Eruvin 15-16 More on Eruv principles, dispute, and הלכה למשה מסיני

Our two daf contain pivotal sugyos regarding the laws of partitions and Eruvin.

One of them is a famous dispute between Abaya and Rava regarding a לחי העומד מאליו (a post that was already there prior to it being designated for use in closing off a מבוי.

The classic example is if a part of the one wall sticks out at a 90-degree angle to the wall, forming an effective post.

So long as he had in mind the day before that it should be used as a post for the Eruv, Abaya is of the view that it is acceptable.

On the other hand, Rava is of the view that seeing as it was not placed there specifically to serve as an Eruv pole, it is invalid.

After much back and forth, the Gemara brings a proof that Rav held like the lenient opinion of Abaya, which seems to be conclusive in allowing us to rule in his favor.

It is interesting that although we have a general rule that whenever Abaya and Rava disagree, we follow the ruling of Rava, the Gemara (Bava Metzia 22b ) gives an acronym יעל קגם for 6 cases where we follow Abaya, and Rashi identifies our case, לחי העומד מאליו as one of them.

We should note that at least in the case of our sugya, as well as the sugya quoted above, this is because the Gemara was able to find strong evidence in his favor.

We mentioned in our previous post that the Rambam (Mamrim 1/3) is of the view that things mentioned explicitly in the Torah or passed on orally to Moshe at Sinai are not subject to מחלוקת (debate,) and debates are only find regarding laws based on Chazal’s interpretations of the former through the rules of interpretation or rabbinical decrees and the like.

He also said (ibid 1/4) that even such debates were always settled eventually by the בית דין הגדול (great court or “Sanhedrin” of 71 ordained judges,) and once they were settled, there was no room for halachik debate.

In contrast, once the great court ceased to function, new debates remained essentially unsettled and each sage was free to follow and teach his own view to his students, who would typically follow their Rabbi- the default rule for undecided debates was to be stringent in biblical matters and lenient in rabbinical ones. (Mamrim 1/5)

In reality, this has not been the case, and in Amoraic Bavel where the much-weakened Sanhedrin back in Tiberius had little power, as well as after it ceased to function altogether, later Amoraim have come to conclusions regarding disputes which have thereafter also been regarded as binding.

There have even been rules of thumb formulated, such as following Rav over Shmuel, Rabbi Yochanan over Rav or Shmuel, and Rava over Abaya etc.

The Rambam himself (introduction to M.T.) explains the dictum of רבינא ורב אשי סוף הוראה (Bava Metzia 86a) as meaning that the later Amoraim, Ravina and Rav Ashi, who sealed the Talmud Bavli, essentially had the authority of בית דין הגדול for the last time in history, given that their rulings spread and were accepted by the Jewish people as a whole and all or most of its sages.

Although there is much to discuss and analyse here, it seems clear that a simple understanding of the earlier-quoted Rambam that makes authoritative dispute resolution entirely dependant on בית דין הגדול itself is not sufficient.

In another pivotal dispute, רב פפא, and רב הונא בריה דר’יהושע debate whether פרוץ כעומד (open area equivalent to closed area) is acceptable to consider a side as partitioned off or not.

The general rule is that when מחיצות (partitions) are used to close off a רשות היחיד, gaps of up to 10 אמות are permitted, and considered to be an acceptable פתח (opening) rather than a פירצה (gap)

However, there is an additional requirement recorded in the Mishna on 15b, that there may not be more open space than closed space (in the absence of a צורת הפתח in which case it is more complex.)

The Gemara on this Mishna opens with the above-mentioned debate regarding whether it is sufficient if the closed area is equal to the open area, or whether it needs to be MORE than the open area.

The Gemara seems to understand that the requirement that most of the partition not be open is a הלכה למשה מסיני (law given orally to Moshe at Sinai and passed on via tradition.)- (the precise term used here is “אגמריה רחמנא למשה” which seems pretty self-explanatory!)

It then understands the dispute to be a question of the nature of this הל”מ.

Was it a requirement not to allow most of the partition to be open, or was it a requirement requiring most of the partition to be closed?

Much debate follows onto daf 16 until in a major curveball, the halacha is resolved according to the lenient view, but this seems to be an explicit example of a dispute regarding something passed on explicitly to Moshe at Sinai, a counter-example to the Rambam’s hypothesis limiting such debate to matters involving the rules of interpretation or rabbinic decrees.

Once again, it seems that a simple explanation of the Rambam might not seem feasible and more analysis is required!

These posts are intended to raise issues and stimulate further research and discussion on contemporary topics related to the daf. They are not intended as psak halacha.

Eruvin 12-13 Tolerance, the origins of dispute, and “”אלו ואלו

In the Mishna on 12b, there is a 3-way dispute between Beis Shamai, Beis Hillel, and Rabbi Eliezer, regarding what is required to mark the open fourth side of a מבוי closed on the other 3 sides.

Whereas we have been working until now under the correct assumption that the lenient view requiring only one post on either side is authoritative, we see that though this is the view of Beis Hillel, Beis Shamai require a post and a beam, and Rabbi Eliezer requires 2 posts, one on each side.

In an early post )Shabbos 130b), we discussed the way Rabbi Eliezer was referred to by the Gemara there as a שמותי , a term that the Yerushalmi quoted in the second explanation in Rashi there, as well as in Tosfos, understood to mean that he belonged to Beis Shamai.

However, as we also know )Avos 2/9) that Rabbi Eliezer was one of the greatest students of Rabban Yochanan ben Zakai, who received his tradition from both Hillel and Shamai, it is very possible that he had influence from the scions of both houses.

In this Mishna, it seems that Rabbi Eliezer was neither bound completely to either Beis Hillel or Beis Shamai, but fiercely independent.

This is somehow despite the fact that he took such pride in the fact that he never said anything that he never heard from his Rabbi (Sukkah 28a.)

This can be explained by the fact that his tradition came directly from Rabban Yochanan ben Zakai who learnt from both Hillel and Shamai, as mentioned above, and thus sometimes was in line with Beis Shamai and sometimes with Beis Hillel.

It can also be that what he meant was not that he heard every precise ruling from his Rebbe, but that he always followed the methodology he learnt from his Rebbe, no matter what conclusion it led to, thus ironically adding to his independence in the realm of practical halacha.

It is a common experience that independents, despite often being revered on both sides of the aisle, usually struggle for acceptance on either side.

Perhaps Rabbi Eliezer was both great and confident enough to have his feet in both worlds, but still able to interpret the Torah and rule according to his own view, even taking a separate stand from both strong “councils of sages.”

Even for the usually tolerant members of Beit Hillel, despite his having learnt from some of their teachers, he was never “Beis Hillel” enough, but a “שמותי”

This independence and consequent lack of acceptance came to a head in the case of the stove of Achnai (Bava Metzia 59b), where his refusal to accept the majority opinion of all the other sages resulted in his virtually unprecedented excommunication, which according to the first explanation in the above-quoted Rashi, was the reason for his being called a שמותי”” , from the word “שמתא” (excommunication.)

The truth is that lacking the safety in numbers that members of both main parties tend to have, independents often suffer the most, and are treated more harshly by members of the dominant party than members of the opposition are treated, even if their ideologies are somewhere in-between.

Whereas Rabbi Eliezer’s independence was virtually stamped out by his colleagues, who burnt all the things that he had declared pure, Beis Hillel are lauded towards the end of daf 13b for their respectful attitude to the views of Beis Shamai, not only quoting their views, but even mentioning them before their own, as illustrated in a Mishna in Sukkah brought by our Gemara.

My beloved son, Noam, asked me the other night, while learning mishnayos Shabbos together, why Beis Shamai are mentioned first so often in Mishnayos even though Beis Hillel are more authoritative.

I answered that this could very well be a reflection of this tolerant attitude first illustrated in the Mishna in sukkah quoted by our Gemara, which Rabbi Yehuda haNasi, a direct descendant of Hillel, carried on when he compiled the Mishna.

This tolerance of the other side, is given in our Gemara as the reason that the view of Beis Hillel became normatively accepted over that of Beis Shamai- In order for one’s view to be accepted, it seems important that one is open-minded, respectful, and confident enough to hear, consider, and even quote dissenting views. This shows that this view was acquired after fully considering all sides and without automatically putting down the other side and is thus a view worthy of acceptance.

Our Gemara points out that this preference given to Beis Hillel was not because the rulings of Shamai were not legitimate, but rather for the above reason- objectively speaking, “אלו ואלו דברי אלוקים חיים”-“these and those are the words of the living G-d!”

It might seem logically impossible that two seemingly contradictory views can both be considered objectively part of the divine Torah, but this seems to be precisely what the Gemara is saying.

The Torah is the word of the “living G-d” and thus constantly branching off into different explanations and possibilities.

So long as different views are all based on the “מסורה”, that living chain of transmission that goes back to Moshe at Sinai, it is not so much the actual conclusion that makes them legitimate, but the way that was achieved.

Not every alternative view has halachik legitimacy- only those that can be justified based on previous stages in the tradition.

Both Beis Hillel and Beis Shamai were required to back their views up with pessukim in the Torah, or oral traditions dating back to Moshe at Sinai, and the same applies to those that come after them.

It is not tolerance alone that gave Beis Hillel their authority, as reading this sugya in isolation might imply. In other places, their authority is derived on their greater numbers and on the “voice from heaven” )see Eruvin 7a for example) that proclaimed that the halacha is like them.

In fact, in the earlier sugya in this masechta, it seems that before this voice from heaven, one was permitted to choose which one of these great schools of Torah to follows, and that according to those who did not consider a voice from heaven to be authoritative, such as none other than Rabbi Yehoshua himself, this was permitted even after this voice from heaven, despite the other factors in Beis Hillel’s favor!


We have explained the idea of “אלו ואלו” with the understanding that in matters subject to debate, there is no objectively true answer, but both sides are legitimate “Torah”- the superiority of Beis Hillel is only practical, and as a result of the traits they possess, their superior numbers, and the voice from heaven.

Yet the Rambam appears to limit this idea significantly.

According to him (Mamrim 1/4), matters mentioned explicitly in the Torah or received orally through tradition tracing back to Moshe’s revelation at Sinai are never subject to debate.

Only matters that are derived though Chazal’s use of the rules for interpreting the Torah, can be subject to debate.

Even the later, were subject to the final ruling of the great court, so long as that court was still functioning, and debate was only legitimate until such a ruling was given.

Once it ceased to function, such matters that had not yet been resolved became subject to debate again.

Given that many or most of the disputes between Beis Shamai and Beis Hillel occurred at a time when the great court was still functioning, it follows that these disputes were subject to a final ruling by that court.

It is those rulings, according to the Rambam, not the tolerance of Beis Hillel or the voice from heaven, that were authoritative.

This fits well with the view that the main reason for their greater authority was their superior numbers, which would have allowed them to dominate the great court they were part of.

How the Rambam would explain the other reasons given for their authority, is subject to further analysis- it is possible, that as might often be his way, he simply regarded one source to be more authoritative in keeping with other accepted rules of halacha, and rules accordingly.

It is also possible that it is precisely that tolerance and extra willingness to engage in respectful debate that swung the majority of the Sanhedrin, including the “independents” towards their side, and that the “voice from heaven” was the מכה בפטיש (final blow) that brought them to this decision.

This also explains the harsh treatment meted out to Rabbi Eliezer by the members of Beis Hillel.

According to the Rambam above, even matters that were subject to dispute, were eventually concluded by the Sanhedrin while it functioned , and thereafter, no-one had the authority to act to the contrary.

Their opinions were still recorded out of respect, but they were now out of the realm of accepted halacha.

They might still have theoretical value in the study-halls, and even be considered “the words of the living G-d,” but the option for anyone to rule accordingly was now closed.

It follows that in post Sanhedrin times, debate in practical halacha is possible once again, and there is no threat of excommunication for those who follow their own or other minority views, but only in matters that had not already been decided by the Sanhedrin, and in matters that fit the Rambam’s strict criteria for debate.

If so, given that the Talmud itself was sealed by Ravina and Rav Ashi long after the Sanhedrin had ceased to function, how do we explain the universally accepted binding authority given to it by all followers of the מסורות?

We will have to leave this for a difference discussion, but a good place to start is the introduction of the Rambam himself to the Mishna Torah, the great masterwork we just quoted from.

Does everyone agree with the Rambam’s strict criteria regarding which matters are subject to debate, and does the huge collection of debates scattered throughout the Mishna and the Gemara back up this very strong claim? This too, will need to be left for a later discussion.

These posts are intended to raise issues and stimulate further research and discussion on contemporary topics related to the daf. They are not intended as psak halacha.

Shmuli Phillips Ari Kahn Johnny Solomon