It is true that they have more studies than anyone else, but that is because they have very limited treatment goals which are very easy to measure, and they do not study complex people who have a lot of different (comorbid) psychological problems. Even so, their claims of the superiority of their evidence base are highly inflated. I go into exactly how in detail in How Dysfunctional Behavior Spurs Mental Disorders.
It is also true that they control the funding for psychotherapy outcome research and deny the followers of other schools a chance to prove their mettle in randomized clinical trials. Psychotherapy researchers refer to the "cognitive behavioral mafia" at the National Institute of Mental Health.
One of the major components of CBT is cognitive therapy, first pioneered by psychologist Albert Ellis and then refined by psychiatrist Aaron Beck. Cognitive therapy is based on the idea that human beings are fundamentally irrational creatures in that they make a lot of logical errors whenever they assess the risks and benefits of various situations and courses of behavior. These irrational ideas then lead to out of control emotions like unreasonable anger and depression.
A current and popular version of cognitive therapy is called Acceptance and Commitment Therapy (ACT). At slight risk of oversimplifying this therapy, it consists almost entirely of trying to teach people that they do not have to believe everything that they think.
It's interesting that when CBT therapists start to deal with more significant self-destructive behavior, such as that seen in personality disorders, then what they do starts to look a lot more like what humanistic or relationship-oriented psychotherapists do. IMO, one big reason for this is the existence of certain types of beliefs that human beings tend to hang on to as if their lives depended on it, notwithstanding even the most obvious evidence to the contrary.
This type of belief was first identified by psychoanalytic pioneer Karen Horney. She referred to them as positive value blockages, for reasons I will describe shortly. They are held by individuals. Later on, family systems therapists noted a similar phenomenon at the level of the kin or family group. They called these collectively held notions family myths. Of course, dogmatic myths are also seen at the level of the subculture, where one might refer to them as theology.
Horney's idea of positive value blocks, which she conceptualized as defense mechanisms, is tied to the idea of a false self, which also called a persona. Children growing up in dysfunctional families who are subjected to rejection, brutality, withering criticism, ridicule, and/or hostile control will feel safer when they act in certain ways which are rewarded by the family environment, but which may run counter to the way they really feel deep down inside of them. The different sorts of behavior that fill this bill leads them to develop certain character types.
According to Horney, when such children - and later when they become adults - act in these ways, they often pretend to be proud of their behavior, but deep down they feel alienated from themselves and full of self-hatred. This neurotic or conflictual pride is a glorification of a phony self. This false pride is usually supported with a number of ideas which justify the character type. These ideas often take the form of proverbs or slogans such as, "Nice guys finish last." Such ideas act as blocks to the expression of a person's true self (which might wish to be nice), and this is what is meant by the term positive value blockages.
An individual's family often not only shares these beliefs, but lives by them. Some beliefs can be specific to certain individuals within the family (for example, what one family member is "really" like and who within the family he or she is closest to), while others apply to everyone. The ideas in this context are what is referred to as family myths. They justify and support a set of rules which dictate how each family member should behave, and what family roles each must fully and compulsively play, in order for the family to function in a predictable way (family homeostasis).
The myths function as a belief system which the family uses, often defensively, to explain its experience to itself. They are sometimes not verbalized explicitly so as to avoid any challenges to them. They can be taught implicitly through various forms of acting out and family rituals. However, they may also take the form of oft-verbalized adages just like positive value blockages do in individuals.
I had one patient who justified never trying to change a bad situation with three different proverbs: "the grass is always greener on the other side," "the devil you know is better than the devil you don't know," and "you've made your bed so now you have to lie in it." All three slogans had been repeated to her ad nauseam by her parents when she was growing up.
Therapists, challenge these ideas without understanding how central they are to a person's psychology at your own risk. Your patient will fight you tooth and nail, and you will get absolutely nowhere. Cognitive therapists, put that in your pipe and smoke it. Or is that just another family myth?