Metaphysics of Identity

Of the many cultural gifts of the Internet, a hidden gem is the term “showerthought.” The name already gives itself away, so there really isn’t much need for explanation. We’ve all had one come to mind at an odd moment when we were zoned out. It just took the meme machine of the Internet to call it for what it is.

Here’s a showerthought I came across recently: if the cells in the human body are replaced every ten years, are we the same person we were a decade ago? An intriguing thought, already invalidated by a fallacious premise, because not all our cells regenerate at the same rate, and some cells don’t regenerate at all. But still!

That idea recalls the thought experiment which we know as the Ship of Theseus. It’s an ancient conundrum, as if the name hasn’t already given it away. It goes like this: consider our titular ship, once majestic but now rotting away. Some carpenters decide to restore it, replacing a board here and some equipment there. At the end of the project, can we consider it to be the same ship? What if all the component pieces were replaced, albeit piecemeal, such that none of the original parts remain? Is it still the same ship?

Giving it a more modern spin, how about we consider a band. When the group replaces its lead singer, can it be considered to be the same band? What happens if all the members are replaced over time so that none of the originals remain? Is it the same band? If the original band members were to regroup, which one is the real band?

The Ship of Theseus has several proposed resolutions. The central idea is one of identity (and in fact, this paradox falls within the category of the metaphysics of Identity). A few solutions introduce the element of time and how it affects identity. Some solutions call into question the nature of identity, and even our definition of what it means to be “the same”. Or is it perhaps that there is no identity at all?

My preferred solution involves the Final Cause, based on the four causes of Aristotle. The Final Cause is the end to which an object is intended. It’s not perfect because it’s not irrefutable, but I find its elegance and simplicity very appealing.

I like best the late Douglas Adams’ epiphany upon seeing the Gold Pavilion Temple of Kyoto. The temple had been burnt and destroyed and rebuilt several times over 700 years (it was originally built in 1397). Is it the same temple?

What Douglas Adams had to say:

“The idea of the building, the intention of it, its design, are all immutable and are the essence of the building. The intention of the original builders is what survives. The wood of which the design is constructed decays and is replaced when necessary. To be overly concerned with the original materials, which are merely sentimental souvenirs of the past, is to fail to see the living building itself.”