Hmmm. So since there is no substantive reference to Paul or things Pauline until Marcion and those references are hostile and mostly second hand what do you propose is our guide to the question of whether Paul KNEW OF a written gospel? You seem to be arguing for the 'shared assumptions' of church believers from the 5th century onward settles the question. I don't even know if Irenaeus's explicitly says that Paul didn't know 'according to Luke' or whether it was certainly written after Paul's death. Here is the reference in Irenaeus - "After their departure, Mark, the disciple and interpreter of Peter, did also hand down to us in writing what had been preached by Peter. Luke also, the companion of Paul, recorded in a book the Gospel preached by him." Certainly if 'departure' means death Irenaeus means to say that Mark wrote his gospel after that event. But it is well documented that some of the ancients assumed that Mark wrote his gospel in Alexandria (and not just Clement in to Theodore). There seems to have been ambiguity if one gospel was written along with Peter and another on his own authority and this - I believe - becomes the basis for the claim that Marcion wrote (or edited) a gospel against the gospel of the apostles while Paul's original written gospel (= according to Luke) agreed with their written gospel. But more on that later.I'm just pointing out how weak your position is. If you can give evidence that within 100 years of Paul's death SOMEONE said that Paul WROTE a gospel, then you might have something. Anything else IMO is a very weak case for his having written a gospel. It would help if the later ones referenced a chain of tradition that goes back to that 100 year period, but they don't even do that.
But are we to simply assume from that statement that he also means that Luke was written after the death of Paul? I am not so sure. Would Origen and Eusebius have argued that Paul knew 'according to Luke' on that basis alone. I remember Carlson showed a number of different ordering of the gospels where Luke actually was placed before Mark in some reckonings, and many of those were explicitly (or at least implicitly) arranged in chronological order (i.e. Luke written before Mark). Why does Tertullian accept that Paul knew of a gospel if the issue was plainly settled by Irenaeus? I am no sure that Irenaeus can be brought forward as a witness for the idea that Paul definitely did not have a written gospel. I will have to research that.
Irenaeus is post-Marcion and Papias doesn't mention Paul. How do any of these people 'reject' the idea that Paul had a written gospel at his disposal?At least in the case of Irenaeus, we have that, but we also have Papias. How does Papias support you Stephan? Or Barnabas, or Ignatius, or ANY of these earliest writers.
Since Marcion is the earliest Pauline tradition and the information about Marcion is second hand and hostile we have a bad time figuring anything out about Paul to the degree of certainty that you demand or expect. I don't understand what your fallback position is. Acts doesn't mention written correspondences nor does it reference the question of whether Paul had a written gospel. So how do we settle the question of whether Paul had at his disposal a written gospel?If PAUL had written a gospel don't you think we would have early testimony of that?
1. when Clement cites the gospel Paul had at his disposal it is a non-canonical reference albeit one that is paralleled in our existing gospels in a different form.Don't you think Paul would have referenced it in ANY of his epistles, especially since he took great pains to remind his 'flock' of the things he had taught them? As Earl likes to say "The silence is deafening", and as such I'm perplexed as to why want to rely so heavily on late attestations, some of which are not even about a written gospel by Paul.
2. when Origen and Eusebius say that Paul knew 'according to Luke' it fits within the framework Irenaeus sets up. Only now the production of Luke took place within Paul's lifetime. Why is this position so problematic for your understanding of the development of the gospel(s)? Why couldn't Paul have known 'according to Luke'? Why couldn't the gospel have been written while Paul was still alive? I find your objection to this proposition perplexing given the fact that we have two pre-Nicene attestations and more when Jerome and the neo-Origenists are factored in.
3. when Tertullian's source in Adv Marc objects to the Marcionite position that Paul wrote the first gospel he nevertheless reads Galatians in a Marcionite manner (i.e. that Paul's 'gospel' in the text = a written gospel and moreover that the Jerusalem Church had another written gospel). His point is that the two gospels agreed (undoubtedly in the same way that 'according to Luke' and 'according to Matthew' are said to 'agree' with one another). The strange part is that Tertullian's source later cites a saying that only appears in Matthew but this isn't as 'strange' as it seems given that Tertullian's source has a strange habit of citing Matthew against Marcion and similarly accuses Marcion of 'cutting' things from his gospel that don't appear now in Luke. William's solution to this difficulty is that Tertullian's 'according to Luke' had Matthean (and Markan) elements in it. I take it one step further and argue that Tertullian is actually using an anti-Marcionite text written by Justin or Rhodo or someone who used a Diatessaron (like Ephrem etc). Still the basic paradigm assumes an understanding compatible with Marcionitism insofar as a wall isn't put up around the common reading of Galatians and the shared assumption that there was a dispute over 'written gospels' in the apostolic era.
4. the Marcionites again assumed 'my gospel' = Paul's written gospel which had no name ascription (like according to Mark)