 In recent important work, Manchak has questioned the need and even the reasonableness of requiring spacetimes to be maximal (i.e., inextendible), pointing out problems with the condition's epistemic status (Manchak 2011), its conceptual cogency (Manchak 2016a), and its metaphysical character (Manchak 2016b). Because inextendibility is the most common assumption made in the physics literature when singular structure is discussed, however, we will continue to assume it for the purposes of this discussion, Manchak's interesting arguments notwithstanding. (Manchak's arguments will be discussed further in  section 4  below.) 