Don't you think if "Luke" knew about gMatthew, she would have written her extreme & unrealistic saying as she did?
This argument is entirely useless. This is something that I think Goodacre makes a very good case against. Trying to conjecture about what someone would or wouldn't have done in how they wrote something like this is baseless speculation. There are cases where this cane be helpful, but the Synoptic problem isn't one of them.
For one thing, we don't actually know the motivations of the writer. So much of Q speculation is based on Christian theological assumptions about Luke presumably wanting to write an eloquent Gospel. They are also based on assumptions about Luke being written relatively early.
For one thing, if Luke had Matthew and Mark and the letters of Paul in hand, then Luke may well have understood that Paul preceded Mark, and Mark preceded Matthew. Having this understanding, the writer may have prioritized Paul over Mark and Mark over Matthew.
If you throw Marcion's Gospel into the mix, then the writer of Marion's Gospel may have introduced: "If any one comes to me and does not hate his own father and mother and wife and children and brothers and sisters, yes, and even his own life, he cannot be my disciple"
Luke then followed Marcion's Gospel, while Matthew toned it down.
I think a lot of recent studies are coming to the conclusion that its far more complicated than just A+B=C or A+(BC)+D = G, etc.
There has been circular copying and multiple layers of redaction. Gospels like Luke and Matthew aren't simply constructed from 1 or 2 or 3 sources.
An easier way to see it is how I'm now proposing that Mark and Acts were written. I'm working on the following proposal:
There was a narrative about Paul in which Paul travels to Macedonia, does some stuff, goes to Ephesus, does stuff, then goes to Jerusalem has his trial, then is "saved" by the Gentiles and goes to Rome. That was its own independent story.
The Gospel of Mark is based on that story, but the writer of Mark replaced Paul with Jesus, and has Jesus killed by the Gentiles instead of being saved by them. Mark also used Paul's letters. So the writer of Mark had in hand a collection of Paul's letters (PL), plus a story about Paul (P).
So Mark (M) is based on P + PL. P + PL > M
Now "Luke" comes along and write Acts. Luke has a copy of P. Luke bases Acts 16-28 on P, but Luke also has a copy of Mark. When Luke writes Acts, Luke constructs the Acts 16-28 by using a mix of Paul's letters, P, and M and the writer of Acts didn't realize that M was derived from PL + P.
So in Acts you see overlaps between Acts and M, along with Acts and PL. It's difficult to determine Luke's use of P because P is also reflected in M. So when you see something that overlaps between Acts and M you can't really tell if that is because both M and Acts use P or if its because Acts just uses M. To make matters worse, there are cases where Acts simply follows M.
So, if we just indulge the theory, sometimes the writer of Acts is following P (let's assume that the "we passages" come from P). Sometimes Acts is following PL. And sometimes Acts is following M. But M also used P and PL so distinguishing between the use of M or P or PL is almost impossible because M used both P and PL. Determining when Acts if directly following P and PL or when its following M, and thus indirectly following P and PL is quite tricky. In the case of Acts, however, we do have the advantage of the "we passages" which just might be a good enough indicator to identify Luke's use of P directly, as opposed to Luke's use of PL or M. In the case of my particular theory, I identify the "we passages" with P, and everything that overlaps with Mark or Paul's letters that is written in third-person I identify as having come from Mark or PL.
Then I identify overlaps between Mark and P as Mark's use of P. But this is only possible on the assumption that the "we passages" come from P.
The point here is that multiple scholars are proposing much more complex models where sources are used and reused multiple times and then redacted in multiple layers by later redactors and then harmonized through scribes in such as a way as to make the puzzle almost infinitely complex.
So for example, if we have a model where we start with Mark (M) which uses PL (let's not even consider P at the moment), then proto-Evangelion (pE) is derived from Mark+PL, then Matthew(Mt) is based on Mark + pE, then E is derived from pE + PL, and Luke is derived from M+pE+E+Mt. At that point, where Luke (L) is using both Mt and pE and E all of those works have been derived from M. In addition, M uses Paul's letters, but pE and E also independently use Paul's letters. So when Luke is using E he's also using a derivation of M, while at the same time he also directly uses M.
Then to top it all off, the scribes who were copying Mt and L accidently harmonized a few areas due to the similarities, causing difficult to explain minor agreements.
Hopefully anything that I just said even makes sense :p
Everything I said here could be wrong, but the point remains that, the problem can be vastly more complicated than the 2 source vs single source hypotheses.
