A Judge's Cruel Promise

A judge sentences a prisoner: "You will be hanged one day next week, but the specific day will be a surprise. You will not be able to deduce it the evening before." The prisoner starts reasoning backward from Friday.

With Friday gone, Thursday becomes the last possible day. But by Wednesday night he would know Thursday is next, so that is no surprise either. The chain continues, and every single day gets eliminated. The prisoner concludes the hanging is logically impossible and relaxes.