(Extra-Physical) Consciousness Is An Illusion

There is no extra-physical aspect to consciousness. There is a thing called consciousness, but it is a fuzzy human classification of configurations of atoms, not some fundamental property of the universe. You have to draw some lines somewhere between more-conscious, less-conscious and unconscious beings, and there is no objectively correct way of doing so, in the same way that there is no objectively correct classification of what configurations of atoms constitute a table (credit to Brian Tomasik for this analogy).

To make this part more explicit: consciousness is not merely determined by the physical world either, “supervening on” the physical world, as the philosophers like to say. It just is a part of the physical world.

My ideas here primarily come from Eliezer Yudkowsky on p-Zombies. Eliezer however does not, as far as I can tell, take the logic to its conclusion and reject extra-physical consciousness altogether. I don’t understand why he doesn’t, but he doesn’t. I thought it would be helpful to put it explicitly in those terms, particularly because I have found that many (most?) people in effective altruism circles have never had these arguments presented before in this way.

In this piece I’m going to use the term extra-physical consciousness to mean any definition of consciousness that is not simply a fuzzy human classification of the physical word. The philosophers like to use the term phenomenal consciousness or qualia, but I’d like to keep the amount of philosophical jargon to the minimum so I’m going to stick to extra-physical consciousness.

Here is the basic argument against the existence of extra-physical consciousness. Why do we think we’re conscious in some extra-physical sense? Put differently: what causes the neurons in the knowledge-processing part of our brain to think that we’re conscious in some extra-physical sense? Whatever that is, that is consciousness.

And that thing isn’t, as far as we can tell, some extra-physical attribute. Physics is causally closed. There is no special consciousness variable that causes us to think about consciousness. Therefore, consciousness cannot be some extra-physical attribute. Extra-physical consciousness is an illusion.

That’s the short version of the argument. Here is the long(ish) version.

The Universe is Causally Closed

The first premise of this argument is that the universe is causally closed. That is, everything is determined by the physical equations we have, and there is no consciousness variable anywhere there.

I won’t go too deep into this point since I’m not a physicist and since I think this is a broadly accepted claim. The one thing I do want to talk about is quantum mechanics, since this seems to be a common counterargument. Quantum mechanics cannot be where consciousness has a causal effect on the world.

For one thing, quantum mechanics is a set of equations that give us precise probabilities of seeing certain observations. It does not say that given certain conditions, we don’t know what’s going to happen, where maybe consciousness could affect what happens. If you posit that consciousness affects the probabilities of certain quantum observations, you should be able to design an experiment to prove that. It’s just not true.

For another, we understand the physics involved in the brain very well and there is just very little quantum mechanics involved. This according to Scott Aaronson, who says this is the consensus of physicists and neuroscientists.

To Know Something, It Must Have Causal Effect On Us*

Every single concept in the world fits in one of three categories:

1. It is external to our brain but has causal effect on our brain that our neurons could pick up.

2. It is implicitly embedded in our brain’s neurons

3. It is fake. Either we know it’s fake, in which case it’s called fiction, or we think it’s real, in which case it’s called an illusion. Extra-physical consciousness is the latter category.

To see the 1/3 distinction, I think it’s helpful to think about something else causally inactive. Suppose that I postulate the existence of a quality called Gility. It has no causal effect on the world, but it’s a quality that most kitchen utensils possess. How do I know that Gility exists? I’m not sure, I just have this strong intuition every time I stare at a fork or knife.

So you might investigate Gility further, seeing if forks and knives have any properties that I could be picking up on. But try and try, you cannot find anything. We understand the physics of forks and knives very well, and there is nothing there resembling Gility. There’s no possible way that Gility could be the cause of the neurons in the knowledge-processing part of our brain firing in the way that corresponds to us thinking about Gility. So it’s obvious that I can’t really know about Gility.

That’s how you should think about consciousness. Try and try, you cannot find any evidence that consciousness has any effect on the world that people could be picking up. We understand the physics of neurons very well, and there is nothing there with any sort of extra-physical attribute.

Now, to see why consciousness can’t fall into the second bucket. Extra-physical consciousness just isn’t implicitly embedded in our brain. You could model our entire brain without any reference to extra-physical consciousness. Extra-physical consciousness is, by definition, a supplemental phenomenon, existing additionally and beyond our brains.

“The One Thing I Know For Certain”

The standard counter-argument to illusionism is that extra-physical consciousness is the one thing in the world that I know for certain. If your theory rejects extra-physical consciousness, people say, it must be wrong.

To counter this, I’d like to make an analogy to free will. Most people in effective altruism circles reject the concept of free will in an extra-physical sense. Consciousness has no causal effect on our actions in the world. We may feel intuitively that we have free will, but that is merely an illusion; we are at the end of the day just executing neural algorithms.

You should think the same way about consciousness. It has no causal effect on the world, so we can have no knowledge of it. We may have very strong intuitions in favor of extra-physical consciousness, but if those intuitions are provably false, we have to reject them, the same way we have to reject free will in some extra-physical sense.

A Model for Reworking Your Intuition

Take any sentence involving the concept consciousness in some extra-physical sense. You can understand this sentence just the same with consciousness as a purely physical classification.

• “This apple looks red to me”→ The apple reflects light waves of a certain wavelength to the human retina, which get transmitted to the human brain in ways that it associates with other objects of the same wavelength

• “Stubbing my toe really hurts”→ When my toe hits a surface hard it transmits an electrical signal to my brain which your brain associates with other similar past signals and provokes the brain neurons to order some actions that reduce the sensation going forward.

This feels extremely weird when you first encounter it. That’s not what I mean when I say the apple looks red! I mean that there is some extra-physical quality to the redness, existing beyond the wavelength of the light!

But the point is that you can interpret it in my illusionist way too, and the sentences make just as much sense. It would be a much bigger problem for extra-physical consciousness if there were at least one sentence that you could only understand in terms of extra-physical consciousness. But there isn’t.

If you want to try to rework your intuitions, you can try reinterpreting every sentence you read the illusionist way. It’s a good exercise.

Why Do We Think We’re Extra-Physically Conscious?

This still leaves open the big question of why we’re conscious in an extra-physical sense. I don’t have a good answer. My understanding is that the empirical evidence on the neural correlate of consciousness is really uncertain, and even once you have that it’ll still be difficult to go from there to an explanation of why we think we’re extra-physically conscious.

But just to be clear: I don’t need an explanation for why you’re conscious for the argument in this piece to hold. I’m not saying “clearly the reason you think you’re conscious is xyz, not that you’re actually conscious“. I’m saying that the reason you’re conscious, whatever it is, cannot be extra-physical consciousness.