A century ago I did not exist nor will I exist a century hence (we’ll assume that religions are all false). But is there a difference between those two states of non-existence? Is there a potentiality for life in both cases? And yeah, I’m getting old and clutching for straws. 
Well, in the case of not being born yet, you have your whole life yet to look forward to ahead of you. After you’re dead, not so much.
Are you asking whether the experience is different, or whether your future in each case is different? Because the answers are no and yes, respectively.
I’ll note that I personally find this rather comforting. There are lots of things worse than mere nonexistence.
If you’re never born, you have no legacy. If you’re dead, you can leave behind children and assets and history that continue.
Think if Lister had never been born. Or Hitler.
StG
You became slowly self-aware at some point after conception, putting it no more controversially than that. That’s when you starts to exist
When you die, you ceases to be. It’s not like you are going to be able to reflect on things, or worry about stuff undone, or how folk are getting on without you. You are gone, absent, null.
If you’ve had children there is continuity there. If you haven’t, then that is a line of ancestry billions of years old that ended with you. I find that quite a thought, to be perfectly honest,
I’ve always thought that the answer to “where do you go when you die?” is “back to where you came from.” Which is to say that I don’t think there’s any difference to “me” 100 years ago and “me” 100 years from now.
We the undead were formerly the unborn but all things must pass. My decaying remains will feed further life. That’s good enough for me.
If one believes one did not exist before birth and will not exist after death, then both are states of nonexistence. By definition, nonexistence is the same no matter when it happens. Therefore, there’d be no difference.
If you were born you existed and affected the world. In fact you probably always will exist because the passage of time seems to be an illusion of human perspective.
If you were never born then you do not and never did exist and you never had any effect on the universe. And you are also a member of a much, much, much larger group of never-realized possibilities; only a very small percentage all all possible people will ever exist.
God said it first! (Gen. 3:19, NKJV)
Haven’t been here in a while, so I hope I don’t mess up my first post, but I remember the tendency to wish there was a like button or it be more acceptable to simply agree with a post without it being seen a non-content. This post is very accurate to my view on the question posed by the OP.
And yet, if one wanted to needlessly be a bother maybe they could respond, “If only a very small percentage of all possible people will exist, were those others possible?” But, not really interested in the reply. It’s more rhetorical and annoying a question to begin with, not a true inquiry.
I mean, unrealized possibilities can’t be measured. But you accounted for that. I feel like you could be more accurate, but lose relatability. Not that I have a right to grade. Nor am I trying to.
Now for my honest answer to the OP, which is hugely egotistical on my part to even imagine I know enough about the subject to reply. No one knows the answer. Yet, here we all are.
I would suggest, in my infinite wisdom (sarcasm and also nudge to the ‘religions’ comment) that only if one exists was there potential to ever exist. And the difference is there, and matters, but from what perspective we’re measuring is not delineated. And the perspectives could be as countless as all the things that never did exist in themselves. Whether existence mattered depends upon the value one places on a life. The impact large or small and what it may have had. Which, of course, cannot be measured.
Going for the most objective answer possible, the fact that you existed at all must have mattered enough to happen. And it did. That cannot be denied. The why of your existence might be obscured, the impact, the worth. But it cannot ever be totally denied, as it was the result of many countless actions of this ever-expanding universe that life even came to be, and your species survived until your birth, and will survive after you.
But, are you insignificant? I think that is the heart of the question. I am assuming, but I think that the question was less academic than it was wistful and forlorn. We are all small when we compare ourselves to others. In truth, we see what amounts to no percent of the wide array of possibilities in life. And we often, to fit in and exist and find acceptance and love, shrink our worlds to fit the space we occupy. That makes our experience of life very distorted.
As a parting last ramble, I’ll add that I am a very weird thinker. And I believe the only way out of that shrunken worldview and into a fully-aware perspective (so much as humans are capable of) is through learning. Facing fear when it is felt. Always asking why and believing the why is something you have the intelligence to glean and understand. It helps to create a separate, stubborn sense of self that discounts the opinions of the others or standards of others to exist. And it cannot be stopped because it is just one’s own reasoning process that creates this unique, vast experience.
That’s my attempt to respond to what I believe was the semi-sweet longing implied in the OP.
This reminds me of the fact that even if I believed in reincarnation it would not comfort me in the least. Since I have no memories of previous versions of me (inarguable), I infer that a future me would have no memories of me and, for this version of me, I am my memories.
I have three children and six grandchildren, so I have some hope for future effect, but my main hope is that at least one of my mathematical ideas would survive as long as there are mathematicians.
The Many Worlds Interpretation of Quantum Stuff suggests that every possible thing that can happen must in fact happen in at least one universe (“world”) somewhere. Some implications, or questions:
- We’ve all, I suppose, heard of Quantum Immortality, the notion that there must be at least one “World” in which you live forever.
- Does this also suggest there must also be a world in which you have already existed forever?
- So there must also be a world in which you have existed forever in the past but will die in the future,
- …and a world in which you are born at some point in space-time, but will live forever into the future,
- …and a world in which you exist, have always existed in the past, and will always exist into the future.
And…
6. There must also be a world in which you have never existed, don’t currently, and never will. You don’t want to go there.
Who’s to say that this isn’t the only possible universe (“world”)? Because I personally am not yet satisfied that it is possible for the events of this universe to have played out any differently, from its inception up to the present, nor am I satisfied that the future of this universe and all the matter/energy in it is not set along a pre-determined path.
So, first demonstrate that it’s possible for some other universe to exist. Then we can talk about whether or not it’s possible for you to have lived forever in any possible universe. Then we can discuss whether such a universe with such a possibility realized must necessarily exist.
Put another way, you might posit that any given atom of Uranium-235 might spontaneously fission at any moment, but it’s not like you can dial back the clock (as in, through time travel) and actually put that theory into practice by re-running time and showing that in some timelines, other things being equal, that particular atom of U-235 spontaneously fissioned just now as I was typing, while in another it spontaneously fissions tomorrow, while in yet another it is the very last atom of U-235 left un-fissioned and un-decayed in the universe.
You may affect the world if you live some time after being born; otherwise, not much. And nonhumans (including plants and geology) seem affected as time passes. Did time exist before something resembling humans evolved? Does time exist on Ganymede?
It’s genetic. If your parents never had children, you probably won’t, either.
Oh, the zillions of human sperm and ova wasted in masturbation etc or menstruation! Oh, the quadrillions of possible people who will never exist! Oh, housing crisis averted!
I apply “human” loosely. The current count of known human species might be up to 15 or 17. Lots of [del]bestiality[/del] interbreeding there led to zagillions more possible “people” who could never be. Oh, the humanity!
The spiritual implications of (non)existence probably involve alternate universes.
Not to you, but not having been born yet does save on the funeral expenses.
A whole lot of drunken debauchery.
Time is everywhere; it’s the passage of time that is likely an illusion. The evidence seems to be that past, present and future are all equally real and co-existent.
And you (along with everything else) affect the entire universe and will continue to do so as long as it exists, in a sphere expanding at light speed.
I believe #6 is unavoidable, under the circumstances.
No, you cant go there!