הַמּוֹצִיא אֳכָלִין פָּחוֹת מִכַּשִּׁעוּר בִּכְלִי, פָּטוּר אַף עַל הַכְּלִי, שֶׁהַכְּלִי טְפֵלָה לוֹ. אֶת הַחַי בַּמִּטָּה, פָּטוּר אַף עַל הַמִּטָּה, שֶׁהַמִּטָּה טְפֵלָה לוֹ. אֶת הַמֵּת בַּמִּטָּה, חַיָּב.
[If] one carries out foods [that are] less than the [prescribed] quantity in a vessel, he is exempt even for [carrying] the vessel since that [the vessel] is an accessory to it [the food]. [If one carries out] a living person on a bed he is exempt even for [carrying] the bed since that is an accessory to him [the person]. [If one carries out] a corpse on a bed he is liable.
Background info: If one carries two things, one being the "main" thing and the other an "accessory" his liability is according to the "main" thing. Thus if he is not liable for the food (because it is less than the prescribed quantity) then he is also not liable for the vessel.
This anonymous Mishnah clearly hold that carrying a live person out from one domain to another (or four amot in the public domain) is not considered a biblical violation of Shabbat (אב מלאכה). In contrast, carrying out a dead body is. Note that in neither case is he liable for carrying the bed because the bed is an "accessory" to the body.
Question for further thought: Why would carrying a live person be different from carrying a dead body? Note there are probably multiple answers to this question.
(יז) המוציא [מין] בהמה [מין] חיה [מין עופות] בין חיים ובין מתים ה"ז חייב ר' נתן אומר מתים חייב חיים פטור.
(17) 17 One who takes out [to the public domain] a domesticated animal, a wild animal or fowl, whether live or dead is liable. R. Natan says: For dead ones he is liable, for live ones he is exempt.
According to the Tanna Kamma, one is liable for carrying live or dead animals. And according to R. Natan, one is liable for carrying dead animals but not live ones.
What is unclear in this Tosefta is whether the tanna kamma holds that there is a difference between animals and a human being. Might the tanna kamma hold that one is exempt for carrying live human beings? In other words, does the Mishnah, according to which a person is liable for carrying a dead human but not liable for carrying a live one, accord only with R. Natan or with the first opinion as well.
Questions for further thought: Why would there be a difference between carrying live animals and live human beings?
את החי במיטה פטור אף על המיטה. דחייא טעין גרמיה. את המת במיטה חייב.
One who carries out at] a live body on a bier is exempt even over the bier. For the living carry themselves
This is the first time we read of the concept that "the living carry themselves." Here the phrase is in Aramaic, whereas in the Bavli it is in Hebrew.
Question for further thought: Taking only the Yerushalmi into account, how would we understand the Tosefta? Particularly, is there a difference between human beings and animals? Does the creation of a "general principle" effect the understanding of the earlier, particular sources?
(1) את החי במטה פטור אף על המטה: לימא מתני' רבי נתן היא ולא רבנן
דתניא המוציא בהמה חיה ועוף לרה"ר בין חיין ובין שחוטין חייב
רבי נתן אומר על שחוטין חייב ועל חיין פטור שהחי נושא את עצמו.
(2) אמר רבא אפילו תימא רבנן ע"כ לא פליגי רבנן עליה דרבי נתן אלא בבהמה חיה ועוף דמשרבטי נפשייהו אבל אדם חי דנושא את עצמו אפילו רבנן מודו
(3) א"ל רב אדא בר אהבה לרבא והא דתנן בן בתירא מתיר בסוס ותניא בן בתירא מתיר בסוס מפני שהוא עושה בו מלאכה שאין חייבין עליו חטאת
ואמר רבי יוחנן בן בתירא ורבי נתן אמרו דבר אחד
ואי אמרת דלא פליגי רבנן עליה דר' נתן אלא בבהמה חיה ועוף משום דמשרבטי נפשייהו מאי איריא בן בתירא ורבי נתן והאמרת אפילו רבנן מודו
כי א"ר יוחנן בסוס המיוחד לעופות
ומי איכא סוס המיוחד לעופות אין איכא דבי וייאדן
(4) א"ר יוחנן ומודה ר' נתן בכפות
א"ל רב אדא בר מתנה לאביי והא הני פרסאי דכמאן דכפיתי דמו וא"ר יוחנן בן בתירא ור' נתן אמרו דבר אחד
התם רמות רוחא הוא דנקיט להו דההוא פרדשכא דרתח מלכא עילויה ורהיט תלתא פרסי בכרעיה:
(1) We learned in the mishna: One who carries out a living person on a bed is exempt even for carrying out the bed. The Gemara suggests: Let us say that the mishna is in accordance with Rabbi Natan and not with the Rabbis, as it was taught: One who carries out a domesticated animal, an undomesticated animal, and fowl into the public domain on Shabbat is liable whether they are alive or whether they are slaughtered. Rabbi Natan says: For slaughtered animals, he is liable, and for live animals, he is exempt, because a living being carries itself. (2) Rava said: You can even say that it is in accordance with the opinion of the Rabbis. The Rabbis disagree with Rabbi Natan only as far as the case of a domesticated animal, an undomesticated animal, and fowl because they stiffen themselves. However, with regard to a live person carries himself, even the Rabbis agree. Therefore, one who carries a live person out is exempt.
(3) Rav Adda bar Ahava said to Rava: And with regard to that which we learned but ben Beteira permits selling a horse to a gentile [even though it will carry a person on Shabbat]. And it was taught Ben Beteira permits selling a horse for riding because the horse is performing an act for which one is not liable to bring a sin-offering, as riding a horse is not actually a prohibited labor. And Rabbi Yoḥanan said: Ben Beteira and Rabbi Natan said one, the same, thing. They both hold that an animal with a rider on its back is not considered to be bearing a burden.
And if you say that the Rabbis only argue with Rabbi Natan with regard to a domesticated animal, an undomesticated animal, and fowl because they stiffen themselves, why did Rabbi Yoḥanan say specifically that ben Beteira and Rabbi Natan agree? Didn’t you say that in the case of a person riding a horse even the Rabbis agree? The Gemara answers: When Rabbi Yoḥanan said that ben Beteira and Rabbi Natan said the same thing, he was referring to a horse designated specifically for carrying fowl. The Gemara asks: And is there a horse designated for carrying fowl? The Gemara answers: Yes, there is the horse for carrying a hunter’s falcons [devei vayadan].
(4) Rabbi Yoḥanan said: And Rabbi Natan agrees in the case of a person who is bound.
Rav Adda bar Mattana said to Abaye: And what of those Persians who are considered as if they were bound and nevertheless Rabbi Yoḥanan said: Ben Beteira and Rabbi Natan said one thing and permitted selling horses even to Persians?
The Gemara answers: There, It is arrogance that keeps them from dismounting their horses. As proof, the Gemara relates: There was that Persian officer [pardashka] at whom the king was angry, and he ran three parasangs on foot.
Section one: This is basically the question that we have been asking about the relationship between the Mishnah and the Tosefta. Does the Mishnah accord only with R. Natan?
Section two: Rava offers a distinction between animals and people. When one holds a person they will naturally try to make themselves lighter. Animals do not. Therefore the Mishnah which talks about people, can accord even with the rabbis.
Question: Does this make sense? What motivates Rava to say this? Is it simply an attempt to say that the Mishnah agrees even with the rabbis from the Tosefta?
Section three: This section quotes a mishnah from Masechet Avodah Zarah (1:6). The issue in that mishnah is selling animals to non-Jews, and the problem is that the non-Jew will work the animal on Shabbat. Ben Batera allows one to sell a horse to a non-Jew because the horse does not perform forbidden labor. The horse carries a rider, and since humans "carry themselves" one is not liable for such an act, and therefore the animal can be sold to a non-Jew.
In that context, R. Yohanan identified Ben Betera with R. Natan who holds that one is exempt from carrying live human beings. R. Yohanan did not identify Ben Batera with the rabbis from the Tosefta who disagree with R. Natan. Assumedly, he thinks that these rabbis hold that just as one is liable for carrying a live animal, so too one is liable for carrying a live human being. This contradicts Rava's statement who said that all agree that one is not liable for carrying a live human being.
Question: How does R. Yohanan relate differently to the Mishnah/Tosefta than does Rava?
Question: How does the answer "a horse designated for fowl" solve the problem?
Section four: Here we have yet another statement of R. Yohanan: R. Natan agrees that if the person is bound one is liable for carrying him on Shabbat. R. Ada b. Matana tries to draw a contradiction between this statement and the other statement of R. Yohanan--if R. Natan thinks horses never perform work then he would have to allow the sale of horses to Persians even though Persians wear so much armor when they ride that it is as if they are bound.
Question: How does this statement of R. Yohanan reflect on his overall thinking about whether the "living carry themselves?"
What is the halakhah that would emerge from this sugya?
אִשָּׁה מְדַדָּה אֶת בְּנָהּ. אָמַר רַבִּי יְהוּדָה, אֵימָתַי, בִּזְמַן שֶׁהוּא נוֹטֵל אַחַת וּמֵנִיחַ אַחַת, אֲבָל אִם הָיָה גוֹרֵר, אָסוּר:
A woman may pull her child along. Rabbi Yehudah says: When [may she do that]? When he [the child] lifts up one [foot] and sets [the other] one down; but if he trails [his feet] it is prohibited.
How does this mishnah relate to the other mishnah we learned above?
גמ׳(1) אמר רבא הוציא תינוק חי וכיס תלוי בצוארו חייב משום כיס
תינוק מת וכיס תלוי לו בצוארו פטור.
(2) תינוק חי וכיס תלוי לו בצוארו חייב משום כיס:
וליחייב נמי משום תינוק!
רבא כרבי נתן סבירא ליה דאמר חי נושא את עצמו
ליבטל כיס לגבי תינוק מי לא תנן את החי במטה פטור אף על המטה שהמטה טפילה לו
מטה לגבי חי מבטלי ליה כיס לגבי תינוק לא מבטלי ליה
(3) תינוק מת וכיס תלוי לו בצוארו פטור וליחייב משום תינוק רבא כר"ש ס"ל דאמר כל מלאכה שא"צ לגופה פטור עליה
(4) תנן נוטל אדם את בנו והאבן בידו
אמרי דבי רבי ינאי בתינוק שיש לו גיעגועין על אביו.
GEMARA: (1) Rava said: If one carried out a living baby to the public domain on Shabbat, and the baby had a purse that was hanging around his neck, he is liable for carrying out the purse. However, one who carried out a dead baby, with a purse hanging around his neck, is exempt. (2) If one carried out a living baby to the public domain on Shabbat, and a purse was hanging around the baby’s neck, he is liable for carrying out the purse. The Gemara asks: And let him be liable for carrying out the baby as well. The Gemara responds: Rava holds in accordance with the opinion of Rabbi Natan, who said: A living being carries itself. Therefore, one who carries a living being from one domain to another is not liable.
The Gemara asks: And let the purse be negated relative to the baby;and he should be exempt for carrying out the purse as well. Didn’t we learn in a mishna: One who carries out a living person on a bed is exempt even forcarrying out the bed, because the bed is secondary to the person? The same should be said with regard to the purse, relative to the baby.
The Gemara answers: In a case where a bed is relative to a living being, the living being negates it, as the bed is needed to carry the person and is secondary to him. However, in a case where a purse is relative to a baby, the baby does not negate it, since it is independently significant.
(3) And Rava said: One who carried out a dead baby with a purse hanging around the baby’s neck is exempt. The Gemara asks: And let him be liable for carrying out the baby. The Gemara answers: Rava holds in accordance with the opinion of Rabbi Shimon, who said: With regard to any labor that is not needed for its own sake, one is exempt for performing it on Shabbat. One who carries out a corpse does not do so because he needs it; rather, he does so for the sake of the corpse, i.e., to bury it or to move it from a degrading place. Therefore, he has not performed a labor prohibited by Torah law. Similarly, he is also exempt for carrying out the purse because due to his distress and mourning he negates the purse, as it is insignificant relative to the baby.
(4) We learned in the mishna: A person may take his son in his hands on Shabbat; even if there is a stone in the child’s hand. As it can be inferred from this mishna that the stone is negated relative to the child, why, then, is he liable in the case of a purse hanging around a live baby’s neck? Let the purse be negated relative to the baby. The Sages of the school of Rabbi Yannai say: The mishna is referring to a baby who has longings for his father. It is permitted for the father to move the stone because if the father does not lift him, the baby might take ill.
Section one contains Rava's statement. Sections two and three explain the statement.
If he carries out a live baby he is liable for the purse. The purse is not ancillary to the baby. He is not liable for the baby because he holds like R. Natan, who says that one is not liable for carrying a living being. What is crucial to note is that the Talmud here thinks that Rava holds that only R. Natan exempts one from carrying a live human.
Section three is really not crucial to the issue at hand. The Talmud explains that Rava holds that one is always exempt for performing labor not needed for its own sake. [Note that the Talmud does not really explain why he is exempt for carrying the purse.]
Section four raises a difficulty from Mishnah Shabbat 21:1. The difficulty is supposedly on the stone--the stone is ancillary to the child. So then why was he liable for carrying the purse in the case of the live child and the purse.
The answer seems to be brought from a statement of the House of Yannai.
However, this answer does not fit the question particularly well. Think about what the "House of Yannai" might really be saying. They say that the Mishnah relates only to a case where the child desperately needs to be picked up by his father. The Talmud takes this to mean that in such a case one is not liable for the stone. Does this make sense? Might the House of Yannai actually be saying that one is allowed to pick up a child only if the child is desperate? This might be in line with the rabbis in the Mishnah, assuming that contra Rava (94a) the rabbis do not generally allow one to carry another human being. But in the context of our sugya, this statement is used to resolve Rava and not to contradict him.
To summarize the rules up until now:
The rabbis and R. Natan disagree concerning carrying a live animal. R. Natan says that one is exempt, whereas the rabbis say that one is liable.
Rava on 94a posits that the rabbis agree with R. Natan when it comes to a human being--the living carry themselves.
Mishnah Shabbat 18:2 implies that one may not carry a small child.
The Talmud on 141b holds that according to Rava only R. Natan allows one to carry a human being.
There are no sugyot that make any overt distinction between human beings. Either one is never liable for carrying a human being (R. Natan, and also the rabbis according to Rava on 94a) or one is liable (the rabbis according to 141b).
שהחי נושא את עצמו - תימה לר"י למה פטור דאי משום שהחי מיקל עצמו והלא אפילו במשא קל יותר חייב?
ואי משום דשנים שעשאו פטורין הא הוי זה יכול וזה אינו יכול שאין הנישא יכול לישא עצמו בלא הנושא והנושא יש בו כח לנושאו אפילו היה מת
ואומר ר"י דממשכן גמרינן שלא היו נושאין דבר חי שהתחשים והאילים היו הולכים ברגליהם והחלזון מיד היו פוצעין אותו טרם ימות דכמה דאית ביה נשמה טפי ניחא ליה כי היכי דליצליל ציבעיה:
For the living carry themselves: The Ri finds this surprising. Why should he be exempt? For if it is because a living being makes itself easier to carry, isn't one liable for carrying even something lighter.
And if it is because if two people jointly perform a forbidden labor, this is a case where one person could do the labor by himself and the other could not, for the carried person cannot carry himself without the carrier, and the carrier could carry him even if he was dead.
The Ri says that we learn this from the Mishkan, where they would not carry anything live, for the techashim and the rams would go by foot. And the snail they would smush before he died for as long as it is alive it is easier for his dye to flow.
Note how the Ri (R. Yitzchak, one of the great Tosasfists, 12th century France) is immediately perplexed by the entire notion that the "living carry themselves." Empirically this is simply not true. People are heavy--even children!
What is the nature of the answer to which he resorts? Do you think this could be the original "pshat" of the concept? Note how this answer reveals two different sides to the laws of Shabbat. The first idea is that one cannot "work" on Shabbat. The second idea is that one cannot do any of the acts that were performed in the Tabernacle.
What bearing would this explanation have on halakhah lema'aseh? How does it accord with other sugyot in the Talmud?
תוספות מסכת שבת דף צד עמוד א
אבל אדם חי נושא את עצמו -
תימה דבריש נוטל (לקמן דף קמא:) משמע דפליגי נמי באדם דקאמר גבי תינוק רבא כרבי נתן סבירא ליה.
ואומר רשב"א דקטן כבהמה דמי דמשרביט נפשיה.
אך קשה לן דבפרק מפנין (שם דף קכח:) תניא מדדין בהמה חיה ועוף בחצר אבל לא ברה"ר והאשה מדדה את בנה ברה"ר ופירש התם בקונטרס דבהמה ברה"ר לא שמא יגביהנה מן הארץ וסתמא כרבנן דר' נתן דמחייבי אבל בנה אי נמי מגבה ליה הא באדם מודו רבנן דחי נושא את עצמו [ושמא ההוא דבפרק נוטל איירי בתינוק בן יומו].
Tosafot Shabbat 94a
(1) But a live human carries himself--
This is perplexing for on Shabbat 141b it seems that they disagree also about a person, for it says with regard to a child that Rava holds like R. Natan.
(2) And the Rashba says that a child is like an animal for it makes itself heavy.
(3) But this is still difficult for on Shabbat 128b it teaches that one may pull along an animal in a courtyard but not in the public domain. And a woman may pull her child along even in the public domain.
And Rashi explained there that an animal may not be pulled along in the public domain lest one lift it off the ground. And the anonymous voice agrees with the rabbis who make one liable [for carrying an animal] and they disagree with R. Natan. But when it comes to her child even if she lifts him up, when it comes to a person the rabbis agree that the living carry themselves.
(4) [Perhaps that case on 141b refers to a newborn child].
Section one points out a contradiction between the two sugyot. On 94a Rava states that even the rabbis agree with R. Natan that one is not liable for carrying a human being.
But on 141b the Talmud says that Rava hold like R. Natan, and not like the other rabbis.
Section two: The Rashba (a Tosafist, not the Spanish rishon) solves the problem by distinguishing between an adult (94a) and a child (141b). The child does not make it easier for himself to be carried. Therefore the sages would say that it is prohibited to carry a child. But R. Natan would still say that it is permitted to carry a child.
But all opinions hold that it is permitted to carry an adult human being.
Section three: The Tosafot then go on to note that this still does not accord with the sugya on 128b (which explains the Mishnah Shabbat 18:2). There it seems like the rabbis agree that one who lifts a child is not liable.
Therefore they solve this by claiming that that sugya refers to a very young child, one who is a day old.
Note how this Tosafot has used the impulse to solve contradictions in the Talmud by creating new halakhot. For the first time we hear explicitly that there is a difference between a very young child and a child who can walk a little bit. One is exempt if one carries the latter, but liable if one carries the former.
(טז) הַמּוֹצִיא בְּהֵמָה חַיָּה וְעוֹף אַף עַל פִּי שֶׁהֵן חַיִּים חַיָּב. אֲבָל אָדָם חַי אֵינוֹ מַשּׂאוֹי. וְאִם הָיָה כָּפוּת אוֹ חוֹלֶה הַמּוֹצִיא אוֹתוֹ חַיָּב. וְהָאִשָּׁה מְדַדָּה אֶת בְּנָהּ בִּזְמַן שֶׁנּוֹטֵל אַחַת וּמַנִּיחַ אַחַת:
One who takes a beast, wild animal or bird [out] even though they are alive, he is liable. But a live human being is not considered carrying. But if he was tied up or sick, one who takes him out is liable.
And a woman can drag her son along as long as he picks up one foot and leaves one on the ground.
What are the Rambam's sources for his halakhah? See if you can go through all of the sugyot and pinpoint each of his sources.
גמרא: רבא כרבי נתן סבירא ליה דאמר חי נושא את עצמו. איכא למידק דהא רבא גופיה דאמר לעיל פרק המצניע (צד, א) דבאדם אפילו רבנן מודו ליה לרבי נתן, ולא נחלקו אלא בבהמה חיה ועוף. ויש לומר דהכא בתינוק קטן דכיון דמשרביט נפשיה דינו כבהמה.
ואכתי איכא למידק מדאמרינן בפרק מפנין (קכח, ב) האשה מדדה את בנה ברשות הרבים, ולא גזרינן דלמא אתי לטלטוליה משום דאדם נושא את עצמו, ולא פליגי רבנן עליה וכדפירש רש"י התם, דאלמא אפילו בקטן מודו רבנן.
ויש לומר דהתם בתינוק הנוטל רגלו אחת ומניח אחרת דכיון דמכיר בהלוך לא משרביט נפשיה, אבל בגורר שאינו מגביה רגלו כלל משרביט נפשיה כבהמה ופלוגתא היא דר' נתן ורבנן,
ומיהו בגורר אפילו ר' נתן מודה דלכתחלה אסור דומיא דבהמה, דלא פליג אלא בחיוב חטאת,
ומיהו בקטן גמור שאינו מכיר בהלוך כלל וכלל כגון קטן בן שמונה או בן חודש וכיוצא בזה, אפשר דאפילו רבי נתן מודה דחייבין עליו חטאת, משום דאין לך כפות גדול מזה ומודה רבי נתן בכפות כדאמרינן לעיל בפרק המצניע (לעיל צד, א).
Gemara: Rava holds like R. Natan, who said that the living carry themselves.
We could raise a difficulty for Rava himself said above on 94a that when it comes to a person even the rabbis agree with R. Natan, and that they disagree only concerning animals.
We could resolve this by saying that this sugya refers only to a child who, since he makes himself heavy, is treated like an animal.
But we could still raise another difficulty, that since we say on 128b that a woman can drag her son in the public domain, and we do not prohibit this lest she come to carry him because a live person carries themselves, and the rabbis do not disagree over this, as Rashi explained there, thus even when it comes to a minor, the rabbis agree.
We can answer this by saying that that case refers to a child who lifts one leg and leaves the other down, that since he knows a little how to walk, he does not make himself so heavy, but a dragged child who does not lift his legs at all would make himself heavy like an animal, and this would be the dispute between R. Natan and the sages.
However, when it comes to dragging (a young child) even R. Natan would agree that ab initio this is prohibited as it is with an animal, for he disagrees only concerning the obligation to bring a sin offering.
However, when it comes to a very young child who cannot walk at all such as an eight day child or a one month child or something like that, it is possible that even R. Natan would agree that one who carries such a child is liable for a sin offering, for there is no one "tied" more than that, and R. Natan agrees that it is prohibited to carry one who is tied, as we said above (94a).
This is similar to the Tosafot, but is more worked out.
Try to trace out the different halakhot and why the Rashba comes up with each of them. What problems is he trying to solve?
חידושי הריטב"א שבת דף קמא עמוד ב
ופרקינן רבא כרבי נתן סבירא ליה דאמר חי נושא את עצמו. הקשו בתוספות והאמר רבא בפרק המצניע (לעיל צ"ד א') דמודים חכמים לרבי נתן באדם דאמרינן חי נושא את עצמו ואם כן אמאי תלינן ברבי נתן, וכי תימא דהכא גבי קטן כבהמה דמי דמש[ר]בט נפשיה, והא בפרק מפנין (לעיל קכ"ח ב') אמרינן [האשה] מדדה את בנה ברשות הרבים ולא גזרינן דילמא אתי לטלטוליה משום דכי מטלטל ליה ליכא איסורא דאוריתא דחי נושא את עצמו, ולא פליגי רבנן עליה, וכדפרש"י ז"ל (שם ד"ה דמקפיא עיין שם) דהתם למאן דאמר דקטן מודו רבנן.
ויש מתרצין דשאני התם [דמיירי] בתינוק שיודע ליטול רגלו אחד וכיון שמכיר בהילוך לא משרביט נפשיה, אבל הכא מיירי בקטן שאינו יודע לדדות אלא שהוא נגרר ואינו מגביה רגליו דדמי לבהמה דפליגי רבי נתן ורבנן, ושלשה דרכים בקטן, דכל דמדדה מודו רבנן לרבי נתן, וכל שאינו מדדה ואף על פי שמכיר כלום בהילוך לענין שיהיה נגרר פלוגתא דרבי נתן ורבנן, ואם הוא קטן גמור כגון בן חדש וכיוצא בו שאינו מכיר כלום בהילוך אפילו רבי נתן מודה דהוה ליה כחולה וכפות, ומודה רבי נתן בכפות כדאיתא בפרק המצניע, זו שיטת קצת בעלי התוספות ז"ל.
אבל הנכון דהא [ד]אוקימנא הכא כרבי נתן לאו לאפוקי מדרבנן, דהא לרבא מודו רבנן באדם, אלא דההיא סברא דרבא הוא דפרישנן הכא ואנן לא שמעינן לה בפירוש אלא לרבי נתן ומשום הכי תלינן לה ברבי נתן, וכן היה מפרש מורי רבינו ז"ל, ואח"כ מצאתי כך בחבור ה"ר ישעיה ז"ל וגם במקצת תוספות.
R. Yom Tov Ishbilli (Ritba) Shabbat 141b
We resolve the difficulty: Rava holds like R. Natan who said that the living carry themselves.
The Tosafot raised a difficulty: But did Rava not say on 94a that the sages agree with R. Natan who says that the living carry themselves. And if so, why does the gemara here attribute this to R. Natan?
And if you were to say, that here where it refers to a minor, he is like an animal who makes himself difficult to carry, behold on 128b we say that a woman can drag her son in the public domain and we are not strict less she come to carry him, for even if she were to carry him, this is not a biblical prohibition, for the living carry themselves, and the rabbis do not disagree with this, as Rashi explained according to the one who holds that the rabbis agree about a minor.
And there are those who say that that case (on 128b) is different because it refers to a child who knows how to lift one leg, and since he knows how to walk, he will not make himself heavy. But here we are dealing with a child that does not know how to shuffle along when he is being dragged, and who does not lift his leg, and he is like the animal that the rabbis and R. Natan disagree about.
And any child who does not shuffle along, even though he knows a little bit about walking, when he is being dragged, there is a dispute between the rabbis and R. Natan. And if he is a really young child, such as a month old who does not know how to walk at all, even R. Natan would agree that he is like a sick person or one tied up, and R. Natan agrees that [one may not carry] a tied up person, as we learn...And this is the resolution of some of the Tosafot.
But the correct resolution is that the reason why we say that he follows R. Natan is not to exclude the rabbis, for to Rava the rabbis agree [with R. Natan] when it comes to a person. Rather, this logic is Rava's that we are explaining, but we have only heard this from R. Natan and therefore we ascribe it to him. And this is what I learned from my teacher. And afterwards I found it in the words of R. Isaiah [De-Trani] and also in some of the Tosafot.
Only this last section differs from the Rashba and the Tosafot. Here he seems to say that there is no difference between human beings--Rava holds that the rabbis always agree with R. Natan. We (meaning those understanding Rava) have not heard that the rabbis agree with R. Natan.
There is a large consequence in halakhah lema'aseh between the Ritba and the Rashba. What is it?
(מא) הָאִשָּׁה מְדַדָּה אֶת בָּנָה, אֲפִלּוּ בִּרְשׁוּת הָרַבִּים, וּבִלְבַד שֶׁלֹּא תִּגְרְרֵהוּ אֶלָּא יְהֵא מַגְבִּיהַּ רַגְלוֹ אַחַת וְיַנִּיחַ הַשְּׁנִיָּה עַל הָאָרֶץ וְיִשָּׁעֵן עָלֶיהָ עַד שֶׁיַּחֲזֹר וְיַנִּיחַ רַגְלוֹ שֶׁהִגְבִּיהַּ, שֶׁנִּמְצָא לְעוֹלָם הוּא נִשְׁעָן עַל רַגְלוֹ הָאַחַת.
A woman can push her child along, even in the public domain, as long as she does not drag him but rather he picks up one foot while leaving the other on the ground and leaning on that foot until he goes back and puts down the foot that he already lifted, such that it turns out that he is always leaning on one foot.
משנה ברורה סימן שח ס"ק קנג
(קנג) אפילו בר"ה - דהא אפילו תגביהנו פטורה דחי נושא את עצמו ולית בזה אלא איסורא דרבנן והוי גזירה לגזירה ואם נושא כפות או חולה חייב דבזה לא שייך שנושא את עצמו.
Mishnah Berurah 308:153
Even in the public domain: For even if she lifts him she is exempt for the living carry themselves and this is only a rabbinic prohibition, and thus would be a "decree on a decree." But if she holds one tied up or sick she is liable for in such a case one does not say "the living carrying themselves."
There is an interesting piece on this in Minchat Shabbat, a commentary on the Kitzur Shulchan Aruch. Its a bit long and I can't comment on it. But here's a link to find it. You may have to cut and paste in order to get to Hebrewbooks.org.
http://hebrewbooks.org/pdfpager.aspx?req=8935&st=&pgnum=180&hilite=
http://hebrewbooks.org/pdfpager.aspx?req=8935&st=&pgnum=181&hilite=