The aim of this study was to investigate the effect of the university-level application of an ArgumentBased Inquiry Approach, as compared to the traditional laboratory teaching method, on the ability of students to learn about optics and to demonstrate critical thinking. In this quasi-experimental study, pretest-posttest scores and CCDTI were used as data collection tools. The study sample consisted of a total of 44 students receiving lessons in science education and laboratory applications in two separate classes within the Faculty of Education at a small university in the north of Turkey in the school year 2013-2014. While the students in the control group carried out experiments using the traditional laboratory method, the students in the experimental group carried out activities in groups of three to four based on research using the ABI approach. Students in both groups performed seven activities. In the study, we used pretest and posttest results. The Cronbach’s alpha reliability coefficient of the test was determined to be 0.71. In addition, the CCDTI scale, adapted into Turkish, was used at the beginning and end of the study in an attempt to determine the change in students’ capacity for critical thinking. The findings show that university-level use of the ABI approach provides a statistically significant contribution to students’ success in learning optics. Moreover, it was established that the argument-based approach produces significant differences in students’ capacity for and tendencies towards critical thinking compared to the traditional method.