This study aimed to investigate the effect of debating activities on prospective science teachers' willingness to argue. The sample group consisted of 27 students studying in the second year of Science Teaching. The Argumentation Willingness Scale and a structured interview form were used as research tools to collect data in the present study, conducted with an exploratory sequential mixed methods design lasting for five weeks for the purpose of examining the variation in prospective teachers' willingness to argue. The Argumentation Willingness Scale was used to determine the prospective teachers' level of willingness to argue before and after the implementation procedure. The resulting data were analysed with the paired samples t-test (a repeated measures t-test). Content analysis was also used to analyse the data obtained from the structured interview forms, which were administered after the procedure was completed in the qualitative dimension of the study. As a result of the quantitative data analysis, the debating activities were found to be efficacious in increasing the participants' willingness to argue. The analysis of the qualitative data, on the other hand, revealed the prospective teachers' views indicating that debating activities helped them acquire a number of skills such as research skills, discussion skills, and self-expression, and that they would use such activities especially while teaching socio-scientific issues in their professional life in the future.