Controlling one's mental agency encompasses two forms of metacognitive operations, self-probing and post-evaluating. Metacognition so defined might seem to fuel an internalist view of epistemic norms, where rational feelings are available to instruct a thinker of what she can do, and allow her to be responsible for her mental agency. Such a view, however, ignores the dynamics of the mind–world interactions that calibrate the epistemic sentiments as reliable indicators of epistemic norms. A ‘brain in the lab’ thought experiment suggests that an internalist view of epistemic feelings is unable to account for the contrast between norm-tracking, educated sentiments, and illusory feelings.