THE HEREDITARIAN THEORY OF IQ
tall sons and relatively short fathers short sons. This high within-
group heritability argues neither for nor against the possibility that
better nutrition in the next generation might raise the average
height of third-world villagers above that of prosperous Ameri-
cans. Likewise, IQ could be highly heritable within groups, and the
average difference between whites and blacks in America might
still only record the environmental disadvantages of blacks.
I have often been frustrated with the following response to this
admonition: "Oh well, I see what you mean, and you're right in
theory. There may be no necessary connection in logic, but isn't it
more likely all the same that mean differences between groups
would have the same causes as variation within groups." Tbe
answer is still "no." Within- and between-group heredity are not
tied by rising degrees of probability as heritability increases within
groups and differences enlarge between them. The two phenom-
ena are simply separate. Few arguments are more dangerous than
the ones that "feel" right but can't be justified.
Alfred Binet avoided these fallacies and stuck by his three prin-
ciples. American psychologists perverted Binet's intention and
invented the hereditarian theory of IQ. They reified Binet's scores,
and took them as measures of an entity called intelligence. They
assumed that intelligence was largely inherited, and developed a
series of specious arguments confusing cultural differences with
innate properties. They believed that inherited IQ scores marked
people and groups for an inevitable station in life. And they
assumed that average differences between groups were largely the
products of heredity, despite manifest and profound variation in
quality of life.
This chapter analyzes the major works of the three pioneers of
hereditarianism in America: H. H. Goddard, who brought Binet's
le to America and reified its scores as innate intelligence; L. M.
erman, who developed the Stanford-Binet scale, and dreamed of
a rational society that would allocate professions by IQ scores; and
R- M. Yerkes, who persuaded the army to test 1.75 million men in
World War I, thus establishing the supposedly objective data that
vindicated hereditarian claims and led to the Immigration Restric-
tion Act of 1924, with its low ceiling for lands suffering the blight
°f poor genes.
The hereditarian theory of IQ is a home-grown American