X-Message-Number: 25333
Date: Wed, 15 Dec 2004 16:16:04 -0800
Subject: Split Brains
From: <>

Since so many people have brought up split brains, I have decided 
to address this issue once and for all. Until now I have ignored 
the issue because it is not directly related to personal survival, 
which is my main concern. However, since many imagine split brain 
research represents a refutation of my views, I have decided to 
discuss this now.

First, let me make something clear. Severing the corpus callosum 
does not produce two brains, but rather, it interferes with the 
internal communication of a single brain. The two hemispheres of 
the brain are still connected via the brain stem, and I recall 
reading that primal emotions (at the least) are still shared 
between the hemispheres.

It is not known whether the brain could survive if actually split 
down the middle (brain stem and all); the result could very well 
produce a non-functional brain. It seems like an experiment 
unlikely to happen any time soon because of the practical and moral 

That said, I will now address the issue of survival in split 

If a doctor cut your corpus callosum while you were awake, but did 
so slowly, and you exhibited signs of consciousness before, during, 
and after the surgery, then according to my view, you definitely 
would have survived.

Surely, after such an operation you would be different. Your range 
of experiences and way of thinking would be altered, but you would 
have survived, in the most fundamental sense of the word. Indeed, 
even while the operation were in progress, you could theoretically 
give a detailed report of the ways in which your inner life were 

On the other hand, if after every such experiment, the subject lost 
consciousness, and it did not return until extensive rewiring of 
the brain had occurred, then it would be *possible* you did not 
survive the experiment. However, I dismiss this possibility on 
grounds that such rewiring would take a long time and there appears 
to be no evolutionary pressure to develop such a rewiring 
mechanism. Therefore, I consider everyone who has undergone a split 
corpus callosum to have survived, even if I would not elect for 
such an operation myself.

Now for a split brain patient, are there TWO QE's, or just one?

I have said before, and I say again, I cannot know how many QE's 
are in my brain RIGHT NOW. I can only know about ME, my own 
subjective inner-life. If there are other 'inner-lives' in my brain 
or in the universe at large, I cannot know for certain; I can at 
best infer their existence (say, in the case of 'other minds') from 
external behavior. I can know only about me---'me' being the one 
whose thoughts are being communicated to you now via this message. 
If there are other selves inside of me, they have no way of 
'getting out' and making contact with the outside world.

Before or after a split brain surgery, at all times and in all 
cases, there is exactly one of me (asuming I am not destroyed). 
There can never be two of me inside my brain. There may be a 
million SELVES inside my brain, each with their own subjective 
inner lives, but there is exactly one of ME.

I am unified in the sense that, there are many different kinds of 
perceived changes, ranging from emotion to visual to auditory to 
mental, and I experience them all; at the center of this diversity 
of experience is a mechanism that enables consciousness, which at 
the very least involves a short-term 'memory'---the 'imaging' of an 
aspect of the external world, with time for reflection on that 
imaging, which somehow creates my sense of experience.

Now as it so happens, I do not believe the brain contains more than 
one self. I think it contains just one---which is me. And if it 
does contain more than one self, unless these other selves have a 
means of communicating their experience to the world (or unless we 
disover the exact mechanism by which experience is possible), we 
will never know about their existence. In any case, my concern for 
survival is all about ME---i.e. about one self, one subjective 
inner life, the one somehow making his subjective inner life known 
to you now.

Is it possible that splitting the corpus callosum results in two 
selves, one of which is me, and one of which isn't? I am not sure 
of the answer to this question. I don't think so, but I could be 
wrong. In any case, it doesn't alter my views on personal survival.

Here are my reasons (such as they are) why I think there is only 
one QE, even in the case of a split brain.

1. Remember that even a 'split brain' is *one* brain, inextricably 
linked at the base, through which some measure of communication 
*does* occur. It is misleading to describe a split brain patient as 
having two brains, because it simply isn't true.

2. Based on the research that has been done, I would tend to say 
that the qualia experiencer is primarily in the left (and possibly 
base) of the brain. Indeed, if you talk to a split brain patient 
about consciousness, they (i.e. their left hemisphere, which is 
responsible for language processing and speech) will say they are 
conscious and will readily discuss their experience of qualia. But 
the right hemisphere, in the few cases where it is actually capable 
of communication (via writing notes), cannot discuss such complex 
things, but is limited to the simplest of constructs, usually 
single words or patterns of oft-repeated phrases. Some people will 
say this doesn't mean the right hemisphere doesn't experience 
qualia, just that it can't talk about it due to lack of skill. 
Well, that might be true, but how could we know such a thing with 
present day technology?

3. Think of all the things you do that are unconcious. For example, 
when you are listening to a conversation in your native tongue, it 
is impossible to successfuly try not to understand what they are 
saying. You understand automatically; the comprehension process 
isn't a part of your conscious life. You experience the qualia of 
sound, but the comprehension of that sound is a skill programmed 
into your brain, over which you have no conscious control. 
Similarly, when you sign your name or type a word into your 
keyboard or reach out for a pen that someone hands you, your brain 
just does these things automatically. In fact, even when you speak 
a sentence, it is as if the words are appearing in your mind; you 
have an experience of them, but it is not as if the experience is 
what generates the words. In some sense, the words are generated 
and you experience them.

From these observations, I would have to say that the brain is 
capable of extremely complex behavior, and that the existence of 
such behavior complex does not imply the behavior is a result of 
experience of qualia---in many (perhaps most) cases, it is not. So 
the fact that the right hemisphere can perform some complex tasks, 
does not imply it has a subjective inner life that is separate from 
the left.

I hope this clarifies my views.

Best Regards,

Richard B. R.

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