The major questoin for this argument is, how can it be verified if we can't distinguish between stories with one verison which are fictional and those which are factual. After all, some stories, such as Little Red Riddinghood, and Robin Hood, have basically one verion, but are none the less either obviously fictional, are largely fictional.
I never said there's a one to one corrospendence between one version and truth. It can be that ficitonal stories only have one version. We can dichotomize between clealry fictional, such as LRRH, and somewhat factual, such as Robin Hood, and historical. But this raises the probelm, brought to me by Peter Kirby in email, if there has to be some basis in historicity to begin with, doesnt' this destory the idea of the argument as a useable paradigm. Becasue at that rate the single viersion is not telling us of the historicity of the narrative, but vice versa.
However, It think the importance of the paradigm is more subtle than just a cold "thumbs up, or down" on truth content. I think the real difference comes in at the point of understanding what was believed, not necessarily what is historical. The fact of one version only tells us that the events were set in stone form an early period. Now we have to ask, why were they set in stone? This would espeicially be improtant for a story like the Jesus narrative. One would think that miracles and amazing happenings would lead over active theological imaginations to invent new versions of the story.
The paradigm is toward an understanding of beilef. The fact of one story tells us that people at least believed the story in that version from an early period. It doesnt' tell us that this is indeed what happened, but it may tell us that this is what people believed happened from early on in the life of the narrative. That doesn't gaurontee truth, but it does mean that the community of faith was shaped by this particualr understanding of its history, and that this understanding forms the inception of the communtiy.
This gives us a history-likeness to the narrative. The importance of history-likeness cannot be over estimated. It means that this is what the community understands as it's history. We have to be prepared to adapt to new understandings as fact warrant, but this is the nature of the community to which we belong and the nature of our faith.
It means the Jesus story as related in the Gosples is still "in the running" as a histoircal event, until proven otherwise. Until the testimony of the community is demonstrated to be inadquate it has to stand as the bench mark of faith. These are the "history making" events that shape our faith.