What is identity in the context of bibliographic description? Two dimensions come to mind – determining the identity of an object in original cataloging and deciding whether a set of properties (i.e. a record) represents the thing in front of me to avoid duplication.
The identity of an item is made up, in its surrogate, the record, of attributes (like title, author, place of publication, year of publication) and identifiers like ISBN (which cannot be said to be unique). They allow us to distinguish resources, and to identify entities.
Establishing the identity of an object in order to decide what kind of bibliographic description, what kinds of rules are to be applied, is part of cataloging. We have a set of guidelines supposed to help us determine the nature of the object – but we cannot be 100 % sure about all criteria. I think every cataloger has come across ambiguous cases. For instance, it is quite hard sometimes (maybe due to limited information on the resource) to decide whether we are dealing with a multi-part item or a series. How can we know for sure when information is lacking or can be interpreted either way? Different catalogers might have different opinions based on experience or weighting of criteria.
So in some cases it’s the catalogers’ judgement that “creates” the identity of the work. Its identity might change over time (it is not unusual that a resource considered a monograph transforms into a multi-part item (or series) when a second volume is published and it wasn’t clear from the first that there would be a sequel). This quandary, though, is somewhat alleviated when, like me, you’re cataloging retrospectively (although you encounter other challenges, like the aforementioned lack of standards in providing information relevant for description). A lot of times, establishing the identity of the object is the hardest part, while the actual input of metadata is not such a big deal anymore.
When copy cataloging or working with incomplete records, it is crucial to add information in order to more unambiguously define the resource at hand. In fact, disambiguation is one of the goals of bibliographic description. I cannot think of one descriptive field that could be left out because they all contribute to the whole picture of resource identity.
Cataloging is determining the identity of an object for the sake of making it describable, of producing data about it, for the sake of representation. It has to be pinned down to be representable by a catalog record. In the end, however, the identity of a resource might just be as fuzzy and ambiguous as any other form of identity.
P.S.: Identity issues continue to exist in the digital realm…