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 implications. That said, I will now address the issue of survival in split brains. 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 changing. 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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=25333