The Paradox of the Ship of Theseus

This paradox based on a myth of Ancient Greece makes us think about the idea of ​​identity.

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The paradox of the ship of Theseus is based on asking the question of if after having been replaced all the pieces that make up an object, this can continue to be considered the same or would become an object different from the initial.

It is a paradox that has its origin in a legend of Greek mythology, which consists of various variations and questions in addition to the original. In this article we will review what this popular and mythical Greek paradox is about.

What is the paradox of the ship of Theseus?

The legend that gives rise to the paradox of the ship of Theseus relates that in an opportunity Teseo returned of the island of Crete, along with its crew, and they went in a boat that already was quite old. During the road (which was quite long) the ship was damaged more and more. Every damage suffered by the ship was repaired by the crew, the broken piece being replaced by one in better condition, and sometimes the pieces were recycled and placed in different parts of the ship.

When Theseus and his crew arrived at port, the ship had been completely modified, there was not a single piece left from the ship in which they left the island of Crete, or else they had been recycled and placed in different places, such as a new piece.

This particular event raised a question on the part of the philosophers of that time: “the ship in which Theseus and his crew have arrived at port is the same ship in which they have left the island of Crete?”.

Explanation of the paradox

What is sought with this Greek paradox is to clarify in some way what is the essence of bodies and objects, their identity, what makes them something unique.

Although the legend tells the story of the ship of Theseus and its crew, the paradox can be extrapolated to almost anything else. It is applicable to other situations and objects that undergo an intense change in most of their initial parts.

Examples of the paradox

Some good examples in our current age that can serve to adequately illustrate the paradox of Theseus’ ship are the following.

1. Repower the computer

When people repower their computer, the process involves replacing a series of elements at the physical (hardware) and programming (software) levels that are quite significant for the operation of the equipment.

Basically, the pieces that are replaced make the computer operate as a different one from what was previously, but … Is it really another computer? Or is it the same computer with new parts?

2. Reconstruction of vehicles

Sometimes, after a disaster, some vehicles are quite damaged by the accident and are repaired almost all parts. The repair of these vehicles consists of replacing all damaged parts with new or used parts in good condition.

The questions that arise once the process of reconstruction of the vehicle is completed are the same as those of the previous example.

3. Sale of commercial premises

When the sale of a commercial real estate is made, in general, almost all of it is changed; the personnel, the infrastructure, and sometimes even the name.

But if the trade continues to be dedicated to the same as the previous one, the questions that we already know arise in the same way.

4. The human body

Humans are old enough that virtually all of their cells are replaced several times by younger generations.
Proposed solutions

The famous philosopher Aristotle proposes a definitive solution to the questions posed by the paradox of the ship of Theseus differentiating between the different types of causes.

1. Formal design

As long as a thing maintains its formal design, that is, it continues to be seen in the same way, it is still the same thing.

2. Material cause

If an object maintains its initial matter, that is, that it is not reconstructed with pieces of another material, regardless of whether these are new or not, the same object can still be considered.

3. Final cause

The final cause consists in the purpose for which said object has been made. While a body or object, however reconstructed it may be, still maintains its final cause (the purpose for which it was designed), it will remain the same initial object.

4. Efficient cause

This last consideration of Aristotle proposes that while the methods used in the repair and replacement of the pieces of an object are made following the protocol stipulated for it, the object remains the same as before, only with modifications designed for the same.

Definition of “the same”

Finally, it is important to understand that the definition of “the same” is something of a completely subjective nature, because for some people it may be the same to have two exactly the same bicycles stored in their garage, but for the puritans this idea would not be worth it.

Bearing in mind that there can not be two bicycles occupying exactly the same physical space in any place even though the bicycles are identical, they would have a feature that the other can not share: the physical space occupied will never be the same.