I’ve pulled a few comments out of this thread to illustrate my argument.
Q: “How would you describe the 'ethereal' parts of yourself?”
A: “… soul and spirit … 5 or 6 different bodies …”
In my opinion, this idea of spirit, ethereal parts, soul, etc. comes from the commonplace experience of the two apparent worlds: the ‘physical’, shared outside and the ‘mental’, personal inside. You can’t see my thoughts or feel my emotions and even if you use every available technology to probe my brain (more of this later) all you will see are electrical or chemical signatures which may correlate, more or less, to my inner experience.
“ … we are a combination of many different aspects, ideas and experiences, but they are all contained in the one physical body, and that’s a fact whether we think of them differently or not.”
This is a sort of materialist circular logic. There is no evidence that our experiences or ideas occur inside a physical body. This assumption comes from the idea that whatever I am lives somewhere inside my head, probably in the brain, but that idea is only an inference. In fact, the body, whatever it is, exists inside our experience.
To illustrate that there is only experience and inference it is useful to see if you can recall any dream or maybe try to imagine being immersed in a virtual reality. In the latter, current technology allows the simulation of sight, sound and motion. It is not hard to imagine that taste, smell and other sensations could be created in future evolutions of this technology. Dreams are even more sophisticated. With the exception of lucid dreamers we do not know that we are dreaming until after the fact. Only when we wake do we realise the experience was a dream even if it flew in the face of logic and physics. While it was happening we were convinced and absorbed.
It is a common theme in science fiction and even popular science that one could be living inside a simulation. The nature of a simulation is that it is an illusion; nothing is what it seems to be. In your night time dream you can live in a world all of your own imagining and interact with any number of people. In fact, if you’ve ever studied your dreams you might realise that you could even be a different character from the one you are in waking life while still being ‘me’.
The purpose of this digression into dreams and simulations was to point out that ideas, and the perceptions and sensations which tell us about the world and body are all a part of a single, undivided experience. Even ideas that there are different aspects to our life – internal or external, physical versus mental - are inferences which are not justified by a sceptical inquiry into our immediate experience.
Returning to the idea that probing the brain can tell us anything about experience, all this can ever show us is correlation. No chemical or electrical signature in the brain can explain the experience of the colour red or the taste of cheese. Even if there is consistent coincidence of the measurement and the experience there is not a single piece of evidence to show how the one could lead to the other.
*Too little value is given to philosophy these days. David Hume, considered by many to be the greatest philosopher to write in the English language, demonstrated in the 18th Century that we cannot demonstrate either any real connection between cause and effect or that there is any substance to the world. Of course, science couldn’t operate without these assumptions but that doesn’t mean that they’re right.