The Ship of Theseus – An Identity Paradox

Model of The Argo, from Jason and the Argonauts. Credit: dimitrisvetsikas1969, Pixababy

The Ship of Theseus is an intriguing thought experiment, first appeared in print by the ancient Greek historian Plutarch, although has been around since antiquity and has been discussed by the ancient Greek philosophers Heraclitus and Plato and has been later discussed by English philosophers Thomas Hobbes and John Locke.

Theseus is described as the mythical king and founder of Athens and a Greek hero. His name comes from the same root as Thesmos, which means rule or precept.

It is supposed that the ship was sailed by Theseus through a battle and was kept in a harbour as a museum. As the time passes by, the wooden parts of the ship start to get damaged and rot and gets repaired and replaced with new parts, the paradoxical question being raised here is about the Identity of the Ship of Theseus overtime – Is it the same ship after its repaired? Is the Identity of the ship same after the parts are being replaced with new ones? Has the Identity of the ship persisted over time?

Plutarch writes (Vita Thesei, 22-23):

“The ship wherein Theseus and the youth of Athens returned had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their place, insomuch that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.”

At the heart of this paradox is the question of persistence over dynamism, question of change over time and challenges the concept of “permanism” of Identity. ?

Heraclitus argued: “On those who enter the same rivers, ever different waters flow.”

Plato did the interpretation of the arguments from Heraclitus on the fluidity and dynamism of Identity: “Heraclitus, you know, says that everything moves on and that nothing is at rest; and, comparing existing things to the flow of a river, he says that you could not step into the same river twice”

There are many interesting variations to the paradox – including the “Grandfather’s axe” where the argument is that if both the handle and the head is replaced in the axe in that case is this still the “Grandfather’s axe” and the related question is if either the head or the body is replaced – is this still the “Grandfather’s axe”.?

In the paradox, one aspect comes out very prominently is the “compositionality” of Identity – which also paradoxically hints at the plurality of Identity.

Following the Ship of Theseus paradox – the logical expression to formulate the notion of Identity using the part-whole dilemma could be as following:

For any compound entities, x and y, x = y only if every part of x is a part of y, and every part of y is a part of x.

What it means is that the Identity of an entity continues to exist intact from time t1 to the time t2, only if the composition of the Identity of the entity was same at t1 and t2; indicating that the sameness of the parts is an essential condition for establishing the sameness of the Identity.

This creates challenges in the Organic world and the challenge is multi-fold in the Digital world. Many of the composing attributes do change over time and the essential condition for the sameness of the “parts” for the sameness of the “whole” is not met. E.g. the address of residence may change over time for a person, so that if that’s an attribute used in the plural space to compose the singular Identity – the Identity is not same over time of that person. Many of the other relationships for the entity around the surrounding may also change over time and hence the sameness of Identity following the sameness criteria gets difficult to establish.

This gives us a catalyst to investigate Identity in a different way – the singularity in duality – especially when the boundaries between the Organic and the Digital Identity starts to get blurred and our lives become embedded in both Organic and Digital world in an inseparable way. Accepting the reality that Identity is not static in space and time is an important aspect to establish the Digital Me. It’s going to be an interesting journey to untangle the Identity crisis in the Digital World, it already is interesting.