Bechorot 46: In defense of Shmuel

The Mishna:

On the point of whether the live head of a nefel which was then retracted prior to the twin's birth effectively is poter (either "exempts" his brother, or consider: effects a peter rechem -- each has the same effect). The Mishna states that it would.

However, the language of the Tosefta strongly suggests otherwise: Tosefta perek 6:

That is, it just says שיצא but does not specify the head. Indeed only for the viable nine-month infant who died is the head mentioned. And then, we see rosho verubo mentioned in the general rule. This Tosefta would be like Shmuel, in the gemara, who is "refuted" by the Mishna.

I think that because of this, the Minchat Bikurim emends the text of the Tosefta, so that it would match the Mishna.

Here is the start of the Gemara:

However, I personally believe that it is difficult to refute Shmuel based on the Mishna, as the setama degemara eventually concludes. He is a first generation Amora, just like Rav (who sometimes is a Tanna who can effectively argue). He surely knows the text of the Mishna. He is arguing with it. And it turns out, there is a brayta that supports him!

If so, I don't think we need to reinterpret the Mishna as the gemara first attempts. If we do, I am somewhat convinced by the reinterpretation - that the focus in the reisha was on the aspect of bechor lanachala rather than on the peter rechem, and the author of the Mishna tried too hard to set up a minimal pair, of a contrasting case, because the main focus was the law in the seifa, where a live head would not only not be a bechor lanachala but even not for peter rechem. That some other distant Mishna states that novelty explicitly or implicitly does not mean, to me, that the gemara is right that the novelty is no longer necessary, and so the kvetch is unnecessary, which means we cannot reinterpret the Mishna. I don't accept the tanina, which I am not sure is even so regularly applied. Rather, it shows that the "novelty" is indeed something that is true, that holds in general. And so the Tanna's focus was similarly on this law, and in this focus ended up loosening the precision of the reisha. Indeed, I suspect that the Tosefta, and its language, is an earlier form of the gemara in reinterpreting the Mishna. (Thus for example the emphasis on rosho verubo.)

But even if we do say the Mishna is against Shmuel, we have a brayta that supports him. This is no refutation.