In this article, we respond to the three critiques of our earlier article about between-groups psychotherapy designs. In the original article, we argued that for between-groups psychotherapy designs, the specificity of the scientific information that we gain is determined by how much is held constant and how specific the factors are that are manipulated between comparative conditions. We recommended dismantling, additive, and parametric designs over comparative and no treatment/placebo designs for increasing specificity about causal mechanisms. In the critiques, the authors recommended idiographic approaches to psychotherapy outcomes focusing on therapists, patients, and settings. We disagree with this viewpoint and endorse the basic scientific method as a means of determining specific therapeutic mechanisms that can reliably alter specific psychopathologies.
