Coherent Qualification

In one of his more recent posts, Jacob posited a definition of literature. While I am a fan of this definition (mostly because it corresponds nicely to his definition of art, which I am also a fan of for personal reasons), the fourth part is the only section that I question. Jacob says that in order for a work to be considered literature, it must have a "coherent narrative." Although I'm inclined to agree that a work of literature must possess a narrative, I am dubious of the merit in including the qualification that the narrative be "coherent." I think that the inclusion of coherent in the definition may bring a host of problems in determining works to be literature. For instance, is Ulysses by Joyce literature? While I think that it clearly has a narrative, some may argue against the coherency of it. But if Ulysses satisfies the criterion, than what work would contain a narrative not coherent enough to include in the category of literature? I think that we must first define narrative and then determine whether or not the inclusion (and definition) of coherent becomes necessary.