 This situation provides a fascinating case study, from both a physical and a philosophical point of view, for questions about the nature of idealization and de-idealization, and the definition of theoretical entities more generally. On what grounds, e.g., could one ascertain the relative merits of each type of definition on its own, and each as proposed for a particular sort of investigation, in the absence of empirical data? In what sense do the different definitions characterize the “same” type of physical system, if they do so at all? Is there a need to settle on a single canonical definition of a black hole? What would be gained or lost with or without one? The situation is closely analogous to that of the lack of a canonical definition of a singularity, except it is even more extreme here: the different definitions of singularities used by different physicists are (almost always) not actually inconsistent with each other. 