Genes, Brains, and Human Potential The Science and Ideology of Intelligence

84 PRETEND INTELLIGENCE

intelligence, and so on. Th e fallacy is that of assuming that such correla-

tions are describing the real structure of intelligence, when, of course,

they merely refl ect overlaps in score patterns, themselves derived from the

contents of the tests.

What is perhaps most remarkable is that investigators are surprised

that per for mances on such tests are correlated at all. Th e items are, aft er

all, devised by test designers from a narrow social class and culture; these

items are based on intuitions about intelligence and variation in it,

and on a technology of item se lection that builds in the required degree

of convergence of per for mance. In addition, the items are chosen using

fairly uniform criteria.

THE SLIPPERY VALIDITY OF IQ TESTS

We cannot say that IQ tests are valid scientifi c mea sures of intelligence.
Th e tests are supposed to mea sure a kind of cognitive power or strength
(g). But we cannot demonstrate that it is diff erences in such a function
that cause diff erences in test per for mances, because there is no agreed-
on description or model of it.
In consequence, all claims about the validity of IQ tests have been
based on the assumption that other criteria, such as social rank or educa-
tional or occupational achievement, are also, in eff ect, mea sures of intel-
ligence. So tests have been constructed to replicate such ranks, as we have
seen. Unfortunately, the logic is then reversed to declare that IQ tests
must be mea sures of intelligence, because they predict school achieve-
ment or future occupational level. Th is is not proper scientifi c validation
so much as a self- fulfi lling ordinance.
For example, Robert Plomin and colleagues have justifi ed hunting
for genes for IQ because, they say, individual diff erences in intelligence
are strongly associated with many impor tant life outcomes, including
educational and occupational attainment. Likewise, Gail Davies, Ian Deary,
and colleagues (see chapter 1) say that “individual diff erences in intelligence
are strongly associated with many impor tant life outcomes, including
educational and occupational attainments, income, health and lifespan.”
A special group set up by the American Psychological Association in 2012

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