Li asked:

If a person is sliced symmetrically in half instantaneously about the vertical axis, before that person's
inevitable death, where would his consciousness lie? Since the brain is also symmetrically divided
perfectly, would it be possible to have two entities of that person in that moment? A "logical" and a
"creative" version of that person, so to speak?

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Your question presupposes that the conscious "I" is somehow independent of the brain in such a
manner that it could function with only half of one. I challenge this assumption as a position for which
we have no evidence. So my answer would be that the consciousness would die in the instant that
the brain was divided.

There is a significant amount of evidence, to which you make passing reference, that the two halves
of the cerebrum contribute different sorts of mental functions to consciousness. But there is no
evidence that consciousness could successfully function without either set of those functions.

There is evidence from victims of severe schizophrenia, that the corpus callosum can be severed
without impairing consciousness. The corpus callosum is the structure deep in the brain that connects
the right and left hemispheres of the cerebrum. But that is not the only pathway that connects the two
halves of the brain. There is more to the brain than the cerebrum. Patients who have undergone such
treatment have never displayed dual personalities. Rather they have demonstrated that there must be
alternate pathways for information to flow from one side of the cerebrum to the other.

There is also evidence from people with various sorts of brain damage, that consciousness can get
along reasonably well without major portions of the brain. But none of that evidence would suggest
that one half of a functioning consciousness could suddenly get along without the other. Survivors of
major brain-cell losses take years to even partially recover. All evidence of this sort would suggest
that loosing any piece of the brain causes severe mental problems for the unfortunate victim. Loosing
one-half of the brain-cells would undoubtedly be instantly fatal.

For more discussion of this issue, in greater depth and with greater expertise than I can muster here,
I refer you to Consciousness Explainedby Daniel C. Dennett.

Stuart Burns

Well actually your experiment has been done. There are people with very severe (i.e., virtually
continuous) epilepsy who, in order to stop the spread of the neural discharges over their brain, have
surgery in which the two halves of their brain are separated, by cutting the connection called the
corpus callosum. This results in "split-brain" people, who do in fact seem to have two
consciousnesses in one body. There is a huge literature on split-brain patients... just go look it up.
The "logic" and "creative" dichotomy is not really the issue; the major dichotomy is between verbal
and non-verbal thinking and expression, since the verbal areas are on the left side of the brain. This
makes communicating with the non-verbal personality difficult, but possible.

Steven Ravett Brown

One problem: the brain is not functionallysymmetrical. But in any case, your version of a logical and
creative brain is so old and obsolete now that I urgently recommend you update your reading. Try, for
example, Eccles' Evolution of the Brain, Creation of the Self.

Jürgen Lawrenz

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