It seems better to accept the suggestion that the
solution of the problem is to be found in the source-criticism of Acts.

The source-criticism of Acts has passed through three more or less
spasmodic stages.[7] The first was early in the nineteenth century
when a number of scholars endeavoured to analyse the book. Their
efforts were not very successful, though they unearthed a great many
interesting phenomena. Later on, in the 'nineties, another series of
efforts were made with, on the whole, even less success than before.
{64} Finally, in our own time there have been some interesting
suggestions by Harnack, Schwartz, and Torrey.[8]

The last named has shown extremely good reason for thinking that there
is an Aramaic source behind the first fifteen chapters of Acts.[9] He
is less convincing when he tries to prove that this was a single
document, and that it was faithfully translated without addition or
change by the editor of Acts. It seems more probable that there was
more than one Aramaic source, and that it was often changed and
interpolated by the editor.

Harnack skilfully tries to distinguish two main lines of tradition,
that of Antioch and that of Jerusalem. He also thinks the Jerusalem
tradition existed in two forms, which can be distinguished as doublets
in Acts i.-v. He attaches Acts xv. to the tradition of Antioch, but it
seems more probable that it belongs to the Jerusalem tradition. The
truth may be as follows: soon after the time when Barnabas had gone
over to the Hellenistic party another body of Christians from Jerusalem
came to Antioch. In the years which followed there grew up two
traditions of what happened next. The tradition at Antioch was that
{65} the Christians from Jerusalem had been chiefly concerned with the
physical necessities of their Church, though they were undoubtedly men
possessed of a prophetic gift. They had so worked on the sympathy of
Antioch that it had accepted the needs of the poor saints in Jerusalem
as a responsibility laid on it by heaven. This tradition is preserved
in a short form in Acts xi., and in the Epistle to the Galatians Paul
energetically sustained its correctness, incidentally mentioning some
other events connected with his stay at Jerusalem, the perversion of
which, as he maintained, had given rise to the tradition of Jerusalem.
This latter tradition the editor of Acts had found preserved in the
document which he has used as the basis of Acts xv.,