Category: logic
Type: thought experiment
Associated thinker(s): John Buridan (traditional association), Aristotle (earlier related example)
Original publication or approximate period: Medieval and later tradition; donkey formulation not found in Buridan’s writings
Difficulty: Beginner
Themes: choice, symmetry, reasons
Related experiments: Newcomb’s Problem; Frankfurt Cases
A hungry donkey stands exactly between two equally attractive piles of hay. Suppose distance, quantity, quality, and every other relevant consideration are balanced. If it can act only when one option is judged better, it seems unable to begin eating. Waiting indefinitely would make the animal worse off than choosing either pile.
Real animals have countless asymmetries and do not satisfy this idealization. The story isolates a claim about reasons and selection. Its traditional name is historically misleading if taken literally: the familiar donkey example is not found in Buridan’s surviving writings.
Can a rational agent select one of equally supported alternatives without an additional reason that favors that particular option?
The case distinguishes having a reason to choose from having a reason to choose this option rather than its twin. It also challenges a decision rule that insists on a unique best alternative before allowing action. Practical systems often need a way to handle ties; the philosophical question is what such a way implies about agency.
Permissive rationality: choosing either option is justified because each satisfies the reasons that matter. Rationality can permit a set of actions without uniquely determining one.
Tie-breaking response: a convention or random process selects an option. A reason for using the procedure need not be a reason favoring its particular result.
Will-centered response: an agent may possess a power of selection that is not exhausted by identifying the strongest prior comparative reason. Critics ask whether this explains control or merely renames the unexplained selection.
The puzzle does not establish that ordinary deliberators starve between restaurant choices. Nor does it prove that uncaused action exists. The symmetry concerns relevant reasons; causal and physical symmetry are stronger assumptions. The absence of a unique best option differs from the absence of any good option.
Aristotle discussed a related balanced food-and-drink example. Modern decision procedures use fixed priorities, lotteries, or “choose any maximum” rules. These are useful applications of the structure, not historical claims that Buridan devised a computer algorithm.
The SEP Buridan entry, section 7, was retrieved specifically to check the naming problem. It reports earlier parallels and suggests the donkey may have originated as a later parody. This possibility is not converted into a secure attribution to an identifiable critic.
Research check: 2026-10-30. References above were retrieved for the support described; this is an original educational explanation, not a substitute for the primary texts. Additional speculative comparisons are teaching prompts, not established historical variations.