Dr. Michael Egnor has recently written a couple of thought-provoking posts over at Evolution News. I’d like to invite readers to comment:
Head transplantation is interesting from a metaphysical perspective. It’s a question that would have interested Dr. Frankenstein: Imagine that spinal cord repair were feasible and patients would not be rendered paralyzed. If heads were successfully switched, where would the souls end up? Is the soul in the brain, in the body, in both, or in neither? Two people would still exist after switching heads. But who would be who? Where would the souls go — with the brains or with the bodies?
In a head transplant, it seems obvious that our senses would follow our sense organs. If my head were transplanted onto my neighbor’s body and vice versa, my eyes would still be on my original head, so I would see with my original eyes.
What about the “ownership” of the body after a head transplant. If my spinal cord worked after the transplant and I moved the fingers attached to the transplanted body that was attached to my original head, would I be moving my fingers or my neighbor’s fingers?
If my head were transplanted onto my neighbor’s body, I would see, hear, smell, and taste where my original sense organs were — in my head. For abilities that include both the head and body, it seems obvious from anatomy and physiology that I (corresponding to my original head) would feel using the touch sensors in the skin of my neighbor’s transplanted body.
It is theoretically possible to remove the right hemisphere from my neighbor and place it in my skull. Let us assume that my neighbor’s right eye was transplanted along with his right hemisphere. I believe that the outcome can be predicted with confidence. My neighbor would see out of his right eye in my skull. My neighbor would also see out of his left eye in his own skull — he would have double vision, in a real sense. If my right hemisphere and eye were transplanted into his skull, I would have corresponding double vision. This might seem strange — to have eyes in two different locations that see different things. But that is the way we would be then. Our eyes are a few inches apart, and the distance between them permits depth perception. After a hemisphere-eye transplant, eyes could be thousands of miles apart. I would see two superimposed scenes — double vision — in completely different parts of the world, depending on where the skulls that contained the hemispheres and eyes traveled. Obviously this would be very strange, but it presents no metaphysical problems that I can see.