In this study, academic freedom in teacher education is related to preservice teachers' possibilities to develop critical and autonomous thinking in teaching practice. Self-awareness and self-confidence provide certainty to deal with the uncertain situation in teaching where creativity and judgment must be given priority over an instrumental teaching based on authorities, effective methods or ready-made solutions. Teacher educators thus need to promote academic freedom as both certainty and uncertainty. The aim of this paper is to provide enhanced understanding of the meanings and implications for teacher education of academic freedom, in the tension between certainty and uncertainty, based on a phenomenological study about preservice teachers' experiences of professional ethics. The results show that teacher educators' function as role models is crucial for preservice teachers' academic freedom in developing their teaching. A consensus on fundamental values provides openness in discussions that promote the student's critical attitude.