So I read that an octopus has neural networks in each limb (a kind of brain that can think independently). Assuming that there is a single consciousness if a limb in separated from the body does a single mind then control both entities at the same time? If so and we could replicate this in humans (in the far future), would it be possible to split our mind in two with a single consciousness that would be able to communicate with both physical bodies at the same time regardless of distance between the two? Or at the point of splitting is the consciousness split also?
Answer by Geoffrey Klempner
If you cut off one of the limbs of an octopus, there is no physical process whereby the ‘mind’ of the octopus is able to control its own body and also the movements of the separated limb. That’s just a matter of physical and physiological fact. However, we can imagine a possible world scenario in which human beings have electronic gadgetry put in place to enable my various spatially scattered ‘parts’ to communicate with one another and with my brain. I could even send part of myself to Mars, my left arm, say, while at the same time I am sitting at home, safely in front of my computer.
Actions and movements on Mars would be difficult to say the least, given the time lapse. It would not be a lot different from what NASA technicians do now, when they control the movements of the various Mars rovers. Say, I want to pick up a rock with my left hand. It would take between 5 and 20 minutes for the radio signal to reach Mars, and the same amount of time to see that my action had succeeded. Anything more than a simple graping movement would be virtually impossible, given the constant two way communication that normally takes place between hand and eye. The setup would also require wireless transmission of almost imaginable capacity compared with what we have now.
One philosophical question raised by this thought experiment is, ‘Where am I?’ If the part of ‘me’ that is sent to Mars is destroyed when the capsule crashes, I am still here. just as in the case of the octopus, it would be like cutting off a limb. But what if I could send half of my brain? I have robot ‘eyes’ on Mars and on Earth, each wired up to one of my separated brain halves. If my Mars body dies, then I am still alive here on Earth. But, equally, if my Earth body dies, I can continue my life on Mars, as a human ‘Mars rover’.
In a sense, the same applies to each of us, now. It is not as if ‘I’ am where my eyes are. My feet are in a different place from my brain. Just from looking that the physiology of the human body, we can say that there are various spatially located parts which are ‘part of me’ and there is a centre, that receives information and controls the functions and movements of the various parts that in the case of human beings is in a particular place, the skull of a living human being, but in different possible world scenarios could be scattered far and wide.
All that is relatively simple. It is indeed possible that what I have imagined might never come to pass, because we are defeated by the complexity of of brain processes. The total number of possible brain states is enormous, even in comparison with the number of atoms in the universe. A similar thing can be said of the bandwidth of the process of communication between the two halves of the human brain, which we still only barely comprehend.
However, there is a deeper philosophical question that can be raised here which attacks the Cartesian idea that there is just one ‘mind’ or ‘self’ controlling our body, or bodily ‘parts’, regardless of how these are distributed in space. The classic article is Thomas Nagel’s ‘Brain Bisection and the Unity of Consciousness’ (Synthese 1971, you can find this in PDF if you search on Google). Nagel’s article is based on an actual experiment on a human subject, where the corpus collosum connecting the two halves of the brain was severed, as a drastic treatment for epilepsy after other treatments had failed.
In this experiment, various setups were used to test the ability of the subject whose brain had been bisected brain to recognize different shaped objects. Amazingly, the subject could recognize, say, a cube by feel and also by sight, but was unable to say whether or not the object they had seen and touched was the same shape or not. This seems impossible, if we think of the mind as a single arena or theatre, where all the contents of consciousness are displayed. Surely, if you see there is a cube there, and feel the cube, you must know that what you have felt and seen are the same shape? It seems that we have to say that what the experiment of brain bisection shows that there is no ‘theatre’, no single ‘you’ here.
You could also look at other classic articles by Sidney Shoemaker, Derek Parfit, Bernard Williams, Daniel Dennett, David Wiggins, and others dealing with a whole range of thought experiments raising questions about our intuition of ‘self identity’. A classic example is Shoemaker’s thought experiment, where my brain is split and each half put in a new body. My response to this, which I argued for in my book Naive Metaphysics, is that this could be plausibly seen as a case of ‘survival’ as two fully separated beings. There would simply be two GKs, both possessing my memories.
If you have doubts about this, or think, ‘this could never happen to me’, imagine that it has already happened, and the other ‘you’ one day knocks on your door, you invite him or her in, and once you have gotten over the awkwardness of the situation talk about old times when there was ‘just the one of you’. For example, my first operation, when my adenoids and tonsils were removed at the age of four, becomes ‘our’ operation. An so on.
That’s only the tip of the iceberg. Factor in the various possibilities of amnesia, as in Derek Parfit’s ‘Methuselah’ thought experiment, in which the future GK, living hundreds or thousands of years from now, has no remaining memories of my self in 2020, and it becomes increasingly plausible to say that either the very notion of ‘self’ is a complete illusion, or that there only ever was one ‘self’ that has split many millions of times, forming all existing human and non-human subjects of consciousness. Some would argue that the two suppositions amount to the same thing. I am not you. You are not me. Imagining that, despite this, in some sense ‘we’ are one seems just a fanciful way of saying that we are both conscious subjects, full stop.
But what about my existence, here and now? I am not you. But, equally, I am not in the future, because the future has not yet happened, and I am not in the past, because the past has gone. If it is logically possible that the universe only came into existence five minutes or five seconds ago, as Bertrand Russell once hypothesized, then all that is indubitably ‘me’ only exists in the present.
And this is the bit I can’t get past. Take ‘me now’ or ‘this’ away, and everything else, the whole universe and all the people in it, remains unchanged. So what is it? Why is it? Why am I here at all? – I am sure that there is a lot more to say at this point but that is as far as I have been able to take the question.