SBL/AARdvent Calendar: Day 23

What is the greatest weakness in the Two Document Hypothesis? 

Supporters of the Two Document Hypothesis do not claim that their hypothesis is flawless:

​"[E]ven though I have (unashamedly?!) sought in this paper to argue that the weaknesses of the 2DH are possibly less than those of other competing hypotheses today, I hope that I have shown that this theory too is open to questioning. It would be a brave, even foolhardy, person who claimed absolute certainty for the correctness of his/her viewpoint."
Christopher Tuckett, From the Sayings to the Gospels, (WUNT, Mohr Siebeck, 2014) 116

​“No hypothesis is without its difficulties, and for any of the existing Synoptic hypotheses there are sets of data which the hypothesis does not explain very well”
John Kloppenborg, Q: The Earliest Gospel, (WJK, 2008) 21

​When pressed to be more specific, 2DH supporters generally point to the problem of the Minor Agreements – places where Matthew and Luke agree against Mark. For example, Gerald Downing, in ‘Plausibility, Probability, and the Synoptic Hypotheses’ ETL (2017) 313-337, devotes considerable attention to attempting to explain the most famous of all the Minor Agreements: Matthew and Luke have: ‘Prophesy … who is it that struck you?’, whereas Mark has only ‘Prophesy!’ (Mark 14.65//Luke 22.65//Matt 26.68).
 
In my view, however, the Minor Agreements – though certainly problematic for the 2DH – are not its worst weakness. A much more severe problem is posed by those passages where Matthew and Luke agree almost exactly (and where there is no direct parallel in Mark). The problem, in a nutshell, is that ancient writers tended not to copy their sources verbatim. Matthew’s treatment of Mark is unusual in this regard inasmuch as Matthew sometimes copies Mark with a high degree of verbatim faithfulness. Luke’s treatment of Mark is, however, more conventional – he tends to paraphrase, rather than copy Mark word for word. We can see in some detail what happens when one author paraphrases his sources while another is more faithful, by looking at the extent to which Matthew and Luke exactly agree in their treatment of Mark. The answer is that they never come close to both copying Mark in exactly the same way for a whole paragraph. The closest they come is in The Parable of the Fig Tree (Matt 24.32-36//Mark 13.28.32//Luke 21.29.33) where 37% of the 86 words fall within Strings of Verbatim Agreement of 4 words or more. The next closest example is, ‘If any man would come after me …’ (Matt 16.24-28//Mark 8.34-9.1//Luke 9.23-27), where 29% of the 110 words fall within strings of verbatim agreement of 4 words or more. Beyond this there is no other example where more than 20% of a given paragraph falls within Strings of Verbatim Agreement of 4 words or more that are identical in Matthew, Mark and Luke.
 
Contrast this with the numerous occasions where 96-50% of the words shared by Matthew and Luke fall within Strings of Verbatim Agreement of 4 words or more (e.g. Matt 6.24//Luke 6.13; Matt 3.12//Luke 3.17; Matt 23.37-39//Luke 13.34-35; Matt 3.7-10//Luke 3.7-9; Matt 12.43-45//Lujke 11.24-26; Matt 11.25-27//Luke 10.21-22; Matt 24.45-51//Luke 12.41-46; Matt 6.22-23//Luke 11.34-36; Matt 7.7-11//Luke 11.9-13; Matt 13.33//Luke 13.20-21, and others).
 
What the 2DH requires, therefore, is that Luke had a particular desire to copy Q exceptionally closely – significantly more closely than he copied Mark. Moreover, this desire has to be mirrored by Matthew – who is required to have had the same attitude to the same passages. Moreover, Matthew and Luke are required coincidentally to have had access to virtually identical copies of Q – even though they were writing in times and places that prevented them from having any direct knowledge one of the other. Q is generally understood to be significantly more ancient than Matthew and Luke and is sometimes attributed to village scribes in rural Galilee. If this were indeed the case, it is necessary to suppose that Matthew and Luke both inherited versions of Q that had been virtually identically adapted (or left pristine) over the decades. Furthermore, it is necessary to suppose that Matthew and Luke both thought that the text of Q they had inherited was, for significant passages, incapable of further improvement (or they both happened to improve it in virtually identical ways). When, in addition, you notice that very high levels of verbatim agreement sometimes occur in the so-called Mark-Q overlap passages (e.g. The Beelzebul Controversy, Matt 12.22-30//Luke 11.14-23), then the credibility of the 2DH is stretched still further. That is to say, even though at least two distinctly different versions of such events were in circulation (as evidenced by Mark 3.22-27 and perhaps also by Matt 9.32-34; John 10.19-21 and Thomas 35) the copies of Q that came down to Luke and Matthew were both equally unaffected (or equally affected) by that environment of diversity.
 
If there were some really cast iron reason why Luke could not have used Matthew and Matthew could not have used Luke, then, of course, we would no choice but to accept these exceptional levels of coincidence (and the many further examples set out by, for example, Francis Watson in Gospel Writing(Eerdmans, 2013) 117-55). The difficulty is, however, that no-one has yet shown that Matthew could not have used Luke. (NB. As demonstrated in the full Matthew Conflator Hypothesis presentation, the standard arguments against Luke’s use of Matthew do not work in reverse). This means that we are not required to imagine (as supporters of the 2DH must), that Matthew and Luke both happened to inherit virtually identical versions of Q and happened to treat them virtually identically. Instead we can propose that passages where Matthew and Luke agree almost exactly are simply the product of Matthew copying Luke much as he also copied Mark.
 
For texts and charts relevant to this discussion, see Video 2.