Gradually losing health is unfortunate. I have to watch what I eat and be careful with my lifestyle due to chronic illness. My vision has degraded pretty badly and I'm forced to use a really gigantic font when I'm programming (you don't want to know how much time I spend fiddling with my colours!). These things pale in comparison to simply knowing what makes me happy.
I've worked hard to learn to be happy. Again, at least for me, I don't think happiness is something that is given to you. It's something that you make yourself. I suppose some people have a talent for it, like everything else, but it's something that you can work on and get better at. Without trying to sound arrogant there is no way that a child can have the kind of happiness that I have every day, because they simply do not have the experience to do it. They have a tumble of conflicting emotions which they have no control over. You couldn't pay me to do that again.
(If possible. I realize that isn't an option for everyone, and some people are working as hard as they can just to reach a secure position in life where they don't have to worry about basic needs. But this applies for those groups as well: if you had a thousand extra years to work with, as a start, you'd have a lot more time to enjoy the secure lifestyle you've worked so hard for, not just to pass that more secure position on to your children.)
That's a big assumption, and one that seems rather unlikely to hold or to suddenly change.
> You'd literally be trading a teenager's first crush for an 80-year old's third marriage.
If you're going to blatantly invoke imagery like that, then how about preserving the wisdom of experience? How much more might we advance the state of the art in every field if the experts in those fields are still around, healthy, and making new discoveries?
And there are plenty of 80-year-olds still enjoying their first marriage.
Youth is a wonder largely because of aging; eliminate aging and you get the pleasures of youth when you're a hundred.
Personally, I'm satisfied with "death is bad; stopping death would be good". Simplistic yet still incredibly true.
That will also keep bad guys around indefinitely. I think we can agree that things can be better. (I mean things like, environmental issues, corruption and foreign policies). But one cannot really hope to change the viewpoints/values/priorities of people already in power. Our only hope is the new generations, which we can hope to bring up with better values, which will eventually replace them.
Imagine if Hitler could live indefinitely or created an army of clones. Imagine every corrupt/powerful person in the world right, has the capability for doing this.
The point I am trying to make, is good cannot do good, when evil forces are in power. And the only thing that prevents evil forces in power indefinitely, is natural death. (We can all agree that things like democracy are not really doing a good job at that, right?)
Because you're questioning the only real moral principle humanity has.
This is probably not the place to argue about the existence of God, but I will say this: your reasoning is circular. "There's no rational justification for it, so it's not true; and since it's not true, there's no rational justification for it." You have made up your mind already, so you don't even realize when you beg the question. In fact, many people do see rational arguments in favor; just because you disagree with them doesn't make them irrational. And your stated arguments are, in fact, irrational.
Food for thought.
https://en.m.wikipedia.org/wiki/Donald_Knuth
I'm sure Knuth is full of joy writing his next book.