思想實(shí)驗(yàn)是一種精神上的觀念或假想，通常和謎語相似，是哲學(xué)家和科學(xué)家用以了解什么是大眾思想的一種簡(jiǎn)單方法。他們的運(yùn)用在如哲學(xué)和理論物理（理論物理無需做實(shí)驗(yàn)）等抽象領(lǐng)域是最為廣泛的。他們像是為思想準(zhǔn)備的一份大餐，最終給出復(fù)雜的答案。即使思想實(shí)驗(yàn)本身也會(huì)有無法理解的時(shí)候，這并不奇怪。下面介紹10個(gè)著名的思想實(shí)驗(yàn)，還有他們所要表達(dá)的哲學(xué)、科學(xué)和倫理意義。

10

The Trolley Problem 電車難題

實(shí)驗(yàn)內(nèi)容：

One of the most well known thought experiments in the field of ethics is the “Trolley Problem” which goes something like this: a madman has tied five innocent people to a trolley track. An out of control trolley car is careening toward them, and is moments away from running them over. Luckily, you can pull a lever and divert the trolley to another track. The only problem is that the madman has also tied a single person to that track. Considering the circumstances, should you pull the lever?

它是倫理學(xué)領(lǐng)域最為知名的思想實(shí)驗(yàn)之一，內(nèi)容大致是：一個(gè)瘋子把五個(gè)無辜的人綁在電車軌道上，一輛失控的電車朝他們駛來，且馬上就要輾過他們。幸運(yùn)的是，你可以拉一個(gè)拉桿，讓電車開到另一條軌道上。但是還有一個(gè)問題，那個(gè)瘋子在那另一條軌道上也綁了一個(gè)人。想想這個(gè)情況，你應(yīng)該拉拉桿嗎？

電車難題最早由哲學(xué)家Philippa Foot提出，是用來批判倫理哲學(xué)主要理論的，特別是對(duì)功利主義的批判。功利主義認(rèn)為，大部分道德決策都是根據(jù)“為最多的人提供最大的利益”的原則做出的。從一個(gè)功利主義者的觀點(diǎn)來看，明顯應(yīng)去拉拉桿，只殺死一個(gè)人來拯救五個(gè)人。但是功利主義的批判者反駁說，一旦拉了拉桿，你就變得不道德——你要為另一條軌道上那一個(gè)人的死負(fù)擔(dān)部分的責(zé)任。然而，其他人認(rèn)為，這種狀況下要求你要有所作為，什么都不做也是不道德?？傊?，不存在完全的道德行為，這也就是重點(diǎn)所在。許多哲學(xué)家都用電車難題作為例子來表現(xiàn)現(xiàn)實(shí)生活中經(jīng)常強(qiáng)迫一個(gè)人違背自己道德準(zhǔn)則的狀況，并且有的時(shí)候根本沒有完全道德的做法。

09

The Cow in the Field 空地上的牛奶

實(shí)驗(yàn)內(nèi)容：

One of the major thought experiments in epistemology (the field of philosophy that deals with knowledge) is what is known as “The Cow in the Field.” It concerns a farmer who is worried his prize cow has wandered off. When the milkman comes to the farm, he tells the farmer not to worry, because he’s seen that the cow is in a nearby field. Though he’s nearly sure the man is right, the farmer takes a look for himself, sees the familiar black and white shape of his cow, and is satisfied that he knows the cow is there. Later on, the milkman drops by the field to double-check. The cow is indeed there, but it’s hidden in a grove of trees. There is also a large sheet of black and white paper caught in a tree, and it is obvious that the farmer mistook it for his cow. The question, then: even though the cow was in the field, was the farmer correct when he said he knew it was there?

認(rèn)知領(lǐng)域中一個(gè)重要的思想實(shí)驗(yàn)就是“空地上的奶?！?。實(shí)驗(yàn)是這樣的，一個(gè)農(nóng)民擔(dān)心自己獲獎(jiǎng)的奶牛走丟了。一個(gè)送奶工來到農(nóng)場(chǎng)后，他讓農(nóng)民不要擔(dān)心，因?yàn)樗吹侥穷^奶牛就在附近。雖然農(nóng)民很愿意相信送奶工，但他還是自己去看了下，他看到了熟悉的黑白相間條紋，為自己的奶牛在那里感到很滿意。過了一會(huì)，送奶工到那里再次進(jìn)行了確認(rèn)。那頭奶牛確實(shí)在那里，但它躲在了樹林里，而且有一大張黑白相間的紙纏繞在了一棵樹上，顯然，農(nóng)民把這張紙錯(cuò)當(dāng)成自己的奶牛了。問題于是來了， 就算奶牛一直在那里，但農(nóng)民說自己知道那頭奶牛在那里時(shí)是否正確？

空地上的奶牛最初被Edmund Gettier用來批判主流對(duì)知識(shí)定義的JTB（justified true belief）理論，即當(dāng)人們相信一件事時(shí)，它就成為了知識(shí)；這件事事實(shí)上是真的，且可以被充分驗(yàn)證。實(shí)驗(yàn)中，農(nóng)民之所以相信奶牛在那里，是送奶工證詞和他自己所見黑白相間物所共同構(gòu)成的結(jié)果。而之后送奶工的確認(rèn)，這件事也碰巧是真實(shí)的。盡管如此，農(nóng)民并非真正知道奶牛在那里，因?yàn)樗J(rèn)為奶牛在那里的結(jié)論是建立在錯(cuò)誤的前提上的。Gettier利用這個(gè)實(shí)驗(yàn)和其他一些例子，說明了將知識(shí)定義為JTB的理論需要修正。

08

The Ticking Time Bomb 定時(shí)炸彈

實(shí)驗(yàn)內(nèi)容：

If you’ve paid any attention to political discourse over the past few years—or ever seen an action movie, for that matter—then you are no doubt familiar with the “ticking time bomb” thought experiment. It asks you to imagine that a bomb or other weapon of mass destruction is hidden in your city, and the timer on it will soon strike zero. You have in your custody a man with knowledge of where the device is planted. Do you resort to torture in order to get him to give up the information?

如果你關(guān)注近幾年的政治時(shí)事，或看過動(dòng)作電影，那么你對(duì)“定時(shí)炸彈”實(shí)驗(yàn)肯定很熟悉。它要求你想象有一個(gè)炸彈或其他大規(guī)模殺傷性武器藏在你的城市中，并且倒計(jì)時(shí)馬上將歸零。城市里有一個(gè)知情者，他知道炸彈的埋藏點(diǎn)。你會(huì)使用酷刑來讓他吐出情報(bào)嗎？

與電車難題類似，定時(shí)炸彈實(shí)驗(yàn)也是強(qiáng)迫一個(gè)人從兩個(gè)不道德行為中選擇其一的倫理問題。它一般用來反駁那些說在任何情況下都不能使用酷刑的言論。它也被用作在極端形勢(shì)下法律可以被放在第二位的情況，如美國(guó)嚴(yán)禁虐囚的法律。歸功于《24小時(shí)》之類的電視節(jié)目，還有一些政治辯論，定時(shí)炸彈已成為最常被提起的思想實(shí)驗(yàn)之一。今年早些時(shí)候，一份英國(guó)報(bào)紙?zhí)岢隽烁鼮闃O端的看法。這份報(bào)紙說，如果這個(gè)恐怖分子對(duì)酷刑毫無反應(yīng)，那么當(dāng)局者是否愿意拷打他的妻子和兒女來逼他吐出情報(bào)。

07

Einstein’s Light Beam 愛因斯坦的光線

實(shí)驗(yàn)內(nèi)容：

It’s a little known fact that Albert Einstein’s famous work on special relativity was spurred by a thought experiment he conducted when he was only 16 years old. In his bookAutobiographical Notes, Einstein recalls how he once daydreamed about chasing a beam of light as it traveled through space. He reasoned that if he were able to move next to it at the speed of light, he should be able to observe the light frozen in space as “an electromagnetic field at rest though spatially oscillating.” For Einstein, this thought experiment proved that for his imaginary observer “everything would have to happen according to the same laws as for an observer who, relative to the Earth, was at rest.”

很少有人知道愛因斯坦著名的狹義相對(duì)論是受到他16歲時(shí)一個(gè)思想實(shí)驗(yàn)的啟發(fā)。在他的著作《自述注記》中，愛因斯坦回憶道他當(dāng)時(shí)幻想在宇宙中追逐一道光線。他說如果他能夠以光速在光線旁邊運(yùn)動(dòng)，那么他應(yīng)該能夠看到光線在空間內(nèi)呈現(xiàn)為“不斷振蕩但停滯著的電磁場(chǎng)”。對(duì)于愛因斯坦，這個(gè)思想實(shí)驗(yàn)證明了對(duì)于他作為一個(gè)富有想象力的觀察者，”在有相同定律和一個(gè)相對(duì)于地球靜止觀察者的情況下，任何事都有可能發(fā)生。”

事實(shí)上，沒人真正知道這意味著什么?？茖W(xué)家一直都在爭(zhēng)論一個(gè)如此簡(jiǎn)單的思想實(shí)驗(yàn)是如何幫助愛因斯坦完成到狹義相對(duì)論這個(gè)巨大飛躍的。在當(dāng)時(shí)，這個(gè)實(shí)驗(yàn)中的想法與現(xiàn)在已被拋棄的“以太”理論相違背?！耙蕴崩碚摷创嬖谝粋€(gè)隱性的空間供光線穿越。他經(jīng)過了好多年才證明了自己是正確，但從某種程度上這個(gè)實(shí)驗(yàn)對(duì)于狹義相對(duì)論是“有害的”，他自己這么說，后者第一次讓他站上了理論物理學(xué)的頂點(diǎn)。

06

The Ship of Theseus 忒修斯之船

實(shí)驗(yàn)內(nèi)容：

One of the oldest of all thought experiments is the paradox known as the Ship of Theseus, which originated in the writings of Plutarch. It describes a ship that remained seaworthy for hundreds of years thanks to constant repairs and replacement parts. As soon as one plank became old and rotted, it would be replaced, and so on until every working part of the ship was no longer original to it. The question is whether this end product is still the same Ship of Theseus, or something completely new and different. If it’s not, at what point did it stop being the same ship? The Philosopher Thomas Hobbes would later take the problem even further: if one were to take all the old parts removed from the Ship of Theseus and build a new ship from them, then which of the two vessels is the real Ship of Theseus?

史上最為古老的思想實(shí)驗(yàn)之一便是被稱為忒修斯之船的悖論。這個(gè)實(shí)驗(yàn)最早出自普魯塔克的記載。它描述了一艘可以在海上航行幾百年的船，這歸功于不斷的維修和部件的替換。只要一塊木板腐爛了，它就會(huì)被替換掉，以此類推，直到所有的部件都不再是最初的那些。問題是，最終產(chǎn)生的這艘船還是原來的忒修斯之船，還是一艘完全不同的新船？如果不是原來的船了，那么從什么時(shí)候開始它不再是原來的船了？哲學(xué)家Thomas Hobbes后來對(duì)此進(jìn)行了更深刻的探討：如果有人用忒修斯之船上取下來的老部件來重新建造一艘新的船，那么兩艘船中哪艘才是真正的忒修斯之船？

對(duì)于哲學(xué)家來說，忒修斯之船被用來研究身份的本質(zhì)，特別是討論一個(gè)物體是否僅僅就是其部件之和。一個(gè)更現(xiàn)代的例子是假設(shè)有一個(gè)樂隊(duì)，到某一階段樂隊(duì)成員中不再有任何一個(gè)原始成員。這個(gè)問題還可以應(yīng)用于其他如商業(yè)等領(lǐng)域。商業(yè)領(lǐng)域中，在不斷并購(gòu)和更換股東后仍然保留企業(yè)原來的名字；對(duì)于人體，人體不斷地進(jìn)行著新陳代謝和自我修復(fù)。這個(gè)實(shí)驗(yàn)的核心思想在于強(qiáng)迫人們?nèi)シ磫柹矸菔欠駜H僅局限在實(shí)際物體和現(xiàn)象中這一普遍知識(shí)。

05

Galileo's Gravity Experiment 

伽利略的重力實(shí)驗(yàn)

實(shí)驗(yàn)內(nèi)容：

One of the earliest thought experiments originated with the physicist and astronomerGalileo. In order to refute Aristotle’s claim that the speed of a falling object is dictated by its mass, Galileo devised a simple mental example: According to Aristotelian logic, if a light object and a heavy object were tied together and dropped off a tower, then the heavier object would fall faster, and the rope between the two would become taut. This would allow the lighter object to create drag and slow the heavy one down. But Galileo reasoned that once this occurs, the weight of the two objects together should be heavier than the weight of either one by itself, therefore making the system as a whole fall faster. That this is a contradiction proved that Aristotle’s hypothesis was wrong.

史上最早的思想實(shí)驗(yàn)之一，由物理和天文學(xué)家伽利略進(jìn)行實(shí)驗(yàn)。為了反駁亞里士多德的自由落體速度取決于物體質(zhì)量的理論，伽利略設(shè)計(jì)了一個(gè)簡(jiǎn)單的思想實(shí)驗(yàn)：根據(jù)亞里士多德的邏輯，如果一個(gè)較輕的物體和一個(gè)較重的物體綁在一起后從塔上扔下去，那么教重的物體會(huì)下落的比較快，且兩個(gè)物體間的繩子會(huì)被拉緊。這時(shí)較輕的物體會(huì)對(duì)較重的物體產(chǎn)生一個(gè)拽力，使得重物的下落速度變慢。但是，伽利略認(rèn)為兩個(gè)物體綁在一起后的重量應(yīng)比其中任意一個(gè)物體都大，那么一起下落的速度應(yīng)該是最快的。于是他用這個(gè)矛盾證明了亞里士多德理論是錯(cuò)誤的。 

關(guān)于伽利略有一個(gè)著名的故事：有一次他從比薩斜塔扔下兩個(gè)鐵球，想要證明較重的物體并不較輕的物體下落速度快?，F(xiàn)實(shí)中這個(gè)故事可能只是作為一種傳奇，但這個(gè)思想實(shí)驗(yàn)證明了一個(gè)關(guān)于重力很重要的理論：無論物體的質(zhì)量，所有物體自由落體的速率都是一樣的。

04

Monkeys and Typewriters 猴子和打字機(jī)

實(shí)驗(yàn)內(nèi)容：

Another thought experiment that gets a lot of play in popular culture is what is known as the “infinite monkey theorem.” Also known as the “monkeys and typewriters” experiment, the theorem states that if an infinite number of monkeys were allowed to randomly hit keys on an infinite number of typewriters for an infinite amount of time, then at some point they would “almost surely” produce the complete works of Shakespeare. The monkeys and typewriters idea was popularized in the early 20th century by the French mathematician Emile Borel, but its basic idea—that infinite agents and infinite time will randomly produce anything and everything—dates back to Aristotle.

另一個(gè)在流行文化中獲得廣泛關(guān)注的思想實(shí)驗(yàn)是“無限猴子定理”，也叫做“猴子和打字機(jī)”實(shí)驗(yàn)。該定理認(rèn)為，如果有無數(shù)多的猴子在無限久的時(shí)間里，在無數(shù)多的打字機(jī)上隨機(jī)打字，那么在某個(gè)時(shí)間點(diǎn)，它們“幾乎必然”會(huì)打出莎士比亞的全部著作。猴子和打字機(jī)的設(shè)想在20世紀(jì)早期由法國(guó)數(shù)學(xué)家Emile Borel推廣，但其基本思想，即無數(shù)多的人員和無數(shù)多的時(shí)間能產(chǎn)生任何/所有東西的理論，可以追溯至亞里士多德。

簡(jiǎn)單來說，“猴子和打字機(jī)”定理是用來描述無限本質(zhì)最好的方法之一。人的大腦很難想象無限的空間和無限的時(shí)間，無限猴子定理可以幫助理解這些概念。猴子碰巧能寫出《哈姆雷特》，聽上去是天方夜譚，但當(dāng)一個(gè)人考慮到所有的可能性后，這個(gè)說法在數(shù)學(xué)上是可以被證明的。這個(gè)定理本身在現(xiàn)實(shí)生活中不可重現(xiàn)，但這并沒有阻止一些人的嘗試：2003年，英國(guó)修讀科學(xué)的學(xué)生在一家英國(guó)動(dòng)物園“試驗(yàn)”了無限猴子定理，他們把一臺(tái)電腦和一個(gè)鍵盤放進(jìn)了靈長(zhǎng)類園區(qū)?？上У氖牵镒觽儧]有打出任何十四行詩(shī)。根據(jù)研究，它們只打出了5頁幾乎完全是字母“s”的紙。

03

The Chinese Room 中文房間

實(shí)驗(yàn)內(nèi)容：

The Chinese Room is a famous thought experiment first proposed in the early 1980s by John Searle, a prominent American philosopher. The experiment asks you to imagine that an English speaking man has been placed in a room that is entirely sealed, save for a small mail slot in the chamber door. He has with him a hard copy in English of a computer program that translates the Chinese language. He also has plenty of spare scratch paper, pencils, and file cabinets. Pieces of paper containing Chinese characters are then slipped through the slot in the door. According to Searle, the man should be able to use his book to translate them and then send back his own response in Chinese. Although he doesn’t speak a word of the language, Searle argues that through this process the man in the room could convince anyone on the outside that he was a fluent speaker of Chinese.

“中文房間”最早由美國(guó)杰出哲學(xué)家John Searle于20世紀(jì)80年代初提出。這個(gè)實(shí)驗(yàn)要求你想象一位只會(huì)說英語的人身處一個(gè)幾乎完全密閉的房間中，房間門上有一個(gè)小窗口。他有一臺(tái)具有英漢翻譯功能的電腦，房間里還有足夠的紙、鉛筆和文件柜。隨后寫著中文的紙片通過小窗口將被送入房間中。根據(jù)Searle的理論，房間中的人可以翻譯這些文字并用中文寫上他的回復(fù)。雖然他完全不會(huì)中文，但Searle認(rèn)為通過這個(gè)過程，房間里的人可以讓任何房間外的人以為他會(huì)說流利的中文。 

Searle創(chuàng)造了“中文房間”思想實(shí)驗(yàn)來反駁電腦和其他人工智能都能夠真正思考的觀點(diǎn)。房間里的人不會(huì)說中文；他無法用中文思考。但就因?yàn)樗麚碛心承┕ぞ?，他甚至可以讓以中文為母語的人以為他能說流利的中文。Searle還說，電腦就是這樣工作的。它們無法真正理解他們所給出的信息，但它們可以運(yùn)行一個(gè)程序、處理信息、然后給出一個(gè)具有人工智能的印象。 

02

Schrodinger’s Cat 薛定諤的貓

實(shí)驗(yàn)內(nèi)容：

Schr?dinger’s Cat is a paradox relating to quantum mechanics that was first proposed by the physicist Erwin Schr?dinger. It concerns a cat that is sealed inside a box for one hour along with a radioactive element and a vial of deadly poison. There is a 50/50 chance that the radioactive element will decay over the course of the hour. If it does, then a hammer connected to a Geiger counter will trigger, break the vial, release the poison, and kill the cat. Since there is an equal chance that this will or will not happen, Schr?dinger argued that before the box is opened the cat is simultaneously both alive and dead.

薛定鍔的貓最早由物理學(xué)家薛定鍔提出，是量子力學(xué)領(lǐng)域中的一個(gè)悖論。內(nèi)容是：一只貓被封閉在一個(gè)盒子里一個(gè)小時(shí)，和它一起的還有一些放射性元素和一瓶毒氣。在一小時(shí)內(nèi)，放射性元素的衰變幾率為50%。如果發(fā)生了衰變，那么會(huì)觸發(fā)一個(gè)連接在蓋革計(jì)數(shù)器上的錘子，打碎瓶子，釋放毒氣，殺死貓。因?yàn)檫@件事是否發(fā)生的概率相等，薛定鍔認(rèn)為在盒子被打開前，盒子中的貓可以同時(shí)被認(rèn)為是既死又活的。

簡(jiǎn)而言之，這個(gè)實(shí)驗(yàn)的核心思想是因?yàn)槭录l(fā)生時(shí)不存在觀察者，盒子里的貓可能同時(shí)存在所有的狀態(tài)（實(shí)驗(yàn)中既死又活）。這個(gè)觀念同一個(gè)古老的謎題相似，謎題內(nèi)容為，如果一棵樹倒在了樹木中，且沒有人聽到聲音，那么它有沒有發(fā)出聲響？薛定鍔最早是在回復(fù)一篇討論量子態(tài)疊加本質(zhì)的文章時(shí)提出這個(gè)實(shí)驗(yàn)的。薛定鍔的貓同時(shí)也說明了量子力學(xué)的理論是多么奇怪。這個(gè)思想實(shí)驗(yàn)因其復(fù)雜性而臭名昭著，同時(shí)也產(chǎn)生了各種各樣的解釋。其中最古怪的是“多重世界”假說，這個(gè)假說表示有一只既死又活的貓，那么兩只貓是存在于不同的宇宙間，且永遠(yuǎn)不會(huì)有交集。 

01

Brain in a Vat 缸中的大腦

實(shí)驗(yàn)內(nèi)容：

There has been no more influential thought experiment than the so-called “brain in a vat” hypothesis, which has permeated everything from cognitive science and philosophy to popular culture. The experiment asks you to imagine a mad scientist has taken your brain from your body and placed it in a vat of some kind of life sustaining fluid. Electrodes have been connected to your brain, and these are connected to a computer that generates images and sensations. Since all your information about the world is filtered through the brain, this computer would have the ability to simulate your everyday experience. If this were indeed possible, how could you ever truly prove that the world around you was real, and not just a simulation generated by a computer?

沒有比所謂“缸中的大腦”更有影響力的思想實(shí)驗(yàn)了，這個(gè)思想實(shí)驗(yàn)涵蓋了從認(rèn)知學(xué)到哲學(xué)到流行文化等各個(gè)領(lǐng)域。這個(gè)實(shí)驗(yàn)要求你想象有一個(gè)瘋狂科學(xué)家把你的大腦從你體內(nèi)取出，放在一個(gè)裝有維持生命液體的缸中。大腦是連著電極，電極還連到一臺(tái)能產(chǎn)生圖像和感官信號(hào)的電腦上。因?yàn)槟惬@取的所有關(guān)于世界的信息都是經(jīng)由大腦過濾，這臺(tái)電腦就有能力模擬你日常的體驗(yàn)。如果這確實(shí)可能的話，你要如何來證明你周圍的世界是真實(shí)的，而不是由一臺(tái)電腦所產(chǎn)生的模擬環(huán)境？

如果你覺得這一切聽起來很像《黑客帝國(guó)》，你說對(duì)了。這部電影以及其他一些科幻小說和電影，都受到了這個(gè)實(shí)驗(yàn)很大的影響。這個(gè)實(shí)驗(yàn)的核心思想是讓人們質(zhì)疑經(jīng)歷的本質(zhì)，并思考作為一個(gè)人的真正意義是什么。這個(gè)實(shí)驗(yàn)的原型可以追溯至笛卡爾，由希拉里·普特南推廣。在笛卡爾的《第一哲學(xué)沉思錄》一書中，笛卡爾提出了是否證明能他所有的感官體驗(yàn)都是他自己的，而不是由某個(gè)“邪惡魔鬼”所產(chǎn)生的幻想。笛卡爾用他的經(jīng)典名言“我思故我在”回答了這個(gè)問題。不幸的是，“缸中的大腦”將問題復(fù)雜化了，因?yàn)檫B著電極的大腦仍然可以思考。這個(gè)實(shí)驗(yàn)被哲學(xué)家廣泛討論，也有許多針對(duì)實(shí)驗(yàn)前提的反駁，但仍沒有人能有力的回應(yīng)其核心問題：你到底怎么才能知道什么是真實(shí)？ 

本文來自譯言，譯者：bio1091

原文作者：Evan Andrews