Now I’m very much in the Stop Picking On Death camp and we’ve had it out on that subject before, but, as you say, setting that aside: something that people who aspire to immortality tech need to grapple with, I think, is that any technology that pushes the boundaries of human survivability is going to change our concept of what “death” is. This has already happened to a limited extent: concepts of what death is and when it occurs have been pushed back by medical advances, while those same advances have also pushed back our concept of what life is, in cases like brain death. Insofar as radical life-extending/life-expanding technology is possible, our present notions of life, death and identity will have completely broken down long before those technologies are perfected, simply because they’ll be obsolete. In a sense this is comforting and in a sense it’s not, since this also means the end of our present notions of what a person is and what it means to say that a thing exists, because those notions are not designed for the kind of pressures that immortality tech would place upon them. You can already see hints of this in the extreme, unbridgeable disagreements over partial-continuity thought experiments.

It seems to me that insofar as there’s a generalized intuition of death, it’s that death is when something changes irreversibly in such a way that you can no longer recognize it as having the same “identity”. This isn’t just a function of the degree of change, though, it also has something to do with smoothness – when you get into situations where the end result is still clearly a living person rather than a pile of topsoil, people’s intuition about “is this death” seems to be almost entirely based on whether they sense an abrupt discontinuity in something they consider central to identity.

Obviously, you get radically different results depending on how you define change, identity, smoothness, and so on, which is why once you start talking about hypothetical futuretech, concepts of death diverge into unrecognizeability. It’s also why the question of whether you’re dead or not depends on who you ask. It’s a fortuitous coincidence that the normal way of dying where your body stops working and disintegrates and isn’t replaced by anything with a close resemblance happens to satisfy nearly everyone’s death formula. In a real sense I think it’s fair to say that, just like selfhood, death is a social construct, and you need to account for that element of it when envisioning a “world without death”.