35 ° THE MISMEASURE OF MAN
innate deficiency of intelligence among blacks. He cites the quota-
tion on p. 271 as "Spearman's interesting hypothesis" that blacks
score most poorly with respect to whites on tests strongly correlated
with g:
This hypothesis is important to the study of test bias, because, if true,
it means that the white-black difference in test scores is not mainly attrib-
utable to idiosyncratic cultural peculiarities in this or that test, but to a
general factor that all the ability tests measure in common. A mean differ-
ence between populations that is related to one or more small group fac-
tors would seem to be explained more easily in terms of cultural
differences than if the mean group difference is most closely related to a
broad general factor common to a wide variety of tests (p. 535).
Here we see a reincarnation of the oldest argument in the
Spearmanian tradition—the contrast between an innate dominant
g and trainable group factors. But g, as I have shown, is neither
clearly a thing, nor necessarily innate if a thing. Even if data existed
to confirm Spearman's "interesting hypothesis," the results could
not support Jensen's notion of ineluctable, innate difference.
I am grateful to Jensen for one thing: he has demonstrated by
example that a reified Spearman's g is still the only promising jus-
tification for hereditarian theories of mean differences in IQ
among human groups. The Bell Curve of Herrnstein and Murray
(1994) has reinforced this poverty, indeed bankruptcy, of justifica-
tion for the theory of unitary, rankable, innate, and effectively im-
mutable intelligence—for these authors also ground their entire
edifice on the fallacy of Spearman's g. The conceptual errors of
reification have plagued g from the start, and Thurstone's critique
remains as valid today as it was in the 1930s. Spearman's g is not an
ineluctable entity; it represents one mathematical solution among
many equivalent alternatives. The chimerical nature of g is the rot-
ten core of Jensen's work, The Bell Curve, and of the entire heredi-
tarian school.
A final thought
The tendency has always been strong to believe that whatever
received a name must be an entity or being, having an independent
existence of its own. And if no real entity answering to the name could be
found, men did not for that reason suppose that none existed, but
imagined that it was something peculiarly abstruse and mysterious.
JOHN STUART MILL