Paul wrote: > Let n be a fixed integer > 1. > n logicians walk into a bar. The barwoman says "Do all of you want a beer?" The first logician says "I don't know." The second logician says "I don't know." ... The n-1st logician says "I don't know." The nth logician says "Yes please." Which value of n maximises the humorousness of the joke? I read it with n = 3 but n = 2 also illustrates the principle.
All applied to three is ok, for two one says both.
-- Nam Nguyen in sci.logic in the thread 'Q on incompleteness proof' on 16/07/2013 at 02:16: "there can be such a group where informally it's impossible to know the truth value of the abelian expression Axy[x + y = y + x]".