Some have argued that saving lives in developing countries does not actually raise the size of the population because people have less children when they feel more of them will likely survive or due to some other mechanism.
This would refute the central point of your case if true. What are your thoughts?
In places where lifetime births/woman has been converging to 2 or lower, saving one child’s life should lead parents to avert a birth they would otherwise have. The impact of mortality drops on fertility will be nearly 1:1, so population growth will hardly change. In the increasingly exceptional locales where couples appear not to limit fertility much, such as Niger and Mali, the impact of saving a life on total births will be smaller, and may come about mainly through the biological channel of lactational amenorrhea. Here, mortality-drop-fertility-drop ratios of 1:0.5 and 1:0.33 appear more plausible.
This suggests saving lives in low income countries decreases fertility, as you said, but still increases longterm population, because the drop in fertility is smaller than the drop in mortality.
In any case, if saving lives did not change longterm population, it would still increase population nearterm. Right after saving the life, the population will be counterfactually larger by 1 person (who was just saved). Consequently, saving lives would still increase person-years, and therefore the consumption of animals.
Saving lives could decrease person-years, and therefore the consumption of animals, if it sufficiently decreases longterm population. However, besides this going against David Roodman’s main conclusions, it could then easily decrease human welfare, as it would then decrease the total number of human years lived. Moreover, it may decrease animal welfare too if farmed animals already had good lives by the time human population is significantly decreased.
Some have argued that saving lives in developing countries does not actually raise the size of the population because people have less children when they feel more of them will likely survive or due to some other mechanism.
This would refute the central point of your case if true. What are your thoughts?
https://www.gatesnotes.com/2018-Annual-Letter?WT.mc_id=02_13_2018_02_AnnualLetter2018_Explainer_BG-YT_&WT.tsrc=BGYT
Thanks for the comment, John. From the abstract of David Roodman’s paper on The Impact of Life-Saving Interventions on Fertility (written in 2014), which is the best research I am aware of on the topic:
This suggests saving lives in low income countries decreases fertility, as you said, but still increases longterm population, because the drop in fertility is smaller than the drop in mortality.
In any case, if saving lives did not change longterm population, it would still increase population nearterm. Right after saving the life, the population will be counterfactually larger by 1 person (who was just saved). Consequently, saving lives would still increase person-years, and therefore the consumption of animals.
Saving lives could decrease person-years, and therefore the consumption of animals, if it sufficiently decreases longterm population. However, besides this going against David Roodman’s main conclusions, it could then easily decrease human welfare, as it would then decrease the total number of human years lived. Moreover, it may decrease animal welfare too if farmed animals already had good lives by the time human population is significantly decreased.