@bhawthorne @julienbidoret @wikipedia Yeah! I think it comes down to agreement. The crew may have replaced all the parts but still sleep and sail on her. They may tell a merchant to load the spices on her, pointing to The Ship of Theseus and they would be none the wiser and agree that is indeed The Ship of Theseus. The knowledge that all parts have been replaced is metadata really, an outside text, requiring additional knowledge. Hence, "Truth is a community."