Thursday, March 30, 2017

Brain transplant and personal identity

Daniel Dennett
In the previous post I wrote about brain transplants, but we must still consider the problem of how a brain transplant would affect our personal identity. Is our identity associated with the brain, and therefore would it be transferred to a different body in the case of a brain transplant? Or could something else happen?
In the first place, I must point out that this digression is not scientific, but philosophical, as for the time being a brain transplant is pure science fiction. It is not feasible now, and it does not seem probable that it will become so in a long time, assuming that it is possible to perform it successfully. This means that I am leaning on the void, the same thing I have criticized a few times when others do it...
In 1978, the American philosopher Daniel Dennett wrote a philosophical essay on this problem entitled Where am I?, where he used the science fiction genre to pose the problem of personal identity in the event of hypothetical scientific advances, such as the maintenance of an active living brain out of the body (although connected with it by wifi), or downloading the contents of a human brain into a computer.

It is well known that some of the feasible transplants (such as heart, face, and to a certain point the hands) can give rise to psychological problems in the patient, but their personal identity is usually not questioned, even though they may feel weird, knowing that a part of their body has belonged before to another person. There are also no identity problems when an individual suffers a poly-transplantation of the heart, liver and lungs, for example.
In another article in this blog I described the four classic philosophical theories on the mind problem. I repeat them here, in the context of brain transplantation:
  1. Reductionist monism or biological functionalism: The mind is completely determined by the brain by the network of neurons that make it. The human mind is an epiphenomenon. Personal identity and freedom of choice are illusions. We are programmed machines. In this case, it is evident that, in case of a brain transplant, the personal identity would accompany the brain.
  2. Emergent monism: The mind is an emergent evolutionary product with self-organization, which has emerged as a complex system from simpler systems made by neurons. In this case, no doubt, personal identity would also accompany the transplanted brain.
  3. Neuro-physiologic dualism: Mind and brain are different, but they are so closely united that they make up a unit, two complementary and unique states of the same organism. I see no difficulty in drawing the same conclusion here as in the two previous cases.
  4. Metaphysical dualism: Mind and brain are two different realities. The first is a spiritual and non-spatial substance (traditionally called the soul), capable of interacting with the brain, which is a material and spatial substance. Both entities can exist independently of one another, although the body without the soul eventually decomposes. But if the soul is an entity that interacts with the body through the brain, and the brain is transplanted to another body, why would it not continue interacting with it? If the soul were to act through the whole body, not just through the brain, any transplant, even of skin, would cause identity problems, something obviously does not happen.
Pierre Teilhard de Chardin
My conclusion, therefore, is this: according to the four philosophical theories, personal identity would accompany the brain after a hypothetical transplant, so that, if this operation became feasible, it would not provide discriminatory evidence to support or refute one of those theories.

Finally, as I have been asked directly about my personal opinion on this subject, I will say that it is obvious from the rest of my posts that I am not a materialist, and that I believe, with Teilhard de Chardin and others, that consciousness is one of the fundamental properties of the universe, apart from, and in addition to matter, but in close connection with it. Therefore, I do not accept either of the two monist positions. As to the two dualist positions, for the time being I am trying to keep an open mind.

Manuel Alfonseca

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