10 Mysteries of Consciousness

Only a fool would deny that consciousness is mysterious. Stranger still is how few people know how weird it gets. After many years of thinking, I've collected for you ten of its gnarliest puzzles. If you have the good fortune to crack some of them, let me know asap.

What exactly am I talking about? Consider the bat. A bat uses ultrasonic sound waves to map out its physical space. It does not see the world as we do, yet it glides through thick vegetation in absolute darkness, catching prey without smashing into branches. So, what is it like to be a bat? We do not know. But presumably, there is something it is like to be one, however alien it may be to us. This is consciousness: this what-it-is-likeness.

Observe what it is like to be you. You have a visual field of shapes and colours that resolve into a three-dimensional world. You have no part to play in its construction; it is already there. Sounds, smells, and the sense of touch overlap this field. They ride alongside, somehow distinct from the view yet woven into the same world. Your own voice narrates these lines as you read them, but it is audible only to you. Undergirding all of this are feelings: perhaps a low murmur of stress, a quiet pleasantness, or a nameless cocktail found nowhere else.

All of these together are what it is like to be you—your consciousness.

(1) The Hard Problem of Consciousness

We grow up learning that reality is, at bottom, just a bunch of particles following the laws of nature. All the rich complexities of the universe—the bacteria, the bats, and even the symphonies of Bach—are reducible to a tightly choreographed dance of little billiard balls. There is nothing more to it: no immaterial souls, no magic, and certainly no miracles.

There is an unmistakable trend of relentless conquest in science. Every mystery is cut down, measured, and explained. The questions that eluded the brightest minds just a few centuries ago are now taught to schoolchildren. We once believed we were hand-crafted by God; Darwin gave us natural selection. We thought plagues were divine punishment; they turned out to be bacteria. We put ourselves at the centre of the universe; Copernicus moved us to the periphery. We believed life required a mysterious vital force; it turned out to be nothing more than complex chemistry following ordinary laws.

So it is believed that consciousness, too, in due time, will fall to the power of science. Yes, it is a mystery today, but so was all of physics a few hundred years ago. For now, we can just say that it is some type of emergent phenomenon. You take a brain, have it perform the right sort of computation, and out will pop consciousness.

It could not be anything else, you see, for brains are made of atoms and we know full well how atoms behave. We can even write the equations down on paper. It is like fluidity: individual water molecules are not fluid, just as individual neurons are not conscious. But if you gather enough water molecules together, you find fluidity; in the same way, a correct network of neurons should produce consciousness.

This is the consensus in most scientific circles. And it is a false confidence in the face of a fundamental misunderstanding of the subject.

Every emergent phenomenon can be explained through a story of how its parts interact. Water molecules are loosely held by weak intermolecular forces such that they easily slide between each other. This is what appears to us as fluidity. Life itself is nothing more than an impressively designed collection of proteins and tissues that captures energy to maintain itself; with sufficient complexity, it becomes manifestly alive. No mystery here.

Consciousness, on the other hand, cannot be broken down this way. The redness you see, unlike water or creatures, has the strange quality of not being composed of anything simpler. Indeed, if you try to describe it, you will be at a loss for words. In the end, all you can muster is that it is "red". This is quite strange; for nothing else can you say such a thing. You could not say this about apples, horses, or even atoms; they are all composed of simpler entities which, when put together, explain the whole’s behaviours and character. No such reduction is possible for redness.

Of course, a story can be told about photons reflecting off a red apple, which hit your retina, stimulate the rod and cone cells, and send electrical signals up to your visual cortex, which then... does what exactly? Which produces a redness in your consciousness? How? How does it suddenly jump from informational structures composed of wet neurons to this magical, ineffable, irreducible appearance of redness? That is the Hard Problem of consciousness. No story, however complex you make it, about neurons computing and constructing representations of apples can ever explain why all that should produce an experience of red apples.

(2) The Qualia Mapping Problem

In your conscious experience, there are distinct individual components—the redness, the sound of birds, the taste of chocolate—and they are called qualia (singular: quale). Consciousness and qualia relate to each other a bit like how space relates to matter. Matter is contained within space; qualia are contained within consciousness.

Whereas the Hard Problem is about why consciousness—and qualia—exists at all when brains do things, the Qualia Mapping problem is about why particular brain states produce particular qualia. Suppose we find that a certain pattern of neural circuitry is responsible for redness; we can ask, then, why is it this pattern and not some other pattern which corresponds to redness?

Think of an analogy; imperfect though it is, I hope it conveys the point: the picture of a cat that you see on your computer screen is represented as 1s and 0s in your computer memory. A string of bits fully represents the cat’s image. This is similar to how the brain circuitry encodes the image of a cat you see in your consciousness. In both cases, there is an image, and it is represented in a different form; in one case as 1s and 0s of a computer’s memory, and in the other, as the excitations and communications between neurons.

In the case of the image of a cat on the screen, however, it is no mystery why the bitstream gets represented as the cat, for we understand fully how the 1s and 0s are transformed through different layers of the software stack, converted to electrical signals, and transmitted to the monitor. The whole process is visible, inspectable, and comprehensible.

What analogous process exists for the relationship between brain states and qualia? It seems there is nothing there; there is some representation of a cat in your brain, and then through a magical process that we cannot see or detect, a process interprets it as a cat’s image in consciousness. What is it that tells the universe that a certain brain state must map to a certain quale state?

Information is subjective; it is observer-dependent. A minor change in the code can flip the colours of the cat on the screen, so that the reds become blue and the greens become yellow. There is no inherent meaning to any bitstream; it all depends on how you choose to interpret it. In which case, why do the brain’s neural patterns get interpreted the way they do? What process does it take? Why is it invisible? And how does it tell consciousness that this is how it is to be shown? All of that seems utterly mysterious; that is the Qualia Mapping problem.

(3) The Evolution Problem

In the physicalist conception of the universe, the world is causally closed. Consciousness, for that reason, cannot have any causal effect on it. Whatever we do can all be explained quite satisfactorily through a third-person account of how the brain interacts with the body. There is no reason to invoke consciousness in any of those explanations. If so, this means consciousness is inert; it has no causal power and no function. It is an epiphenomenon.

Which then begs the question: how did we evolve to have consciousness? How do creatures come into the world and possess conscious experiences? Specifically, how would it possess the complex richness that we have?

Darwinian evolution happens because the replicators (genes) code for how creatures look and function. But how could any process possibly design what a quale looks like? How do you even conceivably put together atoms so that they result in an intricately designed, privately accessible dashboard?

(4) The Self-Report Problem

How is it possible for the brain to know that it is conscious? If the physical universe is causally closed, then how is your mouth speaking words like "I am conscious. I see redness"? How does a physical system spontaneously start uttering these strange words, and how is it, coincidentally, exactly what is going on in its conscious experience?

If physicalism is true, then consciousness is inert and has no purpose, yet we somehow know we are conscious. How is such knowledge possible? Within this stream, there is a knowing that the knowing is happening within an experience. We cannot account for a physical mechanism by which this knowledge is possible, yet we utter things like "I see redness," and there is no doubt a redness there.

(5) The Location Problem

Where is consciousness? It is not in space; indeed, space is only perceivable via consciousness. The feeling of having a head is within consciousness. It is not an invisible overlay on top of the brain, undetectable by physics. There is no central point in the brain where all the information comes together; the correlates of the contents of consciousness are spread about in space and do not collapse into a single point.

It feels as though consciousness does not even have to be part of the universe. Imagine you wear a VR headset and enter an alien world in a video game. Is the headset itself part of that world? No, the headset is part of a different world, through which you can see the alien world.

(6) The Subjectless Subject Problem

Everything we experience is within consciousness, including space, time, matter, our bodies, and crucially, the self—the "I." After all, if we conceive of it as a screen, it is intelligible to ask to whom this screen is presented, and it appears the answer is: no one. There is no thing that is viewing it; there is only the view itself.

The feeling that there is a self that is the author of your thoughts and the recipient of experience is itself an appearance in consciousness. These feelings warp our sense of reality so strongly that we are confused into thinking there is a subject.

But then, what is the alternative? How can there be only the view and no viewer? If we ask how a viewer can see the view, you have to posit, in the internal consciousness of this viewer, yet another viewing without the viewer, which causes an infinite regress. Since the latter leads to an infinite regress, we are forced to pick the former.

(7) The Value Problem

How is consciousness the seat of all value? This is somehow more baffling than all the other questions. How is it that caring about anything only makes sense if it affects some conscious experiences somewhere? If we kick an unconscious rock, nobody cares. If kicking a rock ever matters, it is only because a conscious person prefers the rock not be kicked. Why? How is consciousness the only reason to value things?

(8) The Purposelessness Problem

What is the purpose of consciousness? Naively, it looks like a high-level control center—the place from which decisions are made. But it is not. Consciousness is a structureless, featureless capacity for occupying its contents. Neither is there a self, nor is there free will. Thoughts, intentions, and decisions all appear in consciousness fully formed. So, what is the point of it all?

(9) The Valuable-Purpose Paradox

How is the seat of all value simultaneously a purposeless, inert epiphenomenon?

(10) The Ineliminable Observer Problem

It is impossible to imagine a world without consciousness. I mean that literally. Close your eyes and imagine a pink cow sitting in a meadow chewing grass. Could you see it in your mind's eye? Did you notice yourself in this scene? You were the imaginary observer, observing the imaginary cow chewing.

It is impossible to replace the conscious point of view; it never goes away. Why is a space that is not lit up by consciousness not even conceivable? We believe the Big Bang happened, yet stories about the expansion of space only make sense in light of there being a "God's eye" witness to such events. Remove the observer, and we are left with nothing.

Do not fool yourself with the mathematical abstractions of physics. The equations are only a map. For you to interpret this data, you have to construct the territory in your head. You have to imagine the Big Bang, and inevitably, along comes the imaginary consciousness that sees it—the ineliminable observer.