Hello Kaj,

If you reject both continuity of identity and prioritarianism, then there isn't much left for an argument to appeal to besides aggregate concerns, which lead to a host of empirical questions you outline.

However, if you think you should maximize expected value under normative uncertainty (and you aren't absolutely certain aggregate util or consequentialism is the only thing that matters), then there might be motive to revise your beliefs. If the aggregate concerns 'either way' turn out to be a wash between immortal society and 'healthy aging but die' society, then the justice/prioritarian concerns I point to might 'tip the balance' in favour of the latter even if you aren't convinced it is the right theory. What I'd hope to show is something like prioritarianism at the margin or aggregate indifference (ie. prefer 10 utils to 10 people instead of 100 to 1 and 0 to 9) is all that is needed to buy the argument.