The first logician wanted one but didn’t know whether the other two wanted one each or not, so he said “I don’t know.”
The second realised that the first one wanted a beer and he himself wanted a beer but he didn’t know about the third logician, so he said “I don’t know”.
The third logician realised that both of the other logicians wanted a beer and he himself wanted a beer, so he said yes.
If any one of them didn’t want a beer they would have immediately said no since logically the answer to the barman’s question “do you all want a beer?” Would have been no.
That one took me a second, but it’s a good one
I needed it explained to me when I first heard it :-)
I probably would have got it after a few more hours of processing… I hope.
Explanation for anyone looking for one:
The bar man asked them if “they all” want a beer.
The first logician wanted one but didn’t know whether the other two wanted one each or not, so he said “I don’t know.”
The second realised that the first one wanted a beer and he himself wanted a beer but he didn’t know about the third logician, so he said “I don’t know”.
The third logician realised that both of the other logicians wanted a beer and he himself wanted a beer, so he said yes.
If any one of them didn’t want a beer they would have immediately said no since logically the answer to the barman’s question “do you all want a beer?” Would have been no.