M.A. (Clinical Psychology) / Postmodernistic thinking supports the existence of various realities rather than the existence of an universally accepted objective truth. Knowledge is seen as an aspect of a constructed truth which may change over time, context, therapist and client and is therefore relative. An ethical approach, according to which the observer takes responsibility for his participation in what he observes, replaces the search for "the cause" or "the truth" constructionism and ecosystemic thinking are offered as ways of creating a postmodernistic interpretive framework. In using these frameworks or ways of thinking, the observer's participation in what he observes, as well as the existence of multiple realities and the influence of context, become recognized. The therapist that functions according to a postmodernistic perspective, gives up the idea that therapy is only about diagnosing an objective static condition. The therapists acknowledges that the observed condition always exists within the interaction between people. The therapist assumes a co-operative, respecting, therapeutic stance. The therapist sees himself as a catalyst rather than an expert who forces the therapy in a theoretically chosen direction. The therapist refrains from prescribing solutions, relying rather on the client himself to find new options and realities. Although this thesis focused primarily on a critique of Selvini Palazzoli's theoretical approach, it also comments on the pragmatic application of theories in general. A postmodernistic framework is offered as a broader more functional framework under which a variety of theories can be applied. within this framework already existing theories can be reconsidered and differently applied without rejecting their praqmatic value. A systemic perception of changing ideas replaces a systemic perception of things or objects. A debate about which school of theory is the most effective in dealing with a specific client, is replaced by an ethical approach according to which the observer takes responsibility for his choice of lenses in making distinctions and decisions.