Thomas F. Homer-Dixon, Director, Peace and Conflict Studies Program, University of Toronto

David Dessler, Professor of Political Science, College of William and Mary

September 29, 2000—In order to understand and respond to environmental stress and scarcity more effectively, researchers must develop a broader theory using the strategies of other social scientists including historians according to David Dessler, a respected political scientist and methodologist. Dessler provided comments at a session sponsored by the Environmental Change and Security Project in which Thomas Homer-Dixon, a renowned researcher, presented the key findings from his various research projects on environmental scarcity that spanned the last ten years. In addition to presenting his key findings and pointing to further avenues of research, Homer-Dixon also addressed the points of his critics.

Homer-Dixon detailed a two-step causal model of environmental contributions to violent conflict in developing countries. To explain this model, he highlighted three key renewable resources that play a role in environmental stress. While there are many renewable resources, Homer-Dixon and his colleagues focused on the three key resources of cropland, fresh water, and forests within the context of three sources of scarcity. First, Homer-Dixon identified supply-induced scarcity, which is caused by the loss of resources such as a lack of quality drinking water or fertile land. Second, population growth and/or migration can increase the per person demand leading to demand-induced scarcity. Third, a skewed or disproportionate distribution of, or access to, resources is what Homer-Dixon terms structural scarcity.

Homer-Dixon's environmental scarcity research focused on two types of interactions using the three types of scarcities: (1) resource capture when resource access is shifted in favor of powerful groups (what economists term rent-seeking); and (2) ecological marginalization, where the combined impact of population growth and unequal resource access on a decrease in quality and quantity of renewable resources, can lead to increased environmental scarcity. This scarcity, in turn, can lead to forced migration into ecologically-marginalized areas.

Using a causal diagram from his recent book Environment, Scarcity, and Violence (Princeton University Press, 1999), Homer-Dixon showed the complex interrelationship among environmental scarcity, social capital, population growth and migration, and the potential for violent conflict. In explaining why a country may or may not resort to violence in the face of environmental scarcity, he emphasized that urban unrest and/or rural insurgency occurs in the context of other variables. Environmental scarcity is merely a contributing factor and is neither a necessary nor sufficient cause of violent conflict. Other factors such as the adaptability of social structures (e.g., market (in)stability, autonomy of the states, social norms, etc) and a country's capacity or ingenuity in solving problems play a major role in whether a situation may become violent.

Dessler presented an overview of what methodology does to assist social science research and where Homer-Dixon's methodology falls short in his environmental scarcity theorizing. First he outlined what two questions methodology seeks to answer in the case of environmental stress. The first question is predictive and asks if researchers can predict future levels of conflict from environmental trends? Second, the causal or explanatory questions asks how does environmental change bring about conflict? From the methodological questions, there are two types of information that can be used. The first is descriptive in that the information describes what the subjects under study are. The second type of information is broader in that it offers general knowledge of what it is that the researcher is studying.

This methodological discussion led to an examination of exogenous and endogenous boundary conditions and their impact on predictions of social/human behavior. The key problem with Homer-Dixon's work, claimed Dessler, is that only one of the three scarcities discussed in his environmental scarcity theory is exogenous and therefore unaffected by other social factors. Supply-induced scarcity is exogenous because it has nothing to do with human behavior but rather what resources nature has endowed the Earth. The remaining two scarcities, demand-induced and structural are endogenous conditions that are affected by human activities.

In conclusion, Dessler detailed four actions that could considerably improve theory in this emerging field, including the ability to broaden the debate without diminishing the quality of the data. These four items were to: (1) conduct detailed narratives of individual cases of conflict using existing theoretical work as a guide with the aim of creating data that competing theories can equally use; (2) borrow from social scientists the informal terminology of strategic choice theory wherein actors have preferences and beliefs and the environment constitutes actors and information; (3) borrow the concern for evidence that marks the historian's research; and (4) in the end, ignore methodology that is too restrictive. While critical, Dessler agreed with the scope of the research but pressed for a more finely detailed and exacting methodology to avoid discrepancies, a criticism Dessler has made both in presentations and in publications on the nature of Homer-Dixon's work.

A lively discussion followed the two presentations, in which a primarily practitioner and policymaker audience that works in the field of environmental stress and/or violent conflict, questioned the applicability of Homer-Dixon's research for predictive value. After listening to Homer-Dixon outline his theories, practitioners had a chance to question the research findings by pointing to field experiences that indicated otherwise and engaging in the ongoing debate between Dessler and Homer-Dixon. Early warning indicators have thus far been unsatisfactory and participants as well as the two speakers agreed that much more research with a more refined methodology is needed to rectify this deficiency.