心灵的曙光
物质如何变得有意识并获得生命
作者：詹姆斯·库克（James Cooke, Ph.D.）![]()
第一部分
由内而外
意识的哲学
第一章
物理主义与还原主义
你可能会想，我们无法解释意识，是否真的对现有的科学世界观构成了根本性的挑战？假如确实存在一个科学无法解释的主观体验世界，那又如何呢？也许你会反对说，让科学去描述宇宙的其他部分就好了，不必将你的内心体验纳入其解释范围。你可能认为，看到日落或闻到饼干的私密体验和科学对宇宙的图景毫无关系，但事实并非如此。科学为我们提供了宇宙行为的地图，而不是描述宇宙本质的真相。因此，只有当某物的行为方式能够与我们对其他事物行为的理解建立联系时，它才能在科学的世界图景中被认为是存在的。我们将这些关于事物行为的叙述称为因果性（causality）。目前，意识尚未出现在我们关于因果性和宇宙行为的叙述中，因此在科学的存在地图中，意识实际上是缺席的。按照当前的科学世界观，你在一生中从未真正体验过任何事情。
意识与科学世界观的冲突
意识的存在与维持当前科学世界观之间存在着张力。令人惊讶的是，有些人选择放弃对意识的承认，而不是更新现有的科学视角。哲学家帕特里夏·丘奇兰德（Patricia Churchland）和保罗·丘奇兰德（Paul Churchland）便是著名的消除性唯物主义者（eliminative materialists）。唯物主义（Materialism） 或 物理主义（Physicalism） 是相关的哲学立场，认为物质或“物理”是唯一存在的事物。然而，如何定义“物质”和“物理”决定了立场的细微差别。在简单的层面上，一些唯物主义者相信物质（如物理学研究的粒子）是一种坚实的实体，并且是唯一真正存在的东西。而更复杂的物理主义者则可能认为，我们实际上并未接触到所谓的“物质”；物理学家只是定量描述了世界某些方面的行为。物理主义者可能相信看似非物理的过程（如心灵）依赖于物理学研究的那些过程，但他们未必对这些物理过程的本质作出明确立场。这被称为非还原性物理主义（nonreductive physicalism）。
消除性唯物主义者则认为，唯一存在的是物质，我们认为存在的心理状态实际上并不存在。例如，我们通常认为自己的信念有意义或内容，也就是说，信念通常指向某种事物。此外，我们通常赋予这些信念某种因果力量。如果我相信我面前有一个苹果派，因为我闻到了它的味道；如果我相信自己饿了，因为我感受到了饥饿感，那么常识的解释是，我对苹果派存在的信念以及我的饥饿感信念导致了我接近并吃掉苹果派的行为。对消除性唯物主义者而言，这种对信念的讨论不过是某种“民间心理学”（folk psychology）的想法，就像有人认为恶灵是精神疾病的原因一样。在现实中，只是气味分子进入鼻腔，触发了大脑中的复杂物理过程，最终导致了肌肉的运动。
意识作为幻觉的观点
一种相关的理论是，意识体验本身是一种幻觉。哲学家丹尼尔·丹内特（Daniel Dennett）和基思·弗兰克许（Keith Frankish）认为，当我们反观内心并感到某种体验具有某种特质时，比如受伤带来的痛苦感，其实并不存在这样的特质。相反，大脑通过某种“伎俩”，让我们觉得纯粹的物理信号（如身体损伤的信号）具备某种不存在的特性。然而，你可能会问：如果没有意识体验的空间，这种“印象”如何能够产生？对许多人来说，这是一种荒谬的立场。
神秘主义的立场
另一个路径是所谓的神秘主义（mysterianism），与哲学家科林·麦金（Colin McGinn）有关。神秘主义者认为，有些事物是我们根本无法理解的，而意识便是其中之一。我们只是谦卑的灵长类动物，知识是有限的。正如我们不会期望大猩猩能够理解股票市场一样，为什么我们一定要坚持认为自己能够理解现实的所有方面？然而，对许多人来说，假设我们无法理解意识，仅仅因为我们尚未做到，这无疑是过早地放弃了努力。
重新审视意识与世界的关系
如果我们发现上述这些观点都未能令人满意地解释意识的存在，而我们也不愿轻易放弃努力，那么我们需要考虑是否是我们关于意识及其所处世界的思考方式出了问题。如果我们犯了错误，也许回溯我们的思路，找到潜入我们思想中的错误假设，会有所帮助。
还原主义的主导地位
我们当前的主流范式被称为还原主义（reductionism）。按照还原主义的观点，真正存在的只有物理学的世界；只有亚原子粒子和原子的微观层面被认为对自然的运行图景有贡献。根据这种观点，宇宙中发生的一切事件完全归因于这些粒子的活动。在还原主义者看来，那些看似与微观粒子无关的现象，例如化学反应、生命的生理过程、心灵活动，甚至社会与文明，尽管表面上显得重要，却并不真正属于现实的叙述。它们是“伴生现象”（epiphenomena），不过是物理学所研究的动态展开过程的副产品。你的目标和计划实际上并不会影响你的身体在空间中的运动；相反，这只是一种粒子相互作用的庞大机械过程，而你认为自己“做过什么事情”的想法不过是一个幻觉。
从粒子运动解释一切的局限性
根据这种观点，如果我们能够追踪你身体中每个粒子的位置，我们就不需要神经科学来解释你的行为。大脑本身并没有实现什么目标；它只是微观物理过程的宏观显现，而所有的行动都发生在微观物理层面。1814年，皮埃尔-西蒙·拉普拉斯（Pierre-Simon De Laplace）提出，如果有一个“全知的智能”（即所谓的“拉普拉斯妖”）能够了解所有粒子的位置和运动状态，那么仅凭这些信息便可以精准预测宇宙的演变。更早一些，这种想法甚至可以追溯到牛顿。牛顿的运动定律在描述一个或两个物体如何在空间中运动方面表现得极为出色。然而，这些优雅的定律在引入第三个相互作用的物体后便失效了，这一现象被称为三体问题（Three-Body Problem）。考虑到我们当前的科学图景基于“万物的行为完全由此类定律决定”的假设，你可能会感到震惊，这些定律实际上仅适用于宇宙中极其狭窄的一部分现象。如果尝试将牛顿定律应用于你身体中任何分子的活动，你会发现这些定律完全失效。
还原主义范式试图解释宇宙，却忽略了我们关心的大部分内容，包括所有的心理活动和整个生命世界。为了科学地解释这些现象，我们必须更新我们的思维方式。
THEDAWNOFMIND
HOW MATTER BECAME CONSCIOUS AND ALIVE
JAMES COOKE, Ph.D.
PART I
INSIDE OUTThe Philosophy of Consciousness
ONE
CONSCIOUSNESS
Conscious experience is at once the most familiar thing in the world and the most mysterious. There is nothing we know about more directly than consciousness, but it is far from clear how to reconcile it with everything else we know.—DAVID J. CHALMERS1
PHYSICALISM AND REDUCTIONISM
You might wonder if our inability to explain consciousness is really such a fundamental challenge to our existing scientific worldview. So what if there is a private world of qualitative experience that science doesn’t account for? Just let science describe the rest of our universe, you might object; it can just leave my mind out of its explanations. It may seem that your private experience of seeing a sunset or smelling cookies has nothing to do with our scientific picture of the universe, but this is in fact not the case. Science provides us with a map of how the universe behaves; it doesn’t describe what it truly is, apart from this behavior. As a result, something can only be said to exist in our scientific picture of the world if the way it behaves can be linked up with our understanding of the way everything else behaves. We call the stories we tell about the behavior of things causality. Consciousness does not currently feature in our story of causality—of how the universe behaves—so it is effectively absent from our scientific map of what exists. According to the current scientific worldview, you have never had an experience in your life.We have a tension here between the existence of consciousness and preserving our current scientific worldview. Perhaps surprisingly, there are some who choose to give up on consciousness rather than update our current scientific perspective. Philosophers Patricia and Paul Churchland are famed eliminative materialists of this kind.9 Materialism or physicalism are related philosophical stances that consider matter, or the “physical,” to be all that exists. A lot hinges here on what we mean by matter and physical, and there is a terrain of philosophically nuanced positions in this area. At the more naive end of the spectrum, we might have materialists who believe matter, as in the particles studied by physics, to be a solid substance and the only thing that truly exists. A more sophisticated physicalist might accurately claim instead that we never actually come into contact with some substance called matter; physicists only quantitatively describe the behaviors of certain aspects of the world. The physicalist may believe that seemingly nonphysical processes, like mind, are dependent on these processes that physicists study but without committing to a stance on exactly what physical processes are. Emergent phenomena like biology, minds, and societies can exist, but they are all built on top of the processes of physics. This is known as nonreductive physicalism.Eliminative materialists, though, believe that the only thing that exists is matter and that the mental states we believe we possess do not actually exist. Take the example of a belief. We typically feel our beliefs to have meaning or content; that is, they usually refer to something. We also typically ascribe some causal power to those beliefs. If I believe there is an apple pie in front of me because I can smell it, and I believe I am hungry because I can feel it, then our commonsense explanation of what is going on when I approach and eat some of the pie might involve claims that I held beliefs about the existence of the pie and my hunger, and those beliefs resulted in the action of approaching and eating it. To the eliminative materialist, this talk of beliefs is just some folk-psychological idea of what is going on that doesn’t relate to what is really going on, like someone believing an evil spirit is the cause of someone’s mental illness. In reality, all that happens is odorant molecules enter the nose and trigger complicated physical processes in the brain that result in the movement of muscles.A related idea is the proposal that conscious experience itself is an illusion. According to the illusionist philosophers Daniel Dennett and Keith Frankish, when we introspect and feel that there is a certain quality associated with an experience, such as the unpleasant feeling of pain resulting from an injury, no such quality actually exists.10 Rather, the brain pulls off a trick where it gives the impression that the purely physical signaling of damage to the body has a quality that it doesn’t actually have. You might ask how it could give such an impression if there was no space of experience in which the impression could arise. For many, this is a nonsensical position.There is another path for those who are convinced that science and philosophy cannot connect consciousness to matter in principle. It is known as mysterianism and is associated with philosopher Colin McGinn.11 A mysterian believes that there are some things that we simply can’t understand and that consciousness is one of them. We are humble primates, and there are limits to our knowledge. We wouldn’t expect gorillas to understand the stock market, so why do we insist that we must be able to understand all aspects of reality? For many, however, to assume that we are incapable of understanding consciousness because we haven’t done so yet is to give up the fight prematurely.If we find ourselves in the position that none of these proposals seem to satisfactorily explain the existence of consciousness yet we are not ready to throw in the towel and assume the answer is simply beyond us, then we have to consider the possibility that there is something wrong with how we are thinking about consciousness and the world in which it exists. If we have taken a wrong turn, then it might help to retrace our steps to see where a mistaken assumption or two might have crept into our thinking.Our current dominant paradigm is known as reductionism. According to reductionism, all that truly exists is the world of physics; only the micro-physical level of subatomic particles and atoms is considered to contribute to our picture of how nature works. According to this story, everything that ever happens is entirely due to the activity of these particles. Where we see things happening that seem to not be microphysical particles, such as chemical reactions, the physiology of life, the activity of the mind, or societies and civilizations, they are not really part of the story of reality, despite their appearances. They are epiphenomenal, just a by-product of the unfolding dynamics that physics studies. Your goals and plans do not actually contribute to how your body moves through space. Instead, there is only a vast mechanical process consisting of particles interacting—the idea that you have ever made anything happen in your life is a mere illusion.According to this view, if we could track the location of every particle in your body, then we wouldn’t need neuroscience to explain your behaviors. Brains do not actually achieve anything themselves; they are just the large-scale appearance of microphysical processes, and it is at this micro-physical level that all the action is happening. This idea was first proposed in 1814 by Pierre-Simon De Laplace, who argued that a vast intellect or demon with knowledge of the positions and motions of all the particles in existence would be able to precisely predict the unfolding of the universe based on this information alone.12 This idea that everything can ultimately be explained by the deterministic motion of particles moving through space can be traced back even further to Newton.Newton’s equations of motion do an incredible job of describing how one or two objects move through space. The problem is that these elegant laws break down once you add a third participant to the interaction, a fact known as the three-body problem. Given that our current scientific picture of the world is based on the idea that everything that ever happens is due to laws such as these, you would be right to be shocked by the fact that they only apply to such a narrow range of phenomena in our universe. Try applying Newton’s laws to the activity of any molecule in your body, and you will find that they fail miserably. The idea that the reductionist paradigm explains our universe relies on putting on blinders that exclude most of what we care about, including all of mental life and the whole of the living world. We must update our thinking to be able to account for these phenomena in a scientific fashion.
