Chapter 6. Nature vs. Nature

Among the psychologist's controversies over intelligence, the so-called Nature-Nurture problem is probably the most significant. That is, to what extent is intelligence the product of heredity (nature) and/or of environment (nurture) ? Is a child born with a fixed amount of intelligence which determines what he will or will not be able to accomplish? Or does his intelligence develop as a result of his total experiences and learning?

Psychology is a relatively young and inexact science. It has not yet been able to demonstrate to everyone's satisfaction which of these two factors, nature or nurture, or what combination of them, is the basis of intelligence. At one end of the scale are the extreme hereditarians, who see intelligence as an innate, inherent characteristic that is basically unaffected by environment. At the other end are the extreme environmentalists who see intelligence largely as the product of the many factors of total environment.

The extreme hereditarian viewpoint is well expressed by two leading scholars in psychiatry and physiology, C. C. Fry and H. W. Haggard:

"Studies of families have revealed the fact that intelligence is wholly a hereditary quality. Indeed, it follows closely the so-called Mendelian law of inheritance. A child is predestined by its inheritance to develop a certain degree of intelligence; at the moment of conception the factors are established that will endow it with superior or average intelligence or leave it a moron or an imbecile. No amount of education will increase-and fortunately neither will it decrease-the intelligence. What education does do is to supply information, and if it is good education, as far as intelligence is concerned, it supplies methods of correlation and application. The trained mind has learned the best and most logical methods of approaching its problems; but intelligence is required for the solution. No system has yet been devised that will do man's thinking for him."1

John B. Watson, the father of Behaviorism and one of America's most famous psychologists, was for many years a leading spokesman for the extreme environmentalist viewpoint. His position:

"I should like to go one step further now and say, '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.' I am going beyond my facts and I admit it, but so have the advocates of the contrary and they have been doing it for many thousands of years. Please note that when this experiment is made I am to be allowed to specify the way the children are to be brought up and the type of world they have to live in."2

It must be said that very few psychologists hold to either of these extreme views. The vast majority fall into two great center groups, each of which recognizes both factors as being essential in the formation of intelligence, but which differ as to the relative weight of each. The majority opinion still seems to lean toward the hereditarian view, but the trend over the years has been in the direction of recognizing more and more the influence of environment.

Most environmentalists concede that there is a basic native endowment which is different in each individual and which has far-reaching effects upon the development of each person's intelligence. That endowment is inherited and, in itself, cannot be altered by environment. They see this basic native endowment as something that develops in response to stimulation from the environment. Thus, they hold that each individual is born with a different structure, a different endowment, but that the extent to which this endowment is utilized and developed-the extent to which it is nurtured-will in the end affect what we call the intelligence of the individual. The question for them is not whether the environment affects the intelligence, but how great is that effect.

The average hereditarian probably would consider inborn factors responsible for seventy-five to eighty per cent of the IQ, and environmental factors responsible for twenty to twenty-five per cent. Few environmentalists, on the other hand, would claim more than fifty per cent as the contribution of the environment. This means that the consensus considers environment responsible for from twenty to fifty per cent of the I Q-a range that is significant enough to be worth a great deal of attention. For if environment contributes even as little as twenty per cent of the I Q-a minimum amount set by a fairly strong hereditarian3-then the IQ can be raised by improving the environmental influences on any child. It is true mat the amount of improvement would be limited, but a small increase can make an important difference in the life of a child. And if environment is responsible for as much as fifty per cent of the I Q, then improvement in the environmental influences can increase the I Q to a very large and very significant extent.
Whatever the relative merits of the different positions in Nature-Nurture controversy, the average parent tends to think of the I Q in strictly heredi-tarian terms-that is, as a characteristic which is innate, unchanging, and not subject to external in-influences. The controversy should demonstrate to parents that psychologists differ widely on this question.

There are no definitive answers to the questions of what intelligence is and what produces it; but since we do know that the I Q is not constant, and that there is an increasing tendency to recognize environment as a major factor behind changes in the I Q, any chance of raising the I Q by improving the environment is well worth taking. And there is nothing to be lost in the attempt.