Please pardon my layman's language as I am not a student of philosophy.
I was talking to a friend who has read Advaita Philosophy of Shankara in-depth. He iterated the fundamental theory of this tradition as:
You cannot know whether you are dreaming or awake. A dream is felt as a dream only after "awakening". There is yet another state, state of deep sleep, wherein the self and world both cease to exist. If you say 'I was in deep sleep', it is just what others would have guessed looking at you; not yours (you were 'absent'). So, which of these states is your original state? If you believe the state of awakening is the state, where were you while dreaming? Surely a king can have a dream of becoming a destitute and the other way round, can't he?
But you have been 'witnessing' all these states. That 'witness' is the ultimate truth or 'parabrahma'.
I tried to counter this argument with these questions: 1. If I were absent at the time of deep sleep, how could anybody wake me up by force? If they could (of course!), that would mean an apparatus of consciousness was present throughout my sleep. So, the total absence of consciousness is not valid.
I distinguish dreams and awakening with a simple heuristic: whatever has continuity is awakening and whatever is abrupt, is a dream. When I wake up in the morning I just resume my life where I left it.
It's sure that we are not aware while dreaming, but we tend to remember these dreams. If we don't remember, we would never know if we were dreaming. That means, consciousness was still present in some diminished way at the time of dreaming.
At least some dreams are based on the feelings of the conscious mind and past experience. I dream of my deceased grandmother singing a song for me (I am a kid there). How do dreams know I have a grandmother and she could sing that song? Surely, there is some connection, isn't it?
My friend was curt enough to sweep aside these questions by saying I am too much 'obsessed' with the state of awakening. He asked me to think, for a while, if we were discussing all this in dream.
A certain trend goes to the extent of saying this line of thought is the ultimate philosophy and denigrates the 'westerners' for completely missing it. They could see no philosophy department in the west terribly interested in Advaita (apart from historical and geographical curiosity).
My question is, what do you make out of this argument? I read somewhere that Descartes thought on similar line. Please pardon my tale and let me know what is the correct way of looking at it.