ANSWER:
For Dave to see all the theories in phycology to be the same, it means Dave is one sided in his understanding of those theories, because all those theories is all about the human mind and how it relates to it's internal and external environment.
If we should INTROSPECT Dave using PSYCHOANALYSIS, we will see that his BEHAVIOR was acquired by the way he has conditioned his mindset. To help Dave in his COGNITIVE REVOLUTION, We can only apply HUMANISTIC PSYCHOLOGY which will help him understand his COGNITIVE DISSONANCE, as he needs CONFORMITY in his SOCIAL-CULTURAL PERSPECTIVE.