1) I controversially think the world is currently underpopulated. Yes, as a species we need to get our pollution and resource management under control, but we need to do that at any population size. Once pollution and water is properly handled with technology, there should be enough landmass to handle 20B+ people. That's 10 billion extra potential scientists and artists to propel our species forward.
2) I am terrified that the idea that populations stabilize once a certain level of development and women's education is reached is false and not culturally universal. It seems like a very important untested assumption. If it isn't true, and we continue to see exponential population growth in developed second world countries but not in first world countries, I think that the disruption to the status quo and fear of aggression could lead to massive global wars of the kind we've never seen before.