The Correct Answer on Consciousness

Like everything in philosophy, consciousness is not very clearly defined. But the general idea is that a thing is conscious if it can experience thoughts or feelings. A person is conscious because he can experience pain or pleasure or seeing the color red. A table is not conscious because, as far as we know, it does not experience anything.

A central problem in philosophy is to describe what consciousness is and where it comes from. It seems at first like a difficult or even impossible task, because the thoughts and feelings that make up our experience seem to live outside the physical world. Many people think that the feeling of hearing music is not fully described by the interaction of atoms, even if the arrangement of the atoms in our brain somehow generates that feeling. Therefore, the argument goes, consciousness is outside the reach of physical sciences. Here are a couple of quotes from adherents of this view:

“I think that there are certain features of bodily sensations especially, but also of certain perceptual experiences, which no amount of purely physical information includes. Tell me everything physical there is to tell about what is going on in a living brain … you won’t have told me about the hurtfulness of pains, the itchiness of itches, pangs of jealousy.”

— Frank Jackson, Author of The Qualia Problem

“Many of us think we can explain things like trees, rocks, motion, planets, etc, in terms of more fundamental physical things. We can reduce these things to lower level physical things. Once you’ve got all the atoms in the right place, the right forces in motion, you have a rock. There’s nothing else left to say–a particular rock is nothing more than these things appropriately arranged. Consciousness on the other hand, is irreducible–it cannot be reduced to just lower level descriptions of this sort. If you try, inevitably you’ll leave something out.”

— Winsaucerer, Commenter on Hacker News

This viewpoint makes up a comfortable majority on the internet. Unfortunately, it’s wrong. And this isn’t one of those debates where everyone can speculate but no one can really know. Rather, consciousness is in the same category as religion. Just as a person who is reasonably smart and really wants to know the truth about religion will become 100% certain of atheism,¹ so will a similar person become 100% certain about consciousness. The nature of consciousness is one of those rare questions that is both controversial and easy to answer from first principles.

The Answer

The correct answer is that consciousness is a purely physical process. Every aspect of a person’s experience is captured by physical information. An advanced scientist would be able to explain how consciousness arises out of simpler physical patterns, and ultimately out of the basic physical laws.

To see this, the key is to note that our vocal cords, being made up of matter, are governed entirely by the physical laws. So whenever someone says something out loud, we can fully explain why he said it using only those laws.

In particular, suppose a person pinches himself and contemplates the resulting sensation. He says, “Clearly, this awareness of pain can’t be reduced to the movements of material things.” In this case too, we can explain why he said that using only the rules that govern the movement of matter.

Actually this applies every time someone writes or types or speaks a claim that consciousness has non-material aspects. All of these actions are physical movements, so they can be explained completely in terms of physical machinery. And moreover, if we zoom in on that machinery, we can see why these claims have to be made. The physical world, with nothing extra thrown in, necessitates that people will claim certain aspects of their experience to be non-material, and it gives a satisfying, purely physical explanation for why they do.

Now imagine we have fully absorbed this explanation. We can see why these claims about consciousness are an inevitable consequence of the way our brains are wired. We can see why the laws of physics, mechanistically applied, cause people to say that consciousness is not reducible to the laws of physics. We might want to object that there is more to consciousness beyond any such mechanisms, but we even understand the physical mechanism that drives us to make that objection.

At this point, all of our observations about consciousness have been explained from a physical perspective. Thanks to Occam’s Razor, we’re done: There’s no need to bloat the explanation by adding in anything else.

This is completely convincing, and nothing more is required to conclude that consciousness is a purely physical process. But in fact the argument gets even a little stronger than this. When someone says there are non-physical aspects to his experience, not only are such aspects unnecessary to explain why he’s saying that, but in fact they couldn’t be why he’s saying that. If he were really talking about something non-physical, then it couldn’t have influenced his purely physical vocal cords, so he couldn’t have talked about it!

Mary’s Room

When you argue that consciousness is a purely physical process, people often bring up Mary’s Room. In this thought experiment, Mary has spent her life in a room where everything is black and white. However, she’s incredibly smart and has read all about the physical processes that occur when a human brain perceives color. The question is, when she leaves the room and finally sees color for herself, does she learn something new from the experience? And if she does, then doesn’t that mean there is some aspect of experiencing color that can’t be boiled down to physical information?

My feeling on Mary’s Room is that she very likely does learn something new when she sees color for the first time. However, it’s easy to explain this without resorting to anything non-physical.

For example, Mary’s brain may be organized in such a way that it’s able to recall prior sensory inputs, but not simulate completely new ones.² In that case, seeing a color would teach her how to imagine seeing that color, but no amount of reading would teach her how to imagine seeing a color that hasn’t come in through her eyes.

To be concrete about it, suppose Mary is shown the color green. Now if someone asks her to imagine seeing a green leaf, she can more accurately place her brain in a state that would follow that event, because she can draw upon her new memory of green. We would say she has learned what it’s like to see green.

Of course, Mary knew in advance how her brain would react to seeing green. She knew the state her brain would be in afterwards, and she understood how it would store and access its memory of green. But just knowing about a brain state doesn’t give her the power to induce it. Even though Mary knew what types of brain states are capable of imagining seeing green, maybe the only way to reach such a state was to let green light into her eyes. In that case, all her reading would not have helped.³

With that, we have a reasonable explanation for Mary’s Room, and we were not tempted to leave our purely physical context. We probably made some wrong guesses about how Mary’s brain works, but that’s fine. The point is just that it’s possible for a purely physical Mary to learn something new by seeing color, which means Mary’s Room doesn’t undermine physical consciousness.

I now owe a slight apology to Frank Jackson, whom I previously quoted. I actually agree with the second half of his quote:

“Tell me everything physical there is to tell about what is going on in a living brain … you won’t have told me about the hurtfulness of pains, the itchiness of itches, pangs of jealousy.”

Like Mary trying to understand color, I doubt he could learn what those states are like by being told. But that’s a technical detail about the architecture of his brain. It doesn’t mean we must embrace magic and say things like this:

“I think there are certain features of bodily sensations especially, but also of certain perceptual experiences, which no amount of purely physical information includes.”

Throw Out Consciousness?

Given that so many people allege a non-material aspect to consciousness, and no such thing exists, it’s tempting to throw out the term consciousness entirely. We could say that feeling jealousy and seeing the color red are neural processes, and anyone who tries to claim more by injecting a mystically tinged word like consciousness is confused. I’ve even heard one person say, “I don’t believe in consciousness.”

I disagree with this framing. Our perceptions are fully explained by the laws of physics, but they’re not imaginary. We do experience thoughts and feelings, and that’s a fascinating condition that distinguishes us from most parts of the universe. This phenomenon deserves its own word, and consciousness captures the main idea.

That being said, while I think the word consciousness should stick around, a good 90% of the reverence surrounding it should be thrown out. Once you internalize the consequences of consciousness being purely physical, you realize that a lot of the discussion around it is over-the-top. People treat it as though it holds a more special place in the universe than it actually does.

For example, it should be universally understood that there will never be a natural way to quantify “amount of consciousness in a system,” in contrast with things like heat and entropy. Nor will there be a natural way to define consciousness that perfectly distinguishes between conscious and non-conscious systems. Those beliefs might make sense if consciousness was a distortion in some kind of ethereal field, since in that case you could measure how much the field was being distorted, or if it was being distorted at all. But a purely physical consciousness is a loose concept like friendship. Nobody expects the universe to give us a mathematical criterion for whether two people are friends, and it will not give us one for whether a block of matter is conscious.

There should also be no attempts made to link consciousness to fundamental physics. I once saw a physicist claim that certain particles alter their behavior based on whether they’ve been observed by a conscious entity. Even knowing nothing about physics, I was able to dismiss that claim immediately and with absolute certainty. Consciousness is a high-level process in the brain, and tiny particles do not care about it any more than they care about Alzheimer’s Disease.

Similarly, there is no reason to assume that the brain uses exotic physics to implement consciousness, above and beyond what is used for other bodily functions.

Finally, there should be no speculation that inanimate objects like tables or atoms may be conscious. We can see why humans evolved machinery related to consciousness: We benefit from being able to process sensory information, think about things, and be aware of the world around us. We can also see how the different machines in the brain contribute to consciousness by watching how our consciousness is affected when they’re damaged. But there’s no analogous evolutionary history or computing machinery in tables. To say that a table is conscious is like saying it’s secretly simulating games of Tic-Tac-Toe; there’s no reason it would be doing so and no clear mechanism by which it could. It may be possible to conclude that a table is simulating Tic-Tac-Toe games by viewing it through some pathological lens, but that is not a natural or useful way to interpret the situation.

I could continue this list, but we would be here for a while. Consciousness is a concept that provokes an endless stream of wrong and not-even-wrong ideas. I know that I’m not at all uncommon for having figured out the correct answer on consciousness, and that it has been evident to a lot of people from the time the issue was first discussed. But nevertheless, it’s one of those issues where the rest of the population is not receptive to logic, which means it will always generate controversy. I’m sure there will still be people writing versions of this essay in a hundred years.