Rogers' ‘necessary and sufficient conditions’ revisited
William Lockhart · British Journal of Guidance and Counselling · 1984
Rogers' concept of the ‘necessary and sufficient’ conditions of therapeutic personality change is introduced and the research evidence concerning the efficacy of the core conditions is reviewed. The use of Truax-and-Carkhuff-type rating scales for measuring the conditions is criticised on the grounds of inadequate validity and sampling procedure. It is suggested that relationship inventories such as those produced by Barnett-Lennard (1962) appear to be better suited to test Rogers’ position, although it is conceded that Rogers' hypotheses are in need of some revision.