In this article, the authors provide an overview of mathematics education as a research domain, identifying and briefly discussing four shifts or historical moments. They illustrate how researchers working in various moments conceptualize not only the interactions among teachers, students, and mathematics differently but also teachers, students, and mathematics as subjects of inquiry as they ask different questions made possible by different theoretical perspectives. The authors then provide brief descriptions of critical theory and postmodern theory, and suggest critical postmodern theory as a hybrid theory that offers a praxis of uncertainty for reconceptualizing and conducting mathematics education research. They conclude by summarizing three research articles that they believe exemplify the empowering and humanizing uncertainties of how teachers, students, mathematics, and the multiplicity of interactions therein might indeed be reconceptualized with/in critical postmodern theory.