Continuity Is All You Need

Sci-fi writers and some technologists propose that one day we’ll become immortal by uploading our consciousness to a computer and living in cyberspace. It’s debatable whether you would actually become immortal as there’s no reason to believe your subjective experience will transfer into cyberspace. Wouldn’t the original you remain where it started, in your biological body, and something derived from you would now exist digitally? If that’s the case when your biological body dies, so will you.

What do I mean when I write “you”, “consciousness”, “mind”, “subjective experience”? In this case I’m referring to the “you” that experiences the colour red or the smell of a baking cake or falls in love. The “you” that continues from one moment to the next, from yesterday to today and hopefully tomorrow.

Is there a way to make this mortal “you” and make it immortal?

The Ship of Theseus

We can use the ideas contained in the Ship of Theseus paradox to create a scheme for transferring consciousness from a mortal body to an immortal one. The Ship of Theseus is an ancient thought experiment about whether an object where all of its component parts have been replaced remains the same object. The reason the ship can be considered the same ship is because throughout the story its function and identity are continuous.

The ship wherein Theseus and the youth of Athens returned from Crete had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their places, insomuch that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same. — Plutarch, Life of Theseus 23.1

An Eternal Coat Hanger

Before we tackle something as complex as a brain, let’s start with something simpler, a hanger holding up a pair of trousers in a wardrobe. The idea is to replace every part of the coat hanger without it ever becoming unhooked or the trousers coming off the hanger. Our imaginary coat hanger is connected to a rail inside a wardrobe by a metal hook, the trousers rest on the hanger across a triangular piece of wood. How can we replace the hook without the hanger falling down? In other words, how do we maintain continuity?

If we try and replace the hook in one go then we’ll be forced to separate the original hook from the wooden part of the hanger and so there comes a time when the trousers are no longer hooked to the rail in the wardrobe. What if we took a chunk of the hook and tried to swap it out? If the chunk is too big then we’ll split the hook into two pieces, but, if we zoomed in further we could update the hook atom by atom. Removing a single atom doesn’t break the hook and the atom can be replaced by another one. We carry on in this fashion until the entire object is the same but no longer the same.

An Immortal Mind

So now let us move to you. Rather than upload your entire mind to another system in one go, we replace individual biological neurons one at a time with artificial ones. To preserve continuity of experience we may not need to go to the level of a neuron, it could be at a higher functional level or maybe lower at an atomic level. The point is every artificial component has the exact same function as the original biological but has the bonus of being repairable or replaceable. For now, let’s assume we’re replacing neurons, we’d swap out one biological neuron with an artificial one modelled on it. The artificial neuron behaves exactly as the biological one and is connected to all the neurons the original neuron was connected to.

So you have a number of procedures swapping out bits of your brain and after each one you’d wake up and wouldn’t notice a difference. Eventually your biological brain has been swapped entirely and is now artificial. Your sense of self is continuous.

Philosophies of Mind

There are several philosophies of mind, some such as Materialism or Panpsychism are compatible with our scheme. Others such as Dualism aren’t. Materialism posits matter is the fundamental substance in nature and consciousness arises from the way matter is organised. Panpsychists believe consciousness is a fundamental property of matter such as mass and everything in the universe has some degree of consciousness no matter how insignificant. Certain arrangements of matter combine to form more significant forms of consciousness. Dualism is the idea that mind and body are separate but interact in someway (no-one has figured out how). Finally, Idealists believe everything is consciousness and objects only exist when they are perceived by a conscious mind.