[mistermann]

> That is a very big assumption -that brains have conscious and subconscious levels that are good and bad at different things- that needs to be itself proved, before it can be used to support any other line of inquiry.

Does this assumption itself need to be proven?

Besides, it's not true: you can simply define it as an assumption within a thought experiment and proceed merrily along, or you can just not bother to consider whether one's premises are true in the first place, and proceed merrily along.

The second option tends to be more popular in my experience, perhaps because it is so much easier, and perhaps for some other reasons also.