g and job performance:

g has greater predictive validity for job performance of all kinds than any particular aptitude, although the prediction of job performance in any particular occupation can be significantly improved by taking certain special aptitudes into account, in addition to g. Certain aptitudes are completely irrelevant to success in certain jobs, but there is practically no job for which g is wholly irrelevant. Jobs differ in their g demands just as tests do, and highly g-loaded tests, such as standard intelligence tests and scholastic aptitude tests, are the best predictors of performance in g-demanding jobs. These are the jobs that cannot be routinized and require thinking, judgment, planning, assimilating new information, and making decisions on the basis of complex and changing conditions. Such demands are most typically found in highly skilled technical and professional occupations and in high-level managerial and executive positions. Persons who are low in g, therefore, are virtually excluded from such jobs. The educational requirements for many such highly g-demanding jobs usually screen out persons of below-average intelligence, because secondary and higher education are themselves quite g-demanding.

Arthur Jensen, Straight Talk About Mental Tests, 1981

[g is the technical term for general intelligence. Howard Gardner is a very prominent member of the anti-g-lobby. It would be very interesting to deeply analyze this anti-g-lobby (especially the motivations of Howard Gardner and others, why they are ignoring the facts, etc.). ... Sometimes it seems as if the 20th century was the century of the "anti-movements".]