Wired offers a fascinating article about Dr. Robert White, a neurosurgeon in the mid-20th century who was famous for his extensive research on head transplants. He transplanted heads of various animals, often unsuccessfully (many animals died) but with some success, particularly with monkeys. The medical, ethical, and sociological issues are interesting in themselves, but I’ll focus here on the metaphysical issues. Specifically, if your head is transplanted, does your soul go with it?

First, it’s worth noting that head transplantation is difficult surgery but doable. We know how to sew blood vessels together, how to fuse spinal bones, how to attach tracheas and muscles and peripheral nerves. Transplantation of an entire head (or an entire body, depending on your perspective) would be technically challenging and quite risky.

To Cut the Spinal Cord

Head transplantation has not been done on humans. Not because it wouldn’t work — it would be technically easier on humans than on monkeys because humans are bigger so things would be easier to sew. It has not been done on humans because, in order to transplant a head, you must cut the spinal cord, which causes permanent paralysis. Head transplantation causes quadriplegia. There is no real medical benefit in creating a quadriplegic patient — it might preserve life but at the expense of total paralysis. This question occasionally arises in neurosurgery in a different context. The consensus is that deliberate imposition of a catastrophic neurological disability is unacceptable, even if it may save life. With rare exceptions, we don’t deliberately make people blind or paralyzed or comatose, even to prolong life.

An ethical case for head transplantation could be made in the case of an already quadriplegic patient who had multiple organ failure and who would die otherwise. This is a rare scenario.

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?

The Meaning of Our Words

As with so many metaphysical questions about the mind-body relationship, we need first to understand the meaning of the words we use. The question of the disposition of the soul depends on what we mean by “soul.” Is the soul a thing that lives somewhere in the brain, so to speak, or in the body? Or is it outside the body and brain or somewhere or something else? Or is the soul not a “thing” at all? Does the soul exist?

Read the rest at Mind Matters, published by Discovery Institute’s Walter Bradley Center for Natural and Artificial Intelligence.