u/sewersallalone

A king orders every citizen to bring one cup of wine and pour it into a great bowl for a public feast.

Wine is expensive, and water is free.

One citizen thinks: “If I pour in water instead of wine, my single cup will make no noticeable difference. I will save my money, and the bowl will still taste like wine.”

But then he remembers that every citizen in the kingdom is also a perfect logician. Each of them has the same information, knows the same dilution limit, and knows that if too many cups of water are added, the bowl will be ruined.

He also knows that every other citizen is thinking through the same problem just as perfectly as he is.

No one may communicate, and no one will know who poured what.

What should he pour into the bowl?

[Inspired by the classic folktale]