The ship of Theseus, also known as Theseus’s paradox, is one of the most brilliant ancient thought experiments dealing with the concept of identity.
It may seem irrelevant to the topic of complexity. However, I believe that it has a very simple yet similar idea of illusions like soul and identity emerged in some of the complex systems (e.g. Humans).
Here you can find the original version of the story as appeared in Plutarch’s book (+):
“The ship wherein Theseus and the youth of Athens returned 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 place, 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.”
And here are the two variations of the Theseus puzzle:
Variation A: Theseus completely rebuilds his ship, replaces all the parts, throws the old ones overboard. Does he arrive on the same ship as the one he left on?
Variation B (added to the first part): Following Theseus in another boat is the Scavenger, who picks up the pieces Theseus throws overboard and uses them to rebuild his boat. The Scavenger arrives in port in a ship composed of precisely the parts that composed the ship Theseus started out in. He docks his ship right next to one that Theseus docked.
It’s not hard to understand why such a thought experiment attracted attentions of the great thinkers and philosophers over the course of the last two millennia.
The answer to this thought challenge, implicitly, answers many other real world problems. The concept of human identity is just one of them.
Personal identity has been considered as a valid construct for thousands of years, although there has never been any convincing definition of the construct.
With a very simple and brief search on the web, you will find many different descriptions and answers for this challenge. My recommendation is to check out at least the following articles:
- Identity over time (Stanford Encyclopedia of Philosophy)
- Relative Identity (Stanford Encyclopedia of Philosophy)
- The Ship of Theseus (brain pickings)
One of the small yet significant results of understanding the concept of complexity would be finding answers to such tough thought challenges.
The concept of identity is just an illusion. An illusion that has lead to many profound misunderstandings and misbehaves and misattributions and even misdefinitions of the whole world!
In the best case, if you want to be still loyal to this old, ill-defined concept, would be more logical to believe intransitivity of the identity. It means that the identity changes and evolves and erodes over time and at any time, it would not be the same as before.
We have the Theseus ship at time t, and Theseus ship at time t+ε and they have no relationship with each other. At every time step, you can decide once more than what you do mean by the word Theseus and what you’d like to call the Ship.
Aristotle was happy with his explanation of the answer. He divided the changes into two distinct categories: Accidental and Essential.
But who is in the position to distinguish between this two different types of changes? Aristotle the observer! So we are talking about the perception and contrary to the well-known statement, here the perception has nothing to do with reality!