David Deutsch: A new way to explain explanation

譯者: LI CHENXI 審譯者: Pei-Jan Hung

I'm sure that,

我很確定，在人類這種物種存活的

throughout the 100,000-odd years of our species' existence

數十萬年間，

and even before,

甚至在更早以前，

our ancestors looked up at the night sky and wondered what stars are --

我們的祖先仰望夜空，

想知道星星到底是什麼。

wondering, therefore,

因此，也很想知道

如何以那些看不到的東西

how to explain what they saw

in terms of things unseen.

解釋他們所看到的一切

好吧，當時的大多數的人

OK, so, most people only wondered that occasionally, like today,

就像現在一樣，只是偶而會想知道

in breaks from whatever normally preoccupied them.

在閒暇時，那些

使他們著迷的東西

But what normally preoccupied them also involved yearning to know.

不過那些他們專注的東西

也跟求知的慾望有關。

They wished they knew

他們盼望知道

how to prevent their food supply from sometimes failing,

如何讓食物供給

不致偶有匱乏，

and how they could rest when they were tired

還有他們疲累時該如何歇息

without risking starvation,

且不會挨餓，

be warmer, cooler, safer,

住得更加溫暖，更加涼爽，更加安全

in less pain.

以及讓生活少點的痛苦。

I bet those prehistoric cave artists would have loved to know

我敢說那些史前洞穴的畫家

一定很想知道

how to draw better.

怎麼樣畫得更好。

在生活上的各個方面，

(Laughter)

In every aspect of their lives,

they wished for progress, just as we do.

他們渴望進步，就跟我們一樣。

But they failed, almost completely, to make any.

不過，他們幾乎是一敗塗地，沒有獲得任何進展。

They didn't know how to.

他們不知道如何進步。

Discoveries like fire happened so rarely

像火這類的發現

極少發生，所以從人的觀點而言，

that, from an individual's point of view,

the world never improved.

整個世界沒有進步過。

Nothing new was learned.

也沒有學過什麼新事物。

The first clue to the origin of starlight

最早研究星光的起源

happened as recently as 1899:

發生在約1899年：放射性。

radioactivity.

And within 40 years,

在四十年之內，

physicists discovered the whole explanation,

物理學家發現了全部的解釋，

expressed, as usual, in elegant symbols.

如同往常，這些解釋以優雅的符號表現出來。

But never mind the symbols.

不過別管這些符號。

Think how many discoveries they represent.

想想看這些符號

代表多少發現。

Nuclei and nuclear reactions, of course.

當然，有原子核反應。

But isotopes,

同位素、正負電粒子

particles of electricity,

antimatter,

反物質

neutrinos,

微中子，

the conversion of mass to energy -- that's E=mc2 --

質能變換，就是E=mc平方

gamma rays,

伽馬射線

transmutation.

核嬗變 （一種元素通過核反應轉化成另外一種元素）

That ancient dream that had always eluded the alchemists

這些連古代鍊金術士也無能為力的夢想

was achieved through these same theories

被以上這些理論實現了

that explained starlight and other ancient mysteries

這些方程式解釋了星光

和其他的古代神話

and new, unexpected phenomena.

和那些新的，預料不到的現象

That all that, discovered in 40 years,

所有的這些都在這40年中發現

had not been in the previous hundred thousand

但卻都沒有在過去的千百年中發現

was not for lack of thinking

這不是因為他們缺乏思考

about stars and all those other urgent problems they had.

關於星星，或者那些很緊迫的問題

他們其實是有一套答案的

They even arrived at answers, such as myths,

例如說用神話來解釋現象

that dominated their lives,

這些主宰了他們的生活

yet bore almost no resemblance to the truth.

雖然這些對於事實

幾乎沒任何關聯性

The tragedy of that protracted stagnation

這種知識停滯所帶來的悲劇

isn't sufficiently recognized, I think.

我認為並沒有被充分的意識到

These were people with brains of essentially the same design

人類的大腦

本質上都是一樣的構造

that eventually did discover all those things.

這樣的構造發現了這些現象

But that ability to make progress

但是那種進步的能力

remained almost unused,

並沒有充分地被發揮

until the event that revolutionized the human condition

直到有些事件

徹底地改變了人類的現況

和改變了整個宇宙

and changed the universe.

Or so we should hope,

或者我們希望透過它大幅改變人類的生活

because that event was the scientific revolution,

因為這個事件是

科學革命

ever since which our knowledge of the physical world

從我們有了

對現實世界的知識以來

and of how to adapt it to our wishes

怎麼樣利用科學技術來實現我們的願望

has been growing relentlessly.

這樣的發展就從來沒有停止過

Now, what had changed?

現在，什麽改變了？

What were people now doing for the first time

人們現在要做什麽

that made that difference between stagnation

才能區別開

對於知識追求的停滯

and rapid, open-ended discovery?

和不斷地、開放地探索？

How to make that difference

如何區分兩者

is surely the most important universal truth

無疑地是重要且普遍的真理

that it's possible to know.

這是非常好了解的

And worryingly, there's no consensus about what it is.

麻煩的是，這沒有一個公認的方法

So, I'll tell you.

所以，我將告訴你

(Laughter)

但是在這之前我要回溯一點點時間

But I'll have to backtrack a little first.

Before the scientific revolution,

到科學革命之前

they believed that everything important, knowable,

人們認為任何事情都是重要的，可以認知的

was already known,

而且都已經被知道了

enshrined in ancient writings, institutions

這些蘊藏在古代著作中、習俗中

and in some genuinely useful rules of thumb --

和一些十分有效的經驗法則中

which were, however, entrenched as dogmas,

那些被認為是不可憾動的教義與信條

along with many falsehoods.

事實上伴隨著很多漏洞

So, they believed that knowledge came from authorities

所以他們認為知識來源於權威

that actually knew very little.

但是其實權威知道的很少

And therefore,

所以知識進步為

progress depended on learning how to reject

學習著去抵抗權威

the authority of learned men, the priests, traditions and rulers,

包括學識淵博的人

神父，習俗傳統和統治者

which is why the scientific revolution had to have a wider context:

這就是爲什麽科學革命

擁有更寬廣的背景：

the Enlightenment, a revolution in how people sought knowledge,

我們稱之的啓蒙運動，就是一場

人們怎樣去獲取知識的革命

trying not to rely on authority.

他們試圖不依靠權威

"Take no one's word for it."

"不要把一個人的話當做理所當然的"

But that can't be what made the difference.

但是這些都不能徹底的改變

Authorities had been rejected before, many times.

以前權威也被挑戰過很多次

And that rarely, if ever,

但是很少

可以引起像科學革命這樣的事件

caused anything like the scientific revolution.

At the time, what they thought distinguished science

當時，他們認為

現代科學這種

was a radical idea about things unseen,

對無法觀察到的事物進行解釋是頗為激進的想法

known as empiricism --

這些方法被稱為經驗主義

all knowledge derives from the senses.

所有的知道都來自感覺、感官

Well, we've seen that that can't be true.

好了，我們現在知道那不是正確的

It did help by promoting observation and experiment.

但這確實對理解有所幫助

透過觀察和實驗

But, from the outset,

但是，一開始這就很明顯

it was obvious that there was something horribly wrong with it.

這種想法存在著錯誤

Knowledge comes from the senses?

知識來自於感覺

In what language?

透過什麽語言？肯定不是數學語言

Certainly not the language of mathematics, in which, Galileo rightly said,

伽利略提出正確的聲明

the book of nature is written.

說大自然的著作早已寫成

Look at the world.

看看這個世界。你沒有看見任何數學方程式

You don't see equations carved on the mountainsides.

刻在任何一座山上

If you did, it would be because people had carved them.

如果你看見了，那只是因為人類

刻上去的

By the way, why don't we do that?

順便說一句，爲什麽我們不那樣做呢?

(Laughter)

What's wrong with us?

我們怎麼了?

(Laughter)

(笑)

Empiricism is inadequate

經驗主義是不夠的

because, well, scientific theories explain the seen in terms of the unseen.

因為

科學理論是通過觀察不到的事物解釋觀察到的現象

And the unseen, you have to admit,

那些看不到的，你必須承認

doesn't come to us through the senses.

不是通過我們的感覺就能理解的

We don't see those nuclear reactions in stars.

我們看不到星星上的核子反應

We don't see the origin of species.

我們看不到物種的起源

We don't see the curvature of space-time,

我們看不到時空彎曲

and other universes.

和其他宇宙

But we know about those things.

但是我們知道這些

How?

透過什麽呢？

Well, the classic empiricist answer is induction --

呃，傳統的經驗主義者的回答是"透過歸納法"

the unseen resembles the seen.

看不到的跟能看到的必定有相似之處

But it doesn't.

但是事實並不是如此

You know what the clinching evidence was that space-time is curved?

你知道確鑿的證據表明

如果時空的彎曲

It was a photograph -- not of space-time,

的證據是一張照片，而不是時空本身

but of an eclipse, with a dot there rather than there.

有可能是一次日蝕，上面有小點而不是其他地方

And the evidence for evolution?

再比如說演化的證據

Some rocks and some finches.

是一些石頭和一些雀科鳥類

And parallel universes?

平行的宇宙？同樣地：這有小點，

Again: dots there rather than there, on a screen.

而不是別的地方，顯示在營幕上

What we see in all these cases

我們看到的，在這些例子中

bears no resemblance to the reality that we conclude is responsible --

其實跟現實沒什麼太大的關係

我們的結論是非常合理的

只有進行一連串理論上的推理和解釋

only a long chain of theoretical reasoning and interpretation connects them.

才能把事實和現象做連結

哈！創造論者(相信萬物由上帝一次造成的人)說

"Ah!" say creationists.

"So you admit it's all interpretation.

你承認這都是解釋了

No one's ever seen evolution.

沒有人看見過演化

We see rocks.

我們只看過石頭標本

You have your interpretation. We have ours.

你有你的解釋。我們有我們的

Yours comes from guesswork; ours, from the Bible."

你的從推測中來

而我們的是從聖經來

But what creationist and empiricists both ignore

但是創造論者和經驗主義者都忽略了

is that, in that sense,

在某種意義上

no one's ever seen a Bible either,

沒有人看過聖經是如何被創造的

that the eye only detects light, which we don't perceive.

眼睛只感覺光亮，而我們並沒有察覺

Brains only detect nerve impulses.

大腦只接受神經脈衝

And they don't perceive even those as what they really are,

他們並沒有意識到組成脈衝的

namely electrical crackles.

其實是電子訊號

所以我們常常不了解現實本身為何物

So we perceive nothing as what it really is.

Our connection to reality is never just perception.

感官知覺

絕對不是我們用來與現實產生連繫的唯一方法

It's always, as Karl Popper put it,

如同卡爾‧波普爾所說的，

theory-laden.

科學理論和人類所掌握到的一切知識，都只不過是推測和假想

Scientific knowledge isn't derived from anything.

科學知識無從根據

Like all knowledge, it's conjectural, guesswork,

就像其他知識一樣。是一種推斷，猜測，

tested by observation,

經過觀察的考驗，

not derived from it.

而不是發源於知識本身。

So, were testable conjectures the great innovation

所以，這些禁得起測試的推論

that opened the intellectual prison gates?

是巨大的創新嗎？並且打開了智慧的大門嗎？

No, contrary to what's usually said, testability is common

不。跟一般說法相反，

可測試性是共通的特點

in myths and all sorts of other irrational modes of thinking.

在神話中和各種其他非理性的想法中。

Any crank claiming the sun will go out next Tuesday

任何一個怪人都可以聲稱太陽會在下個星期二升起

has got a testable prediction.

這就是一個可測試的預測。

Consider the ancient Greek myth explaining seasons.

想想古希臘的神話

解釋季節。

Hades, god of the underworld,

黑帝斯，冥界之神，

綁架了普西芬妮，春天之神，

kidnaps Persephone, the goddess of spring,

and negotiates a forced marriage contract, requiring her to return regularly,

逼迫她簽下婚姻契約

並且要求她定時回去，然後才能放她走。

and lets her go.

And each year,

每年

she is magically compelled to return.

她就神奇的歸去

And her mother, Demeter,

她的母親，迪米特，

goddess of the earth,

大地女神，

is sad, and makes it cold and barren.

十分地傷心，所以便讓土地冰冷和荒蕪。

That myth is testable.

這個神話可以驗證。

If winter is caused by Demeter's sadness,

如果冬天是因為迪米特的悲傷，

then it must happen everywhere on earth simultaneously.

那一定會同時發生在世界上每一個角落

So if the ancient Greeks had only known

所以如果古希臘人知道澳洲

that Australia is at its warmest when Demeter is at her saddest ...

在迪米特最傷心的時候是最熱的時段，

(Laughter)

they'd have known that their theory is false.

那他們就知道他們理論的錯誤了

(Laughter)

那些神話

So, what was wrong with that myth

and with all prescientific thinking?

和那些科學的想法有什麽問題嗎？

And what, then, made that momentous difference?

到底是什麽能引起這麼大的不同呢？

I think there's one thing you have to care about

我認為你們只需要關心一件事情

那就是

and that implies testability, the scientific method,

是否有驗證性，用科學的方法

the Enlightenment and everything.

啓蒙運動，和之前說的一切

And here's the crucial thing:

這都是非常重要的

there is such a thing as a defect in a story.

常常在故事裡會有所缺陷

I don't just mean a logical defect.

我不是指邏輯缺陷。我說的是錯誤的解釋。

I mean a bad explanation.

What does that mean?

這意味這什麽呢？好了，解釋

Well, an explanation is an assertion about what's there, unseen,

是一種用看不見的事物

that accounts for what's seen;

來解釋看的見的東西

because the explanatory role of Persephone's marriage contract

所以有關普西芬妮的

婚約導致四季的變化

could be played equally well

用其他各種理由

by infinitely many other ad hoc entities.

來解釋的話

應該也說的通

Why a marriage contract and not any other reason

爲什麽是婚約而不是其他原因

for regular annual action?

導致每年四季規律的行為？

Here's one: Persephone wasn't released.

這裡有一個原因。普西芬妮並沒有被釋放。

She escaped, and returns every spring to take revenge on Hades,

她只是逃跑，然後每年春天回來

向哈德斯報仇

with her spring powers.

用她的春天的能量。

She cools his domain with spring air,

她用春風給她的領地降溫

venting heat up to the surface, creating summer.

讓熱氣到達表面，形成夏天。

That accounts for the same phenomena as the original myth.

這裡用原始的神話解釋了每年同樣的現象。

It's equally testable.

我們可以測試其正確與否

Yet what it asserts about reality is, in many ways, the opposite.

但是神話聲稱的內容

在真實世界中很多方面都是相反的。

And that's possible

那是因為

because the details of the original myth are unrelated to seasons,

神話的細節

跟季節無關

except via the myth itself.

除了透過神話讓兩者產生聯繫以外

This easy variability

這種明顯與現實有差異的

is the sign of a bad explanation,

就是一個不良的解釋

because, without a functional reason

因為，沒有一個合理的推理過程

to prefer one of countless variants,

在這些版本中，

advocating one of them in preference to the others

支持某一個理由，只因為它比其他的好

is irrational.

是不理性的。

So, for the essence of what makes the difference to enable progress,

因此，什麽舉動

能引起科學的大步進展

seek good explanations,

就是尋找一個好的解釋，

the ones that can't be easily varied,

這個解釋不是很容易就改變的，

while still explaining the phenomena.

在解釋各種現象的同時。

Now our current explanation of seasons

現在，我們當今對季節的解釋

is that the Earth's axis is tilted like that,

是地軸像這樣偏轉，

so each hemisphere tilts towards the sun for half the year,

兩個半球輪流在半年中傾斜面向太陽

and away for the other half.

並且輪流遠離太陽

[Not to scale!]

最好提一下。

Better put that up.

(Laughter)

（笑聲）

That's a good explanation:

這就是一個好的解釋：與現實相符，很難改變，

hard to vary,

because every detail plays a functional role.

因為每一個細節都扮演了有效的角色。

For instance, we know, independently of seasons,

比如，我們知道，季節分明，

that surfaces tilted away from radiant heat are heated less,

地球表面遠離

輻射熱導致熱量減少，

and that a spinning sphere, in space,

地球在空間中旋轉，

points in a constant direction.

向著不變的方向。

And the tilt also explains

而傾斜也能解釋

the sun's angle of elevation at different times of year,

爲什麽在同一年中太陽高度是不同的仰角

and predicts that the seasons will be out of phase in the two hemispheres.

這也預測了

兩個半球的季節會是不同的。

If they'd been observed in phase,

這種理論在當時看來，

the theory would have been refuted.

肯定是會被駁斥的。

But now, the fact that it's also a good explanation, hard to vary,

但是現在，事實就是很好的解釋，

很難推翻，與之前的解釋完全不同。

makes the crucial difference.

If the ancient Greeks had found out about seasons in Australia,

如果古希臘人發現

澳洲的季節與他們不同，

they could have easily varied their myth to predict that.

他們可以很簡單的修正他們的神話

去預測並解釋它。

For instance, when Demeter's upset,

比如，當迪米特傷心了，

she banishes heat from her vicinity into the other hemisphere,

她從附近釋放了熱

給另一個半球，這就形成了夏天。

where it makes summer.

So, being proved wrong by observation

即使，這些透過觀察都證明了是錯誤的，

and changing their theory accordingly

修正了他們的理論，

still wouldn't have got the ancient Greeks one jot closer to understanding seasons,

這也並不能讓古希臘人

完全明白季節，

because their explanation was bad -- easy to vary.

因為他們的解釋是不好的：太容易被現實情況推翻

And it's only when an explanation is good

只有那些可禁得起考驗的

that it even matters whether it's testable.

才是好的解釋

如果地軸傾斜理論被推翻了，

If the axis-tilt theory had been refuted,

its defenders would have had nowhere to go.

那些異議者不可能在理論上站的住腳

No easily implemented change

因為不可能有任何的改變

could make that tilt cause the same seasons in both hemispheres.

就能讓傾斜的地軸

導致同時在南北半球上有同樣的季節。

The search for hard-to-vary explanations is the origin of all progress.

追尋符合現實、難以憾動的解釋

就是所有進步的源頭。

It's the basic regulating principle of the Enlightenment.

這就是啟蒙運動

最基本的原則

So, in science, two false approaches blight progress.

所以，在科學領域，有兩個錯誤的方法將會抑制進步。

One's well-known: untestable theories.

一個大家都知道的是：無法驗證的理論。

But the more important one is explanationless theories.

但是另一個更重要的是：沒法解釋的理論。

Whenever you're told that some existing statistical trend will continue

每當你聽到一些現存的統計趨勢不斷持續，

but you aren't given a hard-to-vary account of what causes that trend,

但是他們並不能給你任何難以撼動的說法

解釋什麽因素導致了這些趨勢，

you're being told a wizard did it.

你就好像被人隨便虎爛

When you are told that carrots have human rights

當你被告知胡蘿蔔也享有人權

because they share half our genes,

因為他們與人共享一半的基因

but not how gene percentages confer rights -- wizard.

但這不是依照基因百分比授予的權利—而是瞎扯

When someone announces that the nature-nurture debate

當有些人聲稱天性與教養的辯論

has been settled

已經有了結果因為有證據表明

because there's evidence that a given percentage of our political opinions

我們個人的政治觀點是

來源於基因本身，

are genetically inherited,

but they don't explain how genes cause opinions,

但是他們沒有解釋基因怎麼影響觀點，

they've settled nothing.

他們什麽都沒解決。他們說：

They're saying that our opinions are caused by wizards,

我們的觀點來源於神秘的力量，

其實是他們自己瞎編的。

and presumably, so are their own.

(Laughter)

That the truth consists of hard-to-vary assertions about reality

真理其實就是

符合現實又難以撼動的解釋或理論

is the most important fact about the physical world.

這是最重要的事實

對於這個現實世界。

It's a fact that is itself unseen,

事實就是雖然看不見，

yet impossible to vary.

但是很難改變。謝謝。

Thank you.

(Applause)

(鼓掌)