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Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 2:52 am
by Jeff250
Three logicians walk into a bar.
The bartender asks them, "Does everybody want a beer?"
The first logician says, "I don't know."
The second logician says, "I don't know."
The third logician says, "Yes."
Re: Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 1:43 pm
by Pandora
Ha! Brilliant!
Re: Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 1:57 pm
by Enzo-03
Ha.
Re: Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 5:48 pm
by snoopy
I get it!
Re: Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 6:24 pm
by roid
how does the 3rd one know that the first 2 DID want beers?
:?
Re: Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 7:29 pm
by Top Gun
That took me a disturbingly long time to figure out.
Re: Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 8:28 pm
by Jeff250
roid wrote:how does the 3rd one know that the first 2 DID want beers?
Spoiler:
If you don't want a beer, then you can immediately answer "no," since you know that not everybody wants a beer. Since the first two didn't answer "no," the third knows that they want a beer.
Re: Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 9:58 pm
by roid
aaaaaaaaaaah of course
. thanks
Re: Three Logicians Walk into a Bar
Posted: Sat May 05, 2012 10:53 pm
by Isaac
roid wrote:aaaaaaaaaaah of course
. thanks
x2
I'm not at full mental brain thing at this hour.
Re: Three Logicians Walk into a Bar
Posted: Sun May 06, 2012 5:30 pm
by snoopy
Jeff250 wrote:roid wrote:how does the 3rd one know that the first 2 DID want beers?
Spoiler:
If you don't want a beer, then you can immediately answer "no," since you know that not everybody wants a beer. Since the first two didn't answer "no," the third knows that they want a beer.
# 3 is making assumptions about people's desired being static. What if someone changed their mind?
Re: Three Logicians Walk into a Bar
Posted: Sun May 06, 2012 6:45 pm
by Jeff250
I suppose the joke breaks if they're temporal logic-ians.
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 10:32 am
by Tunnelcat
Isn't
"I don't care" more logically accurate than
"I don't know"?
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 11:28 am
by fliptw
tunnelcat wrote:Isn't
"I don't care" more logically accurate than
"I don't know"?
only if you are snarky.
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 3:13 pm
by Tunnelcat
I'm not being snarky. Think about it. The logic is different between the 2 pronouncements.
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 3:30 pm
by fliptw
tunnelcat wrote:I'm not being snarky. Think about it. The logic is different between the 2 pronouncements.
"I don't care" is the snarky version of "I don't know". Both versions give the barkeep the same information concerning the disposition of the group to beer.
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 3:50 pm
by Tunnelcat
"I don't care" is different from "I don't know". "I don't care" implies that either choice would be fine, so make it for me. "I don't know" implies that I don't have enough information to make the choice one way or another, which means I need more information to give a definite answer to the question.
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 5:28 pm
by fliptw
tunnelcat wrote:""I don't know" implies that I don't have enough information to make the choice one way or another, which means I need more information to give a definite answer to the question.
The barkeep only cares if the group wants beer or not; any answer besides yes or no does him no good.
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 7:47 pm
by Foil
I'm going to steal this one to post on my facebook page, Jeff.
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 8:54 pm
by Tunnelcat
fliptw wrote:tunnelcat wrote:""I don't know" implies that I don't have enough information to make the choice one way or another, which means I need more information to give a definite answer to the question.
The barkeep only cares if the group wants beer or not; any answer besides yes or no does him no good.
Well, I guess it's just semantics then. It comes down to whether you think "I don't know" is a null. I'm of the opinion that "I don't care" is a better null. Maybe I'm being too nit picky.
Re: Three Logicians Walk into a Bar
Posted: Mon May 07, 2012 10:29 pm
by Jeff250
"I don't know" reveals information to the third logician about the first and second logicians' preferences. It's not clear to me how "I don't care" would do this.
Re: Three Logicians Walk into a Bar
Posted: Tue May 08, 2012 5:03 pm
by Tunnelcat
Still not sure.
"I don't know" usually means one doesn't have enough information to make a choice.
"I don't care" usually means, "Whatever you're having is fine by me. I'm cool". Maybe I'm reading too much emotion and not enough logic into this one.
Re: Three Logicians Walk into a Bar
Posted: Tue May 08, 2012 5:16 pm
by Enzo-03
Hmm..
In my digital design class we have "don't cares", which I think is where the voltage level could be either a 1 or a 0 and no matter which one it is, the logical value of whatever circuit element it goes to wouldn't change.
Something like that. I've slept since we actually did anything with don't cares.
Re: Three Logicians Walk into a Bar
Posted: Tue May 08, 2012 6:37 pm
by Jeff250
tunnelcat wrote:"I don't know" usually means one doesn't have enough information to make a choice.
"I don't care" usually means, "Whatever you're having is fine by me. I'm cool". Maybe I'm reading too much emotion and not enough logic into this one.
For the joke to work, in order for the third logician to have enough information to answer "yes," it's crucial that the first two say that they don't have enough information to answer the question. Since he knows that they don't have enough information to answer the question, he knows that they must want beer.
Re: Three Logicians Walk into a Bar
Posted: Tue May 08, 2012 7:58 pm
by roid
I love that no-one is angry that we are ruining the joke.
You are my people.
Re: Three Logicians Walk into a Bar
Posted: Wed May 09, 2012 8:11 am
by Foil
Jeff250 wrote:For the joke to work, in order for the third logician to have enough information to answer "yes," it's crucial that the first two say that they don't have enough information to answer the question.
Yep.
"I don't have any information" is almost an oxymoron, because it is inherently informative!
Re: Three Logicians Walk into a Bar
Posted: Wed May 09, 2012 2:57 pm
by Tunnelcat
Jeff250 wrote:tunnelcat wrote:"I don't know" usually means one doesn't have enough information to make a choice.
"I don't care" usually means, "Whatever you're having is fine by me. I'm cool". Maybe I'm reading too much emotion and not enough logic into this one.
For the joke to work, in order for the third logician to have enough information to answer "yes," it's crucial that the first two say that they don't have enough information to answer the question. Since he knows that they don't have enough information to answer the question, he knows that they must want beer.
Ooooooooooooooooh, now I get it. I was thinking more in terms of
emotional logic than
pure logic. With emotional logic, "I don't care" means that you want the other person to go ahead and choose for you, while "I don't know" actually means "I don't know what I want, let me think about it for a moment". That's what I get for having a female brain. Different thought process altogether, am I right guys?
Spock could never understand emotional logic. It has a totally different set of rules than pure mathematical logic does.