Let's consider a band (just called Theseus band, for convenience) consist of 3 members, Alex, Brad, and Charles.

After the first year, Charles left, and Gary joined the band.

After the second year, Brad left, and Harry joined the band.

After the third year, Alex left, and Isaac joined the band.

Now, we apply the same question for Theseus ship to this band.

  • Are they still "Theseus band"?
  • If they aren't, when did they stopped being "Theseus band"?
  • If Alex, Brad, and Charles then make a new band, and also called it "Theseus band", which one should we considered to be the 'real' one?

And kind of unrelated question, does it matter if the components fungible or not?

  • Is the metaphor of the Argo relevant here wrt Jason, the Argonauts and the Golden Fleece? theoi.com/articles/…
    – DJohnson
    Commented Jul 14, 2023 at 14:16
  • @DJohnson I'm not sure.
    – Tensor
    Commented Jul 14, 2023 at 14:25
  • What is the philosophical point behind this rewriting? Commented Jul 14, 2023 at 14:50
  • Just to make it clear each component that was replaced. Also, in this rewriting, components are not exactly fungible. Which is why I add the 4th question.
    – Tensor
    Commented Jul 14, 2023 at 14:57
  • Because people are involved, this is not exactly like Theseus' ship. Theseus' ship is an inanimate object. So in that case, we can worry about whether there's an objective decision available (there isn't, imo) and decide whatever we see fit. But in your case, it would be up to the participants to decide, whether in advance in the contract or at each stage. I'm not sure whether there may not also be a question of copyright involved.
    – Ludwig V
    Commented Jul 14, 2023 at 15:45

2 Answers 2


There is no proper answer to your question, for the ship of Theseus paradox is used to illustrate the need to define parameters of identity, which you haven't done.

From the standpoint of a record company and copyrights, yes, it might be ruled the same band. Two individuals might be considered "fungible" as adequate drummers, say. From the standpoint of a fan, perhaps, the band is totally different.

The same goes for the identity of a nation, for example, or any individual, whose bodily cells are replaced faster than their driver's license. As John Locke noted in a famous example, the entire makeup of our personal memories may change over time, which has ramifications for legal and moral responsibility.

The ship of Theseus is a physical object, and it illustrates that even in physics, which must employ "concepts," the conceptual whole is not at all the equivalent of the parts. At the atomic level it's all a Heraclitean stream held in place by our powers of conceptualization.

The point being that the relations between form, function, identity, and composition (or Aristotelean "causality") are complex, relative, and open to skeptical analysis.

So, the identity of your band can only be settled by reference to some defining parameters, such as copyright judgments in a court of law, where this ancient paradox is, indeed, always a live issue. In divorce court Phaedra can honestly argue, with full biophysical backing, "this is not the Theseus I married."


Underlying both the original ship of Theseus question and your reworking of it is a mistaken assumption that a label such as Theseus band is unambiguous and points to one and only one entity. Your question foolishly seeks black and white answers to matters that are inescapably grey.

The term 'Theseus band' has multiple interpretations. It can mean, for example, (1) the original line-up of the first band to be called Theseus, or (2) any other line-up of a band called Theseus.

If a member of the original line-up is replaced, then the new line-up is still a band called Theseus. Clearly it is not the same as the original Theseus band but it is still Theseus band in the sense (2) of the term.

Which line-up is the 'real' Theseus band is another ambiguous question, since the use of the word 'real' is open to interpretation in that context. Die-hard fans of the second line-up might considered that to be the only 'real' Theseus band.

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