Weighing the Evidence

It is now a common opinion that discussions of environmental (ecological) issues should be based on evidence. Considering current sources of information from social media flashes and TV clips, one must ask: what constitutes evidence? And how should we weight or value various types of evidence?


Knowledge is produced from research by several groups with differing philosophies that affect how evidence is evaluated. In the social sciences and in literary arts, books are considered to be high value evidence. In the natural sciences, peer-reviewed papers published in international scientific journals are the most highly valued. Other scientists who are leaders in research in that particular subject area review these papers. The papers are not published until their contents have been vetted by such reviewers and an editor who was chosen by peers in the branch of science covered by that journal. In contrast, books may be published with no review by experts in the field of the subject matter. Decisions to publish books or not are more likely to be based on an estimate of “marketability” made by operators of a commercial publishing company, often based on input from managers of big box stores.


Media reports often are stimulated by publication of a book and the press attention it receives. Such media reports seldom do a critical analysis of the science reported in the book. Some such books are culturally and scientifically valuable. For example Rachel Carson’s “Silent Spring” stimulated much-needed and long-lasting cultural awakening. E.O.Wilson’s “Consilience”, Richard Dawkins’ “The Greatest Show on Earth”, and Tim Flannery’s “An Explorers Notebook: Essays on Life, History and Climate” all have had positive cultural effects. But they are not peer-reviewed and accepted by science to be soundly based. Conversely, a very marketable book on cereal in our diet has passed for sound science without benefit of critical review by peers. Many of the public have considered its contents to be absolutely true. Some scientific reviews have doubted the validity of its evidence.




Media personalities are seldom trained in critical review of scientific or “pseudo-scientific” material and may elevate the popularity of books and other materials by following popularity trends rather than critically evaluating scientific evidence. Some trained professionals are attempting to provide an interface to interpret the scientific evidence and offer it in more digestible form to the public. The validity of the interpretation depends on the training and capability of the interpreter and, again, it is not peer-reviewed. This gap between the “hard” science of a peer-reviewed paper and the need for information by the public is not well-filled in most environmental areas. Very often, the interpretation of the science that is most strongly related to human well-being is chosen.


We humans tend to use our own self-interest to weigh and evaluate evidence. This arrogance may be adaptive in the short term and in sociological considerations but in the longer term necessary for ecological considerations, humans must be seen as just one (dangerously powerful) component of a larger system. The excessive emphasis on human comfort and profitable economic outcomes at the expense of structures and ecosystem processes is both immoral and unworkable. Cities certainly will be important in global futures but to consider nothing but cities is unthinking arrogance.


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