@8petros Unfortunately, I don't have the whole thing written down or even fully thought through, if I had I would have at least linked it. :<

The line of reasoning I would start with would go something like: The mere existence of people is not inherently valuable (this is what I was referring to as "anthropics", which is not quite correct, but I tend to think of it as a moral equivalent of the epistemological problem), so there is no moral incentive to produce more of them a priori. This already puts into question whether the future will contain that many more people as longtermists claim is likely or desired (depending on the specific subschool of thought). From there I would also examine assumptions of how much we actually should be deciding for potential people – while I see we might have _some_ obligations towards future generations, assuming too much risks impeding on their autonomy, which is also problematic.

Eh, there would likely be more, but even what I have already written contains so many philosophical holes that I get anxious re-reading it. If I ever get a week free I might end up writing down a semi-rigorous version of this argument. Actually, probably a couple weeks, since I have higher priority things to do... bleh.