I am struck by a remarkable hermeneutical inconsistency in the treatment of the biblical material. There is no direct extra-biblical evidence for the exodus. Therefore, it is often said, we cannot affirm that there was an exodus, and in fact we might have to affirm that there wasn't. Well, there is no extra-biblical evidence for Josiah's existence. In fact, there is more extra-biblical evidence for the existence of King David than for the existence of King Josiah, yet while there remain scholars who doubt David's existence few doubt Josiah's. One could argue that the fact that much of the Deuteronomistic History originates in Josiah's time is sufficient reason to conclude that he existed, but of course that is simply to beg the question of when this material originated. One might argue that the relative temporal proximity between the texts and Josiah versus David and certainly Moses makes the account of Josiah's reign intrinsically more compelling, but that really doesn't hold. Given the text-critical data, these texts could in principle date at least a couple centuries later than Josiah's reign, and any reasonable mechanism that could be considered to have transmitted material reliably over two centuries can almost certainly be considered to have done so reliably over five (we're not dealing with a game of Chinese Whispers here)--and that assumes that the texts should be thought to date so close to their earliest extant copies in the first place (it's hardly unknown for texts to predate their earliest extant copies by several centuries). And even if we grant Josiah's existence, why should we think that the events described in the text have any bearing upon reality? Why should we affirm that with a slight alteration (the text was written rather than "found") this is basically what happened? There is perhaps some shift towards a stronger aniconism in the late pre-exilic era which could be thought to reflect the Josianic reforms, but that convergence between the biblical and the archaeological data is no greater than those between, for instance, the Judges and the settlement patterns of the Iron Age I central hill country. If the Josianic convergence is granted, so too should the Judges convergence be granted.
The above is not to argue that the earlier material reflects the general course of Israelite history. Rather, it is to say that any hermeneutic that allows one to affirm a historical Josiah who was involved in widespread religious reform cannot be abandoned when one turns to other material, and that this hermeneutic will tend to generate a history of ancient Israel that looks much more like traditional narratives than is often granted among contemporary biblicists. One can be methodologically skeptical and one can be methodologically credulous. What one cannot be is methodologically skeptical in the treatment of some biblical data and methodologically credulous in the treatment of other, at least not if one hopes to produce an empirically sound historiography.