PHILOSOPHY - Epistemology: The Problem of Skepticism [HD]
Summary
TLDR本视频由多伦多大学哲学教授Jennifer Nagel主讲,探讨了怀疑论问题。她通过提出人们可能正在做梦的疑问,引导观众思考我们如何确定自己的认知是真实的。视频介绍了古希腊的两种怀疑传统:学院派和皮浪派,以及它们对感官印象和知识可能性的不同看法。接着,Nagel教授通过梦境、邪恶天才和缸中之脑等思想实验,展示了怀疑论如何挑战我们对知识的理解。视频最后提出,尽管怀疑论是一个古老而复杂的问题,但哲学家们已经提出了多种应对策略来捍卫人类知识的可能性。
Takeaways
- 🤔 怀疑论的问题:我们能否确定自己所知的一切,例如现在是否在看视频而非在梦中?
- 📚 怀疑论的起源:古希腊的学术怀疑论和皮浪怀疑论,前者认为感官印象不能作为知识的基础,后者则不断质疑一切而不得出结论。
- 🎙️ 声音的怀疑:即使听到声音,也可能是错觉或梦境,我们无法确定声音的来源。
- 🧐 怀疑论的挑战:怀疑论者质疑人类对世界的知识,认为感官印象可能误导我们。
- 🦋 庄子梦蝶:中国古代哲学家庄子的梦蝶故事,提出了关于现实与梦境的哲学问题。
- 📐 笛卡尔的怀疑:即使在梦中,我们是否能确定数学和几何的真理?笛卡尔提出了“邪恶天才”的假设来质疑一切知识。
- 🧠 大脑在缸中的假设:现代版的笛卡尔邪恶天才假设,提出大脑可能被超级计算机模拟现实,我们无法证明我们不是这样的大脑。
- 👁️ 感官的局限性:即使是在“好情况”下,我们的感官体验也可能与“坏情况”下的体验无法区分,这让我们无法确定我们的知识。
- ⏱️ 局部怀疑论:怀疑论可以针对特定知识领域,例如对过去知识或特定事实的怀疑。
- 🕰️ 时钟的例子:即使是看似简单的事实,如时间,也可能因为怀疑而变得不确定。
- 🛡️ 知识的可能性:尽管怀疑论提出了挑战,哲学家们提出了不同的解决方案来捍卫人类知识的可能性。
Q & A
什么是怀疑论问题?
-怀疑论问题是关于我们能否确定自己所知道的事物的哲学问题。它质疑我们是否能够确信自己的认知,例如,我们是否能够确定自己不是在梦中观看视频。
为什么我们可能会怀疑自己是否在观看一个真实的视频?
-我们可能会怀疑自己是否在观看一个真实的视频,因为有可能我们实际上是在梦中,或者是被某种超能力控制,使我们的感官印象被欺骗。
什么是学院派怀疑论和皮浪怀疑论?
-学院派怀疑论认为感官印象不能作为世界知识的基础,而皮浪怀疑论则进一步,主张持续质疑一切,不达成任何结论,甚至对知识是否可能都保持怀疑。
为什么说感官印象可能是误导的?
-感官印象可能是误导的,因为它们可能受到各种因素的影响,如记忆错误、梦境或幻觉,这使得我们无法仅凭感官印象来确定知识。
笛卡尔是如何提出怀疑论的?
-笛卡尔通过提出‘邪恶天才’的假设来提出怀疑论,即想象有一个极其强大且狡猾的邪恶天才,控制了我们所有的感官印象和数学、几何等本能,使我们无法确定自己所知的任何事物是否真实。
笛卡尔认为我们能否知道数学和几何的真理?
-笛卡尔认为,即使在梦境中,我们也应该能够知道一个正方形有四条边,或者2加3等于5。但他也提出了怀疑,质疑我们的感觉是否必然是真实的。
什么是‘缸中之脑’思想实验?
-‘缸中之脑’是一个思想实验,假设一个大脑被保存在缸中,并通过超级计算机接收感官信号,模拟一个连贯的现实体验。这个实验质疑我们如何证明自己不是这样的大脑。
为什么说‘缸中之脑’实验是一个强大的怀疑论论点?
-‘缸中之脑’实验是一个强大的怀疑论论点,因为它提出了一个我们无法通过感官经验来区分真实世界和虚拟世界的情况,从而质疑我们对现实世界的认知。
怀疑论是否总是针对所有知识?
-怀疑论不一定要针对所有知识,它也可以是局部的,只针对特定范围的知识,例如对过去知识或单个事实的怀疑。
如何回应怀疑论的挑战?
-哲学家们提出了多种回应怀疑论挑战的方法,包括但不限于理性主义、经验主义和实用主义等,旨在捍卫人类知识的可能性。
为什么说怀疑论是一个古老而困难的问题?
-怀疑论是一个古老而困难的问题,因为它挑战了我们对知识的基本理解,迫使我们重新考虑我们的认知过程和知识的本质。
Outlines
🤔 怀疑论问题的提出
Jennifer Nagel教授在多伦多大学教授哲学,她在这一段视频中提出了怀疑论的问题。她首先询问观众他们确信自己知道什么,然后引导观众思考是否能够确定自己不是在梦中观看视频。她介绍了怀疑论的两种传统:学术怀疑论和皮浪怀疑论,分别强调感官印象的不可靠和持续质疑而不得出结论。她还提到了古代中国哲学家庄周梦蝶的故事,以及笛卡尔关于即使在梦中也能确定的数学事实的怀疑。最后,她提出了一个邪恶天才的假设,用来质疑我们对所有事物的理解,包括抽象事实。
🧠 缸中之脑与局部怀疑论
在第二段中,Nagel教授探讨了缸中之脑的思想实验,这是一个现代版的笛卡尔的邪恶天才假设。她描述了一个大脑被保存在缸中,通过超级计算机提供感官信号来模拟现实世界的经验。她指出,即使在这种情况下,大脑也无法区分真实与模拟的体验。接着,她讨论了怀疑论的两种形式:全局怀疑论,它质疑我们对几乎所有事物的知识;局部怀疑论,它关注特定知识领域的怀疑。她用一个关于Alice看钟表的例子来说明,即使在看似简单的情况下,知识也可能因为潜在的错误而变得难以获得。最后,她提到哲学家们已经提出了多种解决怀疑论问题的方法,接下来的视频中将介绍一些主要的回应怀疑论挑战的方式。
Mindmap
Keywords
💡怀疑主义
💡知识
💡感官印象
💡梦境论证
💡笛卡尔
💡邪恶天才
💡缸中之脑
💡局部怀疑
💡全局怀疑
💡休谟
💡知识的可能性
Highlights
Jennifer Nagel 教授介绍了怀疑论的问题,探讨了人们能确信知道的事情。
提出了人们是否真正“知道”正在观看视频的问题,引入了梦境怀疑论。
探讨了能否证明当前是清醒状态而非梦境的问题。
解释了怀疑论的吸引力,及其词源来自古希腊。
介绍了两种怀疑论传统:学院派怀疑论和皮浪怀疑论。
学院派怀疑论认为感官印象不能作为世界知识的基础。
通过声音印象的例子,展示了感官印象可能误导认知。
皮浪怀疑论者的目标是持续质疑而不得出结论。
讨论了自古代以来在东西方哲学中使用的怀疑论论证,尤其是梦境论证。
引用了中国古代哲学家向秀的梦境故事,探讨了梦境与现实的区别。
提到了笛卡尔关于即使在梦中也能知道的基本数学事实的观点。
笛卡尔提出了一个邪恶天才的怀疑论场景,质疑所有知识。
介绍了笛卡尔如何应对怀疑论挑战的方法。
提到了休谟等哲学家提出的怀疑论论证。
描述了现代版的笛卡尔邪恶天才论证——缸中之脑思想实验。
探讨了即使在好的情况下,人们也无法证明不是缸中之脑的问题。
介绍了全局怀疑论场景,如梦境论证、邪恶天才和缸中之脑,它们质疑了几乎所有知识。
讨论了局部怀疑论,即对特定知识范围的怀疑。
通过Alice看钟的例子,说明了即使在看似简单的情况下,知识也可能受到怀疑。
总结了怀疑论是一个古老而困难的问题,并提出了哲学家们提出的解决方案。
Transcripts
[intro music]
My name is Jennifer Nagel.
I teach philosophy at the University of Toronto,
and today, I want to talk to you about the problem of skepticism.
What do you know for sure?
Consider the fact that you are watching a video, on your computer, right now
Is this something you "know?"
Before you say yes, consider the following question:
do you think it is possible for someone to dream that they're watching a video online,
when in fact, they're asleep in bed, with their computer turned off.
Can you prove that you are now awake and not dreaming?
If not, do you know that you are watching a real video
as opposed to dreaming one up?
If you start feeling inclined to doubt that you have knowledge, you're feeling the attraction of skepticism.
Our word, skepticism, comes from ancient Greece,
the home of not one, but two great skeptical traditions,
academic skepticism, and Pyrrhonian skepticism.
Academic skeptics argued that sensory impressions, which are often taken to be the foundation of knowledge about the world,
don't actually enable you to know anything.
Do you have the impression that the voice you're hearing now,
is the voice of the same person who narrated the first video
in this series?
I might have an identical twin.
You might be mis-remembering, dreaming, or in some other way making a mistake.
Because impressions can be misleading,
you can't know that the same person is narrating both videos.
The academics used arguments like that one
to support their general conclusion
that knowledge of the world is impossible for humans.
Pyrrhonian skeptics went one step further.
Their mission was just to keep on inquiring,
and doubting everything
without reaching any conclusions at all.
Where the academic skeptics argued that knowledge was impossible,
the Pyrronian skeptics worked to suspend judgment even on that point,
keeping all questions open.
Some skeptical arguements have been known
since antiquity
and used in both eastern, and western philosophy.
Most famously, the dreaming argument.
If what you are now experiencing
is just a dream,
then it's not clear that you know anything about your immediate environment
Or even about yourself.
The ancient Chinese philosopher Xiang Xiu [Jwang Ju],
reported having dreamed that he was a butterfly,
and worried later that he did not know whether he was then, a man dreaming he was a butterfly,
or whether, he might now be a butterfly,
dreaming he was a man.
You might think that there are some facts you could know whether or not you are dreaming.
The 17th century philosopher, Rene Descartes, suggested that
even if you are dreaming, you should still be able to know that a square has four sides,
or that 2+3=5.
But Descartes found a way
to raise skepticism about those facts, too.
He noted that it feels natural
to us to make those simple mathematical judgments,
but pointed that we could ask whether what feels natural to us
really has to be true.
Where does our nature come from anyway?
Decartes also developed
a powerful skeptical scenario, designed to make you doubt absolutely everything,
including your grasp of abstract fact.
Imagine that there is an evil genius
of utmost power and cunning, devoted to deceiving you.
The evil genius controls all your sensory impressions
and all your instincts, about math, and geometry, and so on.
Making false things seem true to you.
The challenge of skepticism, Descartes argues,
is the challenge of proving that you are not, right now, in the hands of such a demon.
In the next video, we'll look at Descartes' own way of answering that challenge.
Meanwhile, various other powerful skeptical arguments
have emerged since Descartes' time.
The 18th century philosopher David Hume, had some especially good ones
covered in detail in two separate Wi-Phi videos.
Moving to the present day,
we have a new version of Descartes' evil genius argument.
Imagine a brain kept alive in a vat,
and connected to a supercomputer that delivers sensory signals
to simulate the experience of a coherent reality.
The computer also picks up the brain's outgoing motor signals
and adjusts its inputs accordingly.
When the brain sends out motor signals to raise a hand and touch something,
the computer delivers coordinated visual and tactile input
of seeing the hand and feeling what it touches.
If the computer program is good enough,
and let's assume that it is,
the brain-in-a-vat experiences a perfectly realistic virtual world.
He could have experiences of going to the beach on a sunny day,
meeting friends, being stuck in traffic, or being home alone, watching videos about philosophical topics.
Is there anything you could point to, in your present experience, to prove that you aren't a brain in a vat?
It won't help to pinch yourself.
The local feeling of pain, is just the kind of sensory signal
that the supercomputer can easily supply the in-vatted brain.
Typical skeptics don't try to prove that you actually are a brain in a vat,
they will argue instead that it's bad enough that you just might be,
but you can't tell the difference.
Even if you are in an ordinary physical world,
watching a video, and actually looking at a hand in front of you --
we call that the good case --
it's a problem that your experience feels just like the experience of the brain-in-the-vat.
He doesn't know that his hand is in front of him;
he's just a brain.
He doesn't even have hands.
We call this the bad case.
So, even if you are in the good case,
and your experience really is coming
from looking at your hand,
You're just lucky that you're not in the bad case.
You can't prove that you aren't, and your inability to rule out the bad case
means that you don't actually know that your hand is really there in front of you.
The dreaming argument
the evil genius, and the brain-in-the-vat scenario
are known as "global skeptical scenarios."
They raise doubts about virtually everything you would ordinarily take yourself you know.
But skepticism doesn't have to be global.
You can raise skeptical worries about some particular range of knowledge.
For example, you can worry about your knowledge of the past.
What if the whole universe just came into being five minutes ago,
complete with fossils,
antique-looking furniture, and your own apparent memory traces?
If it did, it would look just the way it does now.
But many of your beliefs, like your beliefs about what you did last summer for example,
would be false.
In a more restricted, local skepticism,
we can raise skeptical worries about knowledge of single facts,
just by thinking of some possible way in which things might fail to be as they appear.
Consider Alice, who's walking down the street
and wondering what time it is.
She glances up at the clock, and sees that the hands show 4:30.
Suppose that's right, and that the clock is working fine.
Ordinarily, we'd say, "Now Alice knows that it's 4:30."
But if we highlight something that could have gone wrong --
sometimes clocks are broken --
and Alice didn't look long enough to be sure that the hands were moving,
then it gets harder to see Alice as really knowing the time.
If her quick glance
isn't enough to tell a difference between a working clock
and a broken one,
then how does Alice really know what time it is?
Just thinking about the possibility of error
can make it seem like knowledge is really hard to attain.
Do we always have to double check that the clock is working
in order to know the time?
It's surprisingly easy to generate doubts about human knowledge,
even knowledge of the kinds of things we'd ordinarily consider easily known,
like whether there's a hand in front of your face right now.
Skepticism, whether it's global, or local
is an ancient, and difficult problem.
Philosophers have proposed various solutions to this problem.
The next two videos describe some of the main ways
of answering the skeptic's challenges
and defending the idea that knowledge is humanly possible.
translated by: Seohyun Yoon(윤서현)
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