The first of these stands in contrast to the available evidence we possess concerning early Christian belief. This can be quite clearly seen from passages such as 1 Cor 15, where the actuality of Jesus death and being raised back to life is foundational to the Christian hope. In the opening verses to Luke’s gospel, he expresses his concern for the truth concerning Jesus (Luke 1.1-4). If the gospels embodied the conviction that Jesus actual words and actions were irrelevant in fiction, then it follows that the earliest Christian communities felt likewise, otherwise it is highly improbable that the gospel would ever have gained such a standing within the church as narratives concerning Jesus life. Indeed, they might be considered an insult?
The second assumption is unduly sceptical. Although it may gain strength from the variations between the gospels, the solution seems rather to be that such variations were of no concern to the evangelists. Nevertheless, accepting that the evangelists were interested in the actual happenings of Jesus life, the second assumption assumes that they nevertheless did a poor job in gathering and presenting accurate information. In other words, they did poor history and have distorted the past as a result. The next move is then to purge the sources of inaccuracy by establishing, through the use of the "criteria of authenticity" (or at list indicate probability), what words recorded in the gospels actually came from Jesus lips (or his opponents?), or represent his words accurately, and what actions he actually performed (and his opponents?). And more subtly, establishing the "original form" of these words, the actions, and the settings they most likely occurred in, given the redactional work of the evangelists and possibly the effects of oral memory, transmission, and performance upon the traditions.
But working with the opposite assumption, we can see how the criteria for authenticity are of no real value for historical reconstruction. Upon examination of the criteria, we can see that the evangelists would have been in a far better position to employ them than any historian centuries removed. The criteria of plausibility suggests that Jesus both fits somewhere within the variegated Judaism of the Second Temple period, and somewhere within earliest Christianity, that is, he reflects elements of continuity (and discontinuity) with both. There must be a level of continuity on both sides for a picture of Jesus to be plausible on a macro level. This criterion is also applied on a micro level, to the words placed on the lips of Jesus. Living within both the world of first-century Judaism and earliest Christianity, the evangelists would likely possess a superior understanding of both their Jewish and Christian neighbours, and so be at a far more advantageous position to test the sources by this criteria. Hence it would be fair to assume that none of the material can be ruled out on the grounds that it is foreign in this respect, they would have picked up on something so out of place.
The criteria of multiple attestation is the test of whether a saying occurs in multiple sources or in multiple forms within the same or different sources. Thus, a saying is more likely authentic if it occurs in more than one of the gospels (and other early literature). The evangelists too, may have employed this criterion to their sources (whether written, but most likely received orally from people). This raises the possibility that although they have not cited their sources, they would not have made use of a saying which could not be verified by more than one source. This could leave our employment of the criteria redundant and unnecessary as the job has been done at an earlier level much more effectively.
Further, whether we have any real hope of establishing the "original" or most accurate wording, setting, or place within the chronology of Jesus ministry for any one saying/event that we desire to have, and which the gospel producers were seemingly not interested in having, is highly doubtful.
If what I have argued above is correct, and the early Christians, including the producers of the gospels, were interested in the actual happenings of Jesus life to the degree that their religion was built upon them, then we can only assume that in their quest to stand true to this they did what they could to make sure of the reliability of their written testimony. We should not ascribe to them an undue gullibility, nor should we think the criteria to be too sophisticated for them, as they are obviously very simple. We are on no better grounds (in fact worse) than they were for verifying the actual words and actions of Jesus, or their settings.
The conviction that the producers of the gospels were either uninterested in the actual happenings of Jesus life and deemed them of no significance for their beliefs concerning Jesus is built not upon evidence but on an undue scepticism about the abilities or motives of the authors of the gospels and the early Christians. Consequently, the criteria of authenticity are of little value for establishing either authenticity or probable authenticity. I suppose we just need to be more trusting...
This is largely an experiment in thought and rests on establishing the early Christian conviction that their religion is rooted in history and that Jesus as he actually was is their Lord. I would appreciate your comments and criticisms.
 One holds either one or the other.
 I use the phrase “author” as a simple label without making any judgements about whether there are only one author behind each gospel.
 That the producers of the gospels were different in this account, and that they some how produced largely fictional works which came to be understood as historical, is unlikely, and requires some form of evidence. The simple possibility of it occurring, does not warrant us thinking that it did in the face of evidence to the contrary.
 That this is not simply "Paul’s thing" is clear from the fact that he appeals to it as established tradition, witnessed to by those at the heart of Christian movement from the beginning (vv.3-7). This passage of course says nothing of Jesus words and actions during his initial life. See Michael Birds blog entry, Jim West and Interest in the Historical Jesus.
 The variations are of three basic types: wording, narrative placement, and setting.
 There are other criteria than the two examples mentioned below, see John P. Meier, A Marginal Jew vol.1. But the criteria of embarrassment for instance, as a purely positive criteria does not interest us. Still, a similar line of argument as applied to the two examples could follow. as being closest to the beliefs of the earliest Christians, the producers of the Gospels would be in a better position to observe what saying or actions would have actually caused difficulty or embarrassment for them, sayings or actions we may not pick up on from our perspective.
 These are evidenced by the variations in wording, setting, and order of the telling of the purportedly single events between the gospels.
 I prefer the term "teachings" here over "words" because of the distinction between ispsissima verba and ipsissima vox noted above. By “teachings” I mean to refer to all of the words ascribed to Jesus in the written sources.
 Even if they were unaware of all the writings of the Pseudepigrapha or those found at Qumran
 If a saying came from some one who claimed to be an eye witness, then if the gospel producer was satisfied by some means of criteria that they were indeed, then multiple sources may have been deemed unnecessary.