7 Puzzles And Paradoxes To Twist Your Brain

7. Unexpected Hanging

The Unexpected Hanging Paradox is so tricky that it has never officially been resolved, and philosophers and logicians are still arguing about it (although that's pretty much all philosophers and logicians do anyway).

The riddle goes like this:

A prisoner is told that he will be executed on some day between Monday and Friday, but that he will not know on which day the hanging will occur before it happens, so that it will be a surprise. The prisoner concludes that he will be pardoned and heads to his cell with a cheery wave.

The prisoner's logic was thus:

He couldn't be executed on Friday, because if he had made it through to Thursday without getting it in the neck, he'll know for sure that it will be Friday and it would not, therefore, be unexpected. Using this same logic, the prisoner eliminates Thursday, Wednesday and the rest of the week.

The executioner, however, turns up on Wednesday and the prisoner is still surprised. How?

What's the solution?

Believe it or not, this paradox is actually still unresolved.

Some argue that the problem with it is linguistic, and that the meaning of "surprise" is too ambiguous. Others argue that it's a demonstration of how deductive reasoning fails to eliminate surprise (basically, you can't "logic" your way out of everything). There are literally books and academic papers written on this subject, so good luck figuring it out. Let us know if you have a brainwave in the comments.