> Why we should live in such a universe is a good question, but I don’t see how that can be answered now.

His last point here is salient. Much like the various interpretations of quantum mechanics, any theories of consciousness are untestable. But my problem with "consciousness" is that it's not even a well-defined concept. Suppose I replace all occurrences of "consciousness" in that article with the word "qualgma". It makes just as much sense.

Gravity, electrons, and energy are all concepts that are defined to exist as the manifestation of certain physical phenomena that can be modeled and predicted with mathematical equations. These words are just English simplifications of the equations.

But consciousness has no such analogue. It's just a term that people throw around when they talk about the brain. I believe that over time, it has started to acquire a more well-defined meaning -- something along the lines of "the emergent properties of the brain's activity resulting from lower-level processes". This is similar to how a human body is just the emergent result of many atomic interactions. This version of consciousness can be modeled, theorized about, and tested experimentally. There's nothing magical about. As the brain's neural circuitry becomes better understood, you could say consciousness is a simplified model that still has good predictive capability.

However, I would also like to focus on a much more interesting topic in the article:

> My consciousness is an undeniable fact. One can only infer facts about the universe, such as physics, indirectly, but the one thing I’m utterly certain of is that I’m conscious.

I believe Koch is conflating two distinct concepts. If we take the definition of consciousness as the predictive modeling of the brain, then this is something totally different than what he's talking about here. Let me alter his quote:

> That I experience my existence is an undeniable fact. One can only infer facts about the universe, such as physics, indirectly, but the one thing I’m utterly certain of is that I am experiencing existence.

It's really astonishing to me that he words it this way, because independently I have thought almost exactly the same thing for a long time.

I've often struggled to put this notion into words, but let me try it in a new way with an analogy. Suppose you see an apple floating in front of you. You tell other people "Look at this apple!" But they just go "What apple?" So, you try to get crafty. You take a picture of the apple with a digital camera. But when you show people the photo on the computer, they still see no apple. So you zoom in on the pixels and start copying the RGB values for each one by hand onto paper. "Look, this value is 237!" you say. And you sit down with a friend, and start calling each and every pixel's values out as he puts them in manually into his image editing program. When he's does, you say "Ha! Look, there's my apple, right on your screen! And you put it in there yourself!" But he stares at you quizzically, and says, "I still see no apple; just an empty table." And no matter what kind of tricky experimental method you try to come up with to get everyone else to understand the concept of this apple that's always floating in front of you, every attempt to catch it produces a representation of the apple for you and nothing for everyone else.

It's frustrating because the people you tell about the apple say "Well, you have provided no testable predictions, and no data that can be independently verified by everyone else in society. Clearly your apple doesn't exist." But it does! You know it does! In fact, out of everything that constitutes reality, the floating apple is the one thing you're most sure of. Frustrated, you walk around thinking you're crazy until one day someone says, "Well, I don't see an apple floating in front of you, but do you see the orange floating in front of me?" Which, of course, you don't.

Now replace "apple" with "the fact that I am experiencing my own existence". It's an element of reality that is only apparent to you on a personal level, and since it isn't testable by other people, it is not a part of their reality, and thus does not exist as far as they are concerned. And thus it's not science. Yet even though it's not science, it is the one thing in life I am most certain of. My five senses could all be faked with advanced enough neural circuitry. I could be in an entirely simulated environment, with entirely simulated physics. So when I order things in probability of how likely they are to be an illusion, experiencing existing falls at the lowest probability. In fact, you could strip me of all my senses and put my brain in a vat, and as long as it's running, I'm still experiencing existence.

If the idea bothers you that things might exist that are incapable of being verified consensually by society, look at this image of all the particle interactions (so far discovered): http://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Ele...

If you'll notice, gluons "hang on" to the rest of the particles by merely one interaction. If this interaction was not present, as far as positivists are concerned, then gluons don't exist. But that seems entirely unreasonable to me. I could imagine plenty of particles that could "exist" that simply don't have an interaction with the ones in the standard model that constitute our reality.

Anyway, this is probably the most bizarre post I've ever written on HN, but hopefully what I'm trying to convey "clicks" for some people.