In this blog post, we explore whether the essence of things can be maintained amidst change through the ‘Theseus’ Ship’ paradox.
Among the heroes of Greek and Roman mythology is Theseus. Theseus is the figure who defeated the famous Minotaur. There was a ship Theseus sailed on when he went to defeat the Minotaur, and people decided to preserve that ship to honor his achievement. That ship came to be known as ‘Theseus’s Ship’. However, as time passed, the ship gradually deteriorated, and its old planks were replaced with new ones. Gradually, one plank at a time, the ship was rebuilt until not a single original plank remained. Can this ship still be considered ‘Theseus’s ship’? This debate is known as the ‘Ship of Theseus’ paradox. This debate raises the question of whether judgments about an object can change as the object itself changes. Many similar debates exist in the world, and judgments in such cases can vary. What defines an object is its meaning. If the changes are so significant that the meaning is destroyed, then the object becomes something else. If it still retains its original meaning, then it can still be considered that same object.
Let’s explore this issue more deeply using the example of a bicycle. What is the meaning of a bicycle? A bicycle is a vehicle where a person sits and uses the power of their legs to turn the wheels for movement. Suppose we change the bicycle’s frame, replace the saddle, and modify various parts. While the bicycle itself undergoes many changes, if the meaning of it being a vehicle propelled by turning the wheels with the legs via pedals remains intact, it can still be called a bicycle. However, if you add a motor to the bicycle, the need to turn the wheels with your legs disappears. It is no longer a bicycle but transforms into a motorcycle or a two-wheeled vehicle. This situation becomes even more pronounced when the symbolic meaning of an object is strong.
Take the Blue House in Korea as an example. The term “Cheong Wa Dae” itself literally means “blue roofed house,” referring to a building with blue tiles. However, Cheong Wa Dae carries the symbolic meaning of being the official residence of the President of South Korea. Therefore, even if Cheong Wa Dae undergoes construction and its appearance changes, it will still be called ‘Cheong Wa Dae,’ and its meaning as the presidential residence will remain intact.
Defining objects by their meaning is not limited to physical objects. It can also apply to people. For example, suppose there is a person named Friend A. If A loses a leg in an accident and wears a prosthetic, A has changed, but the meaning that A is a close friend remains unchanged. Meaning is subjective, varying depending on the person, so different judgments are often made. If the meaning of ‘friend’ includes external factors, and a person with a prosthetic leg falls outside that meaning, then A might no longer be considered a friend.
Consider a slightly different scenario. B and C are friends. For B, a friend is someone close, with shared memories and compatible personalities. If C were to receive an artificial brain that preserved all previous memories and retained C’s original personality, C would still be a friend to B. This is because C would still meet the criteria for being B’s friend. Conversely, if B no longer considers C, with the artificial brain, to be human and thus cannot accept them as a friend, this would be because B’s definition of “friend” includes the condition of being “human.” However, if B’s definition of ‘friend’ does not include the condition of being “human,” then C would still be B’s friend regardless of whether they are human or not.
The idea of friendship without the ‘human’ condition might seem strange, but recall your childhood. We considered robots or dolls we played with as friends. They couldn’t speak, weren’t human, and weren’t living beings, yet we regarded them as friends. We might not consider them friends now. This is simply because our definition of friendship changed as we grew up. The same applies to pets like dogs or cats. They are not human, yet they become friends to some people. All these examples illustrate that our judgments vary based on the meaning we assign.
My current definition of ‘Theseus’s ship’ is that it serves to remind us of the fact that ‘Theseus sailed this ship to defeat the Minotaur’ and to honor his achievement. Therefore, I do not believe the ship ceases to be ‘Theseus’ ship’ simply because its planks were replaced. That is why I consider the effort to maintain the ship important. If one were to build a model of ‘Theseus’ ship’, I believe it would merely be a ‘model of Theseus’ ship’, not ‘Theseus’ ship’ itself.
Furthermore, the person with the artificial brain mentioned earlier remains, to me, a person possessing that existence. For me, what defines my relationship with that person is their way of thinking or the events we’ve shared. As long as these things remain unchanged, that person will still be regarded as the same being. But this is merely my current perspective; if my defining criteria change, my judgment could shift.
Every object, including things and people, is defined by each individual in their own way. That definition can also vary depending on time and place. Yet meaning always exists at any given moment, so judgment at that point can be fully formed. Even an individual’s thoughts can shift from moment to moment; it’s impossible for multiple people’s thoughts to be identical. And since standards themselves vary wildly from person to person, even a slight difference in perspective can lead to different conclusions. This is likely why debates like the ‘Ship of Theseus’ paradox persist endlessly.
