Richard Herrnstein (Professor of Psychology at Harvard) died before the book was published (1994). He held the BF Skinner chair in psychology --this is one of the most prestigious ones in the US. Charles Murray, more of a social scientist and intellectual, is alive and is described by many in the liberal media as "the most dangerous conservative in America." Actually, Professor Murray is more of a Libertarian as far as I understand him.
I pulled the Thomas Sowell citation you gave. He alleges things, again, without data on the basis of anecdotal evidence. He is one of my favorite people; however, he is wrong about Dr. Jensen as well. It would seem even genius level, Black people hate the idea of group norms and the inheritance of mental abilities. Incidentally, I watch a lot of football: almost all the great players are now Black. Ditto for the game of Basketball. Ditto for West African ancestory and long distance running. No one alleges these are random events caused by nurture only. Parenthetically, if you keep in mind that Jews, on the average, are smarter than European Whites (Mean Jewish I.Q. is 117), then you are not surprised by the over-representation in Nobel Prizes, scientists, physicians, lawyers and successful business men. When I last checked the Forbes 400 richest, about 1/4 were Jews and they are only 2% or so of the general population. Much of anti-semitism comes from the extroardinary success of Jews whenever they have been treated equal to others. I don't know if this represents a facet of being God's chosen people, or a simple secular finding on long term group characteristics.
It is really an impossible task. Academe is littered with the intellectual corpses of psychologists and others who ascribe mental abilities as well as physical abilities as an interaction between inheritance and the enviornment.
A good parlor test I have given in the past is to pose two questions to the audience. First, do you hold that there is such a thing as human nature and this needs to be taken into account when you choose to reform society? As a corallary of this question, I accept the doctrine of original sin or any kind of secular statement indicating there is a basic, genetically determined human nature and we are not simply a "tabla rasa." The second question I ask do you see differences between individuals and groups that cannot be wiped out by education, income redistribution or egalitarian beliefs. The answer to these to questions is always surprising. There is large group of smart, thinking people who disclaim the evidence of inheritance of almost anything in human beings even though they may purchase dogs and horses on this basis (some of my friends are well off!). There is also a child-like, rather than realistic, belief that you can educate anyone and everyone to fit any job ever designed. Amazing. I believe in education, but there are limits what I or anyone can achieve. No doubt, Dr. Sowell is smarter than 99.9% of the people (and this includes me); however, he has an underlying faulty appreciation of human and group differences.
The 10% increase in I.Q. over a generation is called the "Flynn Effect." It occurs in all races in this country and in Europe. At the same time the SAT Scores have declined. What seems to be the case is that the left hand side of the Bell Curve has been improving on the basis of a better diet and medical care. The lowering of the SAT Scores could be the function of a dysfunctional education system or selective mating where women with I.Q.'S 120 plus are not reproducing sufficient to replace their population while women with I.Q.'s less than 80 are reproducing at a rate, and a younger age that increases their segment of the population. +