This is a greatly oversimplified account, which would doubtless also be challenged by other archaeologists. Nothing so dramatic has happened or is likely to happen on the much smaller scale of New Testament chronology. But it provides an instructive parallel for the way in which the reigning assumptions of scientific scholarship can, and from time to time do, get challenged for the assumptions they are. For, much more than is generally recognized, the chronology of the New Testament rests on presuppositions rather than facts. It is not that in this case new facts have appeared, new absolute datings which cannot be contested - they are still extraordinarily scarce. It is that certain obstinate questionings have led me to ask just what basis there really is for certain assumptions which the prevailing consensus of critical orthodoxy would seem to make it hazardous or even impertinent to question. Yet one takes heart as one watches, in one's own field or in any other, the way in which established positions can suddenly, or subtly, come to be seen as the precarious constructions they are. What seemed to be firm datings based on scientific evidence are revealed to rest on deductions from deductions. The pattern is self-consistent but circular. Question some of the inbuilt assumptions and the entire edifice looks much less secure.
from the Preface, Redating the New Testament