> Anyway, scientific issues aren't decided by credentials, but by data.
This is true – but data in peer reviewed journals not books.
> In other words, what Jensen and others took as a "culture fair," "g-loaded" IQ test turns out to reflect modifiable educational experiences that children have or do not have.
The majority of psychologists believe that the g-factor is an innate and immutable property. The g-factor correlates with reaction times, glucose metallisation rate and is highly heritable. This indicates that the g-factor most likely have a neurobiological basis (see articles by Haier for example).
In a recent article the g-factor also appeared in a battery of 42 tests (Johnson,W Bouchard, TJ, “Just one g: consistent results form three test batteries”). Here is a quote from the abstract:
> The concept of a general intelligence factor or g is controversial in psychology. Although the controversy swirls at many levels, one of the most important involves g's identification and measurement in a group of individuals. If g is actually predictive of a range of intellectual performances, the factor identified in one battery of mental ability tests should be closely related to that identified in another dissimilar aggregation of abilities. We addressed the extent to which this prediction was true using three mental ability batteries administered to a heterogeneous sample of 436 adults. Though the particular tasks used in the batteries reflected varying conceptions of the range of human intellectual performance, the g factors identified by the batteries were completely correlated (correlations were .99, .99, and 1.00). This provides further evidence for the existence of a higher-level g factor and suggests that its measurement is not dependent on the use of specific mental ability tasks.