–by Blog Philosopher Jordan King

 

The ancient thought experiment Ship of Theseus made famous by Plutarch asks a much-debated question.  It asks whether a ship that has all its components replaced, one by one, is still the same ship.  How can a ship with all new parts still be the same ship?  This introduces a puzzling dilemma about living forever.  We may see in the distant (or not-so-distant) future the technology of uploading consciousnesses of dying people into a robot or even another human body.  We may also see pills which allow people to live indefinitely, but for indefinite living to be possible the people taking ever-life pills would have to  replace eventually all of  their body parts as the old ones wear out.  How can a person with an entirely new body still be the same person?

The conundrum, if an object has all of its components replaced, is it fundamentally the same object?

Let’s start off with the ship; it’s easier for now.  To be able to answer the question of whether the Ship of Theseus is wholly original or wholly different, you would need to know what makes a ship a ship.  Is a ship the sum of its parts, or is a ship an overall structure? If you were to take the original pieces of the disassembled Ship of Theseus and build it into a second ship, would it be the same ship? Do the pieces define the originality?

Or, if you replace the original pieces with identical new pieces while retaining identical structure, is it a new ship? Or, the original ship?  I would say the original ship replaced with new pieces would be the real one.  I say this for two reasons.  First off, the ship would have exactly the same structure.  Replacing each piece one by one would stay more true to the initial structure of the ship than it would to rebuild the ship completely.  Secondly, when you are replacing each piece with a new piece, at what point does the ship cease to be the same ship?  The first piece being replaced wouldn’t make it a new ship, nor the second.  The ship’s only identity is The Ship of Theseus, nothing else; the ship has no thoughts, no personality, and no persona.  The ship’s sole purpose of existence is its use as a ship, to transport goods and/or people.  If you rebuild the ship using the same parts after the original ship was replaced with new parts, the rebuilt ship wouldn’t be original.  It’s identity is not the same because it doesn’t exist in the same location.  If the ship had a soul, the ship with the new pieces would be original because it has the same existence, purpose, and structure.  It has the Same identity.

People do change though.  They grow older; their skin falls off; their hair falls out, and their cells replace themselves.  Almost all cells die and replace themselves every 10 years, with the exception of the nervous system, female gametes, and lens cells, which take a lifetime to replace.

 

Here is a chart from bionumbers.org, of the amount of time cells take to replace themselves:

So, every 10 years you are a completely different person (when it comes to what you’re made of).  But… It’s not just your body parts that are different; you actually change psychologically, too.  Your personality will change dramatically over the next decade (Time.com).  You’re not the same as your four-year-old self; you are more mature (hopefully), and you are smarter with more life experience.  

When we are able to transfer human consciousnesses onto machines or take pills to live forever, we will be different people.  But we already become different people every 10 or so years.  Nothing has changed.  When we are able to live forever, we’ll still change, just a lot more, as we will be alive hundreds or even thousands of years.  Five-hundred-year-old you won’t be anything like you were in your teens.