Again referencing the Volokh post from my previous entry, I found it interesting that he takes exception to the comment that one of his posts "vastly overestimates the intelligence of religious people".

But then he goes on to say this:

It's possible, I suppose, that I know a bunch of very intelligent religious people, but they're outliers -- that on average atheists, agnostics, and other nonreligious people are much smarter than religious people.

Now how is that statement not as potentially offensive as the one he took exception to?

He goes on to say that he doesn't have any real statistical evidence to back this claim up. I wondered if any such research has been done.

And I found this page.

It references numerous studies of IQ throughout the 20th century, some of which find positive correlations between nonreligiosity and higher IQ, some which found negative correlations between religiosity and lower IQ, and some that found no correlation whatsoever.

They list the sources of these studies, but not having dug any deeper than that, I'd have to remain highly skeptical about the stats listed. Why? As many here have pointed out in discussions of AI, intelligence is an extremely complex concept, and there is quite a lot of divisive argument regarding its definition, its measurement, or even its existence (some argue that there is no such thing as general intelligence, but rather there are multiple intelligences).

I happen to think there is such a thing as general intelligence, traversing a very complex set of behavioral characteristics, including the ability to learn and acquire new skills, ability to innovate and improvise in newly-encountered situations, and complex problem-solving. Also involved, but I believe to a lesser extent, are verbal acuity, mathematical ability, spatial awareness, and memory skills.

And one reason such studies are specious is due to the fact that the first three attributes I mentioned are incredibly difficult to quantify and measure, and most IQ tests do a relatively poor job of assessing them.

There are more informal polls that simply ask members of particular populations about their religious inclinations, probably on the assumption that members of those groups are inherently more intelligent.

The results?

According to Nature 394:313, a recent survey of members of the National Academy of Sciences showed that 72% are outright atheists, 21% are agnostic and only 7% admit to belief in a personal God.

...Skeptic published the results of another study that compared professions and likelihood of believing in God. The general public was just over 90% likely to believe in God. Scientists in general were just under 40% likely. Mathematicians were just over 40% likely, biologists just under 30%, and physicists were barely over 20% likely to believe in God.

This is suggestive, but hardly a very reliable way of correlating intelligence and religious belief.

Finally, I did find this bit interesting too, an attempt to correlate morality and religious belief:

According to the Skeptic magazine vol.6 #2 1998, in multiple studies, there is a negative correlation between theism and morality. By Franzblau's 1934 study, there's a negative correlation between religiousity and honesty. Ross 1950 shows atheists and agnostics are more likely to express their willingness to help the poor than the deeply religious. 1969 Hirschi and Stark found no correlation in lawbreaking by churchgoing children and non-churchgoing children.

Now that would be an interesting study to read. If nothing else than to check their methodology. How do they test, for example, honesty? Maybe the nonreligious people are just better liars? Ditto with lawbreaking. Maybe non-churchgoing children are simply better at not getting caught. Then again, that might actually correlate with intelligence.

Hmm...

Anyway, I'm extremely suspect of studies that purport to find such correlations, again, because IQ is such a complex and difficult attribute to define and measure. But instinctively and unscientifically I actually tend to agree with Volokh. I think there probably is some correlation between higher IQ and increased skepticism, which naturally tends toward more overt challenging of religious faith, and less religiosity in those individuals.

No doubt, some here will disagree.