To be honest, the case is still the original one, but almost every other part has since been replaced. Now, I’ve taken it back to the shop where I bought it 20 years ago and asked them to upgrade the motherboard, CPU, and memory - the last of the original parts.
So, is it still the same computer?
I also like that I can just keep replacing parts on an existing product rather than buying an entirely new device each time. That’s exceedingly rare feature these days.
It’s less that the identity of the PC slowly changes, and more that you give up assigning it a single identity. Instead you pick a point of reference (let’s say, the PC as OP bought it), and then you measure how much it changed from then to now.
That’s how it works with quantitative logic - you never ask “is this the ship of Theseus?”, you ask instead “how much of this entity is the ship of Theseus, as left initially in the Athenian harbour?”
It can’t be 6/5=120% - adding a secondary drive makes the computer slightly more different. It must be less than 100%.
Since I’m counting long-term storage as 20%, and it changed halfway (the old drive is still there), I’d argue that now it’s 90% of the PC that OP bought. (Of course, those numbers are simply made up, what matters is the reasoning.)
This adds two interesting bits of complexity:
Yup. It isn’t something serious; just some millenniums old talk. As such losing your train of thought is not a big deal, it’s part of the fun.