Before examining the text itself, some methodological questions must be considered. In particular, there is the problem of what criteria one can legitimately use to decide about literary priority. Very often the evidence is ambiguous and open to more than one interpretation. For example, in the case of Mark's ‘duplicate expressions’, where Mark has A+B and where Matthew had A and Luke has B, one can explain this in diametrically opposite ways: either Mark has conflated Matthew and Luke, or both Matthew and Luke have independently abbreviated Mark's apparent redundancy. Each theory explains the facts in one particular example. One requires, therefore, some more wide-ranging criteria for deciding between different possible explanations in any one case.

In this respect, the study of the Synoptic Problem is very similar to the study of the historical Jesus in its attempt to decide what is authentic in the gospel tradition. Both fields of study are concerned with seeking to distinguish between early material and later adaptations. The areas of study differ: historical Jesus research is concerned with the period from Jesus up to that of the earliest gospel, whereas study of the Synoptic Problem is concerned with the period from the earliest synoptic gospel to the latest. Nevertheless, the fundamental similarity in aim means that many of the methodological insights gained in one area can usefully be applied in the other. In the study of the historical Jesus, a great deal of work has been done in analysing and refining the various criteria which can usefully be employed.