Ah, it seems like only yesterday that there was a bit of a row on the biblioblogosphere about James McGrath's post about infancies, Christmas and Q. And here we are about to have another look, during the holiday season, at the same subject. Qoheleth was right. There really is nothing new under the sun.
So today over on Exploring Our Matrix we battle Contradictory Christmases
I'd like to state, from the outset, that I categorically reject the reasoning that gets us from the sort of difficulties McGrath outlines to the existence of Q. I would argue that both the name Joseph and the virgin birth are not only Matthean, but distinctly Matthean. Luke knows the shoes are red, not silver. He knows Dorothy is auburn haired, not blonde. Therefore he knows MGM's musical, in addition to Baum's book.
We can't get around that by suggesting that because the story is closer to the Wiz than The Wizard of Oz they had independent red-shoed-auburn-haired traditions. The presence of difficulties such as those remarked upon by McGrath are not a strong argument in favour of Q, though somewhat ironically in many discussions they are the only type of argument offered.
That said, the difficulties still exist, and whether they point to Q or not they can still be a fun excercise to explore.
The first caveat I have with the general approach is the assumption that Luke, if he had no other source, would use Matthew almost invariably. Even Goodacre falls somewhat prey to this, in postulating a separate tradition that Luke regarded as more authoritative. Here, it seems to me at least, Goodacre has fallen victim to the sort of "cut and paste" scholarship he roundly (and rightly) condemns in his criticism of the 2SH, in postulating a lost source to explain a tradition.
While such a source may well have existed--I certainly don't want to suggest it didn't or couldn't--I don't think it's necessary to postulate to address Luke's break from Matthew. We might suggest such a source to explain why Luke says the things he did, but I do not think such a source is at all necessary to explain why he wouldn't follow his Matthean source.
I think we tend to underestimate Luke. To envision him little more than a copyist, while only marginally a redactor. I live in the twenty-first century, and I'm aware that the slaughter of the innocents is unlikely. Surely Luke, much closer than I in both time and place, was aware that something was suspicious. So whether he had another source or not, surely he was aware that he should be, at best, very cautious in regarding Matthew's infancy as authoritative.
Once we assume that Luke would have good reason not to put too much stock in what Matthew had to say in his infancy in the first place, it becomes much easier to envision him being creative with his sources.
So, the question McGrath puts to the reader is how we are going to explain why Luke has Jesus only in Bethlehem temporarily, while Matthew has it as his family's home.
I think the solution to this is actually simpler than it might first appear, and does not require us to postulate an external source.
Luke's audience certainly seems to be less familiar with "Jewish" sites than the other evangelists, his aversion to naming them is both well known and widely recognized. So it seems reasonable to suggest that they are more sympathetic, and more understanding, of "Jesus the Galilean" than they are "Jesus the Israelite."
So he sits down, the same as Matthew, with the well-established tradition that Jesus was "of Nazareth," but the equally well-known problem--the Messiah would not be Galilean. Since he has already rejected Matthew's slaughter of the innocents, and because his crowd accepts "Jesus of Nazareth," he still has to get his hero in and out of Bethlehem.
There was no slaughter, but there was a census, and even if Luke didn't know all the details of it, he knew enough to put it at roughly the time he needed. So he exploited it to get Jesus in to Bethlehem. Because they were always there only temporarily, it was equally easy to get him out.
In other words, even with Matthew open in front of him, once he has rejected Matthew's slaughter of the innocents--once he has rejected Matthew's Exodus--Matthew's chain of events isn't going to work to get Jesus in and out of Judea. So Luke kept the things he liked--"Joseph," the virgin birth, the birth in Bethlehem--and altered the rest so that it served his purpose and had some basis in what he knew to be historical realities.
Luke's version makes sense in a sense that Matthew's doesn't, because it sounds historical while Matthew's sounds primarily symbolic. Which makes perfect sense of why Luke tells the story he did. And the only external source we need is Lukan knowledge of the census. Which is far easier to explain than sources nobody has seen, and no ancient author has cited.
This is of course subjective conjecture, but unfortunately in this situation we aren't left with much else. Any question of motive is conjecture anyway, unless an author is explicit.