World A: 5 billion future people have good lives. Let’s say their lives are a 8⁄10 on some relevant scale (reducing the quality of a life to a number is a simplification; see footnote for a bit more on this5).
World B: 5 billion future people have slightly better than good lives, let’s say 8.1/10. And there are an additional 5 billion people who have not-as-good-but-still-pretty-good lives, let’s say 7⁄10.
World C: 10 billion future people have good lives, 8⁄10.
Claim: World B > World A and World C > World B. Therefore, World C > World A.
I suspect that there’s some confusion lurking in the fact that “the goodness of a life” isn’t well-defined. When I look at these three worlds, I think I probably prefer C over B, but I’m unsure, and I don’t have any clear position about A versus B. Part of the difficulty seems to be that in order to evaluate them, I would like to do something like visualizing the daily lives of people in world A and world B. But since I don’t know what a “7/10 life”, “8/10 life” and “8.1/10 life” mean in concrete terms, I have no idea of what I should visualize.
I suspect that there’s some confusion lurking in the fact that “the goodness of a life” isn’t well-defined. When I look at these three worlds, I think I probably prefer C over B, but I’m unsure, and I don’t have any clear position about A versus B. Part of the difficulty seems to be that in order to evaluate them, I would like to do something like visualizing the daily lives of people in world A and world B. But since I don’t know what a “7/10 life”, “8/10 life” and “8.1/10 life” mean in concrete terms, I have no idea of what I should visualize.