Theseus Brain: Can you prolong your life by uploading your brain to a computer?

The idea of living forever in a digitalised form has become popular and recently even featured in the Dr. Who Christmas Special 2017. [SPOILER] An advanced civilisation kidnaps individuals at the very last second of their lives, extracts all their memories and returns them for their deaths. It is revealed that this enables the individual to come back to life using an avatar resembling their body shortly before death. [/SPOILER]

Most people will intuitively answer the title question with a strict ‘no’. Thinking about it for a while the answer may change towards ‘yes, but’. Assume a process will someday be engineered, by which the exact physiological properties of your brain can be emulated within a software running on a powerful computer. This emulation would by definition include all your memories and adapt to experiences in the exact same as your brain would have. Most people will agree that we are far from discovering this technology and in fact the laws of quantum mechanics may even prevent it. For sake of argument in this post, I will assume that it will someday be possible. Will that mean you can live forever?

In a way this idea is not very new, as it entails the classical problem of identity. The most ancient thought experiment in this domain is the Ship of Theseus or the Theseus paradox. The Grandfather’s Axe is a modern version of this conundrum: imagine an axe is passed down in the family over generations and over time both head and handle are replaced. Is it still the same axe? (Of course the axe would claim to be the same axe, if you asked it, but that’s whole other story.)

In a similar way, you can ask what would be the consequence of replacing one single biological neuron in a human’s brain with one single artificial neuron that mimics all of the original neuron’s connections and functions. Would this make the respective human a different individual? Over time, you could exchange one neuron, then another, and another until the whole brain is made up of artificial neurons. At what point is the person no longer the original? Most people would agree that this gradual change, if it takes place over a period of say years, would mean the person stays the same individual, whereas, making an artificial copy of the original brain (which is in all important ways equivalent to uploading it to a machine) would mean the new individual is not the same as the original. (This is essentially a rephrasing of the teleportation paradox.)

This paradoxical differentiation is due to a strong subjective feeling of continuity that is violated by the idea of uploading or copying people’s brains. For example you feel this continuity, when you wake up after a night of sleep and are convinced that you are the same person as when you went to bed (I stole this great example from Guilio Tononi’s Phi). As far as we know, this feeling is merely a product of sampling the memories of being yourself and realizing you have not changed. Put more drastically, the only thing that keeps your experience of self continuous, is the constant plastic changes that are occurring in the brain and producing congruent memories that can be sampled. Unless one argues that there exists something like a non-material soul, all these memories can potentially be part of a brain-upload.

In conclusion, there is no difference between the experience of uploading your brain to a computer and experiencing the flow of time in your dedicated biological body. Not because you remain yourself when you are uploaded, but because there is no continuous self. In this sense continuity of self is an illusion and an upload of all your memory would in essence enable eternal life. However, this absence of actual continuity of existence also means that your life only lasts a moment. In the each new moment a fleeting individual is born that inherits all you memories and only lasts a moment before it again is replaced.

If this sounds a bit depressing, you can console yourself with this: When you are out partying and have that one drink too many, it’s not you who suffers that hang-over but future-you. And who cares about her?

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2 Responses to Theseus Brain: Can you prolong your life by uploading your brain to a computer?

  1. GregH says:

    Years of meditation have shown me that “I” am only a part of this experience. And in fact a big part of “I” is reflections of that experience. Which puts me in an odd relationship with my own body…

    Have you read Charles Stross’ “Accelerando”? I thought it had some good ideas about what that transference might feel like. Still fantasy, but quite educational and fun.

  2. Mikels Skele says:

    I would respond, but since there’s no one to respond to …

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