How do you explain consciousness?

Right now you have a movie playing inside your head. It's an amazing multi-track movie. It has 3D vision and surround sound for what you're seeing and hearing right now, but that's just the start of it. Your movie has smell and taste and touch. It has a sense of your body, pain, hunger, orgasms. It has emotions, anger and happiness. It has memories, like scenes from your childhood playing before you. And it has this constant voiceover narrative in your stream of conscious thinking. At the heart of this movie is you experiencing all this directly. This movie is your stream of consciousness, the subject of experience of the mind and the world.

Consciousness is one of the fundamental facts of human existence. Each of us is conscious. We all have our own inner movie, you and you and you. There's nothing we know about more directly. At least, I know about my consciousness directly. I can't be certain that you guys are conscious.

Consciousness also is what makes life worth living. If we weren't conscious, nothing in our lives would have meaning or value. But at the same time, it's the most mysterious phenomenon in the universe. Why are we conscious? Why do we have these inner movies? Why aren't we just robots who process all this input, produce all that output, without experiencing the inner movie at all? Right now, nobody knows the answers to those questions. I'm going to suggest that to integrate consciousness into science, some radical ideas may be needed.

Some people say a science of consciousness is impossible. Science, by its nature, is objective. Consciousness, by its nature, is subjective. So there can never be a science of consciousness. For much of the 20th century, that view held sway. Psychologists studied behavior objectively, neuroscientists studied the brain objectively, and nobody even mentioned consciousness. Even 30 years ago, when TED got started, there was very little scientific work on consciousness.

Now, about 20 years ago, all that began to change. Neuroscientists like Francis Crick and physicists like Roger Penrose said now is the time for science to attack consciousness. And since then, there's been a real explosion, a flowering of scientific work on consciousness. And this work has been wonderful. It's been great. But it also has some fundamental limitations so far. The centerpiece of the science of consciousness in recent years has been the search for correlations, correlations between certain areas of the brain and certain states of consciousness. We saw some of this kind of work from Nancy Kanwisher and the wonderful work she presented just a few minutes ago. Now we understand much better, for example, the kinds of brain areas that go along with the conscious experience of seeing faces or of feeling pain or of feeling happy. But this is still a science of correlations. It's not a science of explanations. We know that these brain areas go along with certain kinds of conscious experience, but we don't know why they do. I like to put this by saying that this kind of work from neuroscience is answering some of the questions we want answered about consciousness, the questions about what certain brain areas do and what they correlate with. But in a certain sense, those are the easy problems. No knock on the neuroscientists. There are no truly easy problems with consciousness. But it doesn't address the real mystery at the core of this subject: why is it that all that physical processing in a brain should be accompanied by consciousness at all? Why is there this inner subjective movie? Right now, we don't really have a bead on that.

And you might say, let's just give neuroscience a few years. It'll turn out to be another emergent phenomenon like traffic jams, like hurricanes, like life, and we'll figure it out. The classical cases of emergence are all cases of emergent behavior, how a traffic jam behaves, how a hurricane functions, how a living organism reproduces and adapts and metabolizes, all questions about objective functioning. You could apply that to the human brain in explaining some of the behaviors and the functions of the human brain as emergent phenomena: how we walk, how we talk, how we play chess, all these questions about behavior. But when it comes to consciousness, questions about behavior are among the easy problems. When it comes to the hard problem, that's the question of why is it that all this behavior is accompanied by subjective experience? And here, the standard paradigm of emergence, even the standard paradigms of neuroscience, don't really, so far, have that much to say.

Now, I'm a scientific materialist at heart. I want a scientific theory of consciousness that works, and for a long time, I banged my head against the wall looking for a theory of consciousness in purely physical terms that would work. But I eventually came to the conclusion that that just didn't work for systematic reasons. It's a long story, but the core idea is just that what you get from purely reductionist explanations in physical terms, in brain-based terms, is stories about the functioning of a system, its structure, its dynamics, the behavior it produces, great for solving the easy problems — how we behave, how we function — but when it comes to subjective experience — why does all this feel like something from the inside? — that's something fundamentally new, and it's always a further question. So I think we're at a kind of impasse here. We've got this wonderful, great chain of explanation, we're used to it, where physics explains chemistry, chemistry explains biology, biology explains parts of psychology. But consciousness doesn't seem to fit into this picture. On the one hand, it's a datum that we're conscious. On the other hand, we don't know how to accommodate it into our scientific view of the world. So I think consciousness right now is a kind of anomaly, one that we need to integrate into our view of the world, but we don't yet see how. Faced with an anomaly like this, radical ideas may be needed, and I think that we may need one or two ideas that initially seem crazy before we can come to grips with consciousness scientifically.

Now, there are a few candidates for what those crazy ideas might be. My friend Dan Dennett, who's here today, has one. His crazy idea is that there is no hard problem of consciousness. The whole idea of the inner subjective movie involves a kind of illusion or confusion. Actually, all we've got to do is explain the objective functions, the behaviors of the brain, and then we've explained everything that needs to be explained. Well I say, more power to him. That's the kind of radical idea that we need to explore if you want to have a purely reductionist brain-based theory of consciousness. At the same time, for me and for many other people, that view is a bit too close to simply denying the datum of consciousness to be satisfactory. So I go in a different direction. In the time remaining, I want to explore two crazy ideas that I think may have some promise.

The first crazy idea is that consciousness is fundamental. Physicists sometimes take some aspects of the universe as fundamental building blocks: space and time and mass. They postulate fundamental laws governing them, like the laws of gravity or of quantum mechanics. These fundamental properties and laws aren't explained in terms of anything more basic. Rather, they're taken as primitive, and you build up the world from there. Now sometimes, the list of fundamentals expands. In the 19th century, Maxwell figured out that you can't explain electromagnetic phenomena in terms of the existing fundamentals — space, time, mass, Newton's laws — so he postulated fundamental laws of electromagnetism and postulated electric charge as a fundamental element that those laws govern. I think that's the situation we're in with consciousness. If you can't explain consciousness in terms of the existing fundamentals — space, time, mass, charge — then as a matter of logic, you need to expand the list. The natural thing to do is to postulate consciousness itself as something fundamental, a fundamental building block of nature. This doesn't mean you suddenly can't do science with it. This opens up the way for you to do science with it. What we then need is to study the fundamental laws governing consciousness, the laws that connect consciousness to other fundamentals: space, time, mass, physical processes. Physicists sometimes say that we want fundamental laws so simple that we could write them on the front of a t-shirt. Well I think something like that is the situation we're in with consciousness. We want to find fundamental laws so simple we could write them on the front of a t-shirt. We don't know what those laws are yet, but that's what we're after.

The second crazy idea is that consciousness might be universal. Every system might have some degree of consciousness. This view is sometimes called panpsychism: pan for all, psych for mind, every system is conscious, not just humans, dogs, mice, flies, but even Rob Knight's microbes, elementary particles. Even a photon has some degree of consciousness. The idea is not that photons are intelligent or thinking. It's not that a photon is wracked with angst because it's thinking, "Aww, I'm always buzzing around near the speed of light. I never get to slow down and smell the roses." No, not like that. But the thought is maybe photons might have some element of raw, subjective feeling, some primitive precursor to consciousness.

This may sound a bit kooky to you. I mean, why would anyone think such a crazy thing? Some motivation comes from the first crazy idea, that consciousness is fundamental. If it's fundamental, like space and time and mass, it's natural to suppose that it might be universal too, the way they are. It's also worth noting that although the idea seems counterintuitive to us, it's much less counterintuitive to people from different cultures, where the human mind is seen as much more continuous with nature.

A deeper motivation comes from the idea that perhaps the most simple and powerful way to find fundamental laws connecting consciousness to physical processing is to link consciousness to information. Wherever there's information processing, there's consciousness. Complex information processing, like in a human, complex consciousness. Simple information processing, simple consciousness.

A really exciting thing is in recent years a neuroscientist, Giulio Tononi, has taken this kind of theory and developed it rigorously with a mathematical theory. He has a mathematical measure of information integration which he calls phi, measuring the amount of information integrated in a system. And he supposes that phi goes along with consciousness. So in a human brain, incredibly large amount of information integration, high degree of phi, a whole lot of consciousness. In a mouse, medium degree of information integration, still pretty significant, pretty serious amount of consciousness. But as you go down to worms, microbes, particles, the amount of phi falls off. The amount of information integration falls off, but it's still non-zero. On Tononi's theory, there's still going to be a non-zero degree of consciousness. In effect, he's proposing a fundamental law of consciousness: high phi, high consciousness. Now, I don't know if this theory is right, but it's actually perhaps the leading theory right now in the science of consciousness, and it's been used to integrate a whole range of scientific data, and it does have a nice property that it is in fact simple enough you can write it on the front of a t-shirt.

Another final motivation is that panpsychism might help us to integrate consciousness into the physical world. Physicists and philosophers have often observed that physics is curiously abstract. It describes the structure of reality using a bunch of equations, but it doesn't tell us about the reality that underlies it. As Stephen Hawking puts it, what puts the fire into the equations? Well, on the panpsychist view, you can leave the equations of physics as they are, but you can take them to be describing the flux of consciousness. That's what physics really is ultimately doing, describing the flux of consciousness. On this view, it's consciousness that puts the fire into the equations. On that view, consciousness doesn't dangle outside the physical world as some kind of extra. It's there right at its heart.

This view, I think, the panpsychist view, has the potential to transfigure our relationship to nature, and it may have some pretty serious social and ethical consequences. Some of these may be counterintuitive. I used to think I shouldn't eat anything which is conscious, so therefore I should be vegetarian. Now, if you're a panpsychist and you take that view, you're going to go very hungry. So I think when you think about it, this tends to transfigure your views, whereas what matters for ethical purposes and moral considerations, not so much the fact of consciousness, but the degree and the complexity of consciousness.

It's also natural to ask about consciousness in other systems, like computers. What about the artificially intelligent system in the movie "Her," Samantha? Is she conscious? Well, if you take the informational, panpsychist view, she certainly has complicated information processing and integration, so the answer is very likely yes, she is conscious. If that's right, it raises pretty serious ethical issues about both the ethics of developing intelligent computer systems and the ethics of turning them off.

Finally, you might ask about the consciousness of whole groups, the planet. Does Canada have its own consciousness? Or at a more local level, does an integrated group like the audience at a TED conference, are we right now having a collective TED consciousness, an inner movie for this collective TED group which is distinct from the inner movies of each of our parts? I don't know the answer to that question, but I think it's at least one worth taking seriously.

Okay, so this panpsychist vision, it is a radical one, and I don't know that it's correct. I'm actually more confident about the first crazy idea, that consciousness is fundamental, than about the second one, that it's universal. I mean, the view raises any number of questions, has any number of challenges, like how do those little bits of consciousness add up to the kind of complex consciousness we know and love. If we can answer those questions, then I think we're going to be well on our way to a serious theory of consciousness. If not, well, this is the hardest problem perhaps in science and philosophy. We can't expect to solve it overnight. But I do think we're going to figure it out eventually. Understanding consciousness is a real key, I think, both to understanding the universe and to understanding ourselves. It may just take the right crazy idea.

Thank you.

此时此刻 正有一部电影在你脑海中放映。 这是一部奇妙的多轨道电影。 这部围绕着你正看到和听到的电影 拥有三维视觉和环绕立体声， 但这仅仅是个开始。 你的电影有嗅觉、味觉和触觉。 它拥有你的身体所拥有的感觉， 痛苦，饥饿，高潮。 它拥有情绪， 愤怒和快乐。 它拥有记忆，就像你的童年 正在你的面前放映。 并且它在你的有意识的思维流中 拥有恒定的旁白。 这部电影的核心 是你直接体验这一切。 这部电影是你的意识流， 它是一部关于 对思想和世界的体验为主题的影片。

意识是人类之所以存在 的基本事实之一。 我们每个人都是有意识的。 我们都有自己的内心电影， 包括你、你、还有你。 没有什么是我们能直接了解的。 至少，我能直接了解我的意识。 我不确定你们是否也能意识到这点。

意识也是一种让生命值得活下去的东西。 如果我们没有意识，那么我们生命中的任何事情 都失去了意义和价值。 同时，意识也是 最宇宙中最神秘的现象。 为什么我们会有意识？ 为什么我们会有这些内心电影？ 为什么我们不只是那种 处理输入 再输出结果 而不会体验任何内心电影的机器人？ 目前为止，没有人知道这个问题 的答案。 我想说如果要将意识整合 到科学中去，一些激进的想法也许是需要的。

有人说意识科学 是不可能存在的。 科学，从它的本质上来看，是客观的。 意识，从它的本质上来看，是主观的。 所以，不可能会有意识科学。 在20世纪的大部分时间里，这种观点占据统治地位。 心理学家客观地研究行为举止， 神经科学家客观地研究大脑， 但是没有人哪怕是提到意识。 即使30年前，当TED刚开始时， 也很少见到关于意识方面 的科学研究。

大约在20年前， 所有这些都开始改变了。 像弗朗西斯·克里克这样的神经科学家 以及像罗杰·彭罗斯这样的物理学家 都说现在正是科学向意识方面进攻 的时候。 从那以来， 关于意识方面的科学研究 遍地开花。 这项研究很奇妙，很了不起。 但是迄今为止它也还有一些 根本的局限性。 近几年 意识科学研究的核心 是寻找相关性， 关于大脑的特定区域 和特定的意识状态之间的相关性。 我们看了南希·坎维舍 做的一些这方面的研究以及几分钟之前 她刚刚提交的精彩工作。 现在我们有了更好的理解，例如， 不同的大脑区域对应着不同 的意识体验：人脸识别 或者感受痛苦 或者感受快乐。 但这仍然是关于相关性的科学。 这不是意识科学。 我们知道这些大脑区域 对应着特定的意识体验， 但是我们不知道为什么会这样。 我想说的是， 神经科学方面的这种研究 正回答着那些 我们想要回答的关于意识、 关于某些特定大脑区域做些什么 以及对应哪种（意识体验）的问题。 但是从某种意义上来说，这些都是简单的问题。 都不是神经科学家想要研究的。 没有真正的关于意识的简单问题。 它没能解开关于这个课题的核心 的真正谜团： 为什么大脑中所有的物理过程 必须伴随着意识？ 为什么会有这种内心的主观电影的存在？ 目前为止，我们对此还没有一点头绪。

也许你会说， 让我们再给神经科学几年时间。 它会被证明是另一种涌现现象， 就像塞车、就像飓风、 就像生命一样，并且我们会弄明白它。 所有涌现现象的经典案例 都是应急行为的表现， 塞车是如何行成的， 飓风是如何作用的， 生物体是如何繁殖、 适应环境和新陈代谢的， 所有这些问题都是关于客观机能的。 你可以把它应用到人类的大脑上 去解释为什么人类大脑的某些行为 和功能 跟涌现现象很像： 我们如何走路，如何谈话，如何下象棋， 所有这些问题都是关于行为的。 但是当谈到意识时， 关于行为的问题 只是一个简单的问题。 当涉及到困难问题时， 问题就变成了为什么 所有的这些行为 都伴随着主观体验。 对此，涌现现象 的标准范例， 甚至神经科学的标准范例， 到目前为止都没有太多可以说的。

现在，我本质上是一个科学唯物主义者。 我希望某种关于意识的科学理论 能够奏效， 在过去很长一段时间里， 我埋头苦干， 努力寻找一种有效的 单从物理的角度去解释的 关于意识的理论。 但我最终得出一个结论， 那就是它不起作用只是因为系统性的原因。 说来话长， 但是这个故事的核心就是 你从在物理方面，在基于大脑方面的 纯粹的还原论者的解释中得到的东西， 是关于一个系统的功能、 它的结构、它的动力、 以及它所产生的行为的， 它可以很好地解决简单问题—— 比如说我们如何表现，我们如何活动—— 但是当它涉及到主观体验时—— 比如说为什么所有这些都感觉像是来自内心的某些东西？—— 这是一些全新的东西， 并且它总会成为一个更深层次的问题。 因此我想我们进入了僵局。 我们已经有了一套美妙的、伟大的解释链， 我们已经习惯了它，那就是用用物理解释化学， 用化学解释生物， 用生物解释部分心理学。 但是意识 似乎并不符合这种情形。 一方面，它是一个已知数 即我们是有意识的。 另一方面，我们却并不知道 如何使它与我们的科学的世界观相适应。 所以我认为就目前而言意识 是一种反常事物， 是一种需要我们将它整合到 我们的世界观中，而我们却还不知道如何整合的事物。 面对这样的反常事物， 我们可能需要一些激进的想法， 并且我认为我们可能需要一两个 在我们可以科学地 面对意识之前 看起来很疯狂的想法。

现在，对于这些疯狂的想法可能是什么 已经有了一些候选项。 我的朋友丹·丹尼特就有一个这样的想法，他今天也在这里。 他的疯狂想法是关于意识 的困难问题并不存在。 整个内心主观电影的想法 涉及一种幻觉或困惑。 事实上，我们现在要做的就是解释 客观功能和大脑行为， 然后自然地我们就解释了 所有需要被解释的。 我想说，给他更多的能量。 这就是那种我们需要去探索的 激进想法， 如果你想获得关于意识的 纯还原论者的基于大脑的理论的话。 同时，对于我和其他很多人来说， 这个观点有一点太接近于简单地 否认关于意识的已知资料 而不能令人满意。 因此我选择了另一个不同的方向。 在余下的时间里， 我想探讨两个我认为可能有希望的 疯狂想法。

第一种疯狂想法是 意识是一种基本概念。 物理学家有时候会把宇宙中的某些方面 作为基本概念，如： 空间、时间和质量。 他们设定了一些基本定律去管理它们， 例如重力定律和量子力学定律。 这些基本性质和定律 不能解释一些更基础的东西。 这相当于以它们为根本， 然后你在它们的基础上建立这个世界。 现在，这张基本定律名单会不时扩大。 在19世纪，麦克斯韦断定 你无法用当时存在的基本概念—— 空间、时间、质量、牛顿定律—— 去解释电磁现象， 因此他设定了电磁学的 基本定律， 并且设定了电荷 作为这些定律的 基本元素。 我认为这与我们在研究意识上的 情形是一样的。 如果我们不能用现存的基本概念—— 时间、空间、质量、电荷—— 去解释意识， 那么从逻辑上而言，你需要去扩充这张名单。 接下来将意识本身设定为 某种根本性的东西， 作为自然界的基本概念就是一件自然而然的事。 这并不意味着突然间你不能用它来研究科学了。 这反而是为你开僻了一条用它来研究科学的道路。 然后我们需要做的就是研究 那些掌控着意识的基本定律， 那些将意识与其它基本概念—— 空间、时间、质量、物理过程—— 联系在一起的定律。 物理学家有时候说 我们希望那些基本定律可以简单到 能够把它们写在T恤上。 我想我们在对意识的研究上 也应该这样。 我希望我们发现的关于意识的基本定律也可以简单到 能够把它们写在T恤上。 我们现在还不知道这些定律是什么， 但这是我们正在寻找的。

第二个疯狂的想法 是意识也许是普通存在的。 也许每个系统都有某种程度的 意识。 这种观点有时被称作泛心论： 万物皆有精神或心理活动， 每个系统都具有意识， 不仅是人类、狗、老鼠、苍蝇， 甚至连罗伯·奈特的微生物、 基本粒子都具有意识。 甚至连一个光子都有某种程度的意识。 这个观点不是说光子是智能的 或者能思考的。 不是说一个光子 会由于焦虑而被破坏， 而这种焦虑是因为它想着“哦，我总是以接近光速的速度 紧张地跑来跑去，从来没有放慢速度来闻一闻玫瑰花香“。 不，事情不是这样子的。 这种观点想要表达的是也许光子可能会有 一些原始的、主观的体验， 一些原始的意识的前兆。

对你来说，这听起来可能有点怪。 我的意思是，为什么不可以有人思考这样疯狂的事呢？ 有一些动机来自第一个疯狂想法， 即意识是基本概念。 如果它是基本概念，就像空间、时间和质量一样， 那么很自然地可以假定它也可能具有普遍性， 就像其它的基本概念一样。 还有一点值得注意的是虽然这个想法 对我们来说是违反直觉的， 但对来自其他文化的人来说 可能就不是那么违反直觉了， 那些（其他文化的）人的心灵 跟自然联系在一起的时间更长。

从这个想法中得到的一个更深的动机是 也许找出将意识与物理过程 联系在一起的 最简单和最有力的方式 就是将意识与信息相结合。 有信息处理的地方 就有意识。 复杂的信息处理，比如说人类的信息处理， 伴随着复杂的意识。 简单的信息处理， 伴随着简单的意识。

一件令人很兴奋的事是最近几年 有一个神经科学家，朱利奥·托诺尼 采用了这种理论 并且严格按照数学理论 的方式发展了它。 他有一个关于信息整合 的数学测量， 他称之为phi， 他用它来测量 一个系统中的信息整合的量。 他推断phi 是与意识相关的。 所以在人类的大脑中， 有着令人难以置信的信息整合量， 高度的phi值， 一大堆的意识。 在老鼠的大脑中，有中度的信息整合量， 但仍然数目庞大， 仍然具有大量的意识。 但是当你将研究目标降至蠕虫、 微生物、粒子， phi的值就会跌落。 信息整合量会跌落， 但不会为零。 在托诺尼的理论中， 意识程度 也不会降为零。 事实上，他正在提出这样一个关于意识的 基本定律：phi值越高，意识度也越高。 现在，我不知道这个理论是否正确， 但是实际上或许它正处于 意识科学的理论前沿， 并且它已经被用于整合 各方面的科学数据， 它还有一个很好的属性就是它足够简单， 简单到你可以将它写在T恤上。

另外一个最终动机就是 泛心论可以帮助我们 将意识和物理世界相结合。 物理学家和哲学家经常注意到 物理学是深奥抽象的。 它用一连串的方程式 去描述现实结构， 但是它又不告诉我们 构成它的现实基础。 正如史蒂芬·霍金所说， 是什么将火放进方程式的？ 而在泛心论者看来， 物理方程可以是它现在的样子， 但是你也可以用它来描述 意识的量。 这是物理学最终要做的， 描述意识的量。 用这种观点看来，是意识 将火放到了方程中。 在那种观点看来，意识 不是晃荡在物质世界之外 的特别的东西。 它存在于物质世界的核心。

我认为，这种泛心论者的观点， 有那种使我们对我们与自然的关系产生改观 的潜能， 并且它可能产生一些相当严重的 社会和伦理方面的后果。 它们当中的一些可能是违反直觉的。 我曾经想我不可以 吃任何有意识的东西， 因此我要做一个素食主义者。 但是现，如果你是一个泛心论者并且采用这种观点， 你只能挨饿。 因此我想当你思考它的时候， 这将会使你有改变观点的倾向， 然而对于伦理目标 和道德考量来说 最重要的不是关于意识的事实， 而是意识的程度和复杂性。

探讨其它系统，比如说电脑中的意识 也是一件很自然的事情。 比如说电影《她》中的 人工智能系统萨曼莎是什么情况？ 她有意识吗？ 如果你用这种信息性的， 泛心论者的角度来看， 她的确能进行复杂的信息处理 和整合， 所以答案很有可能是“是”，她是有意识的。 如果这个答案正确的话， 那么不管是开发智能计算机系统 或者关闭他们 都会引起严重的伦理问题。

最后，你可能会询问 集体意识、 行星的意识。 加拿大有它自己的意识吗？ 或者在一个更地方的层面来说， 一个由一场TED大会的听众 所组成的集体 拥有集体的TED意识吗， 这个TED集体 的内在电影 是与我们每个人自己 的内在电影不同吗？ 我不知道这个问题的答案， 但我觉得至少它 值得重视。

好了，这就是泛心论者的观点， 它是一个激进的想法， 而我不知道它是否正确。 事实上我对第一个疯狂想法 即意识是一种基本概念， 要比对第二个疯狂想法 即意识是普遍存在的 要更有把握。 我的意思是，这个观点引起了很多问题， 拥有很多挑战， 比如说那些小的意识 是如何添加到 我们了解和喜爱 的复杂意识中去的。 如果我们能够回答这些问题， 那么我想我们就会在通往 关于意识的严肃理论的道路上顺利走下去。 如果不能，那么这可能成为 科学上和哲学上最难解的问题。 我们不能期盼一个晚上就能解决这个问题。 但是我相信我们终将弄明白它。 我想，理解意识是 我们理解宇宙 和理解我们自己的一个关键。 而做到这一点也许只需要我们采用正确的疯狂想法。

谢谢。

（掌声）