The Ship of Theseus

I thought I would pause from making long posts in favor of presenting something more concise but hopefully no less thought provoking. In fact, I am considering interjecting brief philosophical questions in-between my longer notes concerning social and political issues;  I may even create a series of scenarios centered around a particular ethical theme.  Doing so will not only diversity my material, but allow me to update my blog without having to expend time and energy into essay-like submissions (let’s face it, do you guys really want to read several pages of my ramblings every other day!?)

Anyway, on to the topic in question.

The Ship of Theseus is a paradox which raises the following question: if an object has had all it’s component parts replaced, is it still fundamentally the same object? What if a ship, after a long period of gradual refurbishing, eventually had all it’s parts replaced? Would it still be the same ship? This topic is pertinent to the concept of identity – what constitutes self, and how do we truly define an object?

There are many similar concepts and variations to this paradox.

Heraclitus was famously quoted as saying that  “upon those who step into the same rivers, different and again different waters flow.” Basically, you never step in the same river twice, as it is always different water.

Thomas Hobbes put an interesting spin on  the ship scenario as well: what if all the planks from one ship were taken, after being replaced, and used to construct another? Which ship, if any, is the “original?

The question becomes more complicated when you consider the fact the average age of a cell in the human body is less than ten years That means that we come to replace our entire cell structure several times throughout our lives. We are cellularly and biologically completely different. This extends all the way down to the molecular and atomic level too – in around seven years, the human body completely replaces all the atoms that comprise us.

It’s strange to imagine how much we change and transform throughout our lives, without even remotely noticing (besides the typical growth that occurs prior to adulthood). Physically, we become completely new beings every few years, yet we’d never realize it. That’d be difficult enough to fathom without considering what all this means about who we are and who we perceive ourselves to be.

12 comments on “The Ship of Theseus

  1. I like this thought experiment.

    I have thought quite a bit on this and for me there is no clear answer except for an inanimate object such as the boat. I think time and use has to be considered. In the Hobbes experiment neither ship was in use or essentially not in use. So when they replaced every single piece of the boat and then put back together the original boat. The original boat is the boat and the new boat is another boat with the same name as the original.

    If they did not use the boats. If they do it piece meal in conjunction with using the boat…Then eventually when all pieces are replaced, for me then the new boat is the original that has just been restored. They could not build or use the old boat until they have all the parts. For me that is another version of the original boat with the same name, even though it has the exact same pieces it did when the original boat was built. It is a copy of it’s past.

    I look at people in a similar manner as the boat. Since the cells are not all replaced simultaneously but over time. We have use of our body while our body is upgrading cells. I am the original version of me.

    If there was a way to do it all at once then I think the old parts version of me, would just be a continuation of me and the new part upgrade is just another copy of me with the same name. For that split second we are essentially the same until one of us has a slightly different experience. A sight sound touch feeling from either bodies individual perspective.

    Thanks for posting this.

  2. Also it was pointed out that i missed a part of the post.

    >>”Heraclitus was famously quoted as saying that ”upon those who step into the same rivers, different and again different waters flow.” Basically, you never step in the same river twice, as it is always different water.”

    He is right that the river is always different and yet so are we. In fact nothing stays the same. Even the black berry on my desk is changing second by second. The battery is deteriorating and the plastic part/components are drying and becoming brittle. Resistors and other electronics are deteriorating too. Rocks degrade in our environment. We are being bombarded from space with neutrinos changing our dna and affect atoms of varying matter as they pass through.

    So everything is essentially different from what it was moment to moment. Nothing is exactly “like” the original.

    That is a highly plausible uncontroversial belief (stolen from ethical realism) and as such does not really for me add to the discussion of the Hobbes scenario. Everything is changing/aging so nothing is the same.

    If we are to have a discussion on something like the Hobbes scenario then we must ignore Heraclitus.

  3. To me, “The ship” or “The object” is an abstract, conceptual label that is best used as a tool for convenient distinction, not as a concrete description.

    Chronologically, each “object” or “person” becomes new and different in accordance with the each and every intrinsic and extrinsic change in each moment, ie exchange of information. This death of the former self occurs not only when the tangible matter of the body regenerates, but also as the “intangibles” (all those things not ‘perceived’ through our 5 human senses) change. To say that identity is inextricably tied to physical matter does not make sense to me. What is a rose? If “I” were only the physical matter that I was born as, who would I be today?

  4. @James – If you do not ignore Heraclitus then you are left with nothing is the original and the question for Hobbes ends.

    You are not the same person from second to second. So there is no original boat even if it was never taken apart. Wood decays. The atoms in the boat are constantly changing.

    So if we want to talk about the original boat or person then I think we have to ignore that line of reasoning because it is obvious that we are different moment to moment.

  5. @MSF – “If “I” were only the physical matter that I was born as, who would I be today?”

    You would be very small. 😀

    You would be a different person today than the day you were born.

  6. Mike DK,

    Is Heraclitus giving us the wrong answer to the question? It seems like he offers one possible answer: “No, it’s not the same boat and it wouldn’t be the same boat even if you left it alone.”

    One issue is: Why do we even say that boats exist? Why do we say, “that’s one boat today, and it will be one boat tomorrow?” Why not say there’s two half boats there? Is there something magical and unifying about wood chunks being meshed together in the right way that transform it into one thing?

    We certainly want a way to say, “that’s my boat!” And we would say that even after all the parts have been replaced. Legally, boats do exist and it’s the same boat after it’s been changed.

  7. @James – >>Is Heraclitus giving us the wrong answer to the question?

    No I think he gives a literal answer. I just thinks Hobbes was asking something different.

    >>Is there something magical and unifying about wood chunks being meshed together in the right way that transform it into one thing?

    No magic. 🙂 It is a boat when it meets the definition of a boat.

    @Romney – How did you answer this?

    • Well, neither of my answers are very satisfactory to me, but I’ll tell you! 😛

      Basically, I reached two conclusions:

      1) What constitutes “something” or “someone” is the sum of it’s parts. As much as you and I may change in every possible way, the perfect alignment of all those molecules, cells, and other components (including those that make up our mind) leaves us as the same over-all person. This leads to my next point..

      2) Something’s identity is dependent upon how it’s viewed in the world. In other words, self is dependent on society. Our identity has a reactionary relationship with the world around us. No matter how much I change – even if I were to secretly be a mere clone of my original self – the world around me would continue to view me as me.

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