1) THE ASSUMPTION THAT THE MISHNAH REFERS TO "MALKUS"
QUESTION: The Gemara rejects its earlier suggestion that the Mishnah refers to Isurim which are punishable with Malkus, because the Mishnah clearly states that, in the case of Tum'as Mikdash v'Kodashav, if there is a "Yedi'ah b'Techilah" and a Yedi'ah b'Sof," a Korban Oleh v'Yored is brought.
What was the Gemara's original reasoning when it suggested that the Mishnah refers to Malkus, if the wording of the Mishnah clearly contradicts that suggestion?
ANSWER: The RITVA explains that the Gemara originally thought that the list of "two which are four" refers to Malkus, while the next part of the Mishnah (beginning with the Yedi'os) teaches a new Halachah about the obligation to bring a Korban.
2) THE SOURCE FOR THE "YEDI'OS"
QUESTIONS: The verse repeats the word "v'Ne'elam" when it discusses Yedi'os ha'Tum'ah. The verse first says, "v'Ne'elam v'Hu Tamei" (Vayikra 5:2), and then it says again, "v'Ne'elam v'Hu Yada" (5:3). Rebbi Akiva and Rebbi disagree about the intention of the verse.
RASHI explains their disagreement as follows: Rebbi Akiva learns from the first word of "v'Ne'elam" that one is liable only for He'elem Tum'ah but not for He'elem Mikdash. He derives from the second phrase, "v'Ne'elam v'Hu Yada," that there was a Yedi'ah that preceded the Ha'alamah, because the phrase "v'Hu Yada" should be read before the second "v'Ne'elam" and after the first, which implies that he forgot after he first knew. The second Yedi'ah (when the person eventually discovers his mistake) does not need to be stated explicitly, because it is obvious that he brings a Korban only when he discovers his mistake; if he has not discovered his mistake, he obviously would not be bringing a Korban. Rebbi, on the other hand, learns from the first "v'Ne'elam" the law of He'elem Tum'ah, and from the second "v'Ne'elam" the law of He'elem Mikdash. Rebbi does not need an extra verse to teach that the person knew about his state of being Tamei and then forgot, because that is the simple meaning of the word "v'Ne'elam."
Rashi apparently means that the Torah does not need to mention the second Yedi'ah, because the person obviously is bringing a Korban only because he discovered that he sinned. Therefore, the words "v'Hu Yada," referring to the second Yedi'ah, are superfluous. This is the source for the Derashah of Rebbi Akiva, who maintains that the phrase "v'Hu Yada" should be placed between the two phrases of "v'Ne'elam."
However, there are a number of difficulties with Rashi's interpretation, as TOSFOS (DH v'Ne'elam) asks.
(a) Why does Rebbi Akiva teach that because it says "v'Ne'elam" twice, there must be a Yedi'ah before the Ha'alamah? The Derashah is not from the second "v'Ne'elam" but from the words, "v'Hu Yada," as Rashi writes that the words "v'Hu Yada" are placed between the words of "v'Ne'elam."
(b) Why indeed does the verse say "v'Ne'elam" a second time, according to Rebbi Akiva, if the first Yedi'ah is already derived from the words "v'Hu Yada"? Perhaps Rashi means that the second "v'Ne'elam" is needed to teach that one is liable only for He'elem Tum'ah and not for He'elem Mikdash. However, this explanation seems illogical, because Rebbi uses the repetition of "v'Ne'elam" to reach the opposite conclusion -- that one is liable for He'elem Mikdash! Indeed, Rebbi's logic is clear: without a second verse, there would be no reason to assume that one is liable for He'elem Mikdash. Why, then, does Rebbi Akiva require a second verse (of "v'Ne'elam") to teach that one is not liable for He'elem Mikdash?
(c) According to Rebbi, who derives the first Yedi'ah from the word "v'Ne'elam," why does the verse need to say "v'Hu Yada" to teach that there was a second Yedi'ah? As Rashi writes in his explanation of Rebbi Akiva's view, the second Yedi'ah is obvious and there is no need to learn it from a verse!
ANSWERS: The RITVA and the MAHARSHA explain that Rashi does not mean that Rebbi Akiva derives the first Ha'alamah from the words "v'Hu Yada." Rather, Rashi means that Rebbi Akiva derives the first Yedi'ah from the repetition of the word "v'Ne'elam" (this indeed is explicit in the text of Rashi according to our Girsa, in DH v'Ne'elam). However, the Rishonim apparently did not have the words "v'Idach Kera Yeseirah Hu l'Derashah" in their texts of Rashi, as is evident from the way the TOSFOS HA'ROSH cites the words of Rashi.)
Although the Torah does not need to mention the second Yedi'ah, it is the manner of the verse to mention that the sinner discovered his sin, as Tosfos writes (DH v'Ne'elam). Therefore, those words ("v'Hu Yada") are not considered superfluous.
This explanation answer all of the questions.
(a) Rebbi Akiva mentions the repetition of "v'Ne'elam" because that is the source for his Derashah.
(b) The second "v'Ne'elam" is not extra, because it is that word that teaches the first Yedi'ah.
(c) Rebbi does not need to explain the words "v'Hu Yada," since it is the manner of the verse to mention one's discovery of his sin even if it is self-evident.
One may ask why, according to this approach, does Rashi write that according to Rebbi Akiva, "v'Hu Yada" should be placed between the two words of "v'Ne'elam"? Rashi should say simply that the second "v'Ne'elam" teaches that there must have been another Yedi'ah!
The answer to this question lies in Rashi's text of the Beraisa, a Girsa which is cited by the RAMBAN and other Rishonim. According to Rashi's Girsa, Rebbi Akiva's words were "v'Ne'elam Mimenu v'Hu Yada v'Ne'elam" (without the words "Shtei Pe'amim"). Rebbi Akiva himself reversed the order of the verse, placing "v'Hu Yada" before the second "v'Ne'elam," to show that there was a first Yedi'ah before the Ha'alamah.