I’m not a philosopher – rather I’m a programmer – so this might come across as a bit odd, but this essay on state in Clojure was something I found helpful.

If you take nothing else away from it, try to hang on to this way of thinking about identity:

By identity I mean a stable logical entity associated with a series of different values over time.

An additional insight I derived from programming is that people often equivocate on the meaning of “the same”. There is not just a single, inherently correct way to determine if two things are “equal”. There are actually a lot of different ways to implement an equality check, and multiple different methods of checking can seem natural in a situation – even though they return incompatible answers. The Ship of Theseus is an example of such a mismatch in different methods of checking equality.