“8. The shared environment usually plays a minor role in explaining personalities, abilities, and social behavior.”
Here I have what I think is a major disagreement with Murray. If he means the term “shared environment” in the narrow sense used by say twin studies, he is probably correct. But in the more literal, Webster-derived conception of “shared environment” I very much disagree. Culture is a truly major shaper of our personalities, abilities, and social behavior, and self-evidently so. For my taste the book did not contain nearly enough discussion of culture and in fact there is virtually no discussion of the concept or its power, as a look at the index will verify.
Now that I have taken a first pass through the book, I believe that this criticism is unfair and should be retracted. Murray uses the term “milieu” to cover what Tyler means by “culture,” and Murray says everything about “milieu” that Tyler would want him to say about culture.
What Murray means by “shared environment” is just about anything that can vary within a (cultural) milieu. Parenting, schooling, government taxes and transfers, etc. All of it runs up against a broader version of the Null Hypothesis. But Murray says very clearly and emphatically that the milieu matters a great deal.
I wish that Murray had written Human Diversity under a pseudonym. Perhaps “Thomas Piketty” or “John Rawls.” It deserves the sort of study and discussion that was afforded Capital in the 21st Century or A Theory of Justice.