Brain of Theseus

Often, students and academics joke about the problems in their fields that keep them awake at night. Usually, I think, these are questions of philosophy but I've known people of other disciplines to be struck by insomnia when wondering about an archaeological site or the meaning of a poem, etc. For a while, I've been wondering about the meaning of this next problem. But until recently, I hadn't thought about it exactly this way. Now I'm not entirely convinced I'll ever sleep again. Convenient, as exams start next week and I have 25 pages of papers on ethics and psychology to write.

The Ship of Theseus
The ship of Theseus is an old philosophical problem of identity that goes like this: Suppose there's a ship, and every year, one plank of it is replaced. If the ship is made of, say, 200 planks, then in 200 years, we're faced with a problem: Is the ship which remains the same ship, or is it a different ship? And if it's different, at which point did it become different? Which plank was the last straw?

This is sort of fun, but it didn't become really interesting and terrifying until I remembered that neurons are being replaced at a constant rate, and that over a certain number of years (7? 12? I can never remember) every neuron in one's brain is replaced. Our brains are ships of Theseus. The problem is that we perceive our consciousness as being continuous. However, the mind is the brain. So the answer has to be that our consciousness is somehow connected to the structure and organization of the neurons. My identity is the exact shape of my brain. I maintain a constant, or at least continuous, personality because my brain is continuous across time, regardless of the existence or replacement of individual neurons.

Which brings us to an even bigger problem, as raised by my fantastic philosophy prof, Dr. Davies: If we took each old plank of the ship as it were being replaced and put it in a warehouse and then, 200 years later, reassembled the ship of Theseus, we would have two ships of exactly identical make. And yet they would not be the same ship. So which one would be the ship of Theseus, the one rebuilt of the original planks or the one that's been continuously sailed upon across those 200 years?

I mentioned my issue with neurons to Prof Davies, who responded simply: "Well that's easy, you aren't the same person from moment to moment." That's nice, and obviously he's correct, but that doesn't change the fact that I have the sensation of continuous consciousness.

Then I started thinking about science fiction. Imagine we could teleport. We would hop into a booth, which would scan our entire body (and, probably, the billions of bacteria that actually make up 90-99% of our body mass) and then transmit that data to another booth, which would decode it and fabricate a body exactly the same structure and initiate CPR to get the heart started. The beta body, possessing the same exact brain as the alpha body, would experience what? The memories and experiences and feelings leading right up until transportation, and then everything afterwords. In short, it would feel like waking up from a nap (on the other side of the universe). The beta body would have the sensation of continuous consciousness. What happens to the alpha body, then? If it disappears, it dies. The consciousness of alpha is not transferred to beta. Consciousness can't be transferred in any meaningful way. You've essentially cloned the body and mind.

But if consciousness can't be transferred, then how is consciousness transferred from my waking self yesterday to my waking self today, across the divide of all of 4 hours of sleep I got last night (and an all nighter tonight and tomorrow night, hooray)? The obvious answer, I think, is that it isn't. I'm not the same person who existed yesterday. His consciousness was gifted to me when I woke to the sound of my damn alarm this morning, but his consciousness ceased to exist when he went to sleep. In other words, we die each night when we go to sleep and are reanimated each morning. But I'm not the one being reanimated, it's a beta or gamma or however many iterations of the Greek alphabet are required after nearly 22 years of nights sleeping. When I go to sleep tonight, that's it. I'm dead.

I hope this doesn't trouble you as much as it troubles me.