(born 1300, Béthune?, France—died 1358) French philosopher, logician, and scientific theorist. He studied under William of Ockham at the University of Paris and later taught there. According to his modified version of determinism, though one must choose what presents itself as the greater good, the will is free to delay reason's judgment by suggesting a more thorough inquiry into the worth of one's motives. The dilemma of a particular kind of moral choice, between two evidently identical alternatives, is illustrated by the celebrated allegory of “Buridan's ass.” Among his achievements in mechanics was a revision of Aristotle's theory of motion; he developed a theory of impetus by which the mover imparts to the moved a power, proportional to the former's speed and mass, which keeps it moving. His studies of optical images prefigured modern developments in cinematics. In logic he explicated the doctrines of Aristotle and Peter of Spain (circa 1210–77). His works include Summula de dialecta (1487) and Consequentie (1493).
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The paradox was not originated by Buridan himself. It is first found in Aristotle's De Caelo, where Aristotle mentions an example of a man who remains unmoved because he is as hungry as he is thirsty and is positioned exactly between food and drink. Buridan nowhere discusses this specific problem but its relevance is that he did advocate a moral determinism whereby, save for ignorance or impediment, a human faced by alternative courses of action must always choose the greater good. Buridan allowed that the will could delay the choice to more fully assess the possible outcomes of the choice. Later writers satirised this view in terms of an ass who, confronted by two equally desirable and accessible bales of hay, must necessarily starve while pondering a decision.
Some proponents of hard determinism have granted the unpleasantness of the scenario, but have denied that it illustrates a true paradox, as such, since one does not contradict oneself in suggesting that a man might die between two equally plausible routes of action. For example, Baruch Spinoza in his Ethics, suggests that a person who sees two options as truly equally compelling cannot be fully rational:
Other writers have opted to deny the validity of the illustration. A typical counter-argument is that rationality as described in the paradox is so limited as to be a straw man of the real thing, which does allow the consideration of meta-arguments. In other words, it's entirely rational to recognize that both choices are equally good and arbitrarily pick one instead of starving. This counter-argument is sometimes used as an attempted justification for faith. The argument is that, like the starving ass, we must make a choice in order to avoid being frozen in endless doubt. Other counter-arguments exist.
Buridan's ass sometimes finds mention in electrical engineering. Specifically, in digital logic, an analog-to-digital converter must convert a continuous voltage value into either a 0 or a 1. The voltage value represents the position of the ass, and the values 0 and 1 represent the bales of hay. Like the situation of the starving ass, there exists an input on which the converter cannot make a proper decision, resulting in a metastable state. Having the converter make an arbitrary choice in ambiguous situations does not solve the problem, as the boundary between ambiguous values and unambiguous values introduces another binary decision with its own metastable state. In the ass illustration, the ass cannot decide whether or not to choose arbitrarily and so starves to death.