Not to excuse the shoddy scholarship of rushton and jensen, but I’d just like to add that a cursory examination of the nisbett article indeed shows some highly dubious claims. In several places he assumes a hypothesis of the form “If the hereditary model is true, then we should see X”. But for many of these it seems that X does not necessarily follow from the hereditary hypothesis. the hereditary hypothesis is not a monolithic structure. it is a spectrum of correlation from 0.0 to 1.0. both ends seem equally implausible to me.
Not to excuse the shoddy scholarship of rushton and jensen, but I’d just like to add that a cursory examination of the nisbett article indeed shows some highly dubious claims. In several places he assumes a hypothesis of the form “If the hereditary model is true, then we should see X”. But for many of these it seems that X does not necessarily follow from the hereditary hypothesis. the hereditary hypothesis is not a monolithic structure. it is a spectrum of correlation from 0.0 to 1.0. both ends seem equally implausible to me.
My own encounter with Nisbett material: http://news.ycombinator.com/item?id=4257220