It is good that people are discussing IQ. Fred Reed’s post has drawn many comments, too many for me to answer individually. Here I outline the main heads of his argument as I see them, and some of the relevant research.

My summary of Reed’s post is:

Intelligence is important; intelligence research is important and can influence social policy; American blacks, the Irish, and Mexicans have similar IQs but different outcomes; IQ scores for some countries have been revised considerably, suggesting that intelligence measures are unreliable; Maya Indians had cultural achievements out of all proportion to the low IQs of the current inhabitants; current research shows European intelligence both falling and rising, the latter because of the Flynn Effect, and this suggests the measures are unreliable; the ancient Greek thinkers were very bright, and not dull as the Flynn Effect might imply; the IQ of India cannot be 81 because of India’s cultural achievements; there is no visible difference in intelligence between Mexicans and Americans, nor also with the inhabitants of Taiwan, Vietnam, or Thailand; and what mean IQ is thought necessary to run the infrastructure of modernity?

The first topic to cover is correlation. Correlations are best understood by looking at scatterplots. Any correlation which is less than unity will have discrepant data points scattered along the trend line. Some countries will be outliers for different reasons, all of them worth debating. For example, the usual link between IQ and GDP is altered by two main artefacts: oil and tourism. However, there are other reasons, and it is certainly worth following up all outliers, and putting forward testable hypotheses about why this is so. Of course, these hypotheses need to be tested on the whole data set. Even when the correlation is strong, say 0.8 there will still be discrepant cases (large residuals, in statistical jargon). https://www.unz.com/jthompson/the-grand-sweep-of-history

A discrepant data point does not destroy a general correlation. If there are many discrepant results the correlation is lowered. If all results are discrepant there is no correlation to discuss. Individual instances do not refute general findings. A test of intelligence which is an excellent predictor of later success in life will not always identify the most successful individual. There will always be exceptions to be pointed to. Rindermann is a good person to read on the relevant research between country IQ and national achievements. https://docs.google.com/document/d/1LCFQWcfhcjPz60xYifkjjaQ6cZeEasYKqMUdDoVnJxo/edit

The Flynn Effect co-exists with the Woodley Effect. Since roughly 1870 the Flynn Effect has been stronger, at an apparent 3 points per decade. The Woodley effect is weaker, at very roughly 1 point per decade. Think of Flynn as the soil fertilizer effect and Woodley as the plant genetics effect. The fertilizer effect seems to be fading away in rich countries, while continuing in poor countries, though not as fast as one would desire. The genetic effect seems to show a persistent gradual fall in underlying ability. Intelligence tests are good at identifying skills with high predictive value for life success, but less good at doing historical comparisons, unless one concentrates on specific subtests. IQ percentile ranks hold up very well over six decades. There is much research on this issue. Jim Flynn works with many of the new researchers on the topic, like Elijah Armstrong. It is a somewhat technical field, but very interesting.

https://www.unz.com/jthompson/105-years-of-flynn-effect-very-fluid

https://www.unz.com/jthompson/what-do-iq-researchers-really-think-about-the-flynn-effect

Country totals may appear to change, but that is to be expected if the initial samples were few and not properly representative. Well organized countries provide better data than less organized ones. As more data comes in the results should get to be more accurate. For that reason the whole Lynn database has been made public, and is being improved and extended. There is more work to be done, particularly adding in the cognitive estimates derived from maths and science examination results from international tests. https://www.unz.com/jthompson/world-politics-guide-2017

For the purposes of this discussion, it should be noted that the Lynn database for Mexico references only 3 studies, all of children, in the 6 to 13 year range, which you can see on the National IQ database, ranging from 80 to 88, for an overall mean IQ of 85. Adult data and more data would be better. However, a recent analysis of PISA, TIMSS and PIRLS data (1995 to 2012, N 93 nations) comes up with an IQ derived from those results of 88. The similarly derived IQ for the USA is 99.6. https://www.unz.com/jthompson/migrant-competence

Historical comparisons over several centuries are harder to carry out, but not impossible. Rindermann and I put in measures of historical cultural ancestors on two time spans: Nobels for the last century, and eminent scientists since 800 BC (the Ancient Greek effect) and showed that they both made a contribution to modern day economies. However, Greece is no longer the centre of the intellectual world, nor are the Mayas. Their accomplishments were real enough in their time. Their best thinkers are still rightly revered, but a nation’s current IQ is not always a good guide to the abilities of very distant ancestors. If populations move of their own volition or are displaced by new entrants, the general intellectual level can change. On the other hand, if selection on a settled population is hard enough then intellectual levels can rise in 8 to 16 generations. That is another interesting story.

The Indian mean IQ of 80 is based on 26 studies, so is well covered. Nevertheless, there is variability according to which province one measures, even more different than the States of the United States. The caste system creates differences. So does the rate of cousin marriage.

https://www.unz.com/jthompson/the-heterogeneous-states-of-india

https://www.unz.com/jthompson/more-sex-cousin

https://www.unz.com/jthompson/inbreeding-two-tribes

Naturally, you can have some bright people from all countries: is it the proportions which differ. Any big deviations from what you would expect from the country bell curve calls into question the stated average for that country. https://www.unz.com/jthompson/the-scrabble-for-africa

“No visible difference in intelligence between Mexicans and Americans, nor also with the inhabitants of Taiwan, Vietnam, or Thailand.” Cannot really comment on that, except to say that in social interaction it is not always either possible or desirable to make intelligence estimates. More relevant is to look at technical innovation rates, patents, science publications and the like. However, it would be a valid point if there were no differences in the achievements of those countries and the functioning of their societies. If there were no differences on the above measures, then the associations between mental ability and social outcomes would be weakened, and eventually disconfirmed. However, the general link between national IQs and economic outcomes holds up pretty well.

What mean IQ is thought necessary to run the infrastructure of modernity?

This interesting question has been much discussed. Smart fraction research suggests that the impact of the brightest persons in a national economy has a disproportionately positive effect on GDP. Rindermann and I have argued, following others, that the brightest 5% of every country make the greatest contribution by far, though of course many others of lower ability are required to implement the discoveries and strategies of the brightest. There have been two supportive replications.

https://www.unz.com/jthompson/is-smart-fraction-as-valuable-as

On this basis you might say that countries depend on those with IQs of 120 and above. These are the people who can follow “college format” education in which they read provided references and work out the implications for themselves, guided by tutor and test feedback. The USA can rely on 8% of their people to do such work, Mexico 2%. If countries can find such people, retain them, and deploy them properly, with a good pyramid of helpers below, then the country concerned has a good prospect of doing well. However, given global competition, countries need many people of IQ 130+ to really prosper, and such people tend to emigrate to the strongest economies, where they will earn most, so less able countries are often denuded of their brightest citizens. The USA can rely on 2% of their population to do such work, Mexico 0.3%.

However, a rule of thumb would be helpful in answering this, and the initial guesstimate was that a national IQ of 93 was required for a reasonable standard of living. I certainly agree that if the overall country data set shows no difference between countries of different intelligence levels, then the intelligence levels are called into question.

As economies globalize, the figure required for innovation and flourishing economies is probably being pushed upwards. At the same time, products are coming out which do many necessary things without requiring much intelligence from users. Mobile phones can perform functions which previously required high ability programing skills. Now, all users have to be able to do is point with their finger. Cars used to be complicated, and require careful maintenance. Now they are more reliable (though harder to service without computer guidance). Cash registers do everything based on pictograms, so a society can function to some extent on the problem solving of others. Good news all round.

Globalization may result in innovative countries being far richer than the countries which don’t innovate but just use the inventions, in the way that most of the world flies on wide body jets made in the USA and Europe. Skyscrapers were an innovation once, and are now commonplace. Nonetheless, the innovators will be the first to get the benefits of modernity, and are likely to retain most of the profits.