I am writing on behalf of my friend James. See, he's a very good boy every year, and every year all he wants for Christmas is Q. I worry very much that he won't get it unless you can bring him a Christmas miracle, because I'm not sure there's any other way it can come. Please help.
All tongue in cheek aside, over on Exploring OUr Matrix, James offers some brief initial reactions to my post on Q and the infancy. As James notes, it's just an initial reaction, so this isn't so much a refutation of his criticisms as it is an elaboration on my proposal.
On the question of plausibility, James wonders if I've met the challenge, and whether or not I've found plausible motive for Luke's actions. So I'd like to just draw the reader's attention to my comments, both on James' post and on my own prior post on the topic here, where I've developed the proposed Lukan thought process a little more.
I proposed that Luke was sure three things were true
1) The Messiah would come from Bethlehem
2) Jesus was the Messiah, and therefore must be from Bethlehem
3) Jesus was regarded as being from Nazareth
We can add to this list two more things:
1) Matthew was wrong.
2) Luke, whether he meets the grade or not, fancied himself an historian, or at least wanted others to see him as such.
Those last two points preclude him from using Matthew's infancy, whether he had Matthew in front of him or not. Whether he's "Jewish" enough to get all of Matthew's symbolism, surely he would know that Matthew's story wasn't true if he heard it, or would at least be highly suspicious.
So what Luke "the historian" does is a sort of ancient historical crit. He takes the facts he knows, and tries to find out how they fit. They seemed to fit with the census, so that must be the result.
What we end up with here is Luke making a conjecture that is perfectly reasonable, given the evidence he had on hand. All he neglected to do was explain the deduction, which doesn't seem that unusually, given that he explains his thought process nowhere else either.
McGrath also notes the likelihood that Jesus' parents' names were circulated. While I can't deny the importance of familial association in the ancient world, this might score against Q, not for.
Jesus is identified as the son of Joseph, outside of an infancy or childhood narrative, three times. Once in Luke, and twice in the gospel of John.
If familial identity is so important, why does Luke only reference it in the same section that Matthew does, save that one reference and why does Matthew feel disinclined to mention it later? I'd propose the simplest solution is that Matthew made it up for his infancy, and had no interest in it after that, while Luke copied it from Matthew in his infancy, and didn't have it in any of his sources after that. The one reference (Lk.4.22) is easily explicable by Luke relying on his own notes. The point here is Jesus' humble origins, not the commonality of identification by the father's name.
In other words, discounting (for the moment, at least) the GJohn, Jesus is described as "the son of Joseph" in the sense of a common identifier, with no other clear motivation, precisely zero times.
Luke does it when Matthew does it because he has Matthew in front of him. That's the simplest explanation.
James has indicated he hopes to engage my post more thoroughly when time permits, so I certainly look forward to further discussion! I'm coming dangerously close to convincing myself I've come up with something here, so hopefully he can disabuse me of that before I start having to take myself more seriously!