TEDGlobal 2009
David Deutsch: A new way to explain explanation
大卫·多伊奇：科学解释之新探
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上古的数万年间我们的祖先通过神话来理解世界，他们认知的发展十分缓慢，而科学认知的兴起仅用几个世纪就在世界上产生了翻天覆地的变革。欲知其因，请看物理学家大卫·多伊奇的精妙分析
David Deutsch - Quantum physicist
David Deutsch's 1997 book "The Fabric of Reality" laid the groundwork for an all-encompassing Theory of Everything, and galvanized interest in the idea of a quantum computer, which could solve problems of hitherto unimaginable complexity. Full bio
David Deutsch's 1997 book "The Fabric of Reality" laid the groundwork for an all-encompassing Theory of Everything, and galvanized interest in the idea of a quantum computer, which could solve problems of hitherto unimaginable complexity. Full bio
Double-click the English transcript below to play the video.
00:18
I'm sure that, throughout the hundred-thousand-odd years
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我十分确信在人类诞生以来
00:23
of our species' existence,
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的大概10万多年
00:26
and even before,
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甚至比这更长的时间里-
00:29
our ancestors looked up at the night sky,
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我们的祖先仰望夜空
00:31
and wondered what stars are.
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想知道那些星星究竟是什么
00:34
Wondering, therefore,
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其实也就是想要
00:36
how to explain what they saw
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把他们看见的东西
00:40
in terms of things unseen.
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用不可见的东西来解释
00:45
Okay, so, most people
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这样的话，大多数人看似
00:49
only wondered that occasionally, like today,
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只是偶尔如此想想，比如说像在今天
00:52
in breaks from whatever
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从日常活动中
00:54
normally preoccupied them.
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抽空解脱出来的时候才行
00:56
But what normally preoccupied them
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但实际上人们的日常活动
01:00
also involved yearning to know.
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同样富含着对知识的渴望
01:03
They wished they knew
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人们希望知道
01:06
how to prevent their food supply
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如何避免食物来源
01:08
from sometimes failing,
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不时的中断
01:10
and how they could rest when they were tired
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如何在疲惫时得以充分休整
01:13
without risking starvation,
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又不会因为停止劳作而断粮
01:17
be warmer, cooler, safer,
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如何创造更温暖，或更凉爽；更安全的环境
01:21
in less pain.
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如何减轻痛苦
01:23
I bet those prehistoric cave artists
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我敢打赌远古时代的岩洞画家们
01:26
would have loved to know
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都想知道
01:28
how to draw better.
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怎样画得更漂亮些
01:30
In every aspect of their lives,
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我们的祖先在生活的方方面面
01:35
they wished for progress, just as we do.
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都像我们一样地期望进步
01:40
But they failed, almost completely, to make any.
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但是他们得到的发展微乎其微
01:46
They didn't know how to.
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他们还不懂其中的秘诀
01:49
Discoveries like fire
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像人工生火这样的重大发明
01:53
happened so rarely, that from an individual's point of view,
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凤毛麟角，于是乎从一个个人的角度看来
01:57
the world never improved.
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世界几乎毫无改善
02:00
Nothing new was learned.
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知识停滞不前
02:04
The first clue to the origin of starlight
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星星闪光的奥秘初步被揭开
02:07
happened as recently as 1899: radioactivity.
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是在不久前的1899年- 放射现象
02:14
Within 40 years,
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而这之后的仅仅40年间
02:16
physicists discovered the whole explanation,
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物理学家们发现了一个完整的解释
02:20
expressed, as usual, in elegant symbols.
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然后像往常一样用简明优雅的数学符号把它表示了出来
02:25
But never mind the symbols.
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可别把这些符号不当回事
02:27
Think how many discoveries
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想想它们表达了
02:31
they represent.
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多少人类的发现
02:33
Nuclei and nuclear reactions, of course.
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这些么就是原子核 核反应
02:36
But isotopes, particles of electricity,
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再看看这些：同位素 带电粒子
02:43
antimatter,
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反物质
02:47
neutrinos,
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中微子
02:49
the conversion of mass to energy -- that's E=mc^2 --
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物质到能量的转化 E=mc^2
02:53
gamma rays,
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伽马射线
02:55
transmutation.
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嬗变（一种元素通过核反应转化为另一种元素）
02:59
That ancient dream that had always eluded the alchemists
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那个古代炼金术师们为之枉费心机的梦想
03:04
was achieved through these same theories
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现在由这些
03:06
that explained starlight
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解释了星光的实质
03:08
and other ancient mysteries,
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以及其他古代的谜团
03:11
and new, unexpected phenomena.
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和意料之外新现象的理论变为现实
03:14
That all that, discovered in 40 years,
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这40年中的所有发现
03:18
had not been in the previous hundred thousand,
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是数千年来所未有的
03:21
was not for lack of thinking
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而这可不能归结为古人思维懒惰
03:25
about stars, and all those other urgent problems they had.
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对星星啊，还有那些迫切的问题不闻不问
03:29
They even arrived at answers,
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他们不光思考了，还给出了答案
03:32
such as myths,
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比如说神话
03:34
that dominated their lives,
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可虽说神话统治了古人的生活，包罗万象
03:36
yet bore almost no resemblance
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却与真正的现实
03:40
to the truth.
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几乎搭不上边
03:42
The tragedy of that protracted stagnation
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这种长期认知停滞所造成的悲哀
03:47
isn't sufficiently recognized, I think.
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我觉得，并没有被古人足够重视
03:49
These were people with brains of
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古人们的大脑
03:51
essentially the same design
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和我们的这些发现了种种新知识的大脑
03:54
that eventually did discover all those things.
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实质上没有分别
03:59
But that ability to make progress
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但是其中那个用来产生进步的潜力
04:03
remained almost unused,
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始终几乎没有被利用
04:06
until the event that
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直到有一件事
04:09
revolutionized the human condition
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彻底更新了人们的生活状态
04:11
and changed the universe.
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改天换地
04:13
Or so we should hope.
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至少我们希望情况是这样的
04:15
Because that event was the
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这个大事件就是
04:17
Scientific Revolution,
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科学革命
04:19
ever since which our knowledge
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从那以后我们对于
04:21
of the physical world,
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物质世界的认知
04:23
and of how to adapt it to our wishes,
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和对如何根据我们的意愿改造它的了解
04:27
has been growing relentlessly.
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就一个劲地增长着
04:29
Now, what had changed?
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现在想想，到底是发生了什么变化呢？
04:32
What were people now doing for the first time
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当时人们
04:34
that made that difference
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究竟初次尝试了什么
04:36
between stagnation
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就打破了僵局
04:38
and rapid, open-ended discovery?
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开始了快速而无休无止的发现之旅？
04:42
How to make that difference
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这一僵局的打破
04:44
is surely the most important universal truth
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肯定是一个极为重要的广泛真理
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that it is possible to know.
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而我们是可以了解它的
04:50
Worryingly, there is no consensus about what it is.
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让人担忧的是，对它究竟是怎么做到的人们众说纷纭
04:55
So, I'll tell you.
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我这就来说说我的解释
04:57
But I'll have to backtrack a little first.
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但先得稍稍回顾一下
05:01
Before the Scientific Revolution,
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在科学革命发生之前
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they believed that everything important, knowable,
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古人相信一切重要而可知的事物
05:07
was already known,
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都已经被了解了
05:09
enshrined in ancient writings, institutions,
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这些知识被高高供起在古籍里，经院中
05:12
and in some genuinely useful rules of thumb --
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还在日常生活的惯用窍门中被深信不疑
05:15
which were, however, entrenched as dogmas,
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而这些窍门，和许多谬论一同
05:19
along with many falsehoods.
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都成了根深蒂固的教条
05:21
So they believed that knowledge came from authorities
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那时人们相信知识来自权威
05:25
that actually knew very little.
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这些权威其实知道的不多
05:28
And therefore progress
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所以知识的进步
05:31
depended on learning how to reject
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取决于学会如何摈弃
05:34
the authority of learned men,
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学究
05:37
priests, traditions and rulers.
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教士，传统习惯和统治者们的权威
05:41
Which is why the Scientific Revolution
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这就是为什么科学革命
05:44
had to have a wider context.
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必须有一个大背景
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The Enlightenment, a revolution in how
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那就是启蒙运动
05:50
people sought knowledge,
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对于求知方法的一场革命
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trying not to rely on authority.
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试着摆脱对权威的依赖
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"Take no one's word for it."
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“切勿轻信人言”
05:58
But that can't be what made the difference.
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可这还不够
06:02
Authorities had been rejected before, many times.
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历史上摈弃权威的例子比比皆是
06:04
And that rarely, if ever,
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而这些事件的结果却很难，或根本不能
06:06
caused anything like the Scientific Revolution.
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与科学革命同日而语
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At the time, what they thought
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在那个时候，启蒙学者们认为
06:12
distinguished science
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科学的独特标志
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was a radical idea about things unseen,
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是一个关于不可见事物的激进看法
06:18
known as empiricism.
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叫做经验主义
06:21
All knowledge derives from the senses.
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认为所有的知识来自我们的感官
06:26
Well, we've seen that that can't be true.
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呵呵，我们知道这样说有些偏颇
06:29
It did help by promoting
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但经验主义成就了
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observation and experiment.
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科学观察与实验
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But, from the outset, it was obvious
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然而乍一看之下，似乎很明显地
06:37
that there was something horribly wrong with it.
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经验主义存在着可怕的漏洞
06:40
Knowledge comes from the senses.
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“知识源自感官”
06:42
In what language? Certainly not the language of mathematics,
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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
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in which, Galileo rightly said,
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可伽利略却有此精辟一语
06:48
the book of nature is written.
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“自然之书乃数学著成”
06:51
Look at the world. You don't see equations
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看看这世界，你看不到山崖上刻着方程式
06:54
carved on to the mountainsides.
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刻着方程式
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If you did, it would be because people
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就算碰巧看到了，那也是因为人们
06:59
had carved them.
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刻上去的
07:01
By the way, why don't we do that?
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顺便问一句，我们干嘛不这样做呢？
07:04
What's wrong with us?
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这不是有毛病嘛？
07:06
(Laughter)
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（笑声）
07:07
Empiricism is inadequate
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经验主义本身是不足的
07:09
because, well,
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这大概是因为
07:11
scientific theories explain the seen in terms of the unseen.
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科学理论用不可见的来解释可见的
07:16
And the unseen, you have to admit,
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而那些不可见的--你得承认--
07:18
doesn't come to us through the senses.
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可不是从感官得来的
07:20
We don't see those nuclear reactions in stars.
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我们可看不见恒星中的核反应
07:24
We don't see the origin of species.
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看不见物种起源
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We don't see the curvature of space-time,
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还有时空弯曲
07:31
and other universes.
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其他的平行宇宙
07:33
But we know about those things.
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但我们知道这些
07:36
How?
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我们是怎么做到的呢？
07:38
Well, the classic empiricist answer is induction.
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经验主义的经典的答案是“归纳法”
07:43
The unseen resembles the seen.
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认为不可见的与可见的相似
07:47
But it doesn't.
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其实不然
07:49
You know what the clinching evidence was
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你能找到一个决定性的反例
07:51
that space-time is curved?
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比如：时空是弯曲的这一事实
07:54
It was a photograph, not of space-time,
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我们知道它的证据是一张照片，不是关于时空本身
07:57
but of an eclipse, with a dot there rather than there.
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而是拍摄的一次日食，上面有个小点在这儿而不在那儿
08:01
And the evidence for evolution?
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至于物种起源的证据呢？
08:03
Some rocks and some finches.
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一些岩石和雀类化石
08:06
And parallel universes? Again: dots there,
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平行宇宙的证据何在啊？又是屏幕上这儿有些点
08:09
rather than there, on a screen.
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而不是那儿
08:11
What we see, in all these cases,
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这些事例中我们眼睛观察到的
08:14
bears no resemblance to the reality
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和事实没有什么相似之处
08:18
that we conclude is responsible --
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--所以前面的“相似说”不成立--
08:20
only a long chain of theoretical reasoning
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只有一条长长的理论推导与解读的链条
08:24
and interpretation connects them.
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把它们（观察现象与真理）连在一起
08:26
"Ah!" say creationists.
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于是那些神创论者就说:“啊哈！”
08:29
"So you admit it's all interpretation.
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“所以你承认这些科学理论都只是某种解读
08:31
No one has ever seen evolution.
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没人知道答案是什么
08:34
We see rocks.
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我们都看得见石头
08:36
You have your interpretation. We have ours.
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你有你的理解，我们有我们的
08:39
Yours comes from guesswork,
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你的理解来自理论猜测
08:41
ours from the Bible."
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我们的来自圣经。”
08:43
But what creationist and empiricists both ignore
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可是有一点神创论者和经验主义者同时忽略了
08:49
is that, in that sense,
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那就是，从先前的那种意义上看
08:51
no one has ever seen a bible either,
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没有人真正切实“观察”到一本圣经
08:54
that the eye only detects light, which we don't perceive.
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眼睛只是探测到阳光，而我们无法有意识地感知它
08:58
Brains only detect nerve impulses.
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大脑只侦测神经脉冲
09:01
And they don't perceive even those as what they really are,
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但却无法感知它们究竟本身是什么
09:04
namely electrical crackles.
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而它们其实是带电粒子“小爆破”
09:06
So we perceive nothing as what it really is.
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如此说来我们无法感知任何事物的现实究竟是什么
09:11
Our connection to reality
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而我们与现实的联系
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is never just perception.
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从不会只是感知
09:16
It's always, as Karl Popper put it,
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而是如卡尔·波普尔所说
09:20
theory-laden.
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充满着理论假设
09:23
Scientific knowledge isn't derived from anything.
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科学知识不是从什么直接推导而来
09:26
It's like all knowledge. It's conjectural, guesswork,
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而是像所有其他知识一样，是假设性的，一种推测
09:31
tested by observation,
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由观察来检验
09:33
not derived from it.
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却不从观察直接推导而来
09:37
So, were testable conjectures
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这么说来，是不是可以检验的假设
09:40
the great innovation that opened the intellectual prison gates?
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就是把人类放出认知牢笼的伟大发明呢？
09:44
No. Contrary to what's usually said,
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不是。和人们常常所说的不同
09:47
testability is common,
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可检验性其实不稀奇，就是
09:49
in myths and all sorts of other irrational modes of thinking.
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在神话和其他非理性的思维方式中都广泛存在
09:53
Any crank claiming the sun will go out next Tuesday
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随便哪个家伙想说下周二太阳将要熄灭
09:57
has got a testable prediction.
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他的假设都是可检验的
10:00
Consider the ancient Greek myth
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让我们想想一个古希腊的神话
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explaining seasons.
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是用来解释季节更替的
10:06
Hades, God of the Underworld,
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哈德斯，冥界之神
10:08
kidnaps Persephone, the Goddess of Spring,
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绑架了春之神普西芬妮
10:11
and negotiates a forced marriage contract,
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又强迫她签下一纸婚书
10:14
requiring her to return regularly, and lets her go.
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只允许她每年定时回到地面，然后就放她走了
10:18
And each year,
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于是每一年
10:20
she is magically compelled to return.
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她都被某种魔力带回冥界
10:23
And her mother, Demeter,
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她的妈妈迪米特
10:25
Goddess of the Earth,
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大地女神
10:27
is sad, and makes it cold and barren.
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十分伤心，土地于是冻结荒芜
10:32
That myth is testable.
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这则神话是可以检验的
10:35
If winter is caused by Demeter's sadness,
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如果迪米特的哀伤导致了冬天
10:39
then it must happen everywhere on Earth simultaneously.
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那么它必须在地球上的所有地方同时发生
10:43
So if the ancient Greeks had only known that Australia
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所以其实只要古希腊人知道澳大利亚
10:46
is at its warmest when Demeter is at her saddest,
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在迪米特最伤心时正经历着最热的天气
10:50
they'd have known that their theory is false.
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它们肯定知道自己的理论错了
10:53
So what was wrong with that myth,
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那么这则神话究竟错在哪儿呢？
10:56
and with all pre-scientific thinking,
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科学到来前人们的思维有什么问题呢？
10:59
and what, then, made that momentous difference?
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又是什么改变了这一切呢？
11:04
I think there is one thing you have to care about.
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我觉得有一样东西我们得关注
11:08
And that implies
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它同时意味着
11:10
testability, the scientific method,
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可验证性，科学方法
11:13
the Enlightenment, and everything.
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启蒙运动，还有前面说的一切
11:15
And here is the crucial thing.
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我现在要说的就是那个万分重要的东西：
11:17
There is such a thing as a defect in a story.
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一个故事里可能出现缺陷
11:20
I don't just mean a logical defect. I mean a bad explanation.
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我不是指逻辑缺陷，我是说坏解释的存在的
11:25
What does that mean? Well, explanation
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什么意思呢？所谓解释
11:28
is an assertion about what's there, unseen,
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是一个关于不可见物
11:31
that accounts for what's seen.
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如何描述可见物的断言
11:34
Because the explanatory role
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因为普西芬妮婚书
11:37
of Persephone's marriage contract
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对季节的解释作用
11:39
could be played equally well
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可以完好无损地
11:41
by infinitely many other
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由无限多个其他
11:43
ad hoc entities.
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临时想出的事物来完成
11:45
Why a marriage contract and not any other reason
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为什么是一纸婚书而不是其他什么原因
11:48
for regular annual action?
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使普西芬妮定期往返呢？
11:52
Here is one. Persephone wasn't released.
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我且来举个例子：普西芬妮并没有被放走
11:55
She escaped, and returns every spring
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她逃走了，每年春天又回冥府
11:59
to take revenge on Hades,
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找哈德斯报仇
12:01
with her Spring powers.
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用她春天的神力
12:03
She cools his domain with Spring air,
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她让春风给冥界降温
12:08
venting heat up to the surface, creating summer.
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热气排到地上，成了夏天
12:12
That accounts for the same phenomena as the original myth.
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这个说法和先前的神话能解释同样的现象
12:16
It's equally testable.
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而且同样可以检验
12:19
Yet what it asserts about reality
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可是它对现实的描述，断言
12:22
is, in many ways, the opposite.
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却和刚才的在许多方面正好相反
12:24
And that is possible because
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这看似矛盾的情况之所以存在
12:26
the details of the original myth
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是因为原先那个神话的诸多细节™
12:29
are unrelated to seasons,
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除了在这则神话的背景中外
12:31
except via the myth itself.
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与季节都没有什么联系
12:35
This easy variability
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这种很随意的可变性
12:38
is the sign of a bad explanation,
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正是坏解释的标志
12:42
because, without a functional reason to prefer
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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
12:46
one of countless variants,
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千万种可能解释中的一个
12:51
advocating one of them, in preference to the others,
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唯独支持这一个而抛弃其他
12:53
is irrational.
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便是不理性的
12:55
So, for the essence of what
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所以，产生变革
12:57
makes the difference to enable progress,
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推进发展的本质原因
13:00
seek good explanations,
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就是追求好解释
13:02
the ones that can't be easily varied,
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那些为了保证解释现象的能力
13:05
while still explaining the phenomena.
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而不能被轻易改变的解释
13:10
Now, our current explanation of seasons
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我们现在对季节的解释
13:13
is that the Earth's axis is tilted like that,
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是说地球的转轴像这样倾斜着
13:17
so each hemisphere tilts toward the sun for half the year,
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所以每个半球在半年中倾向太阳
13:20
and away for the other half.
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另外半年远离阳光
13:23
Better put that up.
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最好放出来看看
13:25
(Laughter)
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（笑声）
13:26
That's a good explanation: hard to vary,
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这就是个好解释：很难改动
13:31
because every detail plays a functional role.
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因为每一个细节都对有至关重要的解释作用
13:34
For instance, we know, independently of seasons,
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比如说，我们不用明白季节就知道
13:37
that surfaces tilted away
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背向发光物体的表面
13:39
from radiant heat are heated less,
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受热的程度较小
13:42
and that a spinning sphere, in space,
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空间中自转的这个球体
13:45
points in a constant direction.
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指向同一个方向
13:48
And the tilt also explains
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地轴的倾斜也解释了
13:51
the sun's angle of elevation at different times of year,
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太阳在一年中不同的仰角
13:55
and predicts that the seasons
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并预测两半球的季节情况
13:57
will be out of phase in the two hemispheres.
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正好相反
14:00
If they'd been observed in phase,
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如果观察显示它们相同
14:02
the theory would have been refuted.
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理论就被驳倒了
14:04
But now, the fact that it's also a good explanation,
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可是它作为一个好解释
14:09
hard to vary, makes the crucial difference.
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一个难以更改的解释，这一点才是最重要的区别
14:14
If the ancient Greeks had found out
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如果古希腊人得知了
14:16
about seasons in Australia,
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澳洲季节的更替
14:19
they could have easily varied their myth
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他们很容易就能修改这个神话
14:21
to predict that.
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然后预测说，
14:23
For instance, when Demeter is upset,
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比如，当迪米特为女儿忧愁时
14:25
she banishes heat from her vicinity,
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她把热气从四周驱赶出去
14:28
into the other hemisphere, where it makes summer.
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赶到另一个半球，形成夏天
14:31
So, being proved wrong by observation,
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这样看来，尽管被观察所否决
14:34
and changing their theory accordingly,
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并被迫据此修改他们的理论
14:36
still wouldn't have got the ancient Greeks
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古希腊人并没有
14:39
one jot closer to understanding seasons,
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离对季节的理解进了那怕一步
14:42
because their explanation was bad: easy to vary.
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因为改过的解释仍旧是坏解释：它太易变了
14:45
And it's only when an explanation is good
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而只有当好解释存在
14:48
that it even matters whether it's testable.
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它是否可以验证才值得考虑
14:50
If the axis-tilt theory had been refuted,
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倘若“地轴倾斜”理论被观察否定了
14:53
its defenders would have had nowhere to go.
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它的支持者们就无路可退了
14:55
No easily implemented change
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没有什么信手拈来的变动
14:58
could make that tilt
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能让地轴的倾斜
15:00
cause the same seasons in both hemispheres.
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在两个半球产生相同的季节
15:05
The search for hard-to-vary explanations
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对难以修改的解释的探寻
15:08
is the origin of all progress.
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是所有进步之源
15:11
It's the basic regulating principle
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这是启蒙运动的
15:14
of the Enlightenment.
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基本纲领
15:16
So, in science, two false approaches blight progress.
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在科学领域，有两种错误阻碍进步
15:20
One is well known: untestable theories.
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第一种众所周知:无法验证的空头理论
15:23
But the more important one is explanationless theories.
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但更重要的却是不带解释的理论
15:27
Whenever you're told that some existing statistical trend will continue,
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每当别人告诉你某个统计数据趋势将会延续下去
15:31
but you aren't given a hard-to-vary account
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而又不给你一个难以改动的好解释
15:34
of what causes that trend,
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告诉你这趋势为什么存在
15:37
you're being told a wizard did it.
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他几乎就是在说某个大仙做了个法就成这样了
15:39
When you are told that carrots have human rights
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当别人说胡萝卜也是有人权的
15:42
because they share half our genes --
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因为我们有一半基因胡萝卜也有
15:44
but not how gene percentages confer rights -- wizard.
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却不说明相同基因的比重怎么引出人权--大仙又来了
15:50
When someone announces that the nature-nurture debate
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当有人宣布认知论中经久不息的“先天-后天”大辩论
15:54
has been settled because there is evidence
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已经解决了，因为有证据说明
15:56
that a given percentage of our
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某个百分比的
15:58
political opinions are genetically inherited,
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政治主张是先天遗传的
16:02
but they don't explain how genes cause opinions,
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但他们却不解释基因怎么导致某些意见
16:06
they've settled nothing. They are saying that our
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它们就什么也没解决。他们只是说
16:08
opinions are caused by wizards,
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我们的主张是变来的
16:10
and presumably so are their own.
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估计他们自己的也是变来的
16:13
That the truth consists of
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真理体现在
16:16
hard to vary assertions about reality
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对现实提出的无法轻易改动的论断
16:20
is the most important fact
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这是物质世界中
16:23
about the physical world.
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最重要的一个事实
16:25
It's a fact that is, itself, unseen,
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这一事实本身其实也是看不见的
16:28
yet impossible to vary. Thank you.
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但却不可能被东改西改。谢谢大家。
16:32
(Applause)
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（掌声）
ABOUT THE SPEAKER
David Deutsch - Quantum physicistDavid Deutsch's 1997 book "The Fabric of Reality" laid the groundwork for an all-encompassing Theory of Everything, and galvanized interest in the idea of a quantum computer, which could solve problems of hitherto unimaginable complexity.
Why you should listen
David Deutsch will force you to reconsider your place in the world. This legendary Oxford physicist is the leading proponent of the multiverse (or "many worlds") interpretation of quantum theory -- the idea that our universe is constantly spawning countless numbers of parallel worlds.
In his own words: "Everything in our universe -- including you and me, every atom and every galaxy -- has counterparts in these other universes." If that doesn't alter your consciousness, then the other implications he's derived from his study of subatomic physics -- including the possibility of time travel -- just might.
In The Fabric of Reality, Deutsch tied together quantum mechanics, evolution, a rationalist approach to knowledge, and a theory of computation based on the work of Alan Turing. "Our best theories are not only truer than common sense, they make more sense than common sense,"Deutsch wrote, and he continues to explore the most mind-bending aspects of particle physics.
In 2008, he became a member of the Royal Society of London.
David Deutsch | Speaker | TED.com