David Deutsch: A new way to explain explanation

翻译人员: Miao Li 校对人员: Tony Yet

I'm sure that,

我十分确信在人类诞生以来

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

的大概10万多年

and even before,

甚至比这更长的时间里-

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

我们的祖先仰望夜空

想知道那些星星究竟是什么

wondering, therefore,

其实也就是想要

把他们看见的东西

how to explain what they saw

in terms of things unseen.

用不可见的东西来解释

这样的话，大多数人看似

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

只是偶尔如此想想，比如说像在今天

in breaks from whatever normally preoccupied them.

从日常活动中

抽空解脱出来的时候才行

But what normally preoccupied them also involved yearning to know.

但实际上人们的日常活动

同样富含着对知识的渴望

They wished they knew

人们希望知道

how to prevent their food supply from sometimes failing,

如何避免食物来源

不时的中断

and how they could rest when they were tired

如何在疲惫时得以充分休整

without risking starvation,

又不会因为停止劳作而断粮

be warmer, cooler, safer,

如何创造更温暖，或更凉爽；更安全的环境

in less pain.

如何减轻痛苦

I bet those prehistoric cave artists would have loved to know

我敢打赌远古时代的岩洞画家们

都想知道

how to draw better.

怎样画得更漂亮些

我们的祖先在生活的方方面面

(Laughter)

In every aspect of their lives,

they wished for progress, just as we do.

都像我们一样地期望进步

But they failed, almost completely, to make any.

但是他们得到的发展微乎其微

They didn't know how to.

他们还不懂其中的秘诀

Discoveries like fire happened so rarely

像人工生火这样的重大发明

凤毛麟角，于是乎从一个个人的角度看来

that, from an individual's point of view,

the world never improved.

世界几乎毫无改善

Nothing new was learned.

知识停滞不前

The first clue to the origin of starlight

星星闪光的奥秘初步被揭开

happened as recently as 1899:

是在不久前的1899年- 放射现象

radioactivity.

And within 40 years,

而这之后的仅仅40年间

physicists discovered the whole explanation,

物理学家们发现了一个完整的解释

expressed, as usual, in elegant symbols.

然后像往常一样用简明优雅的数学符号把它表示了出来

But never mind the symbols.

可别把这些符号不当回事

Think how many discoveries they represent.

想想它们表达了

多少人类的发现

Nuclei and nuclear reactions, of course.

这些么就是原子核 核反应

But isotopes,

再看看这些：同位素 带电粒子

particles of electricity,

antimatter,

反物质

neutrinos,

中微子

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

物质到能量的转化 E=mc^2

gamma rays,

伽马射线

transmutation.

嬗变（一种元素通过核反应转化为另一种元素）

That ancient dream that had always eluded the alchemists

那个古代炼金术师们为之枉费心机的梦想

was achieved through these same theories

现在由这些

that explained starlight and other ancient mysteries

解释了星光的实质

以及其他古代的谜团

and new, unexpected phenomena.

和意料之外新现象的理论变为现实

That all that, discovered in 40 years,

这40年中的所有发现

had not been in the previous hundred thousand

是数千年来所未有的

was not for lack of thinking

而这可不能归结为古人思维懒惰

about stars and all those other urgent problems they had.

对星星啊，还有那些迫切的问题不闻不问

他们不光思考了，还给出了答案

They even arrived at answers, such as myths,

比如说神话

that dominated their lives,

可虽说神话统治了古人的生活，包罗万象

yet bore almost no resemblance to the truth.

却与真正的现实

几乎搭不上边

The tragedy of that protracted stagnation

这种长期认知停滞所造成的悲哀

isn't sufficiently recognized, I think.

我觉得，并没有被古人足够重视

These were people with brains of essentially the same design

古人们的大脑

和我们的这些发现了种种新知识的大脑

that eventually did discover all those things.

实质上没有分别

But that ability to make progress

但是其中那个用来产生进步的潜力

remained almost unused,

始终几乎没有被利用

until the event that revolutionized the human condition

直到有一件事

彻底更新了人们的生活状态

改天换地

and changed the universe.

Or so we should hope,

至少我们希望情况是这样的

because that event was the scientific revolution,

这个大事件就是

科学革命

ever since which our knowledge of the physical world

从那以后我们对于

物质世界的认知

and of how to adapt it to our wishes

和对如何根据我们的意愿改造它的了解

has been growing relentlessly.

就一个劲地增长着

Now, what had changed?

现在想想，到底是发生了什么变化呢？

What were people now doing for the first time

当时人们

that made that difference between stagnation

究竟初次尝试了什么

就打破了僵局

and rapid, open-ended discovery?

开始了快速而无休无止的发现之旅？

How to make that difference

这一僵局的打破

is surely the most important universal truth

肯定是一个极为重要的广泛真理

that it's possible to know.

而我们是可以了解它的

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

让人担忧的是，对它究竟是怎么做到的人们众说纷纭

So, I'll tell you.

我这就来说说我的解释

(Laughter)

但先得稍稍回顾一下

But I'll have to backtrack a little first.

Before the scientific revolution,

在科学革命发生之前

they believed that everything important, knowable,

古人相信一切重要而可知的事物

was already known,

都已经被了解了

enshrined in ancient writings, institutions

这些知识被高高供起在古籍里，经院中

and in some genuinely useful rules of thumb --

还在日常生活的惯用窍门中被深信不疑

which were, however, entrenched as dogmas,

而这些窍门，和许多谬论一同

along with many falsehoods.

都成了根深蒂固的教条

So, they believed that knowledge came from authorities

那时人们相信知识来自权威

that actually knew very little.

这些权威其实知道的不多

And therefore,

所以知识的进步

progress depended on learning how to reject

取决于学会如何摈弃

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

学究

教士，传统习惯和统治者们的权威

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

这就是为什么科学革命

必须有一个大背景

the Enlightenment, a revolution in how people sought knowledge,

那就是启蒙运动

对于求知方法的一场革命

trying not to rely on authority.

试着摆脱对权威的依赖

"Take no one's word for it."

“切勿轻信人言”

But that can't be what made the difference.

可这还不够

Authorities had been rejected before, many times.

历史上摈弃权威的例子比比皆是

And that rarely, if ever,

而这些事件的结果却很难，或根本不能

与科学革命同日而语

caused anything like the scientific revolution.

At the time, what they thought distinguished science

在那个时候，启蒙学者们认为

科学的独特标志

was a radical idea about things unseen,

是一个关于不可见事物的激进看法

known as empiricism --

叫做经验主义

all knowledge derives from the senses.

认为所有的知识来自我们的感官

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

呵呵，我们知道这样说有些偏颇

It did help by promoting observation and experiment.

但经验主义成就了

科学观察与实验

But, from the outset,

然而乍一看之下，似乎很明显地

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

经验主义存在着可怕的漏洞

Knowledge comes from the senses?

“知识源自感官”

In what language?

那么感官得来的知识由什么语言承载呢？肯定不会是数学语言吧

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

可伽利略却有此精辟一语

the book of nature is written.

“自然之书乃数学著成”

Look at the world.

看看这世界，你看不到山崖上刻着方程式

You don't see equations carved on the mountainsides.

刻着方程式

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

就算碰巧看到了，那也是因为人们

刻上去的

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

顺便问一句，我们干嘛不这样做呢？

(Laughter)

What's wrong with us?

这不是有毛病嘛？

(Laughter)

（笑声）

Empiricism is inadequate

经验主义本身是不足的

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

这大概是因为

科学理论用不可见的来解释可见的

And the unseen, you have to admit,

而那些不可见的--你得承认--

doesn't come to us through the senses.

可不是从感官得来的

We don't see those nuclear reactions in stars.

我们可看不见恒星中的核反应

We don't see the origin of species.

看不见物种起源

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

还有时空弯曲

and other universes.

其他的平行宇宙

But we know about those things.

但我们知道这些

How?

我们是怎么做到的呢？

Well, the classic empiricist answer is induction --

经验主义的经典的答案是“归纳法”

the unseen resembles the seen.

认为不可见的与可见的相似

But it doesn't.

其实不然

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

你能找到一个决定性的反例

比如：时空是弯曲的这一事实

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

我们知道它的证据是一张照片，不是关于时空本身

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

而是拍摄的一次日食，上面有个小点在这儿而不在那儿

And the evidence for evolution?

至于物种起源的证据呢？

Some rocks and some finches.

一些岩石和雀类化石

And parallel universes?

平行宇宙的证据何在啊？又是屏幕上这儿有些点

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

而不是那儿

What we see in all these cases

这些事例中我们眼睛观察到的

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

和事实没有什么相似之处

--所以前面的“相似说”不成立--

只有一条长长的理论推导与解读的链条

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

把它们（观察现象与真理）连在一起

于是那些神创论者就说:“啊哈！”

"Ah!" say creationists.

"So you admit it's all interpretation.

“所以你承认这些科学理论都只是某种解读

No one's ever seen evolution.

没人知道答案是什么

We see rocks.

我们都看得见石头

You have your interpretation. We have ours.

你有你的理解，我们有我们的

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

你的理解来自理论猜测

我们的来自圣经。”

But what creationist and empiricists both ignore

可是有一点神创论者和经验主义者同时忽略了

is that, in that sense,

那就是，从先前的那种意义上看

no one's ever seen a Bible either,

没有人真正切实“观察”到一本圣经

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

眼睛只是探测到阳光，而我们无法有意识地感知它

Brains only detect nerve impulses.

大脑只侦测神经脉冲

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

但却无法感知它们究竟本身是什么

namely electrical crackles.

而它们其实是带电粒子“小爆破”

如此说来我们无法感知任何事物的现实究竟是什么

So we perceive nothing as what it really is.

Our connection to reality is never just perception.

而我们与现实的联系

从不会只是感知

It's always, as Karl Popper put it,

而是如卡尔·波普尔所说

theory-laden.

充满着理论假设

Scientific knowledge isn't derived from anything.

科学知识不是从什么直接推导而来

Like all knowledge, it's conjectural, guesswork,

而是像所有其他知识一样，是假设性的，一种推测

tested by observation,

由观察来检验

not derived from it.

却不从观察直接推导而来

So, were testable conjectures the great innovation

这么说来，是不是可以检验的假设

that opened the intellectual prison gates?

就是把人类放出认知牢笼的伟大发明呢？

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

不是。和人们常常所说的不同

可检验性其实不稀奇，就是

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

在神话和其他非理性的思维方式中都广泛存在

Any crank claiming the sun will go out next Tuesday

随便哪个家伙想说下周二太阳将要熄灭

has got a testable prediction.

他的假设都是可检验的

Consider the ancient Greek myth explaining seasons.

让我们想想一个古希腊的神话

是用来解释季节更替的

Hades, god of the underworld,

哈德斯，冥界之神

绑架了春之神普西芬妮

kidnaps Persephone, the goddess of spring,

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

又强迫她签下一纸婚书

只允许她每年定时回到地面，然后就放她走了

and lets her go.

And each year,

于是每一年

she is magically compelled to return.

她都被某种魔力带回冥界

And her mother, Demeter,

她的妈妈迪米特

goddess of the earth,

大地女神

is sad, and makes it cold and barren.

十分伤心，土地于是冻结荒芜

That myth is testable.

这则神话是可以检验的

If winter is caused by Demeter's sadness,

如果迪米特的哀伤导致了冬天

then it must happen everywhere on earth simultaneously.

那么它必须在地球上的所有地方同时发生

So if the ancient Greeks had only known

所以其实只要古希腊人知道澳大利亚

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

在迪米特最伤心时正经历着最热的天气

(Laughter)

they'd have known that their theory is false.

它们肯定知道自己的理论错了

(Laughter)

那么这则神话究竟错在哪儿呢？

So, what was wrong with that myth

and with all prescientific thinking?

科学到来前人们的思维有什么问题呢？

And what, then, made that momentous difference?

又是什么改变了这一切呢？

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

我觉得有一样东西我们得关注

它同时意味着

and that implies testability, the scientific method,

可验证性，科学方法

the Enlightenment and everything.

启蒙运动，还有前面说的一切

And here's the crucial thing:

我现在要说的就是那个万分重要的东西：

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

一个故事里可能出现缺陷

I don't just mean a logical defect.

我不是指逻辑缺陷，我是说坏解释的存在的

I mean a bad explanation.

What does that mean?

什么意思呢？所谓解释

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

是一个关于不可见物

that accounts for what's seen;

如何描述可见物的断言

because the explanatory role of Persephone's marriage contract

因为普西芬妮婚书

对季节的解释作用

could be played equally well

可以完好无损地

by infinitely many other ad hoc entities.

由无限多个其他

临时想出的事物来完成

Why a marriage contract and not any other reason

为什么是一纸婚书而不是其他什么原因

for regular annual action?

使普西芬妮定期往返呢？

Here's one: Persephone wasn't released.

我且来举个例子：普西芬妮并没有被放走

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

她逃走了，每年春天又回冥府

找哈德斯报仇

with her spring powers.

用她春天的神力

She cools his domain with spring air,

她让春风给冥界降温

venting heat up to the surface, creating summer.

热气排到地上，成了夏天

That accounts for the same phenomena as the original myth.

这个说法和先前的神话能解释同样的现象

It's equally testable.

而且同样可以检验

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

可是它对现实的描述，断言

却和刚才的在许多方面正好相反

And that's possible

这看似矛盾的情况之所以存在

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

是因为原先那个神话的诸多细节™

除了在这则神话的背景中外

except via the myth itself.

与季节都没有什么联系

This easy variability

这种很随意的可变性

is the sign of a bad explanation,

正是坏解释的标志

because, without a functional reason

因为当没有什么关于细节的解释作用的理由能使我们选择

to prefer one of countless variants,

千万种可能解释中的一个

advocating one of them in preference to the others

唯独支持这一个而抛弃其他

is irrational.

便是不理性的

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

所以，产生变革

推进发展的本质原因

seek good explanations,

就是追求好解释

the ones that can't be easily varied,

那些为了保证解释现象的能力

while still explaining the phenomena.

而不能被轻易改变的解释

Now our current explanation of seasons

我们现在对季节的解释

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

是说地球的转轴像这样倾斜着

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

所以每个半球在半年中倾向太阳

and away for the other half.

另外半年远离阳光

[Not to scale!]

最好放出来看看

Better put that up.

(Laughter)

（笑声）

That's a good explanation:

这就是个好解释：很难改动

hard to vary,

because every detail plays a functional role.

因为每一个细节都对有至关重要的解释作用

For instance, we know, independently of seasons,

比如说，我们不用明白季节就知道

that surfaces tilted away from radiant heat are heated less,

背向发光物体的表面

受热的程度较小

and that a spinning sphere, in space,

空间中自转的这个球体

points in a constant direction.

指向同一个方向

And the tilt also explains

地轴的倾斜也解释了

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

太阳在一年中不同的仰角

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

并预测两半球的季节情况

正好相反

If they'd been observed in phase,

如果观察显示它们相同

the theory would have been refuted.

理论就被驳倒了

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

可是它作为一个好解释

一个难以更改的解释，这一点才是最重要的区别

makes the crucial difference.

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

如果古希腊人得知了

澳洲季节的更替

they could have easily varied their myth to predict that.

他们很容易就能修改这个神话

然后预测说，

For instance, when Demeter's upset,

比如，当迪米特为女儿忧愁时

she banishes heat from her vicinity into the other hemisphere,

她把热气从四周驱赶出去

赶到另一个半球，形成夏天

where it makes summer.

So, being proved wrong by observation

这样看来，尽管被观察所否决

and changing their theory accordingly

并被迫据此修改他们的理论

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

古希腊人并没有

离对季节的理解进了那怕一步

because their explanation was bad -- easy to vary.

因为改过的解释仍旧是坏解释：它太易变了

And it's only when an explanation is good

而只有当好解释存在

that it even matters whether it's testable.

它是否可以验证才值得考虑

倘若“地轴倾斜”理论被观察否定了

If the axis-tilt theory had been refuted,

its defenders would have had nowhere to go.

它的支持者们就无路可退了

No easily implemented change

没有什么信手拈来的变动

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

能让地轴的倾斜

在两个半球产生相同的季节

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

对难以修改的解释的探寻

是所有进步之源

It's the basic regulating principle of the Enlightenment.

这是启蒙运动的

基本纲领

So, in science, two false approaches blight progress.

在科学领域，有两种错误阻碍进步

One's well-known: untestable theories.

第一种众所周知:无法验证的空头理论

But the more important one is explanationless theories.

但更重要的却是不带解释的理论

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

每当别人告诉你某个统计数据趋势将会延续下去

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

而又不给你一个难以改动的好解释

告诉你这趋势为什么存在

you're being told a wizard did it.

他几乎就是在说某个大仙做了个法就成这样了

When you are told that carrots have human rights

当别人说胡萝卜也是有人权的

because they share half our genes,

因为我们有一半基因胡萝卜也有

but not how gene percentages confer rights -- wizard.

却不说明相同基因的比重怎么引出人权--大仙又来了

When someone announces that the nature-nurture debate

当有人宣布认知论中经久不息的“先天-后天”大辩论

has been settled

已经解决了，因为有证据说明

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

某个百分比的

政治主张是先天遗传的

are genetically inherited,

but they don't explain how genes cause opinions,

但他们却不解释基因怎么导致某些意见

they've settled nothing.

它们就什么也没解决。他们只是说

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

我们的主张是变来的

估计他们自己的也是变来的

and presumably, so are their own.

(Laughter)

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

真理体现在

对现实提出的无法轻易改动的论断

is the most important fact about the physical world.

这是物质世界中

最重要的一个事实

It's a fact that is itself unseen,

这一事实本身其实也是看不见的

yet impossible to vary.

但却不可能被东改西改。谢谢大家。

Thank you.

(Applause)

（掌声）