How to obtain informed consent for psychotherapy: a reply to criticism

In 'Psychotherapy, Placebos and Informed Consent', I argued that the minimal standard for informed consent in psychotherapy requires that 'patients understand that there is currently no consensus about the mechanisms of change in psychotherapy, and that the therapy on offer…is based on disputed theoretical foundations', and that the dissemination of this information is compatible with the delivery of many theory-specific forms of psychotherapy (including cognitive behavioural therapy (CBT)). I also argued that the minimal requirements for informed consent do not include information about the role of therapeutic common factors in healing (eg, expectancy effects and therapist effects); practitioners may discuss the common factors with patients, but they are not part of the 'core set' of information necessary to obtain informed consent.In a recent reply, Charlotte Blease criticises these two arguments by claiming they are not supported by empirical findings about the therapeutic common factors. Blease's response is based on serious misunderstandings of both CBT and what the common factor findings actually find. Nevertheless, addressing the reasons for these misunderstandings is instructive and gives us an opportunity to clarify what, exactly, needs to be explained to patients in order to obtain informed consent for psychotherapy.