> There is no logical basis for it. Or rather, any latticework of logic you erect to justify this choice is based on a foundation that has nothing to do with reason.
Any formal system is going to be based upon some set of axioms. You can't apply reason without some foundational choices (ie. your axioms).
The bright line you are looking for is a lot fuzzier than it seems at first glance.
If you take as axiomatic that "the human race surviving is a good thing we should work towards". Having kids becomes an exceptionally rational thing for people to do.
Funny how my belief system is basically the contrapositive.
"Having kids is not universally good so the survival of the human race might not be that important (but we should still work for the quality of life for the people who are and will be alive.)"
Any formal system is going to be based upon some set of axioms. You can't apply reason without some foundational choices (ie. your axioms).
The bright line you are looking for is a lot fuzzier than it seems at first glance.
If you take as axiomatic that "the human race surviving is a good thing we should work towards". Having kids becomes an exceptionally rational thing for people to do.