Here is a fun philosophical concept, it’s called the Ship of Theseus. I first encountered it in a Sunday funny depicting a man swinging an axe and talking to his elderly wife. He is saying, “Sure I replaced the head twice and the handle three times, but it’s still the same axe!” The Ship of Theseus is a little more complicated. A ship is thousands of pieces, but if you replace each and every one, is it still the same ship.
The modernist perspective is to say, “No, of course not.” But I think the question is a bit more complicated than that. Is a construct greater than it’s parts? If I were to take paint and a canvas and combine them, do I just have paint and a canvas or might I end up with a painting — a work of art even? Now if the paint scrapes off and another artist restores it with new paint, is it still the same piece of art? A restored piece of art?
What if you know someone for seven (to 20 or more) years. All of the individual cells that make them up have been replaced. Do you know a new person or because the change was gradual is it the same person?
I tend to think it is. Or rather, that a person may change from one person to another, but such things have to do more with a person’s essence (I’m queasy about saying soul) rather than a person’s cells. However, assigning such a high compliment to an inanimate object as an essence is a strange thing. I’d be squeamish about doing that.
Then again, I know a few people that have replaced every part of their car except the body and still consider it the same car. Pragmatically, if everything stays basically the same, it will be the same. But might that be a different way of saying essence?