Professor Lynn and colleagues wrote a paper in 2008 in the journal Intelligence which has been widely discussed. Here is a summary of its claims:
"Evidence is reviewed pointing to a negative relationship between intelligence and religious belief in the United States and Europe. It is shown that intelligence measured as psychometric g is negatively related to religious belief. We also examine whether this negative relationship between intelligence and religious belief is present between nations. We find that in a sample of 137 countries the correlation between national IQ and disbelief in God is 0.60 [a high correlation]."
The highlight of the paper is the chart of 137 nations. And it looks pretty convincing until you study it carefully.
Then, picturing the data is a cart for the theory, wheels start wobbling.
I first became suspicious when Lynn et al. tried to explain why the United States is anomalous “in having an unusually low percentage of its population disbelieving in God (10.5 percent) for a high IQ country .”
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The reader may protest, after all, that these are individual cases. Very well, let's be daring. Let's drop from the list all nations where government either enforces or forbids religion or is known to be generally unrepresentative. Most such countries report lower average IQ. But the centralized thinking of authoritarian culture could well cause lower IQ.
Denyse O'Leary is co-author of The Spiritual Brain. Follow me at Twitter!