Another facet of the replaceability argument might come into play in environments where resources are scarce and adoption is not an option. In the case I’m thinking of where there are few enough available resources that the supportable population limit has been reached, it might make more sense for one person to abort an unwanted child to leave resources for a wanted child (who will presumably be treated better and thus be happier than an unwanted child).
Another facet of the replaceability argument might come into play in environments where resources are scarce and adoption is not an option. In the case I’m thinking of where there are few enough available resources that the supportable population limit has been reached, it might make more sense for one person to abort an unwanted child to leave resources for a wanted child (who will presumably be treated better and thus be happier than an unwanted child).
Yeah there are many cases where the math I did would produce a different answer. But I think this concern at least remains hypothetical.