評(píng)論
打印
Carl thinks, "If I have non-green eyes, Adria and Bill were just watching each other,
Carl想：“如果我不是綠眼睛，Adria和Bill只會(huì)互看彼此，
and will now both leave on the second night."
然后兩人將會(huì)在第二個(gè)晚上離開(kāi)。”
But when he sees both of them the third morning, he realizes they must have been watching him, too.
但當(dāng)Carl第三天早上看到其他兩人還在，Carl了解到一件事：其他兩人知道Carl有綠色眼睛。
Adria and Bill have each been going through the same process, and they all leave on the third night.
而Adria和Bill也經(jīng)過(guò)同樣的推理過(guò)程，然后他們?nèi)吭诘谌齻€(gè)晚上要求離開(kāi)。
Using this sort of inductive reasoning, we can see that the pattern will repeat no matter how many prisoners you add.
用同樣的歸納推理方式，我們可以發(fā)現(xiàn)：不論島上有多少居民，這個(gè)模式會(huì)不斷重復(fù)。
The key is the concept of common knowledge, coined by philosopher David Lewis.
這個(gè)解答的關(guān)鍵就在于哲學(xué)家David Lewis所提出的公開(kāi)知識(shí)這個(gè)哲學(xué)概念。
The new information was not contained in your statement itself, but in telling it to everyone simultaneously.
你的敘述本身，并不包含新的訊息，但是一旦告訴了每一個(gè)人，就會(huì)產(chǎn)生新的訊息。
Now, besides knowing at least one of them has green eyes, each prisoner also knows that
現(xiàn)在，除了知道居民當(dāng)中至少一位有綠色眼睛，這些人也想著：
everyone else is keeping track of all the green-eyed people they can see, and that each of them also knows this, and so on.
所有人都在觀察著其他擁有綠色眼睛的人，他們每個(gè)人都知道這件事。
What any given prisoner doesn't know is whether they themselves are one of the green-eyed people the others are keeping track of
居民們唯一無(wú)法確定的是：他們?cè)谄渌搜壑惺遣皇菗碛芯G色眼睛的人，
until as many nights have passed as the number of prisoners on the island.
一直要等到他們等待的夜晚天數(shù)，和島上的居民數(shù)目一樣為止。
Of course, you could have spared the prisoners 98 days on the island by telling them at least 99 of you have green eyes,
當(dāng)然，你可以幫這些居民省下98天觀察等待的時(shí)間。方法就是直接告訴他們：“你們當(dāng)中至少有99位擁有綠色眼睛。”
but when mad dictators are involved, you're best off with a good headstart.
但是別忘了還有獨(dú)裁者正在監(jiān)視，所以你還是小心一點(diǎn)比較好。
