Good AGM question: The Unexpected Hanging. Can the Wrath solve it?

On Monday, a prisoner is sentenced to hang. The judge tells him that he will be hanged by the end of Friday (of the same week), at noon on whichever day it is, and in the morning of that day he will not know he is to be hanged that day.

The prisoner thinks: so, I definitely can't be hanged on Friday, because by Thursday night I will know it's definitely Friday if I'm still alive. So the last day I can logically be hanged is on Thursday.

But hang on - that means they can't hang me Thursday either, because by Wednesday evening if I'm still alive I'll know it can't be Friday so must be Thursday. So the last day I can logically be hanged is on Wednesday.

Using the same argument, I can't be hanged on Wednesday or Tuesday either and it's already after noon today. So they can't hang me and I'll live on. Yay!

He is then totally surprised when the hangman arrives Wednesday at noon. As the judge promised, he didn't know that the hangman was coming that morning.

Where is the flaw in the prisoner's argument?

(this is probably my favourite paradox)

Posted By: Old Man, Nov 23, 11:08:35