Longtermism seems to rely on zero discount rates for the value of future lives. But per moral uncertainty, we probably have a probability distribution over discount rates. This probability distribution is very likely skewed towards having positive discount rates (there are much more plausible reasons why future lives are worth less than current lives, but very few (none?) why they should be more important ceteris paribus).
Therefore, expected discount rate is positive, and longtermism loses some of its bite.
Possible counterarguments
Discount rates are not part of moral uncertainty, but different kind of normativity (decision theoretic?), over which we ought not have uncertainty
Equally plausible reasons for positive as for negative discount rates (although I don’t know which ones?)
Complete certainty in 0 discount rate (seems way overconfident imho)
Main inspiration from the chapter on practical implications of moral uncertainty from MacAskill, Bykvist & Ord 2020. I remember them discussing very similar implications, but not this one – why?
Argument against longtermism:
Longtermism seems to rely on zero discount rates for the value of future lives. But per moral uncertainty, we probably have a probability distribution over discount rates. This probability distribution is very likely skewed towards having positive discount rates (there are much more plausible reasons why future lives are worth less than current lives, but very few (none?) why they should be more important ceteris paribus).
Therefore, expected discount rate is positive, and longtermism loses some of its bite.
Possible counterarguments
Discount rates are not part of moral uncertainty, but different kind of normativity (decision theoretic?), over which we ought not have uncertainty
Equally plausible reasons for positive as for negative discount rates (although I don’t know which ones?)
Complete certainty in 0 discount rate (seems way overconfident imho)
Main inspiration from the chapter on practical implications of moral uncertainty from MacAskill, Bykvist & Ord 2020. I remember them discussing very similar implications, but not this one – why?
If there is a non-trivial possibility that a zero discount rate is correct, then the case with a zero discount rate dominates expected value calculations. See https://scholar.harvard.edu/files/weitzman/files/why_far-distant_future.pdf
You’re right. I had been thinking only about the mean on the distribution over discount rates, not the number of affected beings. Thanks :-)