Acceptance and commitment therapy (ACT) is an experiential therapy that is based in clinical behavior analysis. Philosophically, ACT (as with clinical behavior analysis more generally) is based on the pragmatic world view of functional contextualism. In all forms of pragmatism, truth is measured by how well something works in the accomplishment of a particular goal. Functional contextualism (as compared to social constructionism or other forms of contextualistic thinking) seeks as its goal the prediction and influence of psychological events with precision, scope across phenomena, and depth across scientific domains and levels of analysis. Psychological events are treated as actions of the whole organism, interacting in and with a context. According to the contextual philosophy underlying ACT, the environment, behavior, history, and outcome of the behavior are all part of the context and need to be considered while proceeding through the therapy. The underlying philosophy especially can be seen in ACT’s focus on the function of behavior, in its ontological approach to language (both of clients and of scientists), and in its holistic approach.

THEORETICAL FOUNDATION: RELATIONAL FRAME THEORY