Over the years, despite being on the ‘right’ and a proponent of HBD and HBD-based policy myself, I’ve contested the belief commonly held by many on the alt-right and even some on the rationalist-left that America is ‘dumbing down’:
First, it depends how one defines ‘dumbing -down’. If it’s defined as falling global mean and median IQs, then it’s possible (if it hasn’t already happened) that there is dumbing-down due to excess relative population growth of low-IQ countries. However, the world is not homogeneous. As Charles Murray notes in The Bell Curve, there is more variance among individuals than among groups. The IQ of sub-Sahara Africa, although one standard deviation lower than ‘European norms’, tells you nothing about the IQ of, say, New York or Singapore.
Second, if it’s defined to mean a decline of ‘total intellectual output,’ then as the links above show, the argument is much weaker because the evidence shows intellectual output has not fallen, both in terms of absolute output and output relative to population size.
Most people who talk about dumbing-down allude to the first definition. But I think the second is important, too, and should not be overlooked. It means there is hope, and that even if the world seems like it’s becoming dumber, there is still plenty of intellect if one knows where to look. Just go to Arxiv or do a Google search for high-level math or physics terms, and you’ll soon realize that maybe the world isn’t so dumb after all. If you spend your time in the trenches of the culture wars, then, yes, the world will seem like a pretty dumb place.
But just because there isn’t dumbing-down doesn’t mean America doesn’t stand to benefit from programs (what I call HBD-based policy)  that would boost national IQ and maximize cognitive capital…programs such as eugenics, a high-IQ basic income, and restricting immigration by IQ.
We’re sort of living in an upside-down world, where society devotes most of its resources to those who have the potential to produce the least economically. Governments spend inordinate amounts of money, such as on welfare and special education, trying to get the bottom 10% up to speed but by comparison neglect the top 10% even though the latter are the ones who actually advance society. One can argue the bottom 10% are the most vulnerable thus most deserving of help, but high birthrates suggest this group, from a Darwinian and ‘fitness’ standpoint, if anything, are doing too well.