There is a strong tendency for the sme people to do better or worse on a wide variety of IQ tests. On this basis, some psychologists posit the concept of g, or a general intelligence factor. Does g show that performance on a wide range of cognitive tasks is influenced by individual differences in brain quality? It may, but if so, g lacks a sociological dimension and cannot explain cognitive trends over time or access their significance. It also encourages a paradox about nature versus nurture and over simplifies the causes of the Black-White IQ gap.