Is the Nature-Nurture Debate on the Verge of Extinction?
Bors, Douglas A., Canadian Psychology
Some authors have stated that the nature - nurture debate is no longer as contentious as it once was. This paper presents four arguments in opposition to this position. First, the nature - nurture controversy, conceived of as an attempt to assign relative weightings of importance to genotype and environment in relation to psychological phenomena, is no closer to being settled today than it was at any point in the past -- nor could it be. Second, though of considerable consequence for psychological theory and practice, the mapping of the human genome will not assist in the settlement of the nature - nurture debate. Third, heritability studies are of little value to psychologists and cannot help in the resolution of the debate. Fourth, the nature - nurture controversy is not a scientific issue. Though it is possible to estimate the effect that changes in the environment or specific interventions will have on a given trait at a particular time and place, the question of ontological importance is beyond the scope of empirical investigation.
Recently the work of Rushton (1985) has sparked a debate concerning the causes of group differences in various psychological traits. At the same time, the related and often strongly contested issue of the reasons for individual differences appears to have been subsiding. Though research seemingly pertinent to the question of individual differences with respect to a number of behaviours and psychological traits is being published constantly, the heated exchanges that marked the 1970s are now apparently absent. Some authors would have us believe that this latter issue is no longer as contentious as it once was. For instance, according to Johnson (1990, p. 331), the nature - nurture controversy, as a consequence of recent research, is moving toward an "amicable, if complex, settlement." Further, he also asserted that the mapping of the human genome, which is scheduled to be completed in fifteen years, will provide a "big push" in the direction of the settlement. Johnson is not the first in the history of modern psychology to posit the death, or near death, of the nature - nurture debate. His claim concerning the importance of recent research is one that has always accompanied predictions of the debate's resolution. And though his assertion concerning the mapping of the human genome is not entirely new, in light of recentadvances in genetics, it is deserving of reconsideration.
This paper has two principal goals. First, it will be argued that the nature - nurture controversy, understood as an attempt to assign levels of relative importance to genotype and environment, is no closer to being settled today than it was at any point in the past, nor could it be. Further, regarding the issue of relative importance, it will be argued that heritability studies, which often have been overinterpreted, are irrelevant. Second, though recognized as of considerable consequence for psychological theory and practice, the notion that the mapping of the human genome will assist in the settlement of the nature - nurture debate will be disputed.
As evidence to support his conclusion that the nature - nurture controversy already is on the road to resolution, Johnson (1990) points to contradictory empirical findings. On the one hand, as some others have done in the past, he maintains there is "mounting evidence [that] points to a heavier genetic influence on many behaviours than most psychologists were previously prepared to acknowledge" (Johnson, 1990, p. 331). The key phrase in this declaration is "heavier influence." Like many who have taken one side or the other in this debate, Johnson apparently believes that new data, presumably from heritability studies, are capable of revealing the importance or influence of genotype relative to the environment. If this is Johnson's belief, his report of the death of the nature - nurture debate may be greatly exaggerated. On the other hand, Johnson points out that scientists recently have been discovering how genes are influenced by many internal and external change agents and that "what is encoded in the genes is not nearly as immutable as was once assumed" (Johnson, 1990, p. …