The Story of The Ship of Theseus: The Question of Identity

We have all asked ourselves, who am I? The question of identity is something we have all wondered about. Over the course of history, a number of thinkers have attempted to answer this conundrum. One of which is Thomas Hobbes, a British philosopher born in 1588. He attempts to answer this question by looking at it through an old Greek tale. His philosophy tackles the question of, “what makes something the SAME thing over time, even though it goes through changes?”

Theseus owns and sails a ship. Each month he would sail to a new port and has one old plank of his ship replaced with a brand-new plank. After 10 years, not a single original plank of wood remains in Theseus” ship. Unbeknownst to Theseus, the ship repairman has saved all of the old planks that he removes from Theseus” ship. He then slowly, he constructs a new ship and by the time 10 years has passed, he has acquired all the original planks from Theseus” ship and had arranged them exactly as they were in Theseus” original ship.

With this Hobbes then asks, “Which of the two existing ships is numerically one and the same ship as Theseus” original ship?” Is it the ship with all new parts, or the re-constructed ship with all of the original parts?

With that question and idea in mind, Hobbes then tries to explain and justify his answers through two different principles. The first is the “gradual replacement principle”, whereas if object X is made up of different parts, and a single part of that object is replaced, producing object Y, then objects X and Y are the same object. While the second principle states that, if Object X and object Y share all and only the same exact parts, arranged in exactly the same way, then objects X and Y are the same object. With these two principles in mind, it is concluded that both principles cannot be true, because if they were it would violate the law of “transitivity of identity”. Whereas if A=B and B=A, then there would not be two ships, but instead just one.

Hence with this thought, Hobbes concluded that when it comes to identity; “Is a man, when old and young, the same being, or matter, in number?” it is clear that, because of the biological change he endures, he would not be made up of the same tissues. Therefore, Hobbes states that if a person changes gradually, then they are still the same person. Since a person cannot have the same body for his or her whole life.