Whether one engages in truth-seeking and whether he or she is open-minded are indicative of his or her critical behavior when responding to problems at hand. This research sought to determine the behavioural tendencies of pre-service mathematics teachers in the solution of non-routine problems based on the indicators of truth-seeking and open-mindedness. It was qualitative in nature, with an exploratory descriptive methodology. The participants in the research comprised of 15 pre-service mathematics teachers. The data were collected through tests, direct observation, and interviews. To guarantee the validity and reliability of the research, the triangulation technique was used. It entailed comparing the direct observation results with the results of the test and the interviews. The findings and conclusions were reached and the results indicated that all the pre-service mathematics teachers had not yet attained critical thinking dispositions pertinent to truth-seeking. The participants did not investigate the truth behind the information provided, and they tended to answer questions directly.