Consider the following (well known) problem
heard the judge
"for your crime
s, you shall be executed one day of the coming week. You can not know which day you shall be executed until noon
of that same day"
in short we have
- a convict shall be executed in one of the next 7 days (he know this)
- he must not know which day he shall be executed
until that day arrives
upon hearing the sentence
placed the following argument
I know then that I shall not be executed on the seventh day, for if I were alive I would know that I would have to be executed on that day (thus failing II).
We have eliminated day 7 as a possible execution date so we have 6 days remaining for it.
If the morning of the sixth day comes, I would know that I would have to be executed that day (since number 7 has already been eliminated) and, for II) to be true , I cannot be executed on the sixth day.
I can make the same argument for days 5, 4, 3, 2, 1, and as such I can never be executed based on that sentence
for it would violate II). But if I'm not executed, it'll violate I).
didn't listen, and the convict
was executed in the afternoon of day 4. Both I) and II) were true
This is the element of surprise