Abstract
After determining one set of skills that we hoped our students were learning in the introductory philosophy class at Carnegie Mellon University, we performed an experiment twice over the course of two semesters to test whether they were actually learning these skills. In addition, there were four different lectures of this course in the first semester, and five in the second; in each semester students in some lectures were taught the material using argument diagrams as a tool to aid understanding and critical evaluation, while the other students were taught using more traditional methods. In each lecture, the students were given a pre-test at the beginning of the semester, and a structurally identical post-test at the end. We determined that the students did develop the skills in which we were interested over the course of the semester. We also determined that the students who were taught argument diagramming gained significantly more than the students who were not. We conclude that learning how to construct argument diagrams significantly improves a student’s ability to analyze arguments.