Source: Brain Pickings
“Throughout our lives, we come to inhabit the seven layers of identity, often interpolating between them and constantly changing within each. And yet somehow, despite this ever-shifting seedbed of personhood, we manage to think of ourselves as concrete selves – our selves. Hardly any perplexity of human existence is more fascinating than the continuity of personal identity – the question of what makes you and your childhood self the “same” person, despite a lifetime of change, from your cells to your values. Harvard psychologist Daniel Gilbert captured this paradox perfectly: “Human beings are works in progress that mistakenly think they’re finished.”
Two millennia before modern psychologists came to tussle with this puzzlement, the great Greek historian and writer Plutarch examined it more lucidly than anyone before or since. In a brilliant thought experiment known as The Ship of Theseus, or Theseus’s paradox, outlined (though not for the first or last time) in his biographical masterwork “Plutarch’s Lives” (free ebook/|public library), Plutarch asks: If the ship on which Theseus sailed has been so heavily repaired and nearly every part replaced, is it still the same ship – and, if not, at what point did it stop being the same ship?
He writes: “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.
In this wonderful animation, the visual educators at TED-Ed – who have previously explored how you know you exist by way of Descartes and the nature of reality by way of Plato -examine the famous thought experiment and how it illuminates the perennial question of who we are: