When I said that consciousness "waxes and wanes" throughout our lives, that is what I was saying--that there are states of partial consciousness. Do you consider yourself fully conscious when you are dreaming? I certainly do not. Consciousness is a very slippery subject. We know, for example, that a brain can host more than one consciousness. In cases where the
corpus callosum is severed, scientists have conclusively demonstrated that there are two separate consciousnesses that can operate independently of each other. So it is sometimes said that consciousness is something of an illusion. It is probably more accurate to think of a mind as a complex interaction between many levels of consciousness.
Absolute proof is not a requirement. Reasonable proof is. We have reasonable proof that REM sleep is associated with dreams and non-REM sleep is associated with much lower levels of awareness. Usually, people under general anesthesia are completely unconscious.
Not well said. It is a platitude to claim that we do not understand the relationship between the mind and the brain. There are lots of things we understand about it. One of those things is very clearly that one's state of consciousness is fully dependent on the physical state of the brain. We can measure the various states of sleep in terms of physical changes in the brain. We can use MRI technology to take pictures of different patterns of thought. But we cannot yet associate those patterns with all the complex chains of associations that represent thought. We still have a lot to learn, even though we know beyond reasonable doubt that consciousness correlates with physical changes in a brain.
Rubbish. I am not a radical reductionist in the sense that you are talking about here. There is a difference between explaining a system in terms of its component parts and the
emergence of the system because of the complex interaction of its components. The mind is an emergent effect of a living brain. It is not the same kind of thing as a physical brain.