My earlier comments on Michael Muthukrishna’s A Theory of Everyone are here, here, and here.
Chapter three, “human intelligence,” is the longest chapter of the book. I would love to see the first draft of the chapter. I get the sense that between when it was conceived and when it was published the chapter was revised to death.
Psychologists have a measure of intelligence, called IQ. In my view, this measure is reliable. That is, different tests conducted on the same person at different points in time come up with very consistent answers. This is in contrast with other personality tests, such as Myers-Briggs, where different test instruments can produce different results for the same person, and where someone’s assessed personality characteristics can vary from year to year.
I also believe that IQ is significant. It predicts many outcomes, including material success and life expectancy.
I also believe that IQ is mostly innate. Innate includes genetic inheritance but also development of the brain in the womb. See my review of Kevin Mitchell’s Innate.
MM’s chapter on intelligence is much less clear. I could cite passages that align with my views. I also could cite passages that contradict those views. The latter passages emphasize cultural factors that influence measured intelligence. For example,
not only is the idea of a culture-free intelligence test meaningless, so too is the idea of culture-free intelligence.
MM makes much of a single natural experiment, from Norway.
In the mid twentieth century Norway increased the number of compulsory years of schooling from seven to nine years. Thus children born days apart received a difference of two years of education
…Those two extra years of education gave those who received it an average of over seven IQ points
As far as I know, in the history of education research, no other educational intervention of any sort, when administered after the age of five, has been able to raise average IQ by anything close to seven points. MM’s reliance on this example is not sound practice. If he really believes that each incremental year of education adds 3 or more points to average IQ, I would be happy to bet against him on any experiment going forward.
On the issue of racial differences in average IQ, MM points out that race is socially constructed. Our intuitive idea of someone’s race may not align with a scientific analysis of that person’s genetic ancestry.
Concerning actual genetic differences among populations, differences that are not socially constructed, MM says,
The question, though, is to what extent these genetic differences matter to intelligence, education, work performance, or anything else we care about. . .if the theory of everyone is correct then the most probable answer is that it probably won’t matter all that much, if at all. For now, there is no strong case for genes explaining differences in cognitive or other outcomes between groups, but there is a strong case for the role of culture.
In the end, he says,
To summarize, intelligence is at the heart of who we are and how we got here, but there is no such thing as culture-free intelligence. Intelligence is a co-evolving product of cultural evolution. . .it means that we can structure our education systems and societies to develop the software and the hardware that will be most effective in coping with the changing world in which we live. In doing so, we can maximize our species’ ability to innovate new efficiencies, new energy technologies, and new ways to work together for mutual benefit.
MM strikes me as an extreme education optimist, meaning that he believes that education can make a huge difference in outcomes for individuals and for society as a whole. On the other hand, I am an extreme education pessimist. I do not believe that education can do much to overcome innate differences in ability. I think that educators can fill kids’ heads with ideas that are wise or foolish, but there are innate abilities that educators are unable to alter.
"This is in contrast with other personality tests, such as Myers-Briggs, where different test instruments can produce different results for the same person, and where someone’s assessed personality characteristics can vary from year to year."
Between 11:00 and 14:00 minutes of Razib Khan's most recent podcast psychologist Brent Roberts explains the issues with the Myers Briggs test. He also talks at times about the continuity of personality over years and decades with general percentages.
What about the Flynn Effect? IQ rose by as much as 14 points over just a few generations. I don’t see how that could possibly be genetic. Maybe that involves education, or maybe not, but certainly demonstrates the possibility of big environmental / cultural effects.