"To understand true reality and to know the true nature of the universe and human life, we must discard all artificial assumptions, doubt whatsoever can be doubted, and proceed on the basis of direct and indubitable knowledge. " (Kitaro Nishida: ‘The True Nature of Reality’)
Instead of dumping everything into the universal solvent of doubt why not just take as default what you perceive and if that disappoints you by not behaving as expected ‘come let me clutch thee I have thee not and yet I see thee still; move to the stage of ‘dagger of the mind’. Indeed this is the common sense way which in his next sentence he rejects as a merely conventional assumption.
"From the perspective of common sense, we think that things exist in the external world apart from consciousness and that in the back of consciousness there is something called the mind, which performs various functions."
Insoluble mysteries and the spawning of explanatory epicycles issue from this supposedly critical theory. You have started by assuming a mental approach rather than an experiential one when you espouse doubt as a starting point. Moreover you have cut yourself off from the whole animal kingdom out of which evolution issued. For them as well as for us the brain is an organ of action and reaction replete with routines that do no require thought.
