Philosophical Considerations and Research Ideas About Comparing the Two Approaches: Messer’s Comments Point the Way Forward

In his commentary, Stanley Messer (2021) posed the question of whether it is possible to evaluate the relative merits of different case formulation approaches to psychotherapy. He went on to maintain, based on the pragmatic theory of truth, that it is possible to compare different case formulation approaches, and pointed to a program of research that he and his collaborators conducted as an example for possible future research (Collins & Messer, 1991; Holland, Roberts, & Messer, 1998; Messer, Tishby, & Spillman, 1992; Tishby & Messer, 1995). In this reply, we express our appreciation for Messer’s remarks, with which we agree in large measure, and attempt to highlight and build upon some of the points he made. We discuss Dewey’s (1896) classic critique of the reflex arc concept to point out other ways the philosophical perspective of pragmatism supports the view that different approaches to therapy are not incommensurate. We also offer a number of suggestions for future research comparing psychotherapy based on Interpersonal Defense Theory and IRT, or any two case formulation approaches to therapy. At many points, our suggestions follow along the lines of Messer’s research. We also emphasize the value of case formulation-based studies, not only with regard to research comparing approaches to treatment, but for investigating other issues about therapy as well.