THE REAL ERROR OF CYRIL BURT (^2 95)
prophesied the union of these two great traditions in mental test-
ing: "Each of these two lines of investigation furnishes a peculiarly
happy and indispensable support to the other.... Great as has
been the value of the Simon-Binet tests, even when worked in the-
oretical darkness, their efficiency will be multiplied a thousand-fold
when employed with a full light upon their essential nature and
mechanism." When Spearman's style of factor analysis came under
attack late in his career (see pp. 326-332), he defended g by citing
it as the rationale for IQ: "Statistically, this determination is
grounded on its extreme simpleness. Psychologically, it is credited
with affording the sole base for such useful concepts as those of
'general ability,' or 'IQ' " (1939, p. 79).
To be sure, the professional testers did not always heed Spear-
man's plea for an adoption of g as the rationale for their work.
Many testers abjured theory and continued to insist on practical
utility as the justification for their efforts. But silence about theory
does not connote an absence of theory. The reification of IQ as a
biological entity has depended upon the conviction that Spear-
man's g measures a single, scalable, fundamental "thing" residing
in the human brain. Many of the more theoretically inclined men-
tal testers have taken this view (see Terman et al., 1917, p. 152). C.
C. Brigham did not base his famous recantation solely upon a
belated recognidon that the army mental tests had considered pat-
ent measures of culture as inborn properties (pp. 262—263). He
also pointed out that no strong, single g could be extracted from
the combined tests, which, therefore, could not have been mea-
sures of intelligence after all (Brigham, 1930). And I will at least
say this for Arthur Jensen: he recognizes that his hereditarian the-
ory of IQ depends upon the validity of g, and he devotes much of
his major book (1979) to a defense of Spearman's argument in its
original form, as do Richard Herrnstein and Charles Murrav in
The Bell Curve (1994)—see essays at end of this book. A proper
understanding of the conceptual errors in Spearman's formulation
is a prerequisite for criticizing hereditarian claims about IQ at their
fundamental level, not merely in the tangled minutiae of statistical
procedures.
Spearman's reification of g
Spearman could not rest content with the idea that he had
probed deeply under the empirical results of mental tests and