My title pretty much sums up the story. He looks at the structure of these verses in light of the problem in Galatia. In light of what has been discussed lately with regard to James and the circumcision party I note this statement “Note also that the James Gang are recharacterized as ‘the circumcision,’ further confirming that the Jew/Gentile distinction is the crux of the matter.”
We finally come to ἀλλά in v. 14, which Levinsohn, Brannan and I understand to introduce something the [sic] corrects or replaces some proposition from the preceding context. The question is, what is it? From my view, the proposition that is corrected is v. 12, essentially hanging out with the Gentiles, then deciding it was wrong when distinguished guests arrived. One could argue that v. 13 should be included in the “proposition to be corrected,” but I view it as being an ancillary result of the core issue with Peter. Had he not withdrawn, there is a good chance the others (EVEN Barnabas!) would not have withdrawn either.
Brannan is Ric Brannan, also of Logos Bible Software, who has written extensively on the use of ἀλλά. Head on over for the rest of the post.