Constructing explanations and participating in argumentative discourse are seen as essential practices of scientific inquiry. The objective of this study was to explore the elements and origins of pre-service secondary science teachers' alternative conceptions of tidal phenomena based on the elements used in Toulmin's Argument Model through qualitative research. The data were collected from three pre-service secondary school teachers (D.-K. University, Teachers' Colleges, junior and senior) in the Republic of Korea using a variety of qualitative research methods. We present three pre-service teachers as examples of 20 pre-service teachers for determining each pre-service teacher whether the pattern of his/her responses to all of the questions investigating a given concept can be explained by the consistent use of components of argument. The results of this study showed "the model with the Earth's center at rest" backing their warrants as an element of Toulmin's Argument Model. As a result, science educators must explicitly address these presuppositions or implicit beliefs and must help the students form links between their everyday experiences and scientific knowledge. Therefore, educators must be aware of the influence of students' presuppositions and must use acceptable scientific concepts (the center of mass of the Earth-Moon system) based on argumentation to guide their construction of scientific concepts.