1.) Medical science and neuroscience does not fully understand the human brain, instead it uses theories that reflects on relevant data from research.
Irrelevant. We understand enough to accurately give accounting of human consciousness.
2.) If you cannot prove the spirit exists, you also cannot prove it doesn't exists either regardless of the brain being active or not.
And as I said, if something cannot be proven to exist, the default assumption is one of non-belief. It's not my job, or that of anyone else to prove non-existence, it is the job of the ones making the positive claim to prove that it does. Saying something exists, or might exist without evidence is pointless.
If we were to engage in belief about everything which hasn't proven to not exist, we'd have more stuff to believe in than our brains are capable of managing (everything from goblins and unicorns, to aliens and Egyptian space-travelers).
My point was that, if your definition of spirit doesn't entail consciousness, I would say that the idea of a spirit seems rather useless. If spirit entails consciousness, then since consciousness ends at destruction of brain-activity, then spirits don't survive our death, which is another property people usually ascribe to spirits.
3.) X implies Z, Z is undefined and remains unknown therefore X is also unknown.
This is true. I never said anything to imply anything else, I simply stated the rule as is it in formal logic. If you concede that Z is undefined and therefore unknown, then no argument can be made about Z because that would be tantamount to committing the fallacy known as argument from ignorance.
If you haven't decided what Z is supposed to be, you cannot investigate it, and therefore are not at liberty to say anything about it, least of all whether it exists or not.
Here is a theory : What if the human body is a vessel for the spirit to reside, a shell. And what if a spirit is the sum total of all our knowledge and experience combined in the form of consciousness, including our past lives which defines our soul being. Without our brain, our soul cannot operate the body. Just a theory, but try using it with that formula you made and it might make more sense.
Our experience and knowledge is data accumulated through consciousness. Experience and knowledge cannot exist without consciousness and the brain(or some sort of computer to maintain it). Again, this is something we know through modern science dealing with the brain.
We know that it's possible to break down memory without removing a persons ability to be conscious. Memory-loss and/or false memories are examples of this.
Similarly, memory can be retained even if we lose consciousness at some times, or even if our conscious faculties are impaired, such as loss of our senses, or downgraded cognitive abilities.
Yes, our body is a vessel for our mind. That's true even in the most basic physical sense. However, I thought the point about spirits in most people's minds is that spirits go beyond the physical body, and can exist without it, while retaining some sort of identity of the being it came from or resided within?
This seems highly unlikely, or even impossible, considering that all the stuff with which we usually relate to the spirit can be influenced and broken down prior to death through external stimuli to the physical body.
That's my point here.
