From: tai@ailab.ncsu.edu (Scott Tai)
Newsgroups: rec.org.mensa
Subject: (T) INTELLIGENCE DEBATE:  HEREDITY OR ENVIRONMENT?
Date: 13 Apr 92 03:58:23 GMT
Reply-To: tai@ailab.ncsu.edu (Scott Tai)
Organization: NCSU Artificial Intelligence Systems Laboratory

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INTELLIGENCE AND HEREDITY
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You want facts?  You've got 'em! :)

INTRODUCTION
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	The word "intelligence" was derived from a translation of Aristotle's
term "dia-noesis" which he defined to be the abstract qualities (sensation,
perception, memory, imagination, reasoning) involved in all intellectual
processes.
	It was not until the turn of the last century that scientists began to
search for a more technical definition.  Sir Francis Galton (who in his
Hereditary
Genius, 1869, noted that intelligence and greatness run in families) was
the first
to attempt an intelligence test based on scientific--as opposed to
empirical--data.
His test, based on the hypothesis that there is a high correlation
between sensory
acuity and general intelligence, has since proven to be inaccurate.  It
did, 
however, inspire an international search for a functional intelligence
test.  
Since a modern definition of intelligence was yet to be made, scientists
continued
to rely on intuition and common-sense judgments to verify the validity
of their
intelligence tests.
	It was the pragmatic Frenchman, Alfred Binet (1857-1911), who first
devised a functional intelligence test.  Working with a large number of
Parisian
school children, Binet developed a test that successfully separated the
mentally
retarded from the normal students at an early age.  His tests were based
on a
variety of factors including verbal adroitness, ability to perceive
analogies and
abstractions, a capacity for problem solving, mathematics,
classification, causal
connections and distance perception.
	Since he worked with children, Binet was forced to devise some way to 
compensate for the variation in test performances caused by age
differences.  And
it was this adjustment of test results according to age which led
directly to the
modern "Intelligence Quotient" (I.Q.) which is simply the mental age
(derived by
test performance) divided by the chronological age times 100.  Binet's
test was 
soon widely accepted since it accurately reinforced intuitive judgments
about
individual intelligence (i.e., those judged to be of subnormal
intelligence
scored poorly on the test, while those judged to be highly intelligent
scored
exceptionally well).  So the test was accepted not on the basis of an
exact 
definition of "intelligence" but rather because it reflected accurately
the 
intuitive judgments about a person's intelligence.  It is important,
therefore,
to realize that an intelligence quotient can only be based on relative
performance.  Unlike the more measurable attribute of height--which can
be
determined forever by the immortal inch--intelligence is measured by
comparison.
The fact that it is administered to large numbers of people gives it
solidarity 
and stability.
	It was not long after man first gave birth to the concept of
"intelligence" that he began to conjure about the respective roles of
heredity
and environment in its formation.  Until the development of I.Q. tests,
scientists
could only guess--but given a means to measure intelligence, they could
at last
make more accurate estimates.  For many years the accepted figure for
heredity
(in intelligence causality) was 75 to 80 percent.  More recently,
however,
environmentalists have argued that early training and quality of
environment are
the major factors producing a high or low I.Q.
	The environmentalists had almost dominated the purlieus of I.Q. while
the geneticists sought the quiet paths of the birds and the bees and
the
Drosophilus fruit flies.  But one scientist made certain observations in
print
(favoring heredity 80 percent to 20 percent) and discovered perhaps to
his
surprise that his statements quickly fanned a flame of controversy.
	The scientist was Arthur Jensen, Professor of Educational Psychology
at
the University of California (Berkeley).  Previously the author of
numerous
articles on individual differences in human learning, and cultural,
developmental
and genetic determinants of intelligence and learning ability, Jensen
was invited
by the editors of the Harvard Educational Review to write an article
entitled 
"How Much Can We Boost I.Q. and Scholastic Achievement?"  The article
stated that
since intelligence is largely hereditary, the I.Q. cannot be boosted
substantially
by compensatory education.  The essay evoked many responses both
indignant and
laudatory.  Some labeled the article irresponsible and racist.  Others
claimed 
that the press had seized upon the article, exaggerated a few of its
points and
played them up out of context to bolster their political and social
stance.
	The fields of academia were thus well plowed and sown with the seeds
which
sprouted forth in the Atlantic Monthly.  Professor Richard J.
Herrnstein, then
chairman of the psychology department at Harvard University, wrote a
scholarly
article entitled "I.Q."  In it he reviewed the history of I.Q. tests,
summarized
with scientific detachment many of Professor Jensen's findings, and put
forth the
hypothesis that social standing will be based to some extent on
inherited
differences among people.  Although many scientists felt that Herrnstein
only
summarized familiar conclusions and research that had been done over a
long period
of time--he was roundly attacked by environmentalists.
	The issue, oversimplified, is this:  To what extent does heredity 
influence the intelligence of an individual?  To what extent does
environment 
affect I.Q.?  How valid are I.Q. tests in measuring intelligence?
	The purpose of the series of articles which follow is not to present
an
answer or even an opinion--but rather to present a sampling of the most
lucid,
concise arguments, gathered from prominent researchers and academicians
involved in the dispute.
	Draw your own conclusions, keeping in mind a last word from Thomas
Jefferson, a man who knew how to engage in argument and to rise above
it:  "I
tolerate with the utmost latitude the right of others to differ with me
in 
opinion without imputing them criminality."


---------
Scott Tai 
92 / 911 / 6077