We continue from the point where we left off in the previous Mishnah. There we learned about a dispute regarding a case where a person committed a transgression and does not know which of two transgressions he committed, when both require a sin-offering. Due to the doubt, the Tannaim disagreed on whether he must bring a sin-offering at all.
The clarification of Rabbi Shimon Shezuri and Rabbi Shimon:
Rabbi Shimon Shezuri and Rabbi Shimon come to define the boundaries of the dispute and state: "Lo nechlaku al davar shehu mishum shem echad" - they did not disagree regarding something that is of a single category. In other words, we must distinguish between two types of doubt:
Doubt regarding a single category: We know which transgression was committed, and the doubt is only regarding the details of the act - whether he ate from this olive's volume of nossar or from another olive's volume of nossar. In such a case he is certainly liable to bring a sin-offering, as there is no doubt regarding the very obligation. (If it is not even known whether he ate at all, this is a case for a suspensive guilt-offering, but nevertheless he knows what act was done.)
Doubt regarding two categories: "Al mah nechlaku? Al davar shehu mishum shenei shemos" - on what did they disagree? On something that involves two categories. This is when we are faced with two separate categories of prohibition: whether he had relations with a menstruant woman or perhaps it was his sister, whether he desecrated Shabbos or Yom Kippur, whether he ate nossar or chelev.
Rabbi Eliezer obligates him to bring a sin-offering: Since it is clear that a transgression requiring a sin-offering was committed, even though it is not known from which category it is, he must bring a sin-offering.
And Rabbi Yehoshua exempts him: Based on the exegesis brought above - "asher chata bah" - that he must know which sin he committed. As long as the category of prohibition is unknown to him, there is no sin-offering here.
Rabbi Eliezer, on the other hand, held that the words "asher chata bah" come to exclude a misaseik (one acting unawares), and in fact they both agree that a misaseik is exempt from a sin-offering. From here onwards the Mishnah moves to discuss the definition of the law of misaseik.
The definition of a "misaseik":
The simple case: A person who reaches out his hand to take a book, and while doing so hits the light switch with his elbow. This is not considered shogeg (unintentional), since he did not intend to turn on the light at all. A shogeg is someone who turned on the light intentionally but did not know that the matter was forbidden; however, one who did not intend to perform the action at all is a misaseik.
The more stringent case: All melachos on Shabbos are derived from the definition of "meleches machsheves" - that he has a calculated plan and carries it out, akin to the work of the Holy One, blessed be He, in the act of Creation, as it were. Therefore, a person who planned to pick a specific fig and mistakenly picked another fig, his action does not match his thought, and this is just like reaching out his hand for a book and touching a switch. He too is considered a misaseik and is exempt from the sin-offering.
The dispute in our Mishnah:
The Mishnah discusses an intermediate case: A person who intends to pick both figs and grapes, except that he wanted to pick the figs first and the grapes afterwards, and in practice he picked the grapes first. Ultimately he intended to pick the grapes, except that in that momentary action he did not intend for them. Is this too called a misaseik?
"Amar Rabbi Yehudah: afilu niskavein lilkot te'einim velakat anavim, anavim velakat te'einim, shechoros velakat levanos, levanos velakat shechoros" - Rabbi Yehudah said, even if he intended to pick figs and he picked grapes, grapes and he picked figs, black ones and he picked white ones, white ones and he picked black ones; in all these cases he intended to pick both types, except that he did not do so in the order that he intended, so that his action at that very moment was not the realization of his intention at that time, even though his general intention was to pick everything.
Rabbi Eliezer obligates him to bring a sin-offering: This is not a misaseik, since from a broad perspective he intended to pick both of them, and therefore he brings a sin-offering for his unintentional act.
And Rabbi Yehoshua exempts him: Since at that very moment he did not intend for the fruit that was picked, his thought was not realized into action, and this is a misaseik who is completely exempt from the sin-offering.
Rabbi Yehudah's Wonder:
"Amar Rabbi Yehudah: Tameah ani im yiftor bah Rabbi Yehoshua" - I wonder if Rabbi Yehoshua would exempt a person whose only deficiency was in the sequence of actions alone, as he intended to harvest grapes and figs together, and indeed he harvested grapes and figs. Even though the sequence was not as he intended, this is not enough to exempt him, and he is liable to a chatas for his unwitting sin. (The Bartenura explains that this is not Rabbi Yehudah but Rabbi Shimon, and according to his version, the contradiction with the previous Mishnah is resolved.)
"Im ken, lamah ne'emar 'asher chata bah'?" - If, in his opinion, he is liable in this case, what does the verse come to exclude? To this, the Mishnah answers: "Prat lemitasek" - except for a mitasek. However, here the intention is to a mitasek in its simple sense - not someone who intended both melachos and merely changed their sequence, but someone who intended one action and mistakenly performed a different, forbidden melachah: he reached out his hand to grab an object and mistakenly plucked a fig from the tree. This is the mitasek for whom one is exempt, according to Rabbi Shimon.
In summary: In this Mishnah, it was first clarified that the dispute regarding a doubt in transgressions applies specifically to two categories of melachah, and not to a doubt within one category. From there we moved to the law of a mitasek, where everyone agrees he is exempt, and to the dispute between Rabbi Eliezer and Rabbi Yehoshua regarding someone who intended to pick figs and picked grapes: according to Rabbi Eliezer, the general intention makes him liable to a chatas, and according to Rabbi Yehoshua, the lack of intention at that specific moment makes him a mitasek and exempts him. Rabbi Yehudah wonders about this exemption, and according to his view, the exclusion of "asher chata bah" is directed only at a regular mitasek.