First a thought experiment
A donkey who is much happier than the one in our experiment. (Wikimedia Commons)
Variations on this experiment date back to antiquity, this formulation was named after the philosopher Jean Buridan, whose views on determinism it ridicules.
Imagine a donkey placed precisely between two identical bales of hay. The donkey has no free will, and always acts in the most rational manner. However, as both bales are equidistant from the donkey and offer the same nourishment, neither choice is better than the other.
Question: How can it choose? Does it choose at all, or does it stand still until it starves?
If choices are made based on which action is the more rational one or on other environmental factors, the ass will starve to death trying to decide on which to eat- as both options are equally rational and indistinguishable from one another. If the ass does make a choice, then the facts of the matter couldn’t be all that determined the outcome, so some element of random chance or free will may have been involved.
It poses a problem for deterministic theories as it does seem absurd to suppose that the ass would stand still forever. Determinists remain split on the problem that the ass poses. Spinoza famously dismissed it while others accept that the donkey would starve to death. Others argue that there is always some element of a choice that differentiates it from another one.