(a) Why does the Gemarah always go back and forth as to why Sumchus can not be the Tana of our Mishnah? One reason should be sufficient and there should be no reason to do this.
(b) Also, why when it is talking about Sumchus, does the Gemara interrupt and go to questioning the Rabanan, and whether they can or can not be the Tana?
Matthew Polienecki, Syracuse, USA
(a) The Gemara is trying to determine whether Sumchus is or is not the Tana of the Mishnah. Since the Gemara does not, at any point, come to a clear conclusion, it continues the discussion. It does not close the discussion and then open the discussion again.
(b) The purpose of the Gemara is to determine who is (and who is not) the Tana of our Mishnah. Once we reject the possibility that it is Sumchus, it must follow the opinion of the Rabbanan. However, the Gemara then has to ascertain that this is correct. As far as I can see, this discussion is within the topic under discussion in the Gemara.
All the best,
Yaakov Montrose