Considering the breadth of mathematics education as a field of inquiry naturally leads to the emergence of new theoretical questions on the epistemic agency. Understanding causality, recognising patterns, establishing hypotheses, and debating the reality of mathematical statements vis-à-vis epistemological legitimacy of reasoning, analyses, and offered solutions lies at the forefront of research in mathematics education. When applying theory to mathematics education, we may examine the effects of bringing either the theory of mathematics or the theory of education into the classroom. The study of theory focuses on the methodical examination and critical investigation of primary concerns. Reasoning, analysis, investigation, and thinking are all parts of it, as are the evaluations, beliefs, and knowledge that arise from these rational and cognitive activities. The different manners and styles of incorporating fundamental theoretical ideas into mathematics education is the key focus of this paper.