1. Acts precludes a visit by Paul to north Galatia. Some believe that Acts 16:6 refers to a trip to north Galatia, but this is not possible. We read
16:6 They went through the region of Phrygia and Galatia [or Phrygian Galatia], having been forbidden by the Holy Spirit to speak the word in Asia. 16:7 When they had come opposite Mysia, they attempted to go into Bithynia, but the Spirit of Jesus did not allow them; 16:8 so, passing by Mysia, they went down to Troas. 16:9 During the night Paul had a vision: there stood a man of Macedonia pleading with him and saying "Come over to Macedonia and help us." 16:10 When he had seen the vision, we immediately tried to cross over to Macedonia, being convinced that God had called us to proclaim the good news to them.In this passage Paul and his companions receive three pieces of divine guidance, the common purpose of which was to get the group to Macedonia as quickly as possible. I suggest that they became "convinced that God had called us to proclaim the good news" to Macedonia after reflecting on all three pieces of divine guidance.
This precludes a trip to north Galatia. If they went to north Galatia in 16:6 we would have to suppose that the divine guidance was fickle, sending them first to the north east, then to the west. Why would Luke record such ineffective guidance?
The map shows the route that they may have taken and illustrates that a diversion to north Galatia would not have been consistent with the divine plan that Luke records. The road system here is taken from Stephen Mitchell, Anatolia Land, Men, and gods in Asia Minor Vol i. He firmly supports the south Galatia hypothesis and suggests that
2. Chronology does not allow enough time for a preaching tour of north Galatia. Paul visited Jerusalem (Gal 2:1-10 = Acts 15) no earlier than A.D. 48 and arrived in Corinth no later than A.D. 50. In the interval of two year (or less) Paul returned to Antioch; stayed there 'some days' (Acts 15:36); revisited the churches in Syria, Cilicia, and south Galatia; travelled to Macedonia; founded churches there; and preached in Athens. This itinerary is already slightly more rushed than Paul's usual pace. Adding a preaching tour of north Galatia would put additional strain on the chronology here. Others have made this point.
3. Barnabas was known to the recipients of the letter, as Ramsay and others have pointed out. Barnabas is mentioned without introduction in Gal 2:1, suggesting that he was known to the recipients. Also, Gal 2:13 presupposes that the recipients knew Barnabas's previous position on the issue of Jews eating with Gentiles.
4. The circumcision of Timothy (Acts 16:1-3) looms large in the background of Paul's letter. The Galatians seem to have gained the impression that Paul actually supported circumcision (see Gal 5:11). Indeed, I have argued here, here, and here that Paul wrote in response to the rumor that he was ideologically in favor of circumcision but had preached against it to please the Jerusalem church leaders. The Galatians' misunderstanding of Paul's position is explicable if they were south Galatians. Paul's circumcision of Timothy could have led them to believe that he actually believed in circumcision, and the delivery of the decisions of the Jerusalem leaders (Acts 16:4) could have suggested to them that Paul had acted all along as a messenger of the Jerusalem church.
Furthermore, if Titus was Timothy, as I believe, then Gal 2:4-5 looks suspiciously like a reference to the discovery of Timothy's uncircumcised state and his subsequent circumcision.
5. Paul's illness would not have taken him to north Galatia. Gal 4:13 tells us that Paul preached to the Galatians because of a physical infirmity. Presumably the infirmity prevented him from supporting himself by working, or limited his ability to travel. It is possible that Paul had intended to travel to Asia and/or Europe, and that his infirmity forced him to scale back his ambitions and travel to south Galatia instead. A detour to north Galatia, on the other hand, would have constituted an extension to Paul's travels, not a cut-back, and it is hard to imagine how a sickness could have led him to decide to go there.
6. Timothy would have been named as a co-sender of a letter to north Galatia. Paul names as co-senders those who helped him found the church to whom he writes. Thus Timothy is a co-sender of 1 Thess, 2 Cor, and Phil; Crispus-Sosthenes is the co-sender of 1 Corinthians; and Silvanus is a co-sender of 1 Thess; while Romans has no co-senders. If Galatians was addressed to north Galatia it is somewhat surprising that Timothy, in particular, is not named as a co-sender.
I am surprised that the north Galatia hypothesis has lasted so long. Does it survive only as a reaction against certain conservative scholars who support the south Galatia hypothesis for all the wrong reasons? Or am I missing something here?