This actually reminds me of a movie trailer I saw the other day, for a movie called In Time. (Note: I am not at all endorsing it or saying you should see it. Apparently, it sucks! lol)
General premise of the sci-fi world- People live normally until 25. Then you stop aging and get a glowy little clock on your arm, that counts down how much time you have left to live. "Time" is pretty much their version of money. You work for time. You trade time for goods, etc. Rich people live forever; Poor people die very young. (pretty much imagine if over-drafting your bank account once means that you die)
Anyway, when I saw this preview, being the geek I am, I thought: "That doesn't make sense!"
The reason it doesn't make sense has to do with the extension v. replacement argument. Until the age of at least 16, and more generally 22-ish, people are a drain rather than benefit to society. The economic cost of maintaining a child is not equal to the output of a child. (I'm obviously not talking about love, and fulfillment of the parents, etc.).
This society's idea is that people of working age would be required to provide the economic cost for their life. However what would actually end up happening is that the birth rates would climb sky high (since people die young, and you need some of your children to make it so that once you can't keep working anymore they can provide hours for you). So society would be burdened with raising and educating a disproportionately large amount of children, but not getting full utility out of them. (aka they would start killing them off once they actually reached working/productive age)
In other words, society pays a lot to raise a kid, and then kills it after only getting a couple of productive years out of it. Does not compute.
So my thought, upon seeing this trailer, was that it would make no sense for that society to allow everyone to have children, and only rich people to live forever. It would make way more sense for that society to allow everyone to live forever, and only allow rich people (who could completely pay for their children's upbringing) to have children. (I am not saying this is at all a "good" idea, but given the premise of the film, it was the much more reasonable alternative).
In other words, you can continue getting utility out of one person if they live forever, but if you are going the "replacement" route you constantly have to be pouring money into their education and upbringing.
Note: I am not actually arguing for extension over replacement in any society other than the rather far-fetched one presented in the movie.
Has anyone here ever addressed the question of why we should prefer
(1) Life Extension: Extend the life of an existing person 100 years
to
(2) Replacement: Create a new person who will live for 100 years?
I've seen some discussion of how the utility of potential people fits into a utilitarian calculus. Eliezer has raised the Repugnant Conclusion, in which 1,000,000 people who each have 1 util is preferable to 1,000 people who each have 100 utils. He rejected it, he said, because he's an average utilitarian.
Fine. But in my thought experiment, average utility remains unchanged. So an average utilitarian should be indifferent between Life Extension and Replacement, right? Or is the harm done by depriving an existing person of life greater in magnitude than the benefit of creating a new life of equivalent utility? If so, why?
Or is the transhumanist indifferent between Life Extension and Replacement, but feels that his efforts towards radical life extension have a much greater expected value than trying to increase the birth rate?
(EDITED to make the thought experiment cleaner. Originally the options were: (1) Life Extension: Extend the life of an existing person for 800 years, and (2) Replacement: Create 10 new people who will each live for 80 years. But that version didn't maintain equal average utility.)
*Optional addendum: Gustaf Arrhenius is a philosopher who has written a lot about this subject; I found him via this comment by utilitymonster. Here's his 2008 paper, "Life Extension versus Replacement," which explores an amendment to utilitarianism that would allow us to prefer Life Extension. Essentially, we begin by comparing potential outcomes according to overall utility, as usual, but we then penalize outcomes if they make any existing people worse off.
So even though the overall utility of Life Extension is the same as Replacement, the latter is worse, because the existing person is worse off than he would have been in Life Extension. By contrast, the potential new person is not worse off in Life Extension, because in that scenario he doesn't exist, and non-existent people can't be harmed. Arrhenius goes through a whole list of problems with this moral theory, however, and by the end of the paper we aren't left with anything workable that would prioritize Life Extension over Replacement.