and now you and your brother

你發現一個 通往另一國度的出入口，

are off exploring the wonderful world of Paradoxica.

現在你和你的兄弟 出發前往奇妙的悖論世界探險。

Fantastically paradoxical creatures crawl, run, and fly around you.

奇異的悖論動物在你四周 爬行、奔跑和飛行。

And then you see the troll.

然後你看到巨人，

It's catching all the creatures in an enormous net.

牠正用一個極大的網子 捕捉所有的動物。

You bravely step forward and demand it let them go.

你勇敢地走向前 要求牠釋放牠們。

The troll laughs.

巨人大笑，牠說： 「若你真是個悖論迷的話，

“If you're such a fan of paradoxes,” it says,

那麼我給你一個交換條件， 如果你說真話，

“then I'll make you an offer.

我就釋放所有動物。」 當你正要說：「你是個巨人。」

If you say something true, I'll release all these creatures."

但話還沒出口， 巨人就抓起你的兄弟。

You're about to say, “You are a troll,”

牠又說：「如果你說假話， 那我會放你兄弟。

but before you can, the troll grabs your brother.

你的話只能是單一句子。

“If you say something false,” he continues,

如你所見，我最討厭悖論。

“then I'll release your brother."

假如你試圖 說些矛盾的話來蒙騙我，

Your statement can only be a single sentence.

例如『這話是假的。』 那麼我會吃掉你兄弟和動物。」

And as you can see, I hate paradoxes more than anything.

你能說出哪句真／假的話，

If you try to cheat by saying something paradoxical,

迫使巨人釋放你兄弟和悖論動物呢？

like, 'this statement is false,'

假如你想自己解解看， 現在將影片暫停。

then I'll eat your brother and the creatures."

答案即將公佈：3

What true/false statement can you say to force the troll

答案即將公佈：2

to free your brother and the paradoxical creatures?

答案即將公佈：1

[Pause the video now if you want to figure it out for yourself!]

這似乎是個不可能的任務， 但很奇妙地，你是可以說個

Answer in: 3

迫使巨人釋放所有囚犯的話。

Answer in: 2

這是個「強迫邏輯」的例子， 是由偉大的邏輯學家

Answer in: 1

及益智遊戲創造家 雷德蒙·斯穆里安發明的。

This seems like an impossible situation,

斯穆里安提出解謎的訣竅

but incredibly, you can say something

在於所用的句子是真或假

that will force the troll to release all its prisoners.

是依你希望巨人做什麼而定。

This is an example of coercive logic,

你仍須小心斟酌所說的話。

invented by the great logician and puzzle creator Raymond Smullyan.

例如，假如你說：

The trick Smullyan came up with involves saying a statement

「你會放動物和我的兄弟。」

whose truth or falseness depends on what you want the troll to do.

巨人可能回答： 「錯了…… 我只會放你兄弟。」

Your statement still has to be carefully crafted.

同樣地，若你說： 「你會放悖論動物。」

For example, if you were to say,

巨人可能說：「那是真的。」 然後釋放悖論動物。

“You are going to free the creatures and my brother,”

但注意以下會發生什麼事， 假如你說：「你會放我兄弟。」

the troll could respond, “that's false… I'm only going to free your brother.”

這句話不可能是假的，

Similarly, if you said, “You will free the paradoxes,”

因為如果是假的， 根據牠自己的規則，

the troll could say, “That's true,” and free the paradoxes.

牠就必須釋放你的兄弟。

But watch what happens if you say, “You will free my brother.”

那會使得那句話自相矛盾。

The statement can't be false,

但巨人討厭悖論

because if it were, the troll, by its own rules,

且絕不願意去創造一個。

would have to free your brother.

所以牠唯一的選擇 是把這句當真。

That would make the statement paradoxically true and false.

假如「你會放我兄弟」是真的，

But the troll hates paradoxes

那麼巨人必須釋放你的兄弟。

and would never willingly create one.

根據牠的規則 巨人也須釋放動物，

So his only option is for the statement to be true.

因為你說了一句真話。

If “you will free my brother” is true,

僅用五個字， 如同用邏輯手術刀般，

then the troll has to release your brother.

你已迫使巨人釋放所有囚犯。

And by its own rules, the troll has to free the creatures as well,

當巨人怒氣沖沖跺步離去，

since you said a true statement.

悖論動物為你贏得牠們的自由喝彩，

By wielding just 5 words like a logical scalpel,

而且答應帶你去拿樓梯頂端的寶藏，

you've forced the troll to free all its prisoners.

只要你到得了的話。

As the troll stomps off in anger,

the paradoxes cheer you for winning them their freedom,

and promise to lead you to the treasure at the top of the stairs.

If you can reach it.