In chapters 2-4, Wenham attempts to establish the following steps of his argument:
- Luke knew Mark’s gospel.
- 52 passages shared by Luke and Mark have a common oral origin or some direct literary dependence. 14 other passages cover the same ground but do not show evidence of a common origin.
- Luke keeps to the sense of Mark in the aforementioned 52 passages.
- Luke probably keeps the sense of his other sources. This makes it improbable that Q exists and that Luke borrowed heavily from Matthew, since the Lukan and Matthean forms of the Q material differ in sense.
- Matthew’s relation to Mark can be explained on the lines of the patristic evidence.
Per Wenham, the great majority of scholars believe Luke used Mark. Adherents of the Greisbach hypothesis hold that Mark used both Matthew and Luke to compose his gospel. Wenham finds the Greisbach hypothesis unpersuasive.
If Mark had worked with Peter and taught Peter’s converts, it would have been much easier for him just to write down what he remembered, either inventing the gospel genre or imitating Matthew’s gospel if he had it as his disposal. The whole theory also seems to be made improbable by the small amount of material which is in fact common only to Mark and Luke. Even when one counts the most trivial single words like kai, there are (on my counting of the green words in Farmer’s Synopticon) only some 1,070 words common to Luke and Mark which are not also in Matthew. As Mark’s total word-count is, according to Morgenthaler, 11,229, the distinctive Lukan vocabulary is about 9.5%. There are no lengthy passages that are distinctively Lukan, in the way that 6:45-8:21 is distinctively Matthean. When one thinks of the huge quantity of special Lukan material, which by definition is not found in Mark, the small amount of distinctively Lukan material which is actually to be found there makes the theory implausible.
Again, if Mark is conceived as a book bridging the other two gospels, the material common to Matthew and Luke which Mark omits amounts to a surprisingly large total: the whole of Q. He is supposed to be conflating Matthew and Luke, yet he omits all those ready-to-use parallels. (p. 16-17)
Proponents of the Greisbach hypothesis assert that Matthew and Luke never depart from the order of Mark at the same place. They believe this is unlikely if Mark was the first gospel written. But it appears that Matthew and Luke do depart from Mark’s order at the same place once (Mark 3:13-19). In fact, Matthew only changes order 6 times and Luke 4 times. Wenham uses the statistical analysis of C. M. Tuckett to show that this phenomenon is not statistically significant. If the Greisbach hypothesis is wrong and there is some literary dependence between Mark and Luke, then Luke must have known Mark.
Wenham moves on to steps 2 and 3 of his argument. What he calls Category 1 passages are those 52 passages where Luke and Mark almost certainly share a common origin. What he calls Category 2 passages are those 14 passages where Luke and Mark cover the same ground but need not share a common origin. What passage goes in what category is determined by laying the passages side-by-side and looking at the closeness of the wording.
According to Wenham, there are about 5,000 differences in wording in the Category 1 passages. This mainly involves omitting, adding, and polishing Mark’s wording while keeping the basic meaning. But Wenham is not convinced that Luke would have made hundreds of decisions to modify Mark in what often seem to be pointless ways. Why not just copy Mark word-for-word? This is where Wenham opines that Luke may have used Mark to order his gospel but that he regularly drew from his memory of apostolic preaching to fill in the details. In other words, Luke may be using his own wording and not be modifying Mark.
11 of the 14 Category 2 passages occur in Luke’s passion and resurrection narratives. The Category 2 passages suggest Luke is providing his own version of the story in these places.