Riddles and Logic

[Spinner]

For those who want their minds to work a bit. Feel free to post other riddles you know of, but I do recomment more intellectual riddles. I'll start of with an easy one:

In a land of knight and knave, there is an unbreakable rule that all knights only tell the truth and all knaves only speak lies. I came across 3 of the land's inhabitants one day (namely, A,B,C) and I asked A if whether he was a knight or a knave. He answered, but I wasn't able to follow. So I asked B as to what A had said and the conversation is as follows

B: A said that he was a knave
C: Don't believe B, he is lying.

now tell me, what are A and B? with accompanying explanations of course

[Chris]

I think A is a knight and B is a knave.

Were A indeed a knave, as B says that A said, then he would be bound to the code that says that all knaves must lie, and therefore there is no way that he could truthfully say that he was a knave. Logically, there is absolutely no likelihood that B is telling the truth, as saying that A said that he was a knave can only be a lie. And if knaves must tell lies at all times, then A must be a knight, because B said that A was a knave, but B himself is a knave and is lying.

And therefore, C is probably a knight.

[Cy Skywalker]

Sorry, don't want to think that much (and I've heard the like before), but here's a good one of a different sort. There could probably be multiple good answers but I'll reveal the one I heard as the conclusion when some people have posted if they're going to.

A philosophy professor gives a one-question test to the students. The test question is, "Prove to me that this chair does not exist." Students write long essays, pulling in metaphysical arguments and such, but only one person gets an A. What does that student say?

[Ethan]

"What chair?"

[Spinner]

pestilence said:

I think A is a knight and B is a knave.

Were A indeed a knave, as B says that A said, then he would be bound to the code that says that all knaves must lie, and therefore there is no way that he could truthfully say that he was a knave. Logically, there is absolutely no likelihood that B is telling the truth, as saying that A said that he was a knave can only be a lie. And if knaves must tell lies at all times, then A must be a knight, because B said that A was a knave, but B himself is a knave and is lying.

And therefore, C is probably a knight.

oo... smart...

although it's impossible to tell what A is, having not heard what he said... but everything else was flawless

[Elasticband]

Look it up on the internetz?

[Chris]

LMAO. That's a good one Ethan. Exalt.

Ohmigosh, wait a second! CY! Welcome back!

[Cy Skywalker]

Hi Pest. *waves* Thanks.

Ethan's got it. That's the option I liked anyway...

[Spinner]

hmm...
would it be a sin if a man marries his widow's sister?

[AshVersion2]

Wouldn't the man be dead, so it doesn't matter anyway?

[Chris]

Necrophilia ftw.

Ok, here's one:

You are a bus driver. There are 9 people on your bus. You pick up four people at your first stop and let off one. You pick up 5 people at your next stop, and then two more at your next stop. You let off three at the stop after that, then pick up four and let off two at the stop after that. You pick up five more people before pulling in to the bus station. Now ... how old is the bus driver?

[Erik]

16. I am the bus driver. Hmm, well it kinda makes sense. Am I right, am I. *Looks up in apprehension.*

[Chris]

Sigh. It never manages to fool people when I tell it.

[Erik]

Trsut me I sat here for five minutes, thinking my tired little brain out. It's always the first part people don't read. I was debating different meanings of 'pick up', 'let off' imagining pick hands and human bodily functions. Well, until I got to the question, anyway/

[Chris]

I believe the secret to a trick is efficient misdirection. Too bad I'm not much good at it.