Abstract
In science and philosophy, a relatively demanding notion of understanding is of central interest: an epistemic subject understands a subject matter by means of a theory. This notion can be explicated in a way which resembles JTB analyses of knowledge. The explication requires that the theory answers to the facts, that the subject grasps the theory, that she is committed to the theory and that the theory is justified for her. In this paper, we focus on the justification condition and argue that it can be analyzed with reference to the idea of a reflective equilibrium.