The organizational theorist Charles Perrow invented the term “normal accidents” ([1984] 1999) to apply to the kinds of failures that are inevitable in complex systems, such as chemical plants or nuclear plants, which are “coupled” in a tight way, meaning that when something went wrong in one part of the system it would have consequences for other parts of the system (Perrow [1984] 1999: 72, 89-100). Some of the consequences in such systems are predictable linear consequences of failures of components in the system. Others, which will be my main concern here, will involve multiple failures of components with unpredictable consequences.