Unlike most of the HBD crowd, I don't hold IQ in nearly the esteem that they do. Medicine attracts a lot of highly gifted people, people who still manage to do incredibly dumb things. Still, any fair observer of the literature out there cannot but agree that IQ is a strong correlate to worldly success.
It's therefore with some interest, that I've had the pleasure of acquainting myself with the works of Dr Keith Stanovich, Professor of Human Development and Applied Psychology of the University of Toronto, who has much to say on the subject of intelligence and rationality.
Stanovich is critical of the unquestioning acceptance of the IQ test. Unlike other detractors, he does not claim that the tests are not valid measures of intelligence, or that there are different types of intelligence, rather, Stanovich recognises that the IQ testing is valid for the determination of intelligence but misses the mark with regard to rationality. Rationality, according to Stanovich, is an all-together different thing to intelligence, and unlike most critics of IQ testing, is able to prove his case with some conviction.
Here is an easy-to-read article he wrote for Scientific American.
There is a good YouTube video of him presenting his ideas. (Warning, it's about an hour and a half long). His use of George Bush in the early part of the video, as an example of the limitations of IQ testing--Bush was reputed to have an IQ in the 120-130 range--is reason enough to watch it.
He also has a home page where numerous papers of his are available for those who are interested.
One of the very surprising findings of his research is that high IQ, is in many instances, either weakly or not at all correlated to rationality, as it appears that high IQ individuals are just as able to irrationally "solve problems" as their low IQ peers. The cause of rationality failures amongst the high IQ crowd seem to cluster around cognitive biases, information lack and "cognitive miserliness ". There also seems to be some evidence of cognitive limitations in rationalisation. All in all he provides a convincing, and more importantly, empirically justifiable argument.
There is also a kindle version of his book, What Intelligence Tests Miss. I'm off to read mine now.