"The ship wherein Theseus and the youth of Athens returned from Crete had thirty oars, and was preserved by the Athenians. They took away the old planks as they decayed, putting in new and stronger timber in their places, so that this ship became a standing example among the philosophers... for one side maintaining that the ship remained the same, and the other contending that it was not the same."
Here is the ship. Below, the slider replaces its planks — as the Athenians did, one at a time.
Now imagine: as each old plank is removed, someone keeps it. Eventually they have every original plank. They rebuild the ship in a warehouse, exactly as it was.
Which is the real Ship of Theseus? Both have a claim. They can't both be it. But neither seems not to be.
— Thomas Hobbes, De Corpore, 1655
only physical continuity makes a thing the same thing. swap the matter, and it's a different ship, even if it looks identical. so the rebuilt ship B is the real one.
the arrangement is what makes it a ship. as long as the form is continuous and functional, identity persists. ship A wins — and you, too, are not the atoms you were seven years ago.
the ship is defined by its lineage of purpose — what it did, whose hands steered it, where it sailed. ship A carries that history unbroken. ship B is a museum piece, no matter how authentic its planks.
"the same ship" is a concept we impose on reality, not a property it has. both ships are real. the paradox isn't in the ships — it's in our expectation that identity must be crisp.