SDT is an organismic dialectical approach. It begins with the assumption that people are active organisms, with evolved tendencies toward growing, mastering ambient challenges, and integrating new experiences into a coherent sense of self. These natural developmental tendencies do not, however, operate automatically, but instead require ongoing social nutriments and supports. That is, the social context can either support or thwart the natural tendencies toward active engagement and psychological growth, or it can catalyze a lack of integration, defense, and fulfillment of need-substitutes. Thus, it is the dialectic between the active organism and the social context that is the basis for SDT’s predictions about behavior, experience, and development.
Within SDT, the nutriments for healthy development and functioning are specified using the concept of basic psychological needs for autonomy, competence, and relatedness. To the extent that the needs are ongoingly satisfied, people will develop and function effectively and experience wellness, but to the extent that they are thwarted, people more likely evidence ill-being and non-optimal functioning. The darker sides of human behavior and experience, such as certain types of psychopathology, prejudice, and aggression are understood in terms of reactions to basic needs having been thwarted, either developmentally or proximally.