There is a diversity in the field of mathematics education regarding how the term "concept" is used. In this study, a concept analysis is carried out, analyzing the use of the notion concept in some frequently used frameworks within mathematics education. The study takes an analytic philosophic approach, using an analyzing instrument based on a philosophical literature review resulting in two distinctions used for interpreting views on concept. It was found that intersubjective positions are more common than subjective ones. Furthermore, a main diversity concerns whether concepts are mental representations that have reached a certain level of development, or non-mental abstract objects. When mental and non-mental positions are combined, it becomes difficult to consistently describe the nature of concepts. This leads to unclear theoretical frameworks, and in the long run scientific results become less useful to interpret and compare.