When that theory is isolated from known facts, it is likely not to be productive.

When philosophers try to understand consciousness, much of what they claim is not conceptual analysis at all, though it may be shopped under that description.

When that theory is isolated from known facts, it is likely not to be productive.

Given how long philosophers have been at conceptual analysis (I mean the 20th century stuff), and how many have been doing it, what can we say are the two most important concept results of all that effort?

It is surely important that the differences between coma, deep sleep, being under anesthesia, on the one hand, and being alert on the other, all involve changes in the brain.

If you want to understand the nature of something, to find out the truth, that is one thing. If you want to play semantics, make up wild thought 'experiments', that is another thing. I am not so interested in the latter, though I do appreciate that it can be fun, however unproductive.

Early studies of sleep and dreaming were crucially dependent on waking subjects up during sleep to find out whether they are dreaming or not. Using that strategy, it was found that when the eyes are rapidly moving (REM sleep) people are usually dreaming; when the eyes are not moving, there may be some mentation, but little in the way of visually rich dreams.