Positioning Case Study Research Within Evidence Hierarchies: Epistemological Tensions in Psychotherapy

Case study research has long played a central role in the development of psychotherapy theory, yet within contemporary research cultures it is often positioned as offering weaker forms of evidence when evaluated within hierarchical models shaped by evidence-based medicine. This article examines how such hierarchies, grounded in particular epistemological assumptions, influence the evaluation of case study research in psychotherapy. It argues that the marginalization of case studies is not primarily a methodological issue but reflects assumptions about knowledge, subjectivity, and generalizability that privilege certain forms of inquiry over others. Drawing on the psychotherapy research literature, the article examines the kinds of knowledge generated through case study research, focusing particularly on theory-building case studies and their cumulative contribution to theory development. It concludes by arguing for a pluralistic approach to research evidence, understood as epistemic pluralism, which affirms the legitimacy of theory-building case studies within psychotherapy research.