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Sun 22 Feb, 2004 10:29 am
There was once a mythical village off in the woods somewhere. In this village lived a group of perfectly logical people, each of whom had either a red spot or a green spot in the middle of their forehead. No one in the village was allowed to know the color of the spot on their own forehead, and discussion of the color of other people's spots was strictly forbidden. Care had been taken to remove all mirrors and anything else reflective from the village so that accidental discovery of the color of one's own spot was unlikely. However, if in the unfortunate event that the color of one's own spot was accidentally discovered, village law required that the person throw him/herself down the well.
Each day every villager would gather in the village square for the morning meet-and-greet, during which every villager would shake hands with every other villager.
One day a stranger came into the village during the morning assembly. The stranger, unfamiliar with the customs of the village, spoke hastily and said "I see at least one red spot."
What happened then, and why?
They threw the stranger down the well ?
( Seriously though the stranger gave no new information )
I agree with Fresco, if the stranger didn't indicate where the red spot was then nothing has changed.
Everyone in the village had a green spot on their forehead. When the stranger spoke (lying bastard!) everyone thought that, since all other spots are green, they must be the red spot...
Don't drink the water!
So according to that everybody jumps in the well !
....or if in fact there was only one red spot guy HE jumps into the well !
....which means that after that all the other guys work out they must be green and.....!!!!
fresco wrote:....or if in fact there was only one red spot guy HE jumps into the well !
but He wouldn,t know his spot was red......
Kev...the red spot guy sees only green so assuming the stranger is telling the truth he works out red must be him.
A hushed silence would fall on the town, then gossip roar into overdrive. Civil disobiedence would errupt, the stranger raised to god like status, and a fantastic meal would be prepared over the ancient texts as they burned.
What do you think about these ideas...
Everyone jumps in the well. If the stranger said to one person that he had a red spot and that was the only one then everybody else would know that they have a green spot. Everyone knows so everyone must jump except for the stranger because the law does not apply to those who don't have a spot. (The wording on this one could be misleading--the other answer could be that they take the stranger and throw him in the well before he can identify who has the red spot. He said "I see at least one red spot"--if you take literally then he has not identified who has the spot so everyone is safe. Does him saying "at least one red..." mean that there are more but he can't see them?)
giggicat wrote:What do you think about these ideas...
Everyone jumps in the well. If the stranger said to one person that he had a red spot and that was the only one then everybody else would know that they have a green spot.
The above logic is sound BUT that's not what you said in your riddle.
The riddle posting was given to me by one of my professors. My second posting was the answer my brother gave me.
So... the first posting is the riddle...
If I get the answer right, then I get EXTRA points in my Statistics class.
Thanks!
The following philosophical red (or green) herrings might also apply.
1. The stranger is color blind.
2. If, instead of asking for trouble, the villagers stayed inside and used blue lights, nobody would have a problem.
fresco wrote:Kev...the red spot guy sees only green so assuming the stranger is telling the truth he works out red must be him.
Missed that completely didn't I?
Assume there was only one with a red spot. As has been pointed out he would not see a red spot so he would know he was red and kill himself on day one.
Assume there were two with red spots. They would each see one red spot and, knowing that the other red spot had not killed himself on day one, would reason. "then I too have a red spot" so both of them would kill themselves on day two.
Assume three red spots and no one dead on the second day, each of those three, by the same reasoning, would kill themselves on day three.
And with 'n' red spots 'n' people would kill themselves on day 'n'.
The green-spot people would realise that this meant all of the red spot people had killed themselves so each of the remainder, now knowing that they had a green spot, would kill themselves on day 'n+1'.
There are some huge faults with that logic.
Sorry, I didn't have time to elaborate yesterday. I admit I may be incorrect, but the answer doesn't fit the story. I would assume it isn't the Iacomus' solution which is flawed, for that logic is sound IF it fit the story better. For example, if everyone was logical enough to figure out they need to kill themselves after so many days, it is something they would have already figured out on their own. Since the stranger offered no new information these logical beings would already know. Unless they were not organized enough, in which case, they wouldn't be organized well enough to collectively kill themselves on the correct day.
The stranger did not, as such, bring any new knowledge, but he did start the clock ticking which did not exist before then. He, as it were, set a deadline (excuse the unintentional word-play)
Maybe it would be better to say that he started the countdown. None of the locals could start it as they were not permitted to mention the subject.
To elaborate: suppose that there were only one with a red spot. He would not know this and no one could tell him, so he takes no action. Then a stranger says, 'I can see a red spot'. According to your reasoning the stranger has added no information so nothing happens. But when the one red spot sees no red spots he then knows that he has a red spot. THIS IS SOMETHING HE DID NOT KNOW BEFORE!! The stranger has started the countdown - admittedly a short one for only one red spot - that had not previously existed. He HAS changed the situation!
Now imagine that there are two with a red spot. Everyone who can see two red spots is unaffected. But each of those with a red spot can see only one spot. Each knows the other is smart enough to figure it out and yet has not killed himself. From this, each can reason, 'then he must be able to see someone else with a red spot. I can only see his, so I must have a red spot', and both kill themselves. And so it continues, as I explained earlier.