Developing Sustainable Critical Thinking Skills in First-Year Medical Students: Explicit Fallacy Detection

Abstract

Critical thinking is a core competency in medical education, yet structured methods for fostering it remain limited. This study evaluates an explicit fallacy-detection module embedded within a 45-hour English for Health Sciences course designed for first-year medical students in Thailand (N = 97).The intervention targeted six fallacies—false cause, hasty generalization, confirmation bias, appeal to authority, false analogy, and appeal to nature, through scaffolded instruction, guided practice, and application with authentic medical texts. A mixed-methods design was used: pretest–posttest scores were analyzed with paired-sample t tests, and semi-structured interviews with 15 students were thematically analyzed. Results showed significant improvement (t (96) = 20.15,p < .001, Cohen’s d = 2.42), with the strongest gains in false cause and hasty generalization. Thematic analysis highlighted three developmental shifts: adopting a systematic “critical lens,” balancing respect with skepticism, and applying skills to patient-centered scenarios. Findings suggest that explicit fallacy instruction in ESL medical curricula strengthens analytical ability and cultivates sustainable critical thinking skills.