According to myth, Theseus was an ancient Greek king who fought many battles, and founded the city-state of Athens. Because of Theseus’ success at naval battles in particular, the people of Athens chose to dedicate a memorial in his honor by preserving his favorite ship. This “ship of Theseus” remained in their port for hundreds of years, and as time went on some of the planks of Theseus’ ship began to rot away. In order to prevent the ship from breaking down entirely, these rotting planks were replaced with new planks made of the same material. However, could the ship still be considered Theseus’ ship, if it was no longer made of the same planks that Theseus himself walked upon? If the bed in the captain’s cabin was replaced by a bed of the exact same make, could it still be considered the same bed Theseus slept on? By placing a new plank next to an original one cause it to absorb some of that older plank’s experience, or does that hold no value?
It is a philosophical question that resembles the sorites paradox (sometimes also called the paradox of the heap). In a similar manner concerning identity, the sorites paradox can be summarized by asking this question: when is a heap of sand no longer considered a heap? By first accepting that removing a single grain of sand cannot turn a heap into a non-heap, what happens when enough grains are removed until there is a single remaining grain? Can this still be considered a heap? If not, when did change from a heap into a non-heap? At two grains? At three? Instead of considering identity directly, this paradox instead focuses on when a change from one identity to another specifically occurred. In the context of the ship of Theseus, this paradox considers when the ship could no longer be considered Theseus’ ship. Is it still Theseus’ ship even when there is only one remaining original plank? Or did the change in identity occur before that? Is there even an instance of change like that? Or does that change happen over a long period of time?
When it comes to philosophical questions like these, I liked to listen to what my common sense tells me. Before diving in to a possible answer to these paradoxes (something that I will not attempt in this blog post, as these theories are called paradoxes for a reason), I like to answer them quickly and without much thought, if possible. It provides a basis for me to go off of. Therefore, to quickly address the paradox of the ship of Theseus, my common sense tells me that if you replace one plank, the ship can still be considered Theseus’. But if you replace the whole ship, that ship is no longer Theseus’. And if you replace the whole ship up until there is only one original remaining plank, then it’s just a new ship with one plank that was part of Theseus’ ship. To address the sorites paradox, I believe that the heap of sand is no longer a heap when one would look and the sand and not call it heap. If one cannot look at two grains of sand and call it heap, then it is not a heap. When this change occurs does not depend on the grains of sand being taken away; it depends on who is observing it and what they consider to be a heap or non-heap.
So what is the point of delving into these paradoxes? If I am not trying to answer the paradox surrounding the ship of Theseus or the sorites paradox, then why am I writing this blog post? Because I believe that, commonly, these paradoxes are applied to what makes us us. Could the question of identity surrounding a material object apply to a sentient person? If a person transfers their mind into a computer, leaving their biological body behind, are they the same person? If a person changes so much over many years, many decades, can they be considered the same person that they were all those years ago? To provide myself as an example, am I the same Liz that entered kindergarten at six years old? Or am I someone else now?
To once again practice quickly answering a paradox before delving in to find or attempt to find a truer answer to the question, my answer is yes. I am still Liz, and I am still recognizable as Liz—I am not a clone or a copy, just a Liz who has grown throughout the years.
There is a common saying that states the human body fully replaces itself every seven years. An interesting idea, the thought that our body is brand new after seven years—reminiscent of the ship of Theseus, is this the same body that we lived in seven years ago? Unfortunately, this saying has proven false—though others might state that it’s actually ten to fifteen years, the truth of the matter is we do not fully replace ourselves in the matter the saying implies. And, in the end, I don’t think our body replacing itself matters to the question of identity. The difference between the ship of Theseus and a human person is an observation of sentience. We know that we are the same person, because we observe ourself in that way, and know this is true. Just as we might observe a ship in front of us as Theseus’ ship, or just a normal ship.