the full state of our brain is not known to our consciousness, which appears to be a summarization process which compresses state from across the brain.

there is nothing which keeps there from being a second, identical process lurking in the unsummarized regions, mute and alone.

this is not an entirely hypothetical state. the octopus brain does not have proprioception and has only a limited olfactory sense: that work is delegated to the ganglia at the base of each arm, which communicate with the "brain" through relatively narrow-bandwidth channels.

we know that only half a brain is necessary to operate the human body. perform a hemispherectomy early enough, and the brain unaccountably compensates, resulting in an adult with only a slightly reduced IQ.

but hemispherectomy is not the only way we surgically alter the brain.

in a corpus callostomy, white matter bridging the two hemispheres is cut, substantially reducing the bandwidth between them. the brain then loses its ability to conduct a whole-brain state summary.

the right brain typically cannot speak. a patient with a callostomy cannot speak about things they see with only their nondominant eye.

but in alien hand syndrome, which often follows a callostomy, one arm -- typically the one opposite the unspeaking lobe -- acts on its own.

one would imagine that both sides summarize similarly, and would not disagree. this makes sense. before the cut, they were the same person.

but alien hand syndrome seems like it indicates that there can still be substantial motivational difference between hemispheres.

and, again, this seems to be a consequence of lateralization: it is possible to separately anaesthetize the lobes of the brain by directly catheterizing the communicating arteries.

the left brain, alone, is melancholic. the right brain is typically nonverbal but ebullient.

so we know that it is at least possible for there to be two asynchronous but linked consciousnesses in the same body. anyway, i am finally getting to my point, which is the following:

in Rasmussen Syndrome, a developmental disorder where one hemisphere enlarges and becomes seizure-prone, the typical treatment is to sever one hemisphere from the other -- just the nerves, not the blood supply -- and leave it alone.

i don't think we should do this.