Asks whether or not there is a need, which emerges inescapably during the course of human development, to identify some people as allies and others as enemies. In answering this question, it describes the potential for moral splitting within everyone, and the circumstances that activate this potential. (Author)

Defines moral exclusion. Discusses the antecedents and symptoms of moral exclusion. Explores the interaction between the psychological and social factors that foster its development. Briefly discusses outcomes of moral exclusion. Introduces the articles in this issue by presenting an overview of the themes examined in this issue. (JS)