(1) Flash forwards
My suggestion that in Acts 9 Luke is anticipating the later Jerusalem visit of Acts 11 has been criticized in particular for its use of the term "flash forward". Ben Witherington points out that such a technique is unparalleled among Hellenistic historians -- it is a "modern notion". This is a good point, and it is why I qualified the term by saying "Luke is telling this as (what we would call) a flash forward" (emphasis added). Sometimes a contemporary analogy or current terminology helps one to see a point that otherwise one might miss, even though one thereby runs the risk of anachronism.
With respect to the content of the claim, though, I think Stephen Carlson's point (also in comments) is right, that Luke clearly writes this way, e.g. in 3.19-20, when John is arrested before Jesus' baptism (3.21-22). Perhaps one should avoid the term "flash forward", given its misleading contemporary resonance, and instead speak of dislocated sequence, noting that ancient writers regularly set traditions in their narratives out of their historical sequence in a kind of preferred narrative sequence. It is quite clear that Luke does this regularly on the assumption that he knows Mark's Gospel, drawing some traditions forward (e.g. Luke 4.16-30, Rejection at Nazareth) and taking others later (e.g. Luke 8.19-21, Mother and Brothers). On the whole, Lucan commentators tend to be fairly relaxed about that. No one serious thinks that the Mother and Brothers story happened twice, once in the Marcan setting and once in the Lucan one. But when it comes to the Acts narrative and Paul's movements, Luke is often allowed much less liberty, which I find odd, especially given that we actually possess Paul's own first hand accounts of parallel traditions.
This brings us to a broader, related point which is well expressed by Ben Smith (also in comments):
The events of Acts 9.26-30, the proposed flash forward, end with Saul being sent to Tarsus. The purportedly actual visit to Jerusalem in 11.27-30 is set up in 11.25 by Barnabas going to look for Saul in Tarsus. It looks to me as if Luke wants the reader to suppose that Saul has been in Tarsus from 9.30 to 11.25.These are all excellent points and they suggest to me still further that the term "flash forward" is potentially misleading and needs to be dropped (though I may be tempted to continue its use as an admittedly anachronistic contemporary analogy -- I'll just need to flag this up much more clearly). It is quite clear, as Ben points out, that 9.26-30 is not a kind of parenthesis but rather has its own logical part in the narrative sequence. While there is no direct cause (Paul just appears in Jerusalem, we know not why or when), there are direct effects (Paul is threatened with death and gets taken to Caesarea and then sent to Tarsus). Clearly, Luke embeds the story in his narrative sequence and does not narrate it as a self-contained unit unrelated to its immediate context. But I am reminded here of examples of the same thing elsewhere in the New Testament. Matthew, for example, tells the story of the beheading of John the Baptist as a kind of flashback in Matt. 14.3-12a ("Now Herod had arrested John . . . ., explaining 14.1-2) but then continues with the narrative as if this has just happened (14.12b-13, "Then they went and told Jesus. When Jesus heard what had happened . . ."). Luke is doing something similar in Acts 9.26-30.
Furthermore, if 9.26-30 is a nonchronological parenthesis, as it were, to what exactly is the ουν of 9.31 answering? If 9.26-30 is chronological, the answer is clear enough; the departure of Saul diminished the ill will from his opponents.
Finally, if Luke intends 9.26-30 and 11.27-30 to be the same visit, why does he send Saul and Barnabas into Jerusalem together in the latter but make it appear that Saul entered the city alone in the former, with Barnabas taking him in only after he encountered resistance from the disciples?
My thesis is that he knows that Paul's first visit to Jerusalem was in fact a couple of years after his conversion, and he shows us that he knows this, perhaps inadvertently, by dropping in "his disciples" in 9.25 and offering a particularly vague note of time in 9.26. The historical location of Paul's first visit is, we know from Gal. 1, after three years, just about where Luke puts it in 11.27-30. So I don't think it is a "mistake" that Luke puts the first visit in Acts 9. Rather it is a deliberately dislocated tradition, a piece of typical Lucan dramatic licence.
(2) Public and Private
In comments, Ben Witherington writes:
Secondly, there are far more correspondences between Acts 11 and Gal. 2 than you allow, not the least of which is that Gal. 2 is not describing in any way a public meeting, and Acts 15 is. None of the speaking parties in Acts 15 could be described as 'those who slipped in to spy out our freedom', not even by Paul. And if Paul could actually have appealed to a judgment by James that circumcision was not to be imposed on Gentiles, then it is inexplicable why he does not mention it in Galatians.The issue about public (Acts 15) and private (Galatians 2.1-10) I discussed in the original post, to which I refer the reader, and underline the point made there that if one wishes to stress this apparent discrepancy between Gal. 2.1-10 and Acts 15, all one does is to throw exactly the same kind of discrepancy, this time between Gal. 1.18 (private) and Acts 9.26-30 (public), into sharp relief.
On whether any of the parties in Acts 15 "could be described as 'those who slipped in to spy out our freedom'", I'd guess that the party described by Luke in Acts 15.5 comes pretty close -- it is a group outside of the inner group of the pillars, Paul and Barnabas, regarded in each account as hard-line. Given the difference between authorship, perspective and date that one has here with Galatians and Acts, one could not really wish for more.
Ben's additional point is that "if Paul could actually have appealed to a judgment by James that circumcision was not to be imposed on Gentiles, then it is inexplicable why he does not mention it in Galatians." On the contrary, Paul spends most of Gal. 2.6-10 attempting to make clear that Peter, James and John did not add anything to the gospel he had been preaching to the Gentiles, thus that Paul had not been running in vain, and that his preaching to the uncircumcised (ἀκροβυστία, 2.7) was legitimate and agreed upon and should continue. Indeed, this is the whole point of Paul's anger in Gal 2.11-20, that Peter was acting hypocritically. Having previously agreed on the gospel to the uncircumcised (2.6-9), he was now compelling Gentiles to Judaize (ἰουδαΐζειν, 2.14. Incidentally, cf. Josephus's fascinating use of this verb in relation to the Roman Mitelius in B.J. 2.454, καὶ μέχρι περιτομῆς ἰουδαΐσειν).
(3) Defending the historicity of Acts
I commented that a "major motivation" in the alignment of Acts 11.27-30 with Galatians 2.1-10 is "to defend the historicity of Acts". Michael Pahl commented that this was not a major motive for him, which is fair enough. I am pretty sure that this is a pressing concern for others, though. Ben Witherington III says, for example, at the end of his discussion of the matter in The Acts of the Apostles: A Socio-Rhetorical Study (Grand Rapids: Eerdmans, 1997),
I must conclude that there are no views that are without problems, but the one which creates the most problems is the suggestion that Luke's account has little or no historical value and involves major distortion (94).Or similarly, "Luke has not deceived us about the meetings mentioned in Acts 11 and Acts 15 and their impact" (ibid., 97) and so on. But my general point is that the desire vigorously to defend the historicity of Acts is unecessary here when one pays attention to narrative techniques used by Luke, techniques that show that Luke is not at all times pursuing a wooden, historical-chronological sequence. Luke uses the same liberty in Acts that we can see him using in the Gospel in his use of Mark and Matthew. And as with Synoptic study, the key is often to look carefully at the interesting little narrative indicators here in Acts too.
4. By revelation
Michael Pahl, in agreement with Matthew Bates, also in comments to the original post, feels that Paul's going up to Jerusalem "according to revelation" (Gal. 2.2) makes sense as Paul's going up in response to Agabus's prophecy about famine (Acts 11.27-30). He notes that "apokalupsis can refer to a prophetic revelation mediated through a human prophet" and cites 1 Cor. 14.6, 26. Of course it is the case that in Paul's usage a given revelation is conveyed to or through a human being; it is the divine-human contact that makes it a revelation. But the point is about how Paul uses the term with respect to his own autobiography. We are lucky to have several examples of the way that Paul speaks about receiving revelation with respect to events in his life. When he speaks of the source of his gospel in Gal. 1.11-12, he specifically contrasts "a human source" with "a revelation of Jesus Christ". In 2 Cor. 12.1-10, he speaks of revelations that he has received, again with clear reference to his own communication with God, famously in the third heaven here. Again, it is clearly not with reference to a human prophet talking to him about his or her revelations. And likewise here in Gal. 2.2, it does not make good Pauline sense to see this as a reference to a prophet's word; he has gone up to Jerusalem "according to revelation", that is his own revelation received from God. His whole point is that God had communicated directly with him on this, and that that was his motivation. Gal. 1-2 is largely about Paul's independence from Jerusalem; it would be a weak point if in fact it was well known that Paul had gone up in response to a Jerusalem prophet's word. The evidence of Paul's usage in 1 Cor. 14.6, 26, to which Michael refers, confirms the point: in each case [a] revelation is given to a certain person, whether Paul (v. 6), or a member of the congregation (v. 26). From the perspective of the person doing the speaking, the message has come from God, by revelation.