nature and nurture
The phrase
nature and nurture relates to the relative importance of an individual's innate qualities ("nature" in the sense of
nativism or
innatism) as compared to an individual's personal experiences ("nurture" in the sense of
empiricism or
behaviorism) in
causing individual differences, especially in
behavioral traits. The alliterative expression "nature and nurture" in English has been in use since at least the Elizabethan period
[1] and goes back to medieval French.
[2] The combination of the two concepts as complementary is ancient (
Greek:
ἁπό φύσεως καὶ εὐτροφίας[3]).
The phrase in its modern sense was popularized by the English Victorian polymath
Francis Galton in discussion of the influence of
heredity and
environment on social advancement,
[4][5] Galton was influenced by the book
On the Origin of Species written by his half-cousin,
Charles Darwin.
The view that humans acquire all or almost all their behavioral traits from "nurture" was termed
tabula rasa ("blank slate") by
John Locke in 1690. A "blank slate view" in human developmental psychology assuming that human behavioral traits develop almost exclusively from environmental influences, was widely held during much of the 20th century (sometimes termed "blank-slatism"). The debate between "blank-slate" denial of the influence of heritability, and the view admitting both environmental and heritable traits, has often been cast in terms of
nature versus nurture. These two conflicting approaches to human development were at the core of an ideological dispute over research agendas during the later half of the 20th century. As both "nature" and "nurture" factors were found to contribute substantially, often in an extricable manner, such views were seen as naive or outdated by most scholars of human development by the 2000s.
[6]
In their 2014 survey of scientists, many respondents wrote that the dichotomy of nature
versus nurture has outlived its usefulness, and should be retired. The reason is that in many fields of research, close
feedback loops have been found in which "nature" and "nurture" influence one another constantly (as in
self-domestication), while in other fields, the dividing line between an inherited and an acquired trait becomes unclear (as in the field of
epigenetics or in fetal development).
[7][8]
History of the debate[edit]
John Locke's
An Essay Concerning Human Understanding (1690) is often cited as the foundational document of the "blank slate" view. Locke was criticizing
René Descartes' claim of an
innate idea of
God universal to humanity. Locke's view was harshly criticized in his own time.
Anthony Ashley-Cooper, 3rd Earl of Shaftesbury complained that by denying the possibility of any innate ideas, Locke "threw all order and virtue out of the world", leading to total
moral relativism. Locke's was not the predominant view in the 19th century, which on the contrary tended to focus on "
instinct". Leda Cosmides and John Tooby noted that
William James (1842–1910) argued that humans have
more instincts than animals, and that greater freedom of action is the result of having more psychological instincts, not fewer.
[9]
The question of "innate ideas" or "instincts" were of some importance in the discussion of
free will in
moral philosophy. In 18th-century philosophy, this was cast in terms of "innate ideas" establishing the presence of a universal virtue, prerequisite for objective morals. In the 20th century, this argument was in a way inverted, as some philosophers now argued that the evolutionary origins of human behavioral traits forces us to concede that there is no foundation for ethics (
J. L. Mackie), while others treat ethics as a field in complete isolation from evolutionary considerations (
Thomas Nagel).
[10]
In the early 20th century, there was an increased interest in the role of the environment, as a reaction to the strong focus on pure heredity in the wake of the triumphal success of Darwin's theory of evolution.
[11]
During this time, the
social sciences developed as the project of studying the influence of culture in clean isolation from questions related to "biology".
Franz Boas's
The Mind of Primitive Man (1911) established a program that would dominate American anthropology for the next fifteen years. In this study he established that in any given population, biology, language, material and symbolic culture, are autonomous; that each is an equally important dimension of human nature, but that no one of these dimensions is reducible to another.
The tool of
twin studies was developed after World War I as an experimental setup intended to exclude all confounders based on
inherited behavioral traits. Such studies are designed to decompose the variability of a given trait in a given population into a genetic and an environmental component.
John B. Watson in the 1920s and 1930s established the school of purist
behaviorism that would become dominant over the following decades. Watson was convinced of the complete dominance of cultural influence over anything heritability might contribute, to the point of claiming
- "Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors." (Behaviorism, 1930, p. 82)
During the 1940s to 1960s,
Ashley Montagu was a notable proponent of this purist form of behaviorism which allowed no contribution from heredity whatsoever:
- "Man is man because he has no instincts, because everything he is and has become he has learned, acquired, from his culture [...] with the exception of the instinctoid reactions in infants to sudden withdrawals of support and to sudden loud noises, the human being is entirely instinctless."[12]
In 1951, Calvin Hall
[13] suggested that the dichotomy opposing nature to nurture ultimately fruitless.
Robert Ardrey in the 1960s argued for innate attributes of human nature, especially concerning
territoriality, in the widely-read
African Genesis (1961) and
The Territorial Imperative.
Desmond Morris in
The Naked Ape (1967) expressed similar views. Organised opposition to Montagu's kind of purist "blank-slatism" began to pick up in the 1970s, notably led by
E. O. Wilson (
On Human Nature 1979). Twin studies established that there was, in many cases, a significant heritable component. These results did not in any way point to overwhelming contribution of heritable factors, with heritability typically ranging around 40% to 50%, so that the controversy may not be cast in in terms of purist behaviorism vs. purist nativism. Rather, it was purist behaviorism which was gradually replaced by the now-predominant view that both kinds of factors usually contribute to a given trait, anecdotally phrased by
Donald Hebb as an answer to the question "which, nature or nurture, contributes more to personality?" by asking in response, "Which contributes more to the area of a rectangle, its length or its width?"
[14] In a comparable avenue of research, anthropologist Donald Brown in the 1980s surveyed hundreds of anthropological studies from around the world and collected a set of
cultural universals. He identified approximately 150 such features, coming to the conclusion there is indeed a "universal human nature", and that these features point to what that universal human nature is.
[15]
At the height of the controversy, during the 1970s to 1980s, the debate was highly ideologised. In
Not in Our Genes: Biology, Ideology and Human Nature (1984),
Richard Lewontin,
Steven Rose and
Leon Kamin criticise "
genetic determinism" from a
Marxist framework, arguing that "Science is the ultimate legitimator of bourgeois ideology [...] If biological determinism is a weapon in the struggle between classes, then the universities are weapons factories, and their teaching and research faculties are the engineers, designers, and production workers." The debate thus shifted away from whether heritable traits exist to whether it was politically or ethically permissible to admit their existence. The authors deny this, requesting that that evolutionary inclinations could be discarded in ethical and political discussions regardless of whether they exist or not.
[16]
Heritability studies became much easier to perform, and hence much more numerous, with the advances of genetic studies during the 1990s. By the late 1990s, an overwhelming amount of evidence had accumulated that amounts to a refutation of the extreme forms of "blank-slatism" advocated by Watson or Montagu.
This revised state of affairs was summarized in books aimed at a popular audience from the late 1990s. In
The Nurture Assumption: Why Children Turn Out the Way They Do (1998),
Judith Rich Harris was heralded by
Steven Pinker as a book that "will come to be seen as a turning point in the
history of psychology".
[17] but Harris was criticized for exaggerating the point of "parental upbringing seems to matter less than previously thought" to the implication that "parents do not matter".
[18]
The situation as it presented itself by the end of the 20th century was summarized in
The Blank Slate: The Modern Denial of Human Nature (2002) by
Steven Pinker. The book became a best-seller, and was instrumental in bringing to the attention of a wider public the paradigm shift away from the behaviourist purism of the 1940s to 1970s that had taken place over the preceding decades. Pinker portrays the adherence to pure blank-slatism as an ideological
dogma linked to two other dogmas found in the dominant view of human nature in the 20th century, which he termed "
noble savage" (in the sense that people are born good and corrupted by bad influence) and "
ghost in the machine" (in the sense that there is a human soul capable of moral choices completely detached from biology). Pinker argues that all three dogmas were held onto for an extended period even in the face of evidence because they were seen as
desirable in the sense that if any human trait is purely conditioned by culture, any undesired trait (such as crime or aggression) may be engineered away by purely cultural (political means). Pinker focusses on reasons he assumes were responsible for unduly repressing evidence to the contrary, notably the fear of (imagined or projected) political or ideological consequences.
