Michael Bitton has used this argument as a reductio against longtermism (search “Here’s an argument”).
It seems it could work as to the medium term but would not work as to the very long term because i) if the fertility rate is above replacement, the initial additional people stop having a population effect after humanity reaches carrying capacity and ii) if the fertility rate is below replacement, the number of additional people in each generation attributable to the initial additional people would eventually reach zero.
Michael Bitton has used this argument as a reductio against longtermism (search “Here’s an argument”).
It seems it could work as to the medium term but would not work as to the very long term because i) if the fertility rate is above replacement, the initial additional people stop having a population effect after humanity reaches carrying capacity and ii) if the fertility rate is below replacement, the number of additional people in each generation attributable to the initial additional people would eventually reach zero.