I was recently taken by something that R McLean Wilson wrote in his very early Studies in the Gospel of Thomas (A R Mowbray and Co, London, 1960). He introduces his consideration of the Gnostic element in Thomas by saying:
In the study of an ancient document much depends upon the pre-suppositions with which we begin, on the questions with which we approach the examination of the text.(p 14)
He goes on to say that if you concentrate on details and isolate passages from one another, while you may produce useful information, you may also miss the “range and sweep” of the document. General impressions acquired by looking at the text as a whole, however, may be misleading if not combined with a detailed examination. As Wilson so rightly states, if you start with the assumption that Thomas is dependent on the Synoptics, you can find evidence for dependence, and if you start with the assumption that it’s independent, many of the same things will provide evidence for that, so your initial assumptions are important.
I think Wilson’s comment is sound advice for all studies of ancient text. The challenge is to approach texts with a reasonably open mind and to look at the problematic elements and ask “What sorts of things might cause/explain this? Which of these is most likely and why? What are the minimum conditions that need to apply in order for explanation A to be true? And explanation B? And C, if there is a C? If it doesn’t fulfill either/any of the minimum conditions, what have I missed?”
I try to use this methodology on all occasions and hope that I am usually successful. 🙂