Who is R. Johanan in Baba Bathra 14b? Is this Johanan ben Zakkai or Johanan bar Napcha? And how would we know? There seem to be a mixture of tannaitic and amoraic sources in the gemara.
Many kind thanks, Peter J. Gentry
Hi and welcome to Mi Yodeya!
In this case it's Rabbi Yochanan bar Napacha, and the way to tell is simple: Rabbi Yochanan speaks here in the name of Rabbi Shimon bar Yochai, who lived a few generations after the time of Rabban Yochanan ben Zakkai. In general, though, Rabban Yochanan ben Zakkai is always referred by his name and his father's name, except for one time where he is only called "ben Zakkai" (Mishna Sanhedrin 5:2). Rabbi Yochanan ben Napacha is usually only referred to by his first name and more rarely by his name and his occupation (bar Napacha = blacksmith).