Wanted: 'Other Grounds' for rejecting Matthew's use of Luke

Tobias Hägerland's recent article, "Editorial Fatigue and the Existence of Q", NTS (2019), 190-206, makes an important contribution to the debate by calling into question Mark Goodacre's assertion that there are instances where Luke shows fatigue in his handling of Matthew, but none where Matthew shows fatigue in his handing of Luke. Having called into question cases where Luke supposedly shows fatigue in relation to Matthew, Hägerland goes on to conclude:

Against Goodacre's claim that editorial fatigue does not occur in Matthew's handing of the double tradition, I have developed Allison and Davies' suggestion that Matt 3.7-12 provides an example of 'imperfect editing' of Matthew's source material, which in this case cannot be limited to the Markan source. When compared to Luke's handling of the same material, Matthew can be seen to exhibit fatigue. As Matthew's use of Luke remains unlikely on other grounds, it appears most reasonable to postulate Q as Matthew's source here.
If anything, then, the distribution of editorial fatigue in the Synoptic Gospels speaks not against the existence of Q, but in its favour. (p. 206, emphasis added)

Thus, Hägerland claims to have found an occasion when the differences between Matthew and Luke are best explained by Matthew working from Luke but failing to be entirely consistent in his editing of Luke. This might seem like a good time to propose that Matthew used Luke directly. Nevertheless, Hägerland steers away from this conclusion on the basis that: 'Matthew's use of Luke remains unlikely on other grounds'. When these 'other grounds' are taken into account, Hägerland suggests, the only way to explain the data is to propose that Matthew and Luke both used Q.

This line of reasoning would be legitimate if the 'other grounds' for believing that Matthew did not use Luke were either self-evident or well known. Truly, they are not. The assumption that Matthew could not have used Luke was based, in the initial instance, on an appeal to Alternating Primitivity. However, as demonstrated in Video 1, Alternating Primitivity is entirely irrelevant to the question. Since Streeter made the assumption that Matthew's use of Luke may safely be ignored other scholars have followed suit. For example, Robert Stein, in Studying the Synoptic Gospels (2001) assures the reader that Matthew's use of Luke faces 'insurmountable problems' (p. 76) - but the only problem he cites is Alternating Primitivity. Similarly, Chris Tuckett, in Q and the History of Early Christianity (1996) muses: 'For various reasons ... Matthean dependence on Luke is hardly ever advocated, though one sometimes wonders why given the tendency of many to believe that Luke's versions is very often more original.' (p. 4). Thus, Tuckett shows a flicker of awareness, but not enough to break his stride. Paul Foster's objections to Matthew's use of Luke, in, "Is it Possible to Dispense with Q?" NTS (2003) also include Alternating Primitivity. In addition, Foster cites Matthew's omission of Special Luke material. This would only be problem, however, if it could be shown that there is some element of Special Luke that Matthew would have been bound include. Foster's third and final objection is pleasingly ironic. He notes that there are occasions when Matthew appears ignorant of Luke’s additions to Mark. If Matthew were to duplicate Luke's additions to Mark this would create a very real problem for the Two Document Hypothesis. It might even be worth trying to give a name to such a phenomenon. How about 'Minor Agreements'? 

A more creative attempt to find a reason for rejecting the case for Matthew's use of Luke was offered by F Gerald Downing in, 'Plausibility, Probability, and Synoptic Hypotheses', ETL (2017). Downing's approach rests on the idea that ancient authors would have scoured their sources to find sequences of thirty letters or more where those sources agreed verbatim and, having done so, they would have felt compelled to include these phrases (no matter how incidental) into their own narrative regardless of the impact on the style, theology, economy of their own creation. Downing finds the fact that Matthew fails to comply with this supposed norm a compelling reason to suggest that he could not have used both Mark and Luke. That Downing resorts to such an extraordinary approach might be considered revealing in itself. 

Regular readers of this blog will be familiar with Mark Goodacre's reasons for rejecting Matthew's use of Luke, which are reviewed here, and also in Rob MacEwen's report of Goodacre's paper at SBL Denver in 2018. Perhaps most important among them is his identification of instances where Luke shows fatigue in his handling of Matthew (but not the reverse). This, however, is precisely the argument that Hägerland's article is concerned to undermine.

So, where does this leave us? Worn out in the search for those 'other grounds' or not yet quite fatigued?