Human Diversity is very carefully written. Murray deliberately avoids arguments about intelligence, obviously in an effort to outflank the predictable hysteria that would result from touching a subject so deeply embedded in blind dogmatism. The largest section of the book deals with gender, where Murray discusses differences in the distribution of psychological traits and interests. When he turns to race, Murray focuses primarily on health related differences. The medical research establishment is under heavy and growing pressure to pay attention to genetically based racial differences because the "races," however that term is defined or relabeled, are in fact different in ways that result in statistically significant differences in the incidence of various conditions, best courses of treatment, and research priorities.
Murray's overarching target is something that he calls the "sameness principle," which is the assertion that "whatever their gender, race, or the class they are born into, people in every group should become electrical engineers, nurture toddlers, win chess tournaments, and write sci-fi novels in roughly equal proportions. They should have similar distributions of family income, mental health, and life expectancy. Large groups differences in these life outcomes are prima facie evidence of social, cultural, and governmental defects that can be corrected by appropriate public policy."
Murray stresses continuously that the traits under discussion are very broadly distributed, that groups broadly overlap, that there are outliers among all groups, that people are more alike than different, and that one can infer very little about an individual's mental traits from his or her group membership. This will not slow down the critics who are playing burn the heretic, but it should give pause to any honest reader who actually wants to follow the argument.
The point is, if there are indeed differences in the incidence of various traits among different identifiable groups, one cannot jump to the conclusion that all differences in social outcomes are prima facie evidence of discrimination. That sameness principle establishes a false standard that can never be met in any free society. Which is of course why the left is so attached it it: the left is not interested in the science; the left is hostile to a free society and wants all institutions subjected to political discipline. Fanatical imposition of an objectively unattainable standard is a prescription for tyranny. Murray doesn't spell that out, but the implication is clear.
It is important to note that at no point does Murray deny the importance of socio-cultural factors. Any critic who doesn't grapple seriously with Murray's arguments on this point is simply dishonest. With regard to any issue of importance, teasing out the relative weight of socio-cultural vs. genetic influences is an important and often difficult question. But it is an important question, and it shouldn't be treated as taboo.
It would be fascinating to know how this book was put together. In his acknowledgements, Murray discusses the care with which he vetted everything with specialists in the myriad technical disciplines covered. He also emphasizes that this was done privately because many of the people with whom he was working are much younger and are in vulnerable positions in academia and elsewhere. This is an area in which truth telling can be -- and in the universities, almost certainly will be -- career ending. Murray wrote very carefully and vetted things very carefully, and then put himself out as the point man. Readers should be aware of the Orwellian academic bullying that dominates the background. One of Murray's assertions is that nothing in his book will, if stated precisely, be regarded as controversial by specialists in the relevant field, when they whisper privately among themselves out of earshot of their departmental Stasi informers. I am certainly in no position to referee that discussion, but I am aware of enough bubbling up in the quasi-samizdat of what is now being called the conservative dark web to suspect that Murray is right. When professors of woke studies, anthropology, English lit, etc. savage Murray, or when critics make conclusory accusations without getting into the weeds with careful, data-based counterarguments, my default reaction is to trust Murray.
Murray also argues that the rapid advances in various disciplines related to brain functioning will soon, probably within the next decade, make the sameness principle indefensible. He uses the example of people who tried to defend Aristotelian physics after Galileo did his thing in Pisa. The old paradigm will be rendered foolish. The paradigm shift may happen very quickly. It can't happen soon enough. At this point, unfortunately, the defenders of the sameness principle are playing scorched earth politics, precisely because they are acting in bad faith, and they know it. That they have such a chokehold in academia is a serious problem; our universities have become institutionally committed to a lie, and truth seekers are driven underground or purged.
“our universities have become institutionally committed to a lie, and truth seekers are driven underground or purged.”
Not just one lie—thousands of them—in a variety of different fields of study.
One hundred years from now—if homo sapiens survive—the standard doctrines taught in universities today will be laughed at by all serious people.
The old saying is that the way science advances is when the old scientists die.