The Ship of Theseus

[sdi]

The ship on which Theseus sailed with the youths and returned in safety, the thirty-oared galley, was preserved by the Athenians down to the time of Demetrius Phalereus [e.g. circa 300 BC].​ They took away the old timbers from time to time, and put new and sound ones in their places, so that the vessel became a standing illustration for the philosophers in the mooted question of growth, some declaring that it remained the same, others that it was not the same vessel.

(Plutarch, Life of Theseus XXIII)

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You cannot step twice into the same river, for other waters and yet others go ever flowing on.

(Heraclitus, fragment XCI)

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Speaking of Plutarch, the "ship of Theseus" paradox is such an interesting one to me, since I think it's surprising that people actually argued about it. A river never contains the same water moment-to-moment, and yet we always say it's the same river, right? The cells in your body are replaced, on average, every seven years (to speak nothing of the molecules!), and yet we always treat you as you, don't we? Bodies aren't fixed objects, they're continuous happenings.

It's for this reason that I think the traditional argument for the existence of the soul holds water. (I mean, besides having some minor personal experience of it.) If the river's water is always changing, what is the thing that makes the river the river? If your cells and molecules are always in flux, what is the thing that makes you, you? There must be something that doesn't change, and that something is what we call the soul.