Freethought & Rationalism Archive

chickensoupforthebowl · 01-30-2002, 07:38 PM

Someone randomly talked to me on the internet, and asked me a problem that i can't figure out. Here it is...

knight=always tells the truth
naive=never tells the truth

this anthropologist goes into a room with an astrologer and sorcerer in it
one is wearing all blue, one is wearing all green
he asks "is the sorcerer a knight?"
blue answers "yes" or "no", and we don't know what green answers
and we need to know if the sorcerer is a knight.

That's all your told. The answer is that the guy in blue is naive and the astrologer, and the guy in green is a knight and the sorcerer. But, I (or him) don't see how you arrive/solve the problem. Any idea?

Francois Tremblay · 01-30-2002, 08:07 PM

Obviously the general answer is that only a naive could answer one way or another - the other possibility must be meaningless. Beyond this... I can't figure it out.

Incidentally, are you sure the answer is correct ? I can figure out the riddle if blue is a knight (in fact, it's trivial to see that a knight could give a direct answer), but not with your solution that blue is a naive.

[ January 30, 2002: Message edited by: Franc28 ]</p>

chickensoupforthebowl · 01-30-2002, 08:38 PM

Yeah, he says the answer is correct.

tronvillain · 01-30-2002, 08:48 PM

For starters, it's "knave" rather than "naive."

tronvillain · 01-30-2002, 08:59 PM

Is the sorceror a knight?

Knave:
"Yes" means that the sorceror is not a knight.
"No" means that the sorceror is a knight.

Knight:
"Yes" means that the sorceror is a knight.
"No" means that the sorceror is not a knight.

If blue answers "Yes" then he is a sorceror, and if blue answers "No" then is an astrologer.

As far as I can tell, that's as far as the available information will take us. Weird.

Draygomb · 02-01-2002, 05:49 AM

This seems to be a variant of another problem, the trick is to ask either one what the other one would say if asked are you the knight.

If asked directly both will answer yes.
if you ask the knight what the naive would say he will answer yes.
if you ask the naive what the knight will say he will lie and say no.

02-01-2002, 11:56 AM

A similar puzzle can be found at:
<a href="http://innovativart.com/puzzle2.html" target="_blank">http://innovativart.com/puzzle2.html</a>

Major differences:

1. Although the question asked is "Is the sorcerer a knight?", the puzzle to be solved is, "Which one is the sorcerer?"

2. We are told that the anthropologist is able to figure out which one is the sorcerer.

The solution is that if blue answered yes, the anthropologist wouldn't be able to figure it out.

If blue answered no, then he is the astrologer, because the sorcerer would always answer yes. Therefore, green must be the sorcerer.

In any case, we don't have enough information to figure out if the sorcerer is a knight.

DeadLogic · 02-15-2002, 07:51 PM

I've seen a number of these "Knights & Knaves" logic questions. I've had plenty of them emailed to me as well. The problem is that it's not uncommon for someone to state the question incorrectly, thus making it impossible to answer the question. That may or may not be the case here. These questions must be stated accurately, or there's no point. Whenever I come across a "Knights & Knaves" question, I'm not naive enough to simply assume that the question has been presented correctly.

01-30-2002, 07:38 PM	#1
chickensoupforthebowl Junior Member Join Date: Mar 2001 Posts: 27	Help Someone randomly talked to me on the internet, and asked me a problem that i can't figure out. Here it is... knight=always tells the truth naive=never tells the truth this anthropologist goes into a room with an astrologer and sorcerer in it one is wearing all blue, one is wearing all green he asks "is the sorcerer a knight?" blue answers "yes" or "no", and we don't know what green answers and we need to know if the sorcerer is a knight. That's all your told. The answer is that the guy in blue is naive and the astrologer, and the guy in green is a knight and the sorcerer. But, I (or him) don't see how you arrive/solve the problem. Any idea?

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01-30-2002, 08:07 PM	#2
Francois Tremblay Banned Join Date: Sep 2000 Location: Montreal, QC Canada Posts: 876	Obviously the general answer is that only a naive could answer one way or another - the other possibility must be meaningless. Beyond this... I can't figure it out. Incidentally, are you sure the answer is correct ? I can figure out the riddle if blue is a knight (in fact, it's trivial to see that a knight could give a direct answer), but not with your solution that blue is a naive. [ January 30, 2002: Message edited by: Franc28 ]</p>

01-30-2002, 08:38 PM	#3
chickensoupforthebowl Junior Member Join Date: Mar 2001 Posts: 27	Yeah, he says the answer is correct.

01-30-2002, 08:48 PM	#4
tronvillain Veteran Member Join Date: Oct 2000 Location: Alberta, Canada Posts: 5,658	For starters, it's "knave" rather than "naive."

01-30-2002, 08:59 PM	#5
tronvillain Veteran Member Join Date: Oct 2000 Location: Alberta, Canada Posts: 5,658	Is the sorceror a knight? Knave: "Yes" means that the sorceror is not a knight. "No" means that the sorceror is a knight. Knight: "Yes" means that the sorceror is a knight. "No" means that the sorceror is not a knight. If blue answers "Yes" then he is a sorceror, and if blue answers "No" then is an astrologer. As far as I can tell, that's as far as the available information will take us. Weird.

02-01-2002, 05:49 AM	#6
Draygomb Veteran Member Join Date: Jan 2002 Location: Harrisburg, Pa Posts: 3,251	This seems to be a variant of another problem, the trick is to ask either one what the other one would say if asked are you the knight. If asked directly both will answer yes. if you ask the knight what the naive would say he will answer yes. if you ask the naive what the knight will say he will lie and say no.

02-01-2002, 11:56 AM	#7
tyrrho Guest Posts: n/a	A similar puzzle can be found at: <a href="http://innovativart.com/puzzle2.html" target="_blank">http://innovativart.com/puzzle2.html</a> Major differences: 1. Although the question asked is "Is the sorcerer a knight?", the puzzle to be solved is, "Which one is the sorcerer?" 2. We are told that the anthropologist is able to figure out which one is the sorcerer. The solution is that if blue answered yes, the anthropologist wouldn't be able to figure it out. If blue answered no, then he is the astrologer, because the sorcerer would always answer yes. Therefore, green must be the sorcerer. In any case, we don't have enough information to figure out if the sorcerer is a knight.

02-15-2002, 07:51 PM	#8
DeadLogic Junior Member Join Date: Feb 2002 Location: Third planet out Posts: 16	I've seen a number of these "Knights & Knaves" logic questions. I've had plenty of them emailed to me as well. The problem is that it's not uncommon for someone to state the question incorrectly, thus making it impossible to answer the question. That may or may not be the case here. These questions must be stated accurately, or there's no point. Whenever I come across a "Knights & Knaves" question, I'm not naive enough to simply assume that the question has been presented correctly.

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