Research:
Rationalization is a defence mechanism - a Freudian (read: outdated) construct that is still in common use in clinical psychology, but no longer used much in research, so current studies about such mechanisms are hard to come by.
To some degree, rationalization has been superseded by cognitive dissonance, and related self-perception theory. This is a more general theory about rationalizing that includes normal, healthy ways of dealing with internal conflict, as well as pathological forms. However, this line of research has focused mostly on theorized unconscious rationalizing, rather than verbal explanations provided by subjects. There are many other lines of research into verbalized non-pathological rationalizing, which is very common.
Therapy:
In modern cognitive therapies, the concept of cognitive distortions generally supersedes rationalization. Clinicians are specially trained to detect many varieties of cognitive distortion in patients, including minimisation, intellectualization, and sour grapes. In general, the idea is to look for inconsistencies or contradictions in the patient's descriptions of their thinking. For example, a patient might say: "Cheating on my spouse was a desperate call for attention." That might sound logical at first blush, but then why hide it? Or why not choose a healthier way to get attention?
Confronting patients with inconsistencies in their thinking is a common part of several traditions of therapy. One of the hallmarks of many personality disorders is patients' inability to recognize or failure to admit to the inconsistencies in their thinking. For most patients without symptoms of a personality disorder however, it is expected that they should confront, recognize, accept, and ultimately find healthier alternatives to their maladaptive distortions.
