Nor can we look for much help from the Flynn Effect, the rise in IQ scores that has been observed internationally for several decades. Only a portion of that rise represents an increase in g, and recent studies indicate that the rise has stopped in advanced nations.
He is missing and has always missed the point here. No one understands why the Flynn effect occurs. (The Flynn effect being where it has been observed that as a nation moves up the economic chain the median IQ score, even if measured using tools that don't require education, improves hugely - something more than 15 points since the 30's for the US) So there is hope that there is a Flynn effect within the US for the economically disadvantaged. But we have to systematically look ... and historically we haven't because it is too politically challenging?
BTW - I respectfully disagree with rstor1 inre Gould being a good refutation. Most of the refutations were so politically motivated (and thus tainted by strawmen etc) that they were worthless. I don't rememeber the specifics from Gould, but do remember that he was especially egregious inre the insinuation of his politics. The only refutations I saw that were even passable was a compendium by different scientists in the field.
BTW2 - Another very good book on a related subject is the Nurture Assumption (runner up for the Pulitzer if the year it was released)