Science in Christian Perspective
The Race and Intelligence Controversy
CLAUDE E. STIPE
Department of Sociology and Anthropology
Marquette University Milwaukee, Wisconsin 53233
From: JASA 26
(December 1974): 155-164.
Jensen and Shockley have revived the argument that blacks are
genetically inferior
to whites in intelligence. Jensen has published a number of articles and books
which have been responded to by scholars in such disciplines as anthropology,
education, population genetics, and psychology. Three areas focal to Jensen's
position are discussed here: the concept of race, the nature of
intelligence and
IQ tests, and heritability estimates. The conclusion is that Jensen
uses inadequate
data and questionable methods to support his position, which he
admits is at best
a "not unreasonable hypothesis."
Race and Intelligence
The idea that races differ genetically in intelligence and in their capacity to
create and embrace civilization is hardly new. It is periodically presented as
a scientifically valid position and each time is criticized because
the conclusions
are not warranted by the cited evidence.1 Historically, most advocates of the
genetic inferiority of blacks have been so blatantly racist that few scientists
have felt the necessity of systematically refuting them.
Two current major proponents of the relationship between race and intelligence
are William Shockley, a physicist at Stanford, and Arthur Jensen, an
educational
psychologist at Berkeley. Shockley has been on the lecture circuit for a number
of years warning us that our gene pool is being contaminated by
genetically inferior
blacks and poor whites. Among his suggestions for alleviating the problem is a
voluntary sterilization program which would pay low IQ individuals a bonus of
$1,000 for each 19 point below 100.2 Is is highly questionable whether Shockley
would have received so much attention nationally had it not been that in many
instances his scheduled lectures at prestigious universities such as Harvard,
Yale and Princeton were either cancelled or broken up by shouting
students. Shockley's
lack of understanding of genetics, intelligence and race are profound, and few
scientists take him seriously. His plea to the American Association
for the Advancement
of Science in 1967 for a crash pro
gram to measure genetic differences in intellectual and emotional traits hetwen
racial groups was rejected as not being feasible and as being unlikely to lead
to any conclusive results. The AAAS response stated in part:
There is no scientific basis for a statement that there are or that there are
not substantial hereditary differences in intelligence between Negro and white
populations. In the absence of some now-unforeseen way of equalizing
all aspects
of the environment, answers to this question can hardly be more than reasonable
guesses. Such guesses can easily be biased, consciously or
unconsciously, by political
or social views.3
It might be said that a new era in the discussion of
race and intelligence began in 1969 when the Harvard
Educational Review published Arthur Jensen's article titled "How Much Can
We Boost IQ and Scholastic Achievement?" His article begins with
the statement
that compensatory education efforts have failed to produce any lasting effects
on the IQs and achievement of children, and then suggests that it is necessary
to reexamine the premises on which these programs have been based:
that IQ differences
are almost entirely a result of different environments of the
subjects, and that
there is a cultural bias in IQ tests. He then argues that genetic factors are
much more important than environment in determining IQ scores, and
that furthermore
there exist "real average differences among the [racial]
groups-differences
in the population distributions of those characteristics which are indisputably
relevant to educational and occupational performance."4 In supporting this conclusion he discusses the nature of
intelligence
and of IQ tests, estimates of the heritability of intelligence, and the bases
for his conclusion that blacks score an average of approximately 15
points below
whites on IQ tests. Contrary to the impression given by the mass media at that
time, Jensen offers no new data to support his position, only a reorganization
of existing data.
A major point made by Jensen is that he has discovered two
genetically determined
types of learning ability: associative (or rote) learning (Level I),
and cognitive
or conceptual learning (Level II). He claims that all children have the ability
for associative learning, but that not all have the capacity to learn
conceptually.
Associative learning is seen as characteristic of low socioeconomic
status (SES)
children and conceptual learning of middle SES children. Since low SES subjects
in one test were all black and middle SES subjects were all white,
the differences
are seen as racial differences. Jensen concludes that we need school
systems which
will teach children in terms of their abilities to learn, and not
require conceptual
learning, which could cause failure of those who are capable of only
associative
learning.
Needless to say, the reactions were immediate, and were both positive
and negative.
Although it actually comprised a minor portion of the 123 page
article, Jensen's
views on the relationship between race and intelligence have received the most
attention. One discussant states that the article
is one of those signal events that are rare in any field of science:
the appearance
of a scholarly work that will for years, possibly for decades, he regarded as
the watershed that divides a period of misunderstanding, error and myths from
a new era when emergence of the true facts led to the formation of a
solid theory
upon which future scientific progress can be built.5
On the other hand, a black neuro-psychiatrist comments: "As I
reviewed this
elaborate assortment of truths, half-truths, falsehoods, exaggerations, faulty
deductions and speculations, I experienced mixed emotions -including a generous
portion of hostility."6 Martin Deutsch, who had co-edited an earlier book
with Jensen,7 states that the article contains "many erroneous statements,
misinterpretations, and misunderstandings of the nature of
intelligence, intelligence
tests, genetic determination of traits, education in general, and
compensatory
education in particular." He then comments that
Perhaps so large a number of errors would not be remarkable were it not for the
fact that Jensen's previous work has contained so few, and more malignant, all
the errors referred to are in the same general direction: maximizing
differences between blacks and whites and maximizing the possibility that such differences
are attributable to hereditary factors.8
In a paper of this length it is impossible to cover all the points of Jensen's
article which are open to question.9 Instead the focus is on three major areas
which are crucial to his hypothesis: the concept of race, the nature
of intelligence
and intelligence testing, and estimates of heritability.
The Concept of Race
If one is going to deal with the relationship between race and
intelligence, one
of the crucial concepts is obviously that of race. Almost all who
posit such a relationship imply that the races they are comparing are
distinguished by biologically
relevant criteria. Although the criteria are never stipulated, they so facilely
accept this supposition that they never consider it necessary to justify their
assignment of a specific person to one race or the other. Jensen does not even
consider the problem of definition, but simply states that races are said to be
breeding populations which according to geneticists have different
distributions
of gene frequencies.10 Of course, in technologically advanced
societies such
as the United States, there are no such isolated breeding populations, so that
cannot constitute an operational definition for his study. Neither does Shuey,
whose work The Testing of Negro Intelligence Jensen relies on for much of his
data, attempt any definition. She only states that "except for
small groups
of transitional types, the American Negro constitutes a recognizable
and clearly
defined group, the criterion of membership in which group being that
of more-or-less
African ancestry.11
Most advocates of the genetic inferiority of blacks have been so blantantly racist that few scientists have felt the necessity of systematically refuting them.
It is important to emphasize that race is a statistical concept,
which means that
it is extremely difficult to positively assign a given individual to a specific
race. As Mayr notes, when one looks at different populations he can
see that there
are different races, but "how to delimit them, how to draw the
line between
them is not only difficult, it is impossible."12 In contrast to a
racial analysis, Livingstone has suggested the use of a clinical analysis, which would
describe all
gene frequencies. If, for example the variability of a specific gene
is continuous
from north Africa to south Africa, the variability cannot be described in terms
of race. Also, if two genes vary discordantly, racial classifications based on
the one gene will not describe the variability in the distribution of
the other.13
Each of us probably differs from his neighbor by approximately 400 genes, yet
not more than about a dozen genes can be specified as occurring in one race and
not in others .14 When dealing with polymorphic frequencies between
populations,
it becomes obvious that the extent of variation within any population
is usually
far greater than the average difference between populations, and that there is
a great deal of overlap.
One problem with assigning names to races is that it facilitates the error of
typological thinkingthat is, the assumption that individuals in a given group
are alike, or at least very similar. It is this concept that the typical man in
the street has when he talks about races, and it also seems to be in the back
of the minds of those who posit a relationship between race and intelligence.
"Physical type, heredity, blood, culture, nation, personality,
intelligence,
and achievement are all stirred together to make the omelet which is
the popular
conception of race."15 This attitude is illustrated when Ingle
asks whether
there are "any biological bases for the failure of nations governed by Negroes and
mulattoes to become self-sufficient and creative." He answers his own
rhetorical question
by maintaining that the "genes representing traits that are important in
human affairs are not randomly and equally distributed among racial
groups."16
Because of the problems listed above, there are many who feel that the concept
of race should be abandoned. As it is commonly used, it is clearly arbitrary,
undefinable, and without biological meaning, and as Dobzhansky notes, it is far
from being a self-evident cliche.17
Since race is actually a statistical concept relating to groups and
not to individuals,
how then are individuals assigned to different racial groups in the
United States?
Obviously they are assigned primarily by social rather than genetic criteria.
For evidence we need only note that children of black/white marriages
are regarded
as black rather than white. It is as if children are considered to
have received
their genotype from a population rather than from their particular parents. The
gene pool of American blacks (defined socially) has been estimated to
be approximately
30% derived from white ancestry.18 It has also been estimated that
70% of blacks
have at least one white ancestor and that 30% of American whites have at least
one black ancestor.19 If we choose to call the white individual with
a black grandfather
a Negro, then logic would require us to call the "average" black in
Baltimore or New York a Caucasian. It has been suggested that the
classification
which a person gives of himself should be used, but if race is considered to be
a biological construct, the lay person's view of his own racial
identity is both
incompetent and irrelevant.
An apocryphal story is told about an American newspaperman who had an interview
with the President of Haiti.
They started to talk about Haiti and its population, and most indiscreetly the
American newspaperman asked the President of Haiti what percentage of
the people
were white. And the President of Haiti said, "Oh, about 95 per cent."
The American newspaperman looked a little puzzled and said, "Well, how do
you define white?" And the President of Haiti said, "Well, how do you
define colored?" And the American newspaperman said, "Well, of course
anybody with Negro blood is colored." Said the President:
"Well, that's
exactly our definition too: anybody with white blood is white."20
The same situation obtains in Brazil-anyone who is not "pure black"
is a Caucasian-21
Race is a statistical concept, which means that it is extremely difficult to positively assign a given individual to a specific race.
We do not have an accurate count of the so-called Negro population in
the United
States, because census takers are no longer allowed to ask the race
of the interviewee.
This means that the taker is asked to make a clinical judgment concerning race
that a trained physical anthropologist would hesitate to make. If he
is in doubt,
his instructions are to assign race according to the prevailing
racial composition
of the neighborhood.22 Since skin color is the major basis for classification, studies imply
a direct relationship between the genetics of skin color and the
genetics of intelligence.
In light of the above problems, is it correct to say that race is important in
our society? Unfortunately the answer is yes. Races are real
"because people
believe they are, and social reality-the human worldis determined by
human belief."23
The crucial point in this discussion of race is that most of the studies cited
by Jensen and others have used a social rather than a genetic
definition of race.
Under such conditions, how can one demonstrate a genetic relationship between
race and intelligence?
Intelligence Testing
A second major concern is the nature of intelligence and the validity
of intelligence
test scores. Jensen insists that there is no point in arguing the question to
which "there is no answer, the question of what intelligence
really is,"24
but that it is possible to measure intelligence, for
"intelligence, by definition,
is what intelligence tests measure."25 He limits the term intelligence to
that which is represented, by Spearman's g, which he claims is the
factor common
to all tests of complex problem solving.26 Although he considers it difficult
to define intelligence in so many words, he considers that "it is probably
best thought of as a capacity for abstract reasoning and problem
solving."27
The Binet Test was originally devised to help Paris educational
authorities separate
out the "dull" children who would not benefit from the
education offered
at that time, Both Binet and Simon warned that the results were
useful only when
the tested children came from similar environments. This warning has been often
repeated, but seemingly more often ignored. Jensen acknowledges that IQ tests
have been developed for the express purpose of determining success in school,
but insists that they not only measure school learning or cultural advantages
making for scholastic success, but also tap fundamental psychological
characteristics.28
He maintains that although intelligence has been singled out as
especially important
by educational demands, it is nevertheless "a biological reality and not
just a figment of social convention."29
Jensen's argument that most intelligence tests measure g is not universally
accepted.
Jastak maintains that most IQ scales include a balanced number of associative
and conceptual tests, and that furthermore, the associative tests are
more highly
correlated with IQ than are the conceptual ones.30 Deutseh strongly objects to
the use of Spearman's g as the basis for intelligence, stating that
g represents only one theory of intelligence, among many
others. It is by no means a universally accepted concept
among psychologists and others who work in this area.
Yet from Jensen's paper, the general reader would never
know that there are competing theories, several of which
are more widely accepted and based on more recent information and data than
Spearman's.31
Deutsch suggests as an alternative Piagct's theory, which is based on
intellectual
development interwoven with the child's experiences. Basically it is
a stage theory
with each new level building on the previous one. This approach
reflects process,
whereas Deutsch evaluates Jensen's notions of level as categorical and static.
He claims that Jensen's whole line of reasoning is inextricably linked
with the concept
of g, and questioning g throws doubt on his whole system.
Although Jensen claims that the dispute over
whether or not intelligence is fixed is a spurious one, 32
he writes as though IQ is essentially fixed. He defines intelligence
as 'performance
estimate," but explicitly and implicitly keeps falling into the error of
treating it as a measure of "potential ability." IQ tests
were constructed
with the assumption that intelligence is fixed. Since this assumption resulted
in an attempt to find test items which yield constant scores, the constancy may
be due more to the tests than to the subjects tested. Although Jensen
claims that
it is very difficult to change IQ scores by compensatory education,
It seems quite wrong to attach so much importance to a change-or an absence of
change-in IQ scores, when the test is designed both on the assumption that what
is measured is a fixed and unchanging characteristic, and with the
aim of producing
constant IQ scores. Such a use of intelligence tests suggests
insufficient appreciation
of the assumptions implicit in their construction.33
There certainly is some irony in the fact that people who see IQ as essentially
static in nature should use it as a measure of intellectual change.
Bereiter worked in programs for disadvantaged children in which the
main purpose
was to directly teach academic skills,
Nevertheless, in spite of the fact that the program was never intended to raise
IQ and that twothirds of it was devoted to reading and arithmetic instruction
having littie or nothing to do with the skills called for on IQ
tests, significant
IQ gains have been regularly obtained. Over the last four
replications they have
averaged about 15 points. This seems to he too much of a gain to write off to
test-wiseness and things of that sort, especially since the children's IQs were
in the middle nineties to begin with and thus rose to substantially
above average.34
Rex suggests that the field of psychometrics is possibly the least sensitive of
empirical human studies. Psychometricians claim that no assertions
are made about
essential intelligence, only about measured intelligence.35 Although they
may pretend that this measured intelligence has no reference to
practical, social
and political implications, the repercussions for the tested individual can be
crucial, as the following example illustrates,
The junior-high-.school counselor urged Ralph to drop some of his
academic subjects
on the ground that he was not "college material." The boy's
dissatisfactions
led his parents to see the counselor, who reported to them that
Ralph's test results
showed him to be "average" in ability. When questioned
about the accuracy
of the results, he argued that the boy's grades were consistent with
the IQ test
scores. This seemingly ironclad logic fell apart about eighteen months later.
After the use of private reading and psychological specialists, Ralph's grades
ruse from C's to B's and his IQ test scores from approximately 100 to
120 on comparable tests.36
Although it is not claimed that every student can be helped in this
way, it does
show the fallacy of supporting the validity of the IQ score by
reference to school
grades and vice-versa.
It was mentioncd above that Jensen claims to have isolated two genotypically
distinct basic processes which underlie learning. Since conceptual (Level 11)
abilities have been most important for scholastic performance under traditional
methods of instruction, he postulates that the genetic factors involved in each of these types of ability have become
differentially distributed in the population. 37 He also states that because of
this genetically different ability, ordinary IQ tests tap only one part of the
spectrum of mental abilities of disadvantaged children. Therefore the
low scores
they obtain on IQ tests are not unfair to them because they yield inaccurate or
invalid measurements, but because the tests measure abilities which
they basically
lack.38 Because of this situation
The ideal of educational opportunity should not be interpreted as uniformity of
facilities, instructional techniques, and educational aims of all
children. Diversity
rather than uniformity of approaches and aims would seem to be the
key to making
education rewarding for children of different patterns of ahility.39
Jensen fails to mention that in many cases children are now taught in
one or the
other style of learning. Brazziel notes that in the American south both black
and white schools use an associative (rote) learning style. Since most of the
urban northern black parents were reared in the south and therefore learned in
this way, they pass this learning style on to their children.
However, he states
that if conceptual learning is used early in their educational
experience, children
can be conditioned to think in that manner. He is afraid that if
teachers accept
Jensen's position, many children will never have a chance to be
exposed to conceptual
learning styles.40
It is very interesting to note that Jensen and Rohwer have
collaborated on studies
of paired-associate learning, and yet their interpretations of the results are
diametrically opposed. In these studies a student is presented with
20 word pairs,
such as "elephant and pillow," and in subsequent trials is supposed
to recall the second word when given the first. It was found that if
a child was
taught to elaborate on a pair of words, such as "the elephant is looking
for his pillow," the rate of performance increased sharply. When
this method
was used with children from varied backgrounds, there was no class distinction
in performance, even though the IQs differed. Jensen attributes the results to
the fact that associative learning is genetically more evenly
distributed in the
population. Rohwer, on the other hand, argues that this experiment stresses the
importance of an active process of learning which includes not a rote
principle,
but a highly inventive process of imaging.41 It was also found that simply
coaching lower-class children to make up "meaningful"
associations for
word pairs brought them up to the middleclass rate of learning.42
Since Jensen has concluded that the heritability of intelligence is
0.80, he leaves
very little room for the influence of environment. On the other hand,
most researchers
realize that there are many ways in which environment may be a
factor. It is impossible
to study cognitive abilities in isolation from their social and
motivational determinants,
and if this were explicitly recognized, it might remove much of the
mystery surrounding
the interpretation of IQ test scores. Even the experienced black
interviewer raised
in Harlem gets only monosyllabic, defensive answers when questioning
Harlem boys
lie knows in an indicidual setting, but in discussion with their
peers, the same
children reveal intricate verbal reasoning skills in talking about their
experiences.43
A large number of statistically significant correlates with IQ have
been discovered,
only a few of which are; height, weight, anxiety level, race and
warmth of examiner,
mother's attitude toward achievement, mother's concern for language
development,
home cultural level, father's occupation and years of schooling, and desire to
master intellectual skills.44 In the testing of laboratory animals
there are many
examples of situations in which the apparent strain differences in
learning, activity
levels, memory, etc., were found to stem from differences in
fearfulness or some
other circumstance peculiar to the test situation. Certainly this
would be especially
crucial in testing human behaviors, where the same testing conditions may tap
different functions in different subjects or groups of subjects.45
There are a number of studies which show that the IQ of twins is systematically
lower than that of non-twins by about five points,46 and that
firstborn children
have higher IQ scores than their siblings. Firstborn children are
overrepresented
among high IQ students, and also among a wide variety of both intellectual and
career high achievers. More than half of the National Merit
Scholarship finalists
belonging to families with from two to five children were firstborn.
If one considers
only those from five child families, 52% were firstborn, and only 6%
were fifthborn.47
A common explanation is the reduced attention that parents can give when they
have more than one child, but in keeping with his general approach,
Jensen discounts
sociopsyehological explanations. He attributes the differences to
biological factors,
although he does concede that it "almost certainly is not a
genetic phenomenon."48
Although sensory deprivation in the black population is often cited, Jensen is
not concerned with it. He only cites the black writer Kristin Hunter
to the effect
that ghetto babies must be the most thoroughly loved in the world, for they are
cradled, cuddled, tickled, and passed from one set of loving arms to another,
and then comments that "this does riot sound like sensory
deprivation."49
Yet Ward's study of a black community in the south shows that when a
child starts
talking it is no longer considered to he a baby, and after that time there is
little verbal interaction with adults.50
Another possible environmental factor is the dearth of institutions
in the black
community that function routinely at advanced cognitive levels. For
example, there
are too few black colleges, professional people, newspapers, etc. As
the children
grow older, "their environment is progressively less rich in the frequency
of use of the next developmental cognitive structure."51
Certainly the situation
in which IQs drop solely as a function of age points to the
environment as a major
factor. 52
Rosenfeld has graphically demonstrated that the attitudes of
educational personnel
in Harlem schools affect the performance of black children, not only
on standardized
tests, but everyday in the classroom.53 There seems to be little question that
the self-fulfilling prophecy is at work the belief that blacks are
intellectually
inferior can cause both blacks and whites to behave in such a manner
as to yield
confirmatory evidence. Most of the experienced faculty are assigned to superior
classes, whereas the poor students are saddled
A large number of statistically significant correlates with IQ have been discovered, only a few of which are: height, weight, anxiety level, race and warmth of examiner, mother's attitude toward achievement, mother's concern for language development, home cultural level, father's occupation and years of schooling, and desire to master intellectual skills.
year after year with less qualified teachers.
Statistics are available to support the contention that poorly
supported schools
and poor pupil performance tend to be correlated. In 1963-1964 the
mean expenditure
per pupil in the United States was $455. In Kentucky the average was $300, and
in depressed rural areas it was even less. In the High School Achievement Test
on which the national average score is 100, 69% of the school
districts of eastern
Kentucky had average scores below 80, and none averaged as high as
100.54
Most researchers recognize that it is not valid to compare IQ scores of lower
and middle class children because of their different socio-cultural
environments,
Therefore Socioeconomic Status (SES) measures which use schooling, occupation
and income of parents have been devised in an attempt to equalize environments.
The implication is that when there is a matching of SES between a
sample of blacks
and whites, any differences in IQ scores are due to genetic
differences. Although
Jensen assumes that SES measures actually match environments, this is
not generally
accepted. It is extremely difficult to accomplish standardization, and the fact
is that "comparable groups" have never been standardized
even for simple
physical health or for nutrition during pregnancy.55
Even if one takes a given cut off point for the middle class, those few blacks
who are middle class will be mostly very near the cut off, whereas many whites
will be quite far from it. It follows that the mean class position of
middle class
blacks is likely to he much lower than the mean class position of middle class
whites. Thus even if the class measures were perfect, the groups would not be
equated.56 It should he obvious that black and white families
with identical
incomes do not have equal access to economic options. Housing discrimination is
only the most outstanding example of the fact that a dollar may be worth less
to a black family than to a white one. With the disparity in quality
of educational
institutions, equal numbers of years of education do not imply equal
educations,
nor do they imply equal access to future benefits such as income
levels or jobs.
Therefore, blacks and whites have not been successfully matched for
social class.
Bodmer concludes that the only real approach to determining the
effect of environment
on IQ would be to adopt black children into white families and vice
versa, after
which a comparison would he made of the IQs of black children adopted into white families with white children adopted
into comparable white families. He doubts that even this kind of
experiment could
be controlled, because it still would not remove the effects of race prejudice
against blacks which exists in most white communities.57 Rex maintains that any
studies in which one attempts to equalize environments should be supplemented
by an experiment in which
the peoples of Africa conquer, capture and enslave sonic millions of European
and American whites under conditions in whirls a very large proportion of the
white population dies and in which the white culture is
systematically destroyed,
and in which finally a group of emancipated whites living in
"good neighborhoods"
are then compared to their Negro masters.58
Washburn has long argued that when comparing IQs between groups of people the
same criteria which are applied to comparisons between white groups should be
applied to comparisons between blacks and whites, If one looks at the
literature,
he finds that when two groups of whites differ in their IQ scores,
the explanation
is immediately sought in SES differences, but when blacks and whites differ in
precisely the same way, the differences are said to he genetically
determined."59
In attempting to correlate race and IQ, Jensen relies primarily on the results
obtained by past studies of IQ. He seems to have no qualms in
accepting the results
of some 380 investigations of black intelligence reported in Shuey,
which provide
the basis for the conclusion that blacks average 15 points lower than whites on IQ
tests. Since Jensen states that he puts very little confidence in a single
test score-especially if it is the first test of a child from a poor background
and of a different race from the examiner-it is surprising that he
does not question
the validity of the test results in Shuey. In his own testing programs Jensen
usually spends from two to four sessions of one-half hour each to ensure that
the child feels at ease in the testing situation. There is regularly
an increase
of from 8 to 10 IQ points between the first test and the subsequent one given
after the orientation sessions.60 Jensen certainly most be aware that these
conditions were not present in the studies cited by Shuey, and yet he accepts
the data as being valid.
The amount of credence Jensen places in test results seems to depend on whether
or out they agree with his suppositions. For example, in commenting
on the studies
which have demonstrated that high birth rates among lower socioeconomic status
people have not led to a general decline in average IQ, he states
that the studies
are far from adequate to justify complacency, and that they cannot be
generalized
beyond the specific generation studied or the white population upon which the
studies were made.61 On the other hand, studies made in the 1920s are used
to substantiate his arguments, and he even applies to black IQ the heritability
estimates standardized no the white population.
Even if one were to accept the data as correct, it is difficult to understand
the importance of the average racial differences in IQ upon which Jensen places
so much emphasis. He sees the 15 point average difference between
blacks and whites
as crucial, yet acknowledges that the average between siblings is about 12 points, and that some 20% of siblings differ by more than 20
IQ poiots.62
Heritability
The pivotal facet of Jensen's argument is his estimate of the heritability of
intelligence, which has been derived primarily from the studies of moonzygotic
and dizygotic twins raised apart. Estimates of broad heritibility
answer the question:
"What fraction of the variance of a phenotypic trait in a given population
is caused by (or attributable to) genetic differences?"63
Jensen denies
that the problems in measuring intelligence affect determining its heritability.
Whether we can or cannot measure intelligence ... let it be emphasized that it
makes no difference to the question of heritability. We do not
estimate the heritability
of some trait that lies hidden behind our measurements. We estimate
the heritability
of the phenotypes and these are the measurements themselves. Regardless of what
our tests measure, the heritability tells us how much of the variance in these
measurements is due to genetic factors.64
However, tests of IQ differ from measurements of conventional phenotypic characters in two different ways.
IQ tests are analogous to physical readings made with a black box-a
device whose
internal working is unknown. Since it is not known what an IQ test or a black
box measures or how it works, it is impossible to know to what extent
the measurements
carried out on different subjects are comparable or to what extent
they are influenced
by extraneous factors. "Thus IQ scores contain uncontrollable, systematic
errors of unknown magnitude."65 IQ scores also differ from
conventional phenotypic
characters in that they have no strict quantitative meaning. IQ is a rank order
on a standardized test, and the intervals have been chosen so that
the frequency
of test scores in a reference population will be approximately normal.
The heritability index used by Jensen has been widely questioned. Reservations
have been expressed about both the quantitative validity of the methods and the
reality of the necessary assumptions. It is recognized that the
choice of a particular
statistical procedure with which to handle data to a great extent also chooses
the result to be obtained .66 Since heritability measurements are
somewhat arbitrary,
alternative methods of computing the fraction of genetic variance for
intelligence
might he less striking. Jensen concludes that the heritability of intelligence
is 0.80,67 but using the same data Cavalh-Sforza suggests an estimate
of between
0.40 and 0.60,68 and Jencks has stated that the chances are about two out of
three that the heritability of intelligence is between 0.35 and 0.55.69
Since Jensen emphasizes the studies of monozygotic twins raised apart
to support
his estimate of heritability, it is instructive to note the actual IQ scores rather
than just the overall average. In the four existing
studies of monozygotic twins raised apart, average differences range from 6 to
14 points. In one sample of 38 pairs, at least 25% had within-pair differences
of 16 IQ points on one of the tests,70 and the average difference in those 38
pairs was 14 points.71 This is only one point under the average
difference between
blacks and whites, and mnnozygntic twins have identical genotypes!
It might seem likely that a comparison between monozygotic and dizygotic twins
raised apart would lead to a measure of the relative importance of genetic and
environmental factors. However, there are two problems with such a
method. First,
the differences between the dizygous pairs represent only a fraction
of the genetic
differences which can exist between two individuals, that is, they
are more related
than two individuals taken at random from the population at large. Second, the
environmental differences between monozygous twins encompass only a fraction of
the total environmental differences which can exist between two
individuals, that
of the family. "In short, whereas the contrast between monozygous
and dizygous
twins minimizes genetic differences, it also tends to minimize
environmental differences."72
A major problem is that heritability estimates have been derived only
from studies
on European and North American white populations. Jensen is aware of this and
states that such estimates are "specific to the population
sampled, the point
in time, how the measurements are made, and the particular test used to obtain
the measurements. "73 He also recognizes that estimates represent average
values in sampled populations and do not necessarily apply either to
differences
within various subpopulations or to differences between subpopulations.74 Nevertheless,
he uses those estimates to discuss the differences in
"inherited" intelligence
between blacks and whites, and states that when used in conjunction with other
information about the amounts of "relevant environmental variations within
groups and overlap between groups," they can be used to formulate testable
hypotheses that could "reduce the heredity-environment
uncertainty concerning
group differences."75
There are at least two implications of the fact that heritability is
a population
statistic. Since estimates depend on the extent of genetic and
environmental variation
in the population at the time it is studied, they are invalid not
only for other
populations, but also for the same population at a different time.76
Also, since
estimates represent an average of the individuals who make up the population,
there is no way in which they can be used to predict how much any
given individual
will he affected by a change in his environment. There may possibly
be a few relatively
rare optimum environments in which a given individual's performance
would be extensively modified.77 Jensen carefully notes that heritability is a population statistic,
and therefore has no sensible meaning with reference to a measurement
or characteristic
in an individual, which makes it impossible to partition a given
person's IQ into
hereditary and environmental components, e.g., 80% due to heredity and 20% due
to environment. However, he does claim that one can make a probabilistic
inference
concerning the average amount of difference between the obtained IQ
of an individual
and the "genotypic value" of his intelligence.78
A second major problem is that of genotype-environment interaction.
Since differences
in IQ are certainly related to some extent to genetic differences, it is safe
to assume that the genotype-environment correlation is significant in
subpopulations
composed of children raised by their biological parents or close
Since it is not known what an IQ test measures or how it works, it is impossible to know to what extent the measurements carried out on different subjects are comparable or to what extent they are influenced by extraneous factors.
relatives. If this is true, then estimates of heritability based on data which
refer to such subpopulations cannot he valid, and yet the bulk of all
the available
data is precisely of this kind. In one set of twins data, two-thirds
of the separated
pairs were placed with members of the family, 79 and in the largest
and most homogeneous
of the four major twin studies (that of Burt), one member of each of
the 53 pairs
included in the study was raised by his or her natural parents.80
Correlations
between separated monozvgotic twins would be highly sensitive to distortion by
genotype-environment correlation, and yet in the published studies, no serious
attempts have been made to minimize the effects of
genotype-environment interaction.
Genotype-environment interaction can only be controlled by
randomizing environments,
and heritability estimates would be completely valid only if each
possible genotypic
child were placed randomly in each conceivable environment. At the
least one would
have to include black children in a representative range of
environments. Hirsch
is concerned with the number of possible genotypes and the number of potential
environments which may influence trait expression. If one takes the
next to smallest
ease-two genotypes in three environments or three genotypes in two
environments-there
are 60 types of interactions. He concludes that
it is ridiculous to attempt to characterize an environment as
generally favorable
or unfavorable, or any genotypes as generally superior or inferior.
Some average
measure of an environmental influence is applicable only to those
genotypes affected
by it in the same way. Similarly, any rank ordering of genotypes can be applied
only to those environments which preserve the ranks of their phenotypes.81
Layzer maintains that the only potentially useful data are phenotypic
correlations
between foster children raised together, which could possibly provide the lower
limits for the effect of environment. The available data on such
children suggest
a broad heritability between 0.0 and 0.5.82
It seems to be generally agreed that certain studies of
genotype-environment interactions
vitiate heritability studies. For example, it has been noted that
amino acid excretion
patterns of monozygotic twins was less affected by separation than
was the pattern
of dizgotic twins, and a suggested explanation is that monozygotic twins select
similar diets and environments. If this is a general phenomenon, the limits of
behavioral genetics are very broad, because one would not ordinarily consider
amino acid excretion to be a behavioral trait.83
A third major problem is that of gene-gene interaction. Although
Jensen is aware
that some traits may be truly polygenic, he prefers the assumption
that intelligence is not polygenic, but rather is due to a number of genes
with additive
effects.
It may be more heuristic . . to work on the hope that
the trait in question, though seemingly polygenic, is po
tentially analyzable into a number of Mendelian characters . . . If
it is a false
hope, we can find out only by trying. I know of no scientific laws or
principles
which a priori make it a false hope.84
However, the greater the number of genes which contribute to a given trait, the
more likely it is that nonadditive genetic effects will play an important role.
It is therefore possible that human intelligence depends on the total genotype
in a way that is too complex for the application of conventional heritability
analyses.
Even if it could be demonstrated that there is a high heritability of
intelligence
in both black and white populations, that would still not be
convincing evidence
that the differences between the groups are genetic.
No matter how high the heritability (unless it is 1),
there is no assurance that a sufficiently great environmental difference does
not account for the difference in the two means, especially when one considers
that the environmental factors may differ qualitatively in the two groups.85
Conclusion
In reacting to his detractors, Jensen argues that reasonable
hypotheses concerning
questions which are socially and educationally relevant should he appropriately
investigated and that the findings should be published and widely discussed not
only by the scientific community, but the "general public as well."86
This raises the question of the educational relevance of his
hypothesis that blacks
as a group are genetically inferior in intelligence. Jensen
reiterates the caveat
that we must maintain the distinction between the individual and the population
when discussing racial differences in mental abilities, and that all
persons must
be regarded in terms of their individual qualities and merits.
However, the implications
of his hypothesis prevent the drawing of this distinction between individuals
and groups. If each child is to be taught according to his potentialities, he
would have to be tested individually for the ahilty to learn in one way or the
other, and his position in a racial or ethnic group would be
irrelevant. Yet Jensen
includes no suggestions for identifying a potential conceptual
learner other than
by noting skin color. He states that
The question of race differences in intelligence comes up not when we deal with
individuals as individuals, but when certain identifiable groups or subcultures
within the society are brought into comparison with one another as
groups or populations.
It is only when the groups are disproportionately represented in what
are commonly
perceived as the most desirable social and occupational roles in society that
the question arises concerning average differences among groups.87
Since learning is essentially an individual rather than a group process, it is
not clear how one's membership in a racial or ethnic group is
educationally relevant.
It is not surprising that Jensen's work is seen by many as an attack on special
education programs for blacks.88 They would agree with a statement
written before
publication of Jensen's article that
With indecent haste, evidence is adduced to raise suspicions about the alleged
inferiority of a people before society has completed even the early stages of
correcting the inequities and the consequences of centuries of
inequality in every
form. Their inferiority is established be/ore they have a chance to
prove otherwise,89
And, in fact, Jensen's arguments have been used in opposition to the funding of
various poverty programs.90
Jensen accuses his critics of demanding almost impossible criteria of certainty
before proposing and investigating genetic hypotheses as opposed to
environmental ones,91 and complains that no one has yet produced any evidence on a properly
controlled sample to demonstrate that it is possible to equalize the
intellectual
ability in representative samples of black and white children through
statistical
control of environment and education.92 Situations which tend to
support the importance
of environment are interpreted in genetic terms. For example, he
refers to a 6th
grade class in the Windsor Hills Elementary School in Los Angeles,
which was 90%
black and in which the mean IQ score was 115. Rather than considering this as
possible evidence that environment affects performance on IQ tests,
he asks "why
should anyone be surprised that there are Negro children having IQs of 115 or
higher, or that they should he concentrated in the affluent
integrated neighborhood
of Los Angeles?"93 He then "explains" the situation in terms of
the superior genetic endowment of the parents rather than as a result of a good
environment.
It is relatively easy to gain the impression that Jensen feels that
his hypothesis
has been validated by the data. Yet this is not so, for he states:
So all we are left with are various lines of evidence, no one of
which is definitive
alone, but which, viewed all together, make it a not unreasonable
hypothesis that
genetic factors are strongly implicated in the average Negro-white intelligence
difference.94
Since he is convinced that the research to test his hypothesis is
entirely possible,
but just has not been done,95 one wonders why he did not conduct the research
rather than publish so many articles and books based on the same
inadequate data.
It would seem that if Jensen were really concerned with an unbiased testing of
the heritable component in intelligence differences between human
groups, he would
have attempted to develop an operational definition for equal social
conditions.
He then could have devised scientific experiments in which a systematic effort
would he made to ensure that his subjects fit that definition.
One attempt to explain Jensen's approach is that he has "girded
himself for
a holy war against 'environmentalists,' 96 and that his position is must
understandable when seen as a reaction against the
"iniquities" of his
professional colleagues who take an essentially environmentalist viewpoint,97
and whom he accuses of having branded him as a "moral pariah" for his
approach.98
Jensen sees little validity in the many criticisms of his work. He
refers to the
"storm of ideologically, often politically, motivated protests,
misinterpretations,
and vilifications" which his article prompted,99 and
characterizes the majority
of the letters and articles in the summer 1969 issue of the Harvard Educational
Review as "only masquerading as serious critiques of my article."100
Eysenck, who is Jensen's British counterpart,
claims that "truly competent judges" have not found any serious error
in Jensen's statements,101 and in 1972 Jensen saw no reason to
substantively revise
any of the main points of his 1969 article.102
Jensen is unhappy with critics who are concerned
with the moral, political and social policy dimensions of a general acceptance
of his hypothesis. He insists that such issues should be kept clearly distinct
from the scientifically answerable aspects of the question,103 giving
the impression
that he sees the situation only as representing a normal scientific
exchange between
the representatives of two alternative scientific theories. But as Fried points
out:
This is not a question of digging the "Mohole" or not,
or whether Homo habilis is or is not an Australopithecus. It is more
like dividing
on the question of whether or not to exterminate six million Jews:
one side says
no and presents its arguments, and the other side says yes and
presents its arguments,
and this too becomes a debatable scientific question.104
REFERENCES
1Cf. Klineberg, Otto. 1935. Race Differences. New York: Harper and
Brothers; Comas,
Juan. 1961. " 'Scientific Racism' Again?" Current
Anthropology 2:303-14; Stipe, Claude E. 1964. "Race and Culture: A Valid Basis for
Segregation?"
Journal of the American Scientific Affiliation 16:36-41.
2Tobach. E. 1972. "The Meaning of the Crytanthroparian," in
Genetics,
Environment, and Behavior: Implications for Educational Policy, Edited by Lee
Ehrman, Gilbert S. Omenn and Ernst Caspari. New York: Academic Press.
p. 229.
3Craw, James F., James V. Ned and Curt Stern, 1967. "Racial
Studies: Academy States Position on Call for New Research,"
Science 158:893.
4Jensen, Arthur R. 1969a. "How Much Can We Boost IQ and
Scholastic Achievement?"
Harvard Educational Review 39:79.
5Freeman, Roger A. 1969. "Letter to the Editors," Harvard
Educational Review 39:599.
6Nelson, James D. 1969. "Letter to the Editors," Harvard
Educational Review 39:615.
7Deutsch, Martin, Irwin Katz and Arthur R, Jensen (Eds.). 1968. Social Class,
Race, and Psychological Development. New York: Halt, Rinehart and Winston,
8Dentsch, Martin. 1969. "Happenings an the Way Back to the Forum: Social
Science, IQ, and Race Differences Revisited," Harvard Educational Review
39:524,
9A list of 117 articles and books written in response to Jensen's l969a article
is given in Jensen, Arthur R. 1972b. Genetics and Education. New York: Harper
and Row. pp. 356-364.
10Jensen, Arthur R. 1969a:80.
11Shuey, Audrey M. 1966. The Testing of Negro Intelligence (Second
Edition). New
York: Social Science Press, p. 3,
l2Mayr, Ernst. 1968. "Discussion," in Science and the
Concept of Race,
Edited by Margaret Mead, et al. New York: Columbia University Press.
p. 103.
13Livingstane, Frank B. 1964. "On the Nonexistence of Human Races," in
The Concept of Race, Edited by Ashley Montagu. New York: Free Press. p. 54.
14Glass, Bentley. 1968, "The Genetic Basis of Human Races,"
in Science
and the Concept of Race, Edited by Margaret Mead, et. al. New York:
Columbia University
Press. pp. 88-89.
15Maotago, Ashley. 1962. "The Concept of Race," American
Anthropologist
64:920.
16Ingle, Dwight J. 1968. "The Need to Investigate Average
Biological Differences
among Racial Groups," in Science and the Concept of Race, Edited
by Margaret
Mead, et al. New York: Columbia University Press. pp. 113-114.
I7Dobzhansky, 'l'hcodosius. 1968. "Discussion," in Ibid. p. 78. 'Cf.
Glass, Bentley. 1968:92; Badmer, W. F. 1972. 18Race and IQ: the
Genetic Background,"
in Race and Intelligence: the Fallacies Behind the Race-IQ Controversy, Edited
by Ken Richardson and David Speers. Baltimore: Penguin Books Inc. p. 90.
19Downs, James E. 1971. Cultures in Crisis. Beverly Hills:
Gleocne Press. p. 3.
Even if it could be demonstrated that there is a high heritability of intelligence in both black and white populations, that would still not be convincing evidence that the differences between the groups are genetic.
20Mayr, Ernst. 1968:104.
21Erlich, Paul B. and Richard W. Halm. 1964. "A Biological View
al Race,"
in The Concept of Race, Edited by Ashley Montagu. New York: Free
Press. p. 173.
22Gottesman, I. I. 1968. "Biogeneties of Race and Class," in
Social
Class, Race, and Psychological Development, Edited by Martin Deutsch,
Irwin Katz
and Arthur R, Jensen. New York: Holt, Rinehart and Winston, p. 21,
23Brace, C. Loring. 1971. "Introduction to Jensenism," in
Race and Intelligence,
Edited by C. Loring Brace, George R. Gamble and James T. Bond.
American Anthropological
Association: Anthropological Studies No. 8. p. 5.
24Jeosen, Arthur R. 1969a:S-6.
25Jensen, Arthur R. 1969a:9,
26Ihid.
27Jensen, Arthur R. 1969a:19.
28Jensen, Arthur R. 1969a:8.
29Jensen, Arthur B. 1969a: 19-20.
30Jastak, Joseph F. 1969, "Letter to the Editors," Harvard
Educational Review 39:609.
31Deutsch, Martin. 1969:542.
32Jensen, Arthur R. 1969a: 17.
33Ryan, Joanna. 1972. "The Illusion of Objectivity," in Race
and Intelligence: the Fallacies Behind the Race-IQ Controversy, Edited by Ken
Richardson and David Speers. Baltimore: Penguin Books Inc. p. 45.
34Bereiter, Carl. 1969. "The Future of Individual
Differences," Harvard
Educational Review 39:315.
35Rex, John. 1972. 'Nature versus Nurture: The Significance of the
Revived Debate,"
in Race and Intelligence: The Fallacies Behind the Race-IQ Controversy, Edited
by Ken Richardson and David Speers. Baltimore: Penguin Books Inc. p. 168.
36Schwebel, Milton. 1968. Who Can Be Educated. New York: Grove
Press. p. 74.
37Jeosen, Arthur R. 1969a: 114.
38Jenseo, Arthur B. 1961a:113.
39Jensen, Arthur R. 1969a: 117.
40Brazziel, William F. 1969. "A Letter from the South,"
Harvard Educational
Review 39:355.
41John, Vera P. 1971. "Whose is the Failure?" in Race and
Intelligence,
Edited by C. Loring Brace, George B. Gamble and James T. Rood.
American Anthropological
Association: Anthropological Studies No. 8. p. 38.
42Cronbaeh, Lee J. 1969.." Heredity, Environment, and
Educational Policy,"
Harvard Educational Review 39:342.
43John, Vera P. 1971:37.
44Gottessnao, I. I. 1968:25.
45Erlenmeyer-Kimling, L. 1972. "Gene-Environment Interactions
and the Variability
of Behavior," in Genetics, Environment and Behavior:
Implications for Educational Policy, Edited by Lee Ehrman, Gilhert S. Omenn and Ernst
Caspari. New
York: Academic
Press. p. 198.
46Bodmer, IV. F. 1972:107-108.
47Sowell, Thomas. 1973. "The Great IQ Controversy," Change
5:35 (May).
48Jeosen, Arthur R. 1969a:74.
49Jensen, Arthur B. 1969b. "Reducing the Heredity-Environmental Uncertainty: A Reply,"
Harvard Educational Review 39:473.
50Ward, Martha Coonfield. 1971. Them Children: A Study in Language Learning New
York: Holt, Rinehart and Winston.
51Stiischeomhe, Arthur L. 1969. "Environment: The Cumulation of Effects is
Yet to he Understood," Harvard Educational Review 39:521.
52Gottesosao, I. I. 1968:27.
53Rosenfeld, Gerry. 1971. "Shut Those Thick Lips!": A Study of Slum
School Failure. New York: Halt, Rinehart and Winston.
54Schwebel, Milton. 1968:157-158.
55Lederberg, Joshua. 1969. "Letter to the Editors," Harvard
Educational
Review 39:613.
56Stinchcombe, Arthur L. 1969:514-515.
57Bodmer,W. F. 1972:111.
58Rex, John. 1972:170-171.
59Washburo, Sherwood. 1963. "The Study of Race," American
Anthropologist 65:529.
60Jensen, Arthur R. 1969a: 100.
61Jensen, Arthur R. 1969a:83.
62Jensen, Arthur R. 1969c. "An Embattled Hypothesis: An
Interview with Arthur R. Jensen," The Center Magazine
2(5):79.
63Layzer, David. 1974. "Heritability Analyses of IQ Scores:
Science or Numerology,"
Science 183:1259. Genotype refers to the totality of factors that make up the
genetic complement of the individual, and phenotype refers to the totality of
physically or chemically observable characteristics of an individual
that result
from the interaction of his genotype with his environment.
64Jensen, Arthur B. l969a:44.
65Layzer, David. 1974:1262.
66For different statistical procedures see: Layzer, David. 1974; Daniels, John
and Vincent Houghton. 1972. "Jensen, Eysenck and the Eclipse of the Galton
Paradigm," in Race and Intelligence: The Fallacies Behind the
Race-IQ Controversy,
Edited by Ken Richardson and David Speers. Baltimore: Penguin Books
Inc. pp. 68-80;
and Light, Richard J. and Paul V. Smith. 1969. "Social Allocation Models
of Intelligence: A Methodological Inquiry," Harvard Educational
Review 39:484-510.
67Jensen, Arthur R. i969a:S1.
68Anandalakshmy, S. and Janice F. Adams. 1969. "Letter to the
Editors,"
Harvard Educational Review 39:585.
69Layzer, David. 1974:1259.
70Deutsch, Martin 1969:549.
71Kagan, Jerome 5. 1969. "Inadequate Evidence and Illogical
Conclusions,"
Harvard Educational Review 39:275.
72Bodmer, W. F. 1972:96.
73Jensen, Arthur B. 1969a:43.
74Jensen, Arthur B. 1969a:64.
75Jensen, Arthur B. 1969b:460.
76Bodmer, W. F. 1972:98.
77Workman, Peter L. 1972. "Comment," in Genetics, Environment, and Behavior: Implications for Educational Policy,
Edited by Lee Ehrman, Gilbert S. Omenn and Ernst Caspan. New York:
Academic Press.
p. 26.
78Jensen, Arthur B. 1969a:42-43.
79Fehr, F. S. 1969. "Critique of Hereditarian Accounts of 'Intelligence'
and Contrary Findings: A Reply to Jensen," Harvard Educational
Review 39:575.
80Layzer, David. 1974:1263,
81Hirsch, Jerry. 1968. "Behavior-genetic Analysis and the Study
of Man,"
in Science and the Concept of Race, Edited by Margaret Mend, et. al. New York:
Columbia University Press. p. 42.
82Layzer, David. 1974:1265.
83Morton, N. E. 1972. "Human Behavorial Genetics," in
Genetics, Environment,
and Behavior: Implications for Educational Policy, Edited by Lee Ehrman, Gilbert
S. Omenn, and Ernst Gaspari. New York: Academic Press. p. 251.
84Jensen, Arthur R. 1972a. "Discussion," in Ibid. p. 241.
85Grow, James F. 1969. "Genetic Theories and Influences:
Comments on the Value of Diversity," Harvard Educational Review 39:308.
86Jensen, Arthur B. 1969b:461.
87Jensen, Arthur B. l969a:78-79.
88Cf.Smith, Paul M. Jr. 1969. "Letter to the Editors," Harvard
Educational Review 39:628.
89Sehwebel, Milton 1968:6.
90Rex, John. 1972:176.
91Jensen, Arthur B. 1971. "Can We and Should We Study Race
Differences?"
in Race and Intelligence, Edited by C. Luring Brace, George R.
Gamble, and James
T. Bond. American Anthropological Association: Anthropological Studies No. 8.
p. 10.
92Jensen, Arthur B. 1969a: 82-83.
93Jensen, Arthur B. 1972b:43-44.
94Jensen, Arthur B. l969a:82.
95Ibid.
96Cronbach, Lee J. 1969:338.
97Hudsun, Liam. 1972. "The Context of the Debate," in Race
and Intelligence:
The Fallacies Behind the Race-IQ Controversy, Edited by Ken
Richardson and David Speers. Baltimore: Penguin Books Inc. p. 14.
98Jensen, Arthur B. 1972b:55.
99Jensen, Arthur B. 1972b: 1.
100Jensen, Arthur B. 1972b: 28.
101Eysenek, H. J. 1972. 'The Dangers of the New Zealots," Encounter 39:88
(December).
102Jensen, Arthur B. 1972b:60.
103Jensen, Arthur B. 1971:10.
104Fried, Morton H. 1968. "The Need to End the Pseudoscientific Investigation of Race," in
Science and the Concept of Race, Edited by Margaret Mead, et. al. New York:
Columbia University Press. p. 129.