> a would-be birth vs. loss of life in an accident are immeasurably different things; incomparable.
They're not incomparable, in fact they must be traded off at some rate, otherwise you could just dose everyone in the world with chemicals to sterilize us and say "well now there definitely won't be any child deaths"
This is clearly a case of “a difference in amount makes a difference in kind”. The complete sterilization of the human race is so different from “multi child households will be less likely to have a third child”. They are incomparable to actual living child deaths because they are theoretical vs real. A theoretical person is not a conscious creature. It is an idea in an actual conscious creatures head. It cannot suffer. Its value is measured purely in how it could affect society, positively and negatively, if it had have been born. A real person is conscious and can suffer and their death is a direct loss to them and those around them. That is not comparable.
Yeah, I understand this argument but I think it's bad philosophy. You need to think 4-dimensionally: everyone was a "theoretical" person if you go back far enough and making rules that harm people in the future but not in the present leads to wild temporal inconsistencies.
Perhaps it's clearer to think about a person-slot of a particular type in a particular time. If I go back to say 1930, you were probably just a person-slot, not an actual person.
They're not incomparable, in fact they must be traded off at some rate, otherwise you could just dose everyone in the world with chemicals to sterilize us and say "well now there definitely won't be any child deaths"