 Yli-Vakkuri and Hawthorne (hereafter YVH) begin by offering a rigorous definition of narrow content intended to capture mainstream ideas in a more precise way. For YVH, “thoughts” are token representational mental states “which occur in an agent at a time” (18). A “content assignment” is a systematic assignment of contents to thoughts, i.e a function from thoughts to contents. Narrowness is a property of content assignments: roughly, a content assignment is narrow if, for any thought, the content assigned to it is completely determined by the purely qualitative properties of the thought and the purely qualitative relations it stands in to other things going on in the agent (see YVH 2018, Chapter 2, for a more careful and detailed account). A consequence of the definition is that, given a narrow content assignment, if two agents are exact duplicates (like Oscar and Twin Oscar), then any thought of one of them will be assigned the same content as the corresponding thought of the other.