344 THE MISMEASURE OF MAN
had admitted the second-order general factor. The two schools
were not united and Spearman's g was not vindicated for three
basic reasons:
- For Spearman and Burt.g cannot merely exist; it must dom-
inate. The hierarchical view—with a controlling innate g and subsid-
iary trainable group factors—was fundamental for the British
school. How else could unilinear ranking be supported? How else
could the 11+ examination be defended? For this examination
supposedly measured a controlling mental force that defined a
child's general potential and shaped his entire intellectual future.
Thurstone admitted a second-order g, but he regarded it as
secondary in importance to what he continued to call "primary"
mental abilities. Quite apart from any psychological speculation,
the basic mathematics certainly supports Thurstone's view. Second-
order g (the correlation of oblique simple structure axes) rarely
accounts for more than a small percentage of the total information
in a matrix of tests. On the other hand, Spearman's g (the first
principal component) often encompasses more than half the infor-
mation. The entire psychological apparatus, and all the practical
schemes, of the British school depended upon the preeminence of
g, not its mere presence. When Thurstone revised The Vectors of
Mind in 1947, after admitting a second-order general factor, he
continued to contrast himself with the British factorists by arguing
that his scheme treated group factors as primary and the second-
order general factor as residual, while they extolled g and consid-
ered group factors as secondary.
- The central reason for claiming that Thurstone's alternate
view disproves the necessary reality of Spearman's g retains its full
force. Thurstone derived his contrasting interpretation from the
same data simply by placing factor axes in different locations. One
could no longer move directly from the mathematics of factor axes
to a psychological meaning.
In the absence of corroborative evidence from biology for one
scheme or the other, how can one decide? Ultimately, however
much a scientist hates to admit it, the decision becomes a matter of
taste, or of prior preference based on personal or cultural biases.
Spearman and Burt, as privileged citizens of class-conscious Brit-
ain, defended g and its linear ranking. Thurstone preferred indi-
vidual profiles and numerous primary abilities. In an
