Interesting question on Notestein's motives! It feels like Notestein's justification around humanitarianism was more important to him, at least in his own retrospective discussion around it. Szreter mentions how Notestein talked about his experience with a "peasant village" in China, and how the people there wanted the ability to control their fertility. However, we have no idea who the questions were asked of these people and whether Notestein is interpreting the interaction through the lens that he, himself wanted to interpret it. Either way, the response reinforced his methodologies and ideas. Notestein seemed to see his own work in supporting family planning efforts through the demographic transition theory, and then as a circular way to then justify that it helped others meet their needs. However, at the time global development was still so new, run almost entirely by white men in high-income settings, and suffered from (and still does in many areas) a god complex. I think that economic and geopolitical interests were the more dominant driver and motivation, but humanitarian justification was the better rationale and cover story for Notestein.