Synopsis Theories systems and Paradigms psychology is the study of the way people think and  behave. The field of psychology has a number of sub-disciplines devoted to the study of the different levels and contexts of human thought and behavior that includes theories, systems, and paradigms. theories, systems, and paradigms have had an important effect on psychology. A theory is a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena. A theory can also be explained as an abstract thought or speculation. There are many different theories of abnormality and treatment. These approaches include the psychoanalytic, neo-Freudian, gestalt, cognitive behavior therapy, humanistic psychology, and transactional analysis. Theories have provided psychology with the way to analyze a set facts and how they relate to one another. Traditional studies of theory have generally focused on individual theorists, core concepts intellectual histories, or schools of social thought.