpened into a crisis. In the uni...
The Central Idea
At the center of Buridan’s Ass lies a simple scene with a devastating philosophical edge. A donkey is placed midway between two identical bales of hay. The hay ...
The System
The donkey problem only makes sense inside a larger psychology of action. In Buridan’s discussions of the will in works such as the *Quaestiones* on Aristotle’s...
Tensions & Critiques
The first and most persistent objection is obvious: if two options are exactly equal, why must a rational agent remain motionless? Critics have long suspected t...
Legacy & Echoes
Buridan’s Ass outlived the scholastic lecture hall because it names a permanent embarrassment in theories of freedom. Later thinkers could reject Buridan’s psyc...
Timeline
Birth of Jean Buridan
**1300** — Jean Buridan is born in France, likely in or near the early fourteenth century that would shape his intellectual world. His later career at Paris would place him at the center of scholastic debates about motion, causation, and voluntary action.
Buridan enters the University of Paris milieu
**1320** — Buridan’s formation takes place in the disputational culture of the University of Paris, where Aristotle was studied through careful commentary and objection. This environment made extreme cases like equal alternatives philosophically useful rather than merely amusing.
Development of Buridan’s account of the will
**1330** — In his discussions of the soul and action, Buridan articulates a view of the will as a power capable of self-determination when reasons do not decisively incline the agent. The famous donkey image later attached to his name crystallizes this kind of case.
Buridan’s impetus theory gains prominence
**1335** — Buridan’s natural philosophy introduces impetus as a way of explaining continued motion after the mover is no longer in contact with the moved body. Though not the same as the will’s freedom, it shows the same explanatory style: motion can originate and then persist according to an inner condition.
Death of Jean Buridan
**1361** — Buridan dies, leaving behind a body of work that would remain influential in late medieval scholasticism. His name would later become attached to the donkey parable that made his problem famous far beyond the university.
Buridan’s ideas circulate through later medieval commentators
**1370** — Students and successors such as Albert of Saxony help transmit Buridan’s methods and problem-sets into broader scholastic and natural-philosophical discussion. The will, motion, and equality of reasons become shared points of reference in late medieval debate.
Birth of Martin Luther
**1483** — Luther’s arrival marks the beginning of a new theological context in which human agency would be argued over in relation to sin and grace. His criticisms would later reframe scholastic confidence in the will.
Luther and Erasmus debate the will
**1525** — The controversy over free will and bondage of the will brings older questions of agency into the Reformation spotlight. Even when not directly about Buridan, the debate renews the problem of whether the will can decide itself or must be determined by something prior.
Descartes and the early modern turn to mechanism
**1637** — Early modern philosophy increasingly explains natural motion in mechanical terms, which changes the background against which voluntary action is understood. Buridan’s question survives but now appears beside the problem of whether mind can resist a mechanized nature.
Modern analytic discussions of freedom revisit symmetry cases
**1954** — Philosophers of action and decision theory begin to treat tie-breaking and underdetermination as formal problems, echoing the structure of Buridan’s dilemma. The donkey becomes a classic way to ask whether reasons suffice for action.
Scholarly reassessment of Buridan’s psychology
**1994** — Late twentieth-century scholarship clarifies that the donkey is a later simplification of a richer medieval account of the will. This work distinguishes Buridan’s actual texts from the proverb that bears his name.
Buridan’s Ass remains a live philosophical test case
**2026** — The thought experiment continues to appear in discussions of free will, rational choice, and the problem of symmetric reasons. Its endurance shows that the medieval question is still ours: can a will choose without a reason?
Sources
- primary_textJean Buridan, Questions on Aristotle's De anima, trans. John A. Zupko and others (selected passages in scholarly editions)
Primary source for Buridan's psychology of intellect and will.
- primary_textJean Buridan, Quaestiones super libros De generatione et corruptione
Relevant for Buridan's natural philosophy and explanatory style.
- reference_encyclopediaStanford Encyclopedia of Philosophy: "Medieval Theories of the Will"
Overview of scholastic accounts of volition and freedom.
- reference_encyclopediaStanford Encyclopedia of Philosophy: "Jean Buridan"
Scholarly overview of Buridan's life and thought.
- reference_encyclopediaInternet Encyclopedia of Philosophy: "Jean Buridan"
Accessible overview with discussion of the donkey problem and impetus theory.
- scholarly_articleJohn M. Rist, "Buridan's Ass: A Problem in the Theory of Free Choice"
Classic discussion of the thought experiment and its philosophical significance.
- scholarly_bookJack Zupko, John Buridan: Portrait of a Fourteenth-Century Arts Master
Major modern study of Buridan's intellectual context and doctrines.
- scholarly_bookAnneliese Maier, On Buridan's Theory of Impetus
Important historical study of Buridan's natural philosophy.
- primary_textThomas Aquinas, Summa theologiae, I-II, questions on the will and choice
Essential medieval background on intellect, will, and choice.
- primary_textJohn Duns Scotus, Ordinatio / lectures on the will
Key medieval account of self-determining will in relation to Buridan's problem.
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