The only thing that convinces me is that nobody knows. Next, with somewhat less conviction, comes the fact that nobody can ever know.
I, like most physicists, cognitive scientists and philosophers, believe that ‘naive realism’ is an illusion. Naive realists, which are the great majority of people, believe that they are in direct contact with their outside environment — which would mean that somehow their minds are exiting through their eyes and covering the outside reality, or, that the properties of outside reality are somehow entering their minds via sense organs and neural pathways. But it’s equally impossible to explain how the mind exits as it is to explain how the properties of the physical environment somehow “rip” themselves up from their substrate, entering and navigating inside my being through neuronal wires (like the optic nerve).
What i have reason to believe in is called ‘indirect realism’. If true, it means that everything that i’ve ever saw, touched, smelled, etc, was a property of my internal hologram. All the sceneries i’ve ever saw were internal VR-like representations happening within the confines of my skull. Organisms have been pressured into evolving internal hallucinations that map everything in their outside environment that is relevant for their survival. Across millions of years of evolution this internal hallucination has been constantly upgraded and fine tuned — organisms whose “map” wasn’t in accordance to the “territory” have simply died. This is why when i pick a stone with my hand and throw it towards an apple (even though all these three things are only an internal representation of the outside real things) this internal VR activity is just so coupled to my muscles that my outside physical hand really manages to throw the real physical rock towards the real physical apple. You can even recalibrate your VR machinery — for instance, there are experiments done where human and animal subjects are being mounted special glasses that turn the whole light-field upside-down. For the first week or so, the subjects see the world upside-down and struggle to navigate, but after the brain’s VR machinery has had sufficient interaction with the environment through muscle-action, it recalibrates itself and generates a normal right-side-up VR simulation (see youtube for mini-documentaries on the subject).
What’s known by us is called ‘phenomena’ (everything you see, feel, think, etc) and what’s outside and beyond this intimate realm is called ‘noumena’. About the nature of this ‘noumena’ there are many different speculations. Some say it’s the mind of God itself, others have more rational explanations but which are just as weird if you think about it. I personally like two of them:
The first says that the nature of ‘phenomena’ is exactly the same with the nature of the ‘noumena’, because they are continuous with each-other. And their nature is: a conscious fabric. My soul, as it were, is only a region of the noumena that is highly patterned and integrated, generating a complex entity. A brick, a chair or a computer, on the other hand, are not an entity — they’re just a collection of trillions and trillions of particles, “conscious pixels instead of an integrated conscious entity”. If you brake a chair, in reality you don’t brake an entity (a chair is just a functional entity) — it’s just clusters of atoms coming appart. If you brake a human, a cat or a bird, you’re braking an entity. Any conscious living being has three degrees of integration: 1) is functionally integrated (it’s a collection of different parts that collectively do something that separately do not), 2) is a “Kantian whole” (a type of integration where each part exists for and by means of the whole and the whole exists for and by means of the parts), and 3) is quantumly entangled (a quantum entanglement, no mater how many quantum systems are involved, is just one single unitary state). The 3rd degree seems impossible because within biological brains there is a very very high temperature which within femtoseconds brakes any entanglement (this is why quantum computers need to cool down its quntum systems to near absolute zero, in order to preserve the computationally meaningful entanglement). And yet, in the last years all sorts of evidences have appeared that meaningful quantum entanglements may be the case even within wet and hot biological beings. If our brain can somehow, almost miraculously, preserve these meaningful entanglements, then entanglement becomes science’s main possible explanation for consciousness. The main property of a conscious experience is that “it is one, whole, integrated experience”, and entanglement is the only thing known in physics that has this same general quality of oneness. In the words of philosopher David Pierce, when you go to sleep (deep sleep, not REM) your central nervous system’s entanglement decoheres into “mind dust”. If someone is hit in the head in such a way that the brain looses its ability to preserve entanglement, than you can beat that body with a baseball bat all you want, because there’s NO ONE entangled entity there, and there’s no ability to be ONE in the future either (unless it’s an operable problem). Note of warning: this description of entanglement is erroneous, but purposely so for the scope of simplicity; entanglement and decoherence are very subtle complex notions that can only be understood in the language of maths, not in the written word; more so, physics maintains that the whole universe is already entangled, thing that appears to go against this explanation, but the inconsistency is only a side effect of having to explain everything in simple words.
The second hypothesis maintains that the ‘phenomena’ realm is a phenomenal virtual-reality model generated by a noumenal outside machine-like organism (my body) to help itself maintain its structure within the noumenal world (navigating away from harm and towards energy sources). If this hypothesis is true then the “material” from which the ‘noumena’ (including my body) is made out from.. is of unknowable! All we know, and all we can ever know are the properties of the internal VR model. When someone asks something like “How does the outside look like?”, there is no answer because the question is absurd to begin with. “Looking” is a property of the VR models, there’s no “looking” outside of an internal model. Nobody can ever look at the noumena directly, without seeing it through a VR model — and as long as we’ll do that we’ll only see the model’s phenomenal properties. These internal model properties must be correlated with the outside noumenal properties (otherwise we won’t be able to correctly navigate the world and stay alive) but they’re not the same. There are philosophers and AI researchers saying that the outside noumenal world probably doesn’t even happen in a tridimensional space, this being only a property of our internal phenomenal space.
“So what actually “exists” outside of the nervous system?”
My belief is that we cannot ever know. But we must keep asking questions. Also, i think we must have immense gratitude and reverence towards the evolved esthetic of our phenomenal world. If you force yourself to look at your world knowing that it’s an VR simulation, you’ll find out sooner or later that you’ve lost some of life’s magic. I’ve been going through life for a couple of years like that and things definitely lost their charm. This doesn’t happen to everyone, there are philosophers of mind that find great mystery and excitement while seeing their world as a VR-like simulation. Also, in some Buddhist branches that cultivate the view that everything is a construction of mind (from the sense of touch, smell, colors, shapes, all the way to the sense of having a hand and being a self), they say that eventually, after one is firmly settled into knowing that they are a “hallucination living inside an illusion”, there is great freedom and joy to be experienced. I believe that, but in the same time i believe that the way in which a naive child sees the world is just as magic as any other way, including that of a Buddha.
