Individuating psychotherapies.

One goal of an empirically oriented psychotherapist is to implement the same psychotherapy across similar clients for a similar specified problem. Adherence to a specified treatment is imperative when following a treatment manual. In other cases, such as when developing a new treatment, psychotherapists desire that the intervention be different from those currently available. To develop new treatments and to substantively increase the arsenal of psychological "tools" available to alleviate human suffering, criteria by which treatments are judged to be novel must be developed. The authors discuss criteria to make such delineations. They argue that psychotherapies are defined by two key properties: (a) a mechanism or mechanisms that causally produce the treatment's effects (if any) and (b) a manner or manners of instantiating these mechanisms. They also argue that if two psychotherapies share these two properties, then they are the same treatment: if not, they should be considered different treatments.