The following is an argument for an odd conclusion: That we are not merely one mind in one body, but one of two minds in one body. Normally people tend to think of themselves as being alone, but it seems as though findings in empirical science suggest that there is more to the brain than we would like to think. Here's a helpful video that illustrates what I am talking about:



People who have had their brains split in two (their corpus callosum severed) have been known to exhibit some very strange behaviour. Under certain experimental situations where split-brain subjects are shown certain images on the left side of their vision, they do not report ever seeing anything in their visual field, and yet their hands may be able to draw out what they claim to not see. In other situations, a person may also be shown a funny image in their peripheral vision, causing them to laugh but not be able to explain why they are laughing.

In addition, in more extreme cases, people who suffer from alien hand syndrome may even find themselves fighthing with themselves, or at least, their own hands. They may reach for objects that they didn't consciously want to reach out for and they may have to restrain themselves in such cases. In these situations the people who are afflicted are also known to have had severed or at least damaged corpus callosums as well.

So what are we to make of this? Let us consider some of the possible explanations that are available:

One Mind, Scattered Experiences: The first suggestion states that there is only one mind, but that the contents of their consciousness are scattered and disunified. This means that a single conscious subject will find themselves at any time to be having an experience of one set of experiences that feels alone while having another that similarly feels that way as well, despite them being had together. In the experiments above, subjects may see red in their entire visual field, as well as green in their entire visual field, or they may find themselves wanting and not wanting to reach for an object simultaneously. This approach pushes ahead with the One Mind view even in the situations above. The problem with this view though is that it sounds impossible, as the requires that one conscious subject has an incompatible set of experiences. What would it possibly be like to see a red patch and a green patch in the exact same region of your vision for instance? Or two experiences alongside one another in one experience when both feel like they are had alone? It would be like imagining a square circle, a married bachelor, or (literally in this case) a red-green ball, which is to say it is an impossible experience.

One Mind, One Hemisphere: There have been explanations which try to limit the mind to one hemisphere in the brain. It can be either of the hemispheres but generally people seem to favour the left hemisphere as that is the hemisphere that is capable of speech. This view, unlike the former, is not strictly impossible as it gives a coherent view of experience for the conscious subject by taking only one side of the story in each of those cases as the one that is had by the conscious mind. However this proposal seems problematic as well, as both hemispheres are equally functional post severing of the corpus callosum. Thus it doesn't seem as though we should say that one of them suddenly loses it's mind. Even if we are forced to say which one is which, it doesn't seem like we have any means for favouring one hemisphere over the other either. Although both hemispheres serve different functions, they are both equally complicated in their own right. So given the similar complexity in both hemispheres it is hard to believe that only one retains a mind while the other does not.

One Mind that splits into Two Minds under certain conditions: According to this option, there is one mind that operates in normal day to day activities, but splits into two minds under certain situations such as the ones mentioned above. This concedes that there are two minds involved in the situations above, but retains the view that there is one mind in normal everyday situations. I am not a fan of this view either since it seems a bit much to say that a new mind is literally created when a split brain subject is subject to certain situations where two minds are necessary, only to destroy that mind when that situation passes. In addition, such a proposal does sound contrived to me as well.

Two Minds: At last, we are left with the option that I have been trying to lead to all this time. The proposal here is that there are two minds at play within the split-brain individual, each of which represent one hemisphere in the brain. One is able to see the things on the left side of their vision while the other sees nothing there and they react accordingly. One may want to reach out for an object, while another may disagree with that desire. The notion that there are two minds in contrast, though strange, is not inherently implausible. It allows us to make sense of the split brain cases without creating impossible experiences, privileging one hemisphere, or making the dual minds a temporary case. As far as I see it this seems to be the commonly accepted view, given that other explanations that try to endorse one mind are known to end up with serious problems as mentioned above.

Of course, this story is usually intended to be reserved for people who have severed corpus callosums to begin with, and not regular people like you or me. As some may argue, we would normally have one mind, but when we have our brains split, we acquire a new mind in the process. Although one may say that, I don't believe that this duality is just a unique feature for severed brains alone.

In a way, it is hard for me to believe that the act of cutting the corpus callosum would lead to such a radical change as an addition of a new mind. For consider a ship of theseus style case where one tries to sever the corpus callosum bit by bit. When does the addition occur; is there a step in the process that determines when one mind becomes two? What happens to the old mind? Is it going to cease to exist or does it become one of the hemispheres? Given these considerations, it seems easier to say that we have two minds all of the time and sounds alot more simpler by comparison.

So this leaves us with the final option, and the one that I have been trying to argue for: That the brain has two minds all along! There is no conceptual problem in envisioning two minds in one body, and the worst problem seems to be in explaining how split brain individuals function normally most of the time despite their severed corpus callosum. And although I do not deny the strangeness of this view, it isn't all that surprising when we understand how the brain operates. In fact a deeper understanding of the brain shows that this idea isn't so far fetched at all. As neuroscientists study the brain more, they have discovered that both hemispheres are quite autonomous, capable of processing information and making decisions independently of the other. There have been reported cases where patients have had entire hemispheres removed from their brain and yet they are still capable of functioning normally despite the missing half. This has been seen in both the removal of the left and the right hemisphere and seems to suggest that each half can alone be sufficient for a conscious mind.

So it seems that we are not really alone, even when we are. There may be a second "you" in your body having essentially the same experiences (with some exceptions of course) as you do.

Questions? Objections? Thoughts? Feel free to leave them here.