 The study of some concepts such as preferences or obligations gives raise to an epistemic concern: how much do the involved agents know about such preferences and obligations? In most examples where such concepts play a role, whether or not the agent knows about the involved preferences or obligations makes an important difference. In case of the first, should an agent act according to her and other agents’ preferences, even when she does not know what these preferences are? In case of the second, is an agent compelled to obey a duty even when she does not know what the duty is?