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Originally written by Student of Trinity:

Prisoner is sentenced to death in a state where judges have arbitrary power. Judge's sentence is as follows: "You will be executed at dawn on one of the seven days of next week, but you will not know which day until noon on the day before."

Prisoner sits in cell a couple of days before the fatal week begins, and reflects on the sentence. He notes that if he is so lucky as to survive through the first six dawns, he will then know at dawn on day 6 that day 7 will be his doom. But this would be contrary to the sentence, since he would know before noon. So the prisoner concludes that he cannot actually be executed on day 7.

Prisoner then concludes that day 6 is out as well, for with day 7 eliminated, the same reasoning as before would now apply to day 6. And so on: with each last day eliminated by the perverse wording of the sentence, all the days are eliminated in order. Prisoner concludes that he cannot be executed at all, because the judge's perverse sentence is actually self-contradictory. Yahoo!

At noon on day 3, the prisoner is informed that he will be executed at dawn on day 4. And so he is. The seemingly self-contradictory sentence was carried out flawlessly.

What was wrong with the prisoner's analysis?

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quote:

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Originally written by Walter:

The confusing bit is, is that based on the almost certainly correct prediction, the money is already either in the box or not in it, and taking both boxes won't change that so there is no reason to decide not to take them. However if you are smart and decided that is the correct strategy you probably just cost yourself $90 by being that smart and logical.

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