In The Blank Slate: The Modern Denial
of Human Nature, Steven Pinker, a psychologist at M.I.T. and author of
several books and articles on cognition and linguistics, attempts to shatter
the widely popular belief that the human mind at birth is a tabula rasa (blank
slate) to which the environment (nurture) gives form and substance. The book is based on the premise that the
influence of nurture and the consequences of genetic predispositions on human
development (nature) can be empirically decoupled. On the basis of this premise, Pinker marshals the view that
regarding the human mind (or brain) as devoid of an innate structure
(hardwiring) at birth is more of a dogma than a tenable position and that human
nature is largely inscribed in the genome, which is the product of our
evolutionary history.

Pinker starts his scientifically-oriented
journey into the nature-nurture controversy by examining conceptions of the
mind that embody the tabula rasa belief and the empirical evidence that is
generally used to support it. Here
Pinker does a skillful job at pointing out theoretical inconsistencies and
empirical weaknesses. For instance, two
of the most famous and extreme versions of the tabula rasa view, which Pinker
finds easy to refute, are that of John Watson (1878-1958), the founder of
behaviorism, who made the claim that he could train any infant to become what
he fancied (from doctor to beggar) regardless of the infant’s talents and abilities,
and that of B. F. Skinner (1904-1990), another behaviorist, who asserted that
behavior could be understood by examining the environmental factors
(contingencies) that surround a person without regard to the influence of
genetic makeup and evolutionary history. 
Pinker emphasizes that these claims are untenable by reminding us of the
fortunes of Skinner’s disciples who attempted to
train various animals to insert chips into vending machines and discovered that
the animals not only resisted their attempts, but also insisted on handling the
chips in species-specific manners (i.e., chickens pecked the chips whereas
raccoons washed them). He also reminds
us that inscriptions on blank slates would be useless without “interpreters”
(hardwired mechanisms) and that “interpreters” vary across species (e.g., a
speech sound is a warning sign for a bird but a word for a representative of
the human species).

Pinker’s task is more cumbersome when
extreme positions are put aside and he takes issue with views that embody the
belief that experience is the chief determinant of human development while
acknowledging the possibility of some hardwiring in the brain (i.e., a slate
not entirely blank at birth). Pinker
calls attention to three areas of scientific inquiry whose evidence has been
interpreted as supporting the tabula rasa view: (1) The discovery of a
lower-than-expected number of genes comprising the human genome, which suggests
that genetic information may be too limited to account for the complexity and
variety of human nature. (2) The
finding that generic artificial neural networks (computer models that mimic the
complex functioning of populations of neurons in the human brain with very few
“hardwired” constraints regarding their functioning) can replicate complex
human cognitive activities (e.g., reading, remembering, etc.) via patterns of
activity induced by massive environment stimulation. (3) Findings of neural plasticity indicating that experience
(e.g., specific sensory stimulation) shapes the human brain as it develops to
adult levels. Pinker skillfully
examines the available evidence to advance his argument that any claim that the
mind has either no innate structure or a very limited one is indefensible. For instance, with respect to the claim that
the human genome is too small to produce much hardwiring, he reminds us that
research has still to shed light on how genes build the brain, and thus the
number of genes that would be necessary to produce a largely hardwired brain is
yet to be known. With respect to
generic artificial networks, Pinker relies on linguistic development, a topic
familiar to him, to demonstrate that environmental stimulation alone cannot
shape general-purpose learning devices into replicating complex cognitive
activities and that only hybrid models with networks hardwired to handle
specific computational functions can do so, suggesting that innate circuitry is
an indispensable component of the human mind/brain. Lastly, Pinker reminds us that the plasticity of the brain, as
demonstrated by the successful reallocation of brain tissue to new functions,
has its limitations, arguing against the notion that sensory information can
magically mold amorphous brain tissue into a structure that performs some
specific computations. For instance,
ferrets whose auditory thalamus and cortex are re-wired to receive information
from the eyes can process visual information, but with some deficiencies (e.g.,
fuzzier and less organized representations of the visual field) and little
change in the basic signal-processing operations that these areas were destined
to perform.

Of course, Pinker acknowledges that a
one-to-one correspondence between traits and genes is largely unrealistic. He
admits that genes create predispositions, and that experience is necessary to
realize the predispositions encoded in the human genome. However, he answers the critical question
“How much of what we are is due to genes and how much to the environment?” by
asserting that the human genome is responsible for much of the structure and
functioning of the brain and that experience cannot alter either
substantially. Indeed, in his attempts
to provide a comprehensive idea of human nature based on cognitive science and
evolutionary theory, Pinker seems to undermine evidence pointing to the
considerable role played by nurture in human development and appears to
dispense with accounts of the dynamic nature of the interaction between the
human genome and the environment. For instance, near the end of the book,
Pinker claims boldly that violence, gender differences, and personality traits,
even the arts, are not so much upshots of cultural pressure but aspects of
human nature and thus are largely heritable. 
Here the writing becomes exceedingly skewed in favor of genetic
influences, making it more an exercise in persuasion than a fair trial for each
of the usual culprits. Of course, if
Pinker had fully acknowledged the dynamic character of the interaction between
environment and genes, and objectively examined the available research evidence
in this light, he would have questioned his core premise that the respective
influences of nature and nurture can be unambiguously separated.

Pinker believes that fears about the
possible tragic consequences of accepting a view of human nature that appeals
to the human genome and evolutionary history to explain what we are instead of
granting environmental factors most of the explanatory power has led to
abounding rejections of such a view by the scientific community and the press
alike. Among the fears that Pinker
argues made the tabula rasa view a taboo is the recognition that innate
differences can lead to discrimination, the idea that if humans are innately
immoral, there will be no room for social interventions intended to improve
human conditions, and the belief that if humans are biological products, there
will be no room for free will, personal responsibility, and lives will not have
purpose besides that of genetic determinism. 
Pinker attempts to counteract each fear by arguing that disregard of
human nature, which he equates to failing to know ourselves, prevents us from
understanding the causes of human catastrophes (e.g., ethnic cleansing), and
thus leaves us unable to prevent their re-occurrence. He contends that
acknowledging human nature does not thwart efforts at social change. On the contrary, he asserts that identifying
those aspects of human nature that make change possible is the precondition for
such efforts to be effective. Pinker,
however, seems to believe that knowledge of human nature, alone, can prevent
human catastrophes and bring about social changes that ameliorate human life,
but he stops short of addressing head on how to prevent “innocent” ideas about
human nature, albeit grounded on scientific evidence (like his own), from being
used in the interest of exploitation and discrimination.  

In conclusion, Pinker’s latest book is an
interesting, exquisitely written, book for readers who want to be introduced to
the nature-nurture controversy by examining scientific evidence rather than
simply absorbing moralizing positions. 
This is true even though Pinker’s attempts to persuade the reader of the
indefensible nature of the tabula rasa view lead him astray from a more
balanced and less emotional presentation of the evidence. But then Pinker’s book was not titled “the
unsolvable controversy of nature and nurture”.

© 2003 Maura Pilotti

Maura Pilotti,
Ph.D., Department of Psychology, Dowling College, New York.