Knowledge Puzzles :)

I found these rather intriguing... (C/o Esther's 24.00 notes)

Surprise
Teacher: There will be a surprise exam next week.
Students: No Way! The class meets on Monday, Wednesday, and Friday. If the exam was given on Friday, it wouldn't be a surprise; on Thursday we'd know it was coming. It would have to be Monday or Wednesday then. A Wednesday exam would not be a surprise either; now that Friday is ruled out, we know on Tuesday it was coming. So the exam can only be on Monday. But then were's the surprise? Sorry, Teacher, there can be no surprise exam next week.

Oracle
I believe that the Oracle is infallible. I believe that if the Oracle says that p, then it is true. Suppose now the Oracle says, e.g, that I don't exist. Given my belief in the Oracle's infallibility, am I forced to conclude that I don't exist.

Paradox of Tragedy
Oliver Twist is given away to pickpockets when he asks for more gruel. I find this horrifying. I am disgusted by Bill Syke's cruelty, and am overcome with pity for Nancy. Why keep reading, then? The fact that I keep on with it suggest that I somehow want to feel these things. People are "never so happy as when they emply tears, sobs and cries to give vent to their sorrow, and relive their heart, swollen with the tenderest sympathy and compassion" (Hume). Why would I seek out an encounter with horrifying events? How can tragedy be so deeply satisfying?