the BULL
Looks mafia associate (accept the mog)
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- Oct 1, 2021
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1)Stephanie has invited her friends Rowan and Colleen to her home. They are all perfectly logical. She tells them that she has hidden a surprise under one of the blue squares.
Stephanie has privately told Rowan the row number of the surprise and Colleen the column letter of the surprise, and everyone is aware of this. The following conversation ensues.
Rowan: I don’t know where the surprise is, but I also know that Colleen doesn’t know.
Colleen: Yes, indeed, at first I didn’t know the location of the surprise. But now I know where it is.
Rowan: In that case, I now also know where it must be.
Question. Where is the surprise?
Follow up: Suppose that before any conversation took place, someone trips over B1, which opens, revealing it to be empty. a) Could the conversation have proceeded as before? b) Were either of them surprised to see it empty? c) How can it have changed the conversation, if they both knew it already. d) How can it be that adding information, that B1 is empty, makes Rowan’s statement become false? (This is the most interesting aspect of the puzzle, since it seems paradoxical that adding information can reduce knowledge.)
2) Alice has invited her friends Caroline and Susan to her home, and she has placed several boxes on the table before them. The women are all perfectly logical.
Caroline: I don’t know which box contains the gift, and I also know that Susan doesn’t know.
Susan: I already knew before you spoke that you didn’t know which box contains the gift.
Caroline: Ah, now that you say that, it suddenly occurs to me which box must contain the gift.
Question. Which box contains the gift?
Follow up: After the conversation, does Susan also know which box contains the gift? If so, who came to the knowledge first, Caroline or Susan?
3) At a party for our perfectly logical philosophy friends Sheila and Colin, a surprise has been hidden under one of these coloured tiles:
Each friend is privately told a piece of information about where the surprise is.
Host: Do either of you know where the surprise is?
. . . Awkward long silence. . .
Host: Do you know now?
. . . More awkward silence. . .
Sheila, Colin: (simultaneously): Now I know where it is!
Question. Where is the surprise?
Follow up: a) Did either of them expect the first silence? b) What effect on their knowledge did that silence serve? How did they learn anything from it? c) Did Colin know that Sheila knew that Colin didn’t know initially where the surprise was? d) Did either of them expect the second silence?
Stephanie has privately told Rowan the row number of the surprise and Colleen the column letter of the surprise, and everyone is aware of this. The following conversation ensues.
Rowan: I don’t know where the surprise is, but I also know that Colleen doesn’t know.
Colleen: Yes, indeed, at first I didn’t know the location of the surprise. But now I know where it is.
Rowan: In that case, I now also know where it must be.
Question. Where is the surprise?
Follow up: Suppose that before any conversation took place, someone trips over B1, which opens, revealing it to be empty. a) Could the conversation have proceeded as before? b) Were either of them surprised to see it empty? c) How can it have changed the conversation, if they both knew it already. d) How can it be that adding information, that B1 is empty, makes Rowan’s statement become false? (This is the most interesting aspect of the puzzle, since it seems paradoxical that adding information can reduce knowledge.)
2) Alice has invited her friends Caroline and Susan to her home, and she has placed several boxes on the table before them. The women are all perfectly logical.
- small red box
- medium red box
- large black box
- small blue box
- large blue box
Caroline: I don’t know which box contains the gift, and I also know that Susan doesn’t know.
Susan: I already knew before you spoke that you didn’t know which box contains the gift.
Caroline: Ah, now that you say that, it suddenly occurs to me which box must contain the gift.
Question. Which box contains the gift?
Follow up: After the conversation, does Susan also know which box contains the gift? If so, who came to the knowledge first, Caroline or Susan?
3) At a party for our perfectly logical philosophy friends Sheila and Colin, a surprise has been hidden under one of these coloured tiles:
Each friend is privately told a piece of information about where the surprise is.
- Sheila knows the shape of the tile.
- Colin knows the colour of the tile.
Host: Do either of you know where the surprise is?
. . . Awkward long silence. . .
Host: Do you know now?
. . . More awkward silence. . .
Sheila, Colin: (simultaneously): Now I know where it is!
Question. Where is the surprise?
Follow up: a) Did either of them expect the first silence? b) What effect on their knowledge did that silence serve? How did they learn anything from it? c) Did Colin know that Sheila knew that Colin didn’t know initially where the surprise was? d) Did either of them expect the second silence?
