The proposal of six necessary and sufficient conditions for therapeutic change is an integrative statement describing the elements of any successful therapeutic relationship. It is untrue that the practice of person-centred therapy involves but three ‘core conditions’

Rogers states that, if these conditions are present, positive change will occur regardless of the orientation of the practitioner. Thus he is making an integrative statement. From a person-centred perspective, this explains why in comparative studies of the efficacy of different approaches to therapy such as Stiles et al. (2006) there is no significant difference between them. The assumption must be that when the hypothesis of the necessary and sufficient conditions is met and other elements of the particular therapeutic style of the practitioner do not significantly conflict with them, the effects of therapy will be broadly the same. What is important to note is that the hypothesis depends on all six conditions not merely the so-called core conditions. Exclude any and the proposition falls. Rogers (1957: 100) states this quite unambiguously:  ‘if one or more of [the six conditions] is not present, constructive personality change will not occur’. Although in Rogers (1959: 213) these conditions are stated slightly differently, with respect to the basic hypothesis, this is not of much significance (see Wilkins 2003: 64-65) and the same arguments apply. However, as well as including a(n integrative) statement of the necessary and sufficient conditions for successful therapy the 1959 paper comprises a statement of person-centred theory.