Abstract
This article is the last of four in a debate between a critical rationalist (falsificationist) and a positivist (justificationist) about the value and utility of theory in social work. The critical rationalist position and its criticism of the positivist approach to theory and the pursuit of science in social work are reviewed and explained in seven theses and a little commentary. Some criticisms about how critical rationalists choose among theories and interventions are answered. Finally, the use and misuse of quasi-experimental research in social work are addressed briefly.