To date little information is available for describing the actual process of farmers' reasoning processes in creating simple rules in their decision making. It is critical as farmers often use the rules as a means to deal with complex situations, particularly when subsistence is an issue. Farmers' reasoning processes are also unlikely to be straightforward thus requiring approaches capable of capturing the intricacies of farmers' thought patterns and paths. This book, therefore, offers an analysis using the Theory of Planned Behavior, Personal Construct Theory and Ethnographic Decision Tree Modeling to trace the origins of subsistence farmers' beliefs, and extract the critical elements and paths in their decision making systems. The analysis should help explain how farmers' cognition and simple decision rules give rise to a particular decision or behavior, and provide a more realistic description of the farmers' decision-making process. The results should be particularly useful to academia, agricultural researchers, extension services and policy makers who seek better ways to assist farmers, particularly with respect to developing countries.