It’s Christmas time. Albert decides to sell Christmas trees in a suburb of Baltimore. He sets up a big tent in an empty parking lot, fills it with trees and puts up his sign. To pay for his tent, he charges 20% more per tree.
Customers come and park their cars by the tent. Some mumble but buy a tree, take it out of the tent, tie it on the roof of their car and leave. Others say: “What! 20% more!” and leave without a tree.
As this happens three space aliens, Einsty, Moraly and Tardy, orbiting far above the Earth, observe the tent and the cars coming and leaving.
Tardy says: “Cars move about randomly. When a car collides with the tent it sometimes shakes a tree loose and leaves with it. What happens inside the tent is unknowable.”
Einsty says: “Trees don’t leave the tent randomly, if we knew what happens inside the tent we could predict when a tree leaves it“.
Moraly says: “Who says cars move randomly?, it is what makes the cars collide with the tent that determines the outcome“.