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It really depends on who says what, but here a version of the problem where Bernard speaks first: Bernard: I don't know when Cheryl's birthday is. Albert: I d
by andrewprock 12y ago
It really depends on who says what, but here a version of the problem where Bernard speaks first:
Bernard: I don't know when Cheryl's birthday is.
Albert: I don't know when Cheryl's birthday is.
Bernard: I know when Cheryl's birthday is now.
Albert: Then I also know when Cheryl's birthday is.
- stephen_g 12y agoThat breaks the whole problem because you've removed the part where Albert says something that gives Bernard the information he needs to work out the date. I don't think it's really a good critique of a logic problem to say, "but if you remove this extremely important part, it doesn't work anymore"! The conversation would need to be: Bernard: I don't know when Cheryl's birthday is Albert: I don't know when Cheryl's birthday is, and I knew that Bernard didn't know. Bernard: Then I know when Cheryl's birthday is now. Albert: Then I also know when Cheryl's birthday is. Then it works. You only have to assume that the parties are logical and tell the truth.
- andrewprock 12y agoYou have to make quite a few more assumptions as well. If they were logical and told the truth, the conversation would be more like: Bernard: Cheryl told me it's the 17th. Albert: Cheryl told me it's in August.