"If intelligence were deeply encoded in our genes, that would lead to the depressing conclusion that neither schooling nor antipoverty programs can accomplish much."
More optimistically, it means that they're already working pretty well. In a chaotic environment where smart people are likely to be randomly struck down, most variation in intelligence is environmental: The smartest are those who avoid malnutrition, neonatal infections, mothers with drug addictions, etc. In a utopia where everyone receives perfect education and lives up to their full innate potential, all variation is due to genetics, because we're holding everything else constant.
Edit: Less optimistically, it also means that there are no additional gains to be had at the margin. Maybe the benefit of public schooling has been just to sort smart-student pegs into high-paying-job holes, and now that most of that sorting is done there's nothing left for schools to do.
Another reply in this thread cites some of the research on IQ score trends over time. There probably is more gain yet to be had among disadvantaged populations than among advantaged populations (which have already enjoyed huge gains), but the mechanism of causation of IQ gains is unclear enough that there may yet be a lot of room for increase for all populations.
Even if IQ gains grind to a halt in particular places, there is still much to be done to raise the level of rationality in the population there. (Another reply to this thread just cited Keith Stanovich's recent book What Intelligence Tests Miss,
which is all about how to improve rationality among people of various IQ levels.) And for general social improvement, it is also possible to shape public policies so that they take into account common forms of human irrationality,
More optimistically, it means that they're already working pretty well. In a chaotic environment where smart people are likely to be randomly struck down, most variation in intelligence is environmental: The smartest are those who avoid malnutrition, neonatal infections, mothers with drug addictions, etc. In a utopia where everyone receives perfect education and lives up to their full innate potential, all variation is due to genetics, because we're holding everything else constant.
Edit: Less optimistically, it also means that there are no additional gains to be had at the margin. Maybe the benefit of public schooling has been just to sort smart-student pegs into high-paying-job holes, and now that most of that sorting is done there's nothing left for schools to do.