Beginning his career when classical behaviorism was ending and neobehaviorism was beginning, he was responsible for the conceptual framework for the study of behavior. When there were issues with the variability and spontaneity with the S-R model, he addressed these concerns stating that the stimuli and responses were related to a number of classes and reflexes influenced by the environment. This process was known as respondent and operant behavior. He also is known for his work in Verbal Behavior.
According to Moore (2008), radical behaviorism "seeks to clarify the philosophical implications of the behavioristic approach to experimental research. applied research and service delivery" (p. 3). This philosophy, derived from B. F. Skinner, focuses on the scientific analysis of behavior, the assessment of behavior and subject matter, verbal behavior and knowledge, and the nature of intellectual activity that underlies the science and its application. (p. 3) It comprises of three levels that embrace behavioral relations such as phylogeny, ontogeny, and culture. It also considers the phenomena which aren't publicly observable, but is regarded to as behavioral and not mental. It is the foremost principle that sees behavior as its own subject matter and is still evolving.