β Scribed by Susan Leigh Anderson
No coin nor oath required. For personal study only.
Recently there has been some interest among philosophers in a physiological phenomenon known as the 'split-brain '1 -a phenomenon in which the individual's corpus callosum, which normally connects the two hemispheres of the brain, has been severed (an effective technique for stopping the spreading of seizures from one hemisphere to the other in certain severe and otherwise untreatable cases of epilepsy) or is missing due to a congenital factor in the development of the individual. What has interested philosophers is the problem it presents concerning the issue of personal identity. Roger W.
Sperry of the California Institute of Technology, the man largely responsible for the experiments that have been performed on split-brain patients to determine the effect the severing of, or the absence of, the corpus callosum has on these individuals, remarks that In the surgically separated state, the two hemispheres appear to be independently and often simultaneously coconscious, each quite oblivious of the opposite hemisphere and also of the incompleteness of its own awareness. 2
These remarkable indications of a doubling of the psychic machinery in the brain raise a number of new questions ... There are also many intriguing philosophical implications. When the brain is bisected, we see two separate 'selves' -essentially a divided organism with two mental units, each with its own memories and its own willcompeting for control over the organism) Whether or not one agrees with the interpretation Sperry seems to have put forth -namely that there are two persons associated with one body, even at a single moment in time, in a split-brain case -it cannot be denied that it is a possible interpretation and it deserves consideration.
There is another, similar phenomenon which philosophers writing on the subject of personal identity have largely ignored. This is the psychological phenomenon of multiple personality. I shall attempt to show, in section one of this paper, that in connection with this phenomenon, too, the'question can be raised as to whether there is one or more than one person associated with a body even at a single moment in time.
The consequence of merely asking this question, I believe, is that we must Philosophical Studies 30 (1976) 1-10.
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