Plenty is doing.
"The main significance of [the positive correlations between experimental performances in children, yielding a general intelligence factor] is, as it appears to me, that we are led to infer that all the functions of the human mind, the simplest and most complicated alike, are probably processes within a single system."
Disclaimer: this quote appears here only to spark discussion. It is not endorsed one way or the other. Make up your own mind. Or just refresh the page for another viewpoint. From a collection assembled by the late Chris Brand.