A series of increasingly intemperate debates in politics and social media about which claims about the world are true, how we can tell they are true, and what the relation is between truth and fiction reveals a deeper crisis of authority (which authorities have earned the right to be trusted?) and of trust (what kinds of trust are different communities prepared to invest in their chosen authorities?). After reviewing the extended historical background of these crises, this essay addresses them by recasting the apparently absolute distinction between fiction and nonfiction, considering the two terms instead as institutional or generic classifications that can be variously defined as media, intermedia, or transmedia—that is, as mutually exclusive representational modes or genres, as generic categories whose definitions depend on a more authoritative series of texts, or as byproducts of an ongoing text-making process—that rely in every case on each other for their definitions and their common understanding and are subject to constant renegotiation as that understanding changes. Instead of endorsing any of these three possibilities over the alternatives, the essay concludes by examining the advantages and disadvantages each of them presents.