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The Ship of Theseus: How Does Identity Sail Through Change?

Written by Dila Kurbanoglu

The fabled ruler of Athens, Theseus, sails a ship headed toward the Island of Delos. Through this odyssey, the Athenians continuously replaced the decaying planks with new, stronger boards until all of the ship's components had been supplanted. With this journey, Plutarch presents the following query: Does Theseus' ship remain the same once all of its parts have been changed? What makes the ship “Theseus’ ship”? After what amount of replacements does Theseus' ship diverge from the original? The English philosopher Thomas Hobbes extends this question, asking whether a new ship would be considered Theseus' ship if every plank that had been taken out of the original ship was reassembled and used in its construction of it. Which of his two ships, if either—or none—would be regarded as his?

How one views identity and their takes on the field of mereology (study of parthood relations) affects the viewpoint one adopts on this matter. If one approaches this thought experiment from the standpoint of a mereological essentialist, who holds that a part is the whole and if the whole were to lose or acquire a component, it would cease to exist, they would state that the instant the first deteriorating plank has been replaced, it is no longer Theseus' ship. Some people may find this line of thinking absurd because identity, like everything else in life, is dynamic, ever-changing, and ever-flowing. We, humans, are continually regenerating new cells, changing our worldview, and growing both psychologically and physiologically, yet we preserve our identity. As French writer Jean-Baptiste Alphonse Karr wrote “The more things change, the more they stay the same.” Even if all of the original parts of Theseus’ ship were taken out and reassembled to create a new one, the new ship would merely be a replica of Theseus’ ship since it is not planks or other physical components that make up Theseus’s ship, but rather the thinking, memories, and sentiment that goes into it.

Whether or not one believes that the ship of Theseus remains the same, the thought experiment continues to be an important concept in philosophy because of the many solutions and ideas put forth on the subject by philosophers, and its capacity to evoke questions about personal identities as well as make people reflect on the reasons for and methods by which we identify objects.


  1. Worley, P. (n.d.). The Ship of Theseus. The Philosophy Foundation - The Ship of Theseus.

  2. Plutarch. (n.d.). The Internet Classics Archive: Theseus by Plutarch. The Internet Classics Archive | Theseus by Plutarch.

  3. Varzi, A. (2016, February 13). Mereology. Stanford Encyclopedia of Philosophy.

  4. Wikimedia Foundation. (2023, May 9). Mereological essentialism. Wikipedia.

  5. Encyclopædia Britannica, inc. (n.d.-a). Ship of Theseus. Encyclopædia Britannica.

  6. Gallois, A. (2016, October 6). Identity over time. Stanford Encyclopedia of Philosophy.


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