Does Nature Versus Nurture Makes Sense?

 My PsycCRITIQUES review is about to release for James Tabery's book "Beyond Versus: The Struggle to Understand the Interaction of Nature and Nurture." Here are some highlights:



If, like many people, you think the nature-nurture debate is fascinating and relevant to our time, add James Tabery’s book to your shelf. If, like me, you have long wondered why the nature-nurture debate still exists in scientific circles, add this book to your shelf. Beyond Versus: The Struggle to Understand the Interaction of Nature and Nurture focuses on providing novel insights into the confusions that have plagued scientific attempts to resolve the nature-nurture controversy. Tabery’s analysis of barriers to consensus in actual, on the ground, science is crucial to the book’s value... whichever side you are on, Beyond Versus well help you understand and communicate with those who think differently.

I know that sounds a bit gushing, but let me give you some context: I was convinced at least 20 years ago that the nature-nurture issue had been resolved beyond a doubt at least 40 years before that (e.g., Lehrman, 1970). Since that time, I have had tremendous difficulty understanding scientists who still want to have nature-nurture discussions, and they have had tremendous difficulty understanding me. To put it in the language of this book, I had been taught to view nature-nurture interactions as a developmental phenomenon, which should be treated as “vitally important to understanding the relationship between nature and nurture.” In contrast, many others have been taught to view nature-nurture interaction as statistical phenomenon, which should be viewed as “a potential nuisance. . . quite rare in nature.” These approaches are labeled the “mechanism-elucidation approach” and the “variation partitioning approach,” respectively, and much of the book goes to showing that there is an “explanatory divide” between the two approaches. That is, proponents of the two approaches appear to be studying the same phenomenon, and use much the same language, when they are, in fact, trying to explain quite different things. Tabery’s elaboration regarding this explanatory divide clarified many aspects of problematic conversations I have been having for decades....

Chapters focus on the late 19th and early 20th century Eugenics debates, the mid-20th century debates about race and IQ, and the late 20th to early 21st century studies of gene-environment interactions in relation to mental disorders... In each case, the contrast is drawn out between researchers asking “how much” questions (e.g., how much variation in outcome can be explained by variation in genes or certain variations in the environment) and researchers asking “how” questions (e.g., what are the multileveled processes by which these outcomes develop).

In addition...  Tabery does not neglect to discuss the importance of unfortunate scientific realities in guiding scientists’ behaviors. These include many pressures the practicing scientist will be all too familiar with, but of which the student and layman remain blissfully unaware: pressures to get funding, to get media attention, to promote the work of your students and mentors, etc....


In the middle section Tabery lays out his own framework for integrating the different approaches to understanding interaction, his “Population Thinking About Mechanism.” With that, he seeks to meet some serious challenges:

I am challenged to answer the following questions: since the study of populations is not the study of development, how can the study of populations shed any light on the developmental process? Since it is widely known that correlation is not causation, how can the study of causes of variation provide any understanding of causal mechanisms? And since how-much questions are about trait differences, while how questions are about trait development, how can answers to the former say anything at all about answers to the latter? (p. 108)

....After laying his solution out, Tabery breaks down what an interaction is (p. 133), why and how interactions should be investigated (p. 142), and what counts as empirical evidence for interaction (p. 147). It is not possible to say whether this solution will stand the test of time, but that issue is surprisingly not crucial to the book’s value; rather than leave his approach sitting on a pedestal to be admired, Tabery sets off immediately to place his approach into the applied context of bioethical decision making. In such a context, it is more important that Tabery’s approach yield key insights than that it be philosophically perfect....

Tabery’s book is not perfect. From the standpoint of a psychologist, especially one considering assigning this book for a class, I should note that the book is clearly written by a philosopher. It is not pedantic, but it is careful and considered, and it takes pains to make its terminology clear. It gets dry in spots, and often focuses more on the particulars of individual researchers than is necessary for its purpose. However, such depth gives a richness, and reminds us that these debates have taken place between people, not abstract ideas....The book is short, with 207 pages of text in the main body, and it offers a healthy 22 pages of footnotes for those who want more detail. In that space, it provides a compelling view of how a sophisticated understanding of gene-environment interaction can be achieved and put to use.