Until now, we have discussed how to close off the fourth side of a מבוי (alley) already closed on 3 sides, to permit carrying within the מבוי and to and from the מבוי and the adjoining courtyards.

We will see later that in addition to the pole or beam on the open side, one needs to make the actual eruv, known in this case as שתוף מבואות  (joining of alleys) by placing some food in one of the courtyards on behalf of all the inhabitants of the מבוי.

These laws are all based on the assumption that at a scriptural level, an area enclosed on 3 sides is already considered a private domain, and it is only a rabbinical requirement that the fourth side be marked or closed off in some way.

On today’s daf, we begin to address the more complex question of how to make an eruv in a real public domain, where carrying is a biblical prohibition.

The case discussed is a public thoroughfare with buildings flanking either side.

A Beraita is brought where the Tana Kama (first opinion) rules that one can make a צורת הפתח (a structure resembling an entrance, consisting of 2 poles on either side and a plank running from one side to the other on top) on one side, and the other side only requires pole or a beam (acc the version of the Rif and Rosh,) like a closed מבוי.

The Tana Chananya disagrees and says that the law in this case is subject to a dispute between Beis Hillel and Beis Shamai, and both are more stringent than the Tana Kama.

Beis Shamai holds that both ends need to be shut by doors which need to be locked as people enter or exit, a rather cumbersome process in a busy public place.

Beis Hillel are more lenient and require a door only on one side, making do with a pole or a beam on the other side, like a closed מבוי.

Even though Chananya’s view is substantially more stringent when it comes to a making an Eruv in a public domain, the Gemara is still unwilling to accept it due to 2 other statements of Chazal.

In the first, a Beraisa, Rabbi Yehuda opines that if someone has two houses on either side of a public thoroughfare , one may put either a pole or a beam on both of the open sides and carry from one house to another. This view is even more lenient than the Tana Kama in the previously Beraisa who requires at least a צורת הפתח on one side.

The Chachamim retorted that a public domain may simply not be closed off in such a lenient way.

In case one answers that the Chachamim did not mean to reject even Beis Hillel’s more stringent suggestion involving a door on one side, the Gemara brings an extremely stringent  view stated by Rabbah bar bar Hana in the name of the leading Amora, Rabbi Yochanan.

Rabbi Yochanan’s reported view is that even a walled city like Yerushalayim, would be considered a public domain on a biblical level, if its doors were not locked at night.

We are talking about a walled city enclosed on ALL sides, open only at the gates, yet Rabbi Yochanan holds that the gates required doors which were locked at night to convert it into a private domain (termed a חצר כל רבים, or public courtyard.)

We see from there that turning a public domain into a private domain is no simple matter, and even Beis Hillel’s requirement to have doors on one side are not sufficient for this- all sides have to be completely enclosed and even aligned gates on opposite sides of the city need to be completely closed with doors that are locked at night.

On the basis of this stringent ruling of Rabbi Yochanan, the Gemara reinterprets the first Beraisa to refer not to a real public domain, but to a מבוי that is open on both sides to a public domain, referred to as a מבוי מפולש לרשות הרבים.

Unlike the מבוי that is closed on 3 sides, this is treated more stringently, and the three opinions in the Beraisa refer to closing off its two open sides.

The Gemara then records a dispute between the leading first-generation Amoraim of Babylon, Rav and Shmuel, as to which opinion we follow for this open מבוי.

Rav rules like the Tana Kama and requires only a צורת הפתח on the one open side of the מבוי and a pole or beam on the other.

Shmuel is more stringent and requires doors on one side and a pole or beam on the other side, like Beis Hillel according to Chananya.

It follows that there are 3 different situations we have discussed so far:

1.       A real public domain, that satisfies all the criteria to be defined as such- making an eruv is almost impossible and requires doors in all openings that are locked at night.

2.       A מבוי that is open on two sides to the public domain, but is not itself considered a public domain, for reasons that need to be clarified. According to Rav, a צורת הפתח is required on one side and a pole or beam is sufficient on the other.  According to Shmuel, one side requires doors and the other can make do with a pole or beam.

3.       A מבוי that is only open on one side- This is the case we have been discussing from the beginning of the masechta, and either a pole or a beam on the open side is sufficient.

I have a few questions on the שקלא וטריא (give and take/flow) of the sugya, among them

1.       The Gemara initially rejected the simple interpretation of the first Beraisa based on the second Beraisa’s rejection of Rabbi Yehuda’s lenient view.

Although the Gemara later admits that one can retort that the views are not equivalent, and Rabbi Yehuda was more lenient than Beis Hillel who requires doors, it seems strange that it did not immediately see that.

2.       In addition, Rabbi Yehuda’s view making do with either a pole or a beam on both sides seems even more lenient than the most lenient view  seen in the first beraisa, namely that of the Tana Kama who at least required a צורת הפתח on one side.

As such, Even if we found a way to explain why the Gemara initially thought that the second Beraisa was a good proof against the simple explanation of the first, we need to explain why the Gemara assumes that it is at least a proof for the more stringent view of Chananya requiring doors. Surely all it proves is that a beam or a pole on both sides is not sufficient?

3.       Once the second Beraisa is rejected as a proof against the simple understanding of the first Beraisa, Rabbi Yochanan’s statement about Yerushalayim is brought to show that even Beis Hillel according to Chananya are too lenient.

Yet Rabbi Yochanan was only an Amora, and his view was only reported by another Amora. Is such a view authoritative enough to reject the simple meaning of a Beraisa and interpret it to refer not to a real public domain but rather a מבוי open on two sides to one?

Perhaps one can answer based on the fact that Rabbi Yehuda holds that an area enclosed on two sides is already considered a private domain on a biblical level.

As such, it is the equivalent to him of an area enclosed on 3 sides according to the majority opinion.

If the Chachamim rebuked Rabbi Yehuda for allowing such an area to be enclosed with just a pole or a beam, it could be that they are saying that even according to his lenient definition of a public domain, such an area is still a public domain on a rabbinic level and requires at least a צורת הפתח on one side.

It follows that according to Chachamim who consider such an area to be a proper public domain even on a biblical level, a צורת הפתח  would not be sufficient and doors would be needed, at least on one side, and possibly on both.

The Gemara then says that it is true that the second Beraisa implies that the Chachamim would require doors on one side, but who says that they would require these doors to be on both sides AND locked.

It then brings the statement of Rabbi Yochanan to prove that they would indeed. Although Rabbi Yochanan is an Amora, his statement is based on a reinterpretation of the first Beraisa, and given that no other Amora of his stature has suggested sticking to the simple interpretation, we need to consider his view as authoritative and discover what this reinterpretation is.

This is only my own analysis of the sugya, but a look at the various Rishonim will show that these issues are discussed, and similar answers are given.

What is a רשות הרבים (public domain.)

Now that we have seen that making an eruv in a true public domain is almost impossible, we can see that attempting to make an eruv in a busy and crowded city is fraught with difficulty.

The key to understanding where this could be possible is understanding what makes an area a public domain.

Given that the prohibition of transferring from domain to another or 4 אמות  within a public domain is derived from the mishkan in the biblical מחנה ישראל (camp of Israel,) it follows that the properties of this camp should serve as  guidelines for what is considered a public domain.

Rashi, on our daf, gives various criteria, which in his view, were shared by the public domain in the desert:

1.       It needs to be at least 16 אמות wide (approximately 8 metres)

2.       It needs to be a city where at least 600,000 people are present (שמצויין בה שישים רבוא)

3.       If it is walled on all sides, it needs to have two gates on opposite sides with a public thoroughfare running from one to the other.

What Rashi does not tell us here is what happens if an area in a city fulfills all the requirements, but another area does not. He also does not tell us if the city requires 600,000 to be there all the time, or only at certain times.

A major issue raised by Tosfos on our daf, is how the second requirement can be derived from the biblical camp.

We already learnt (Shabbos 99 and see our post on that daf) that the area underneath the wagons was also considered part of the public domain, and there were certainly not 600,000 people there. In addition, the number 600,000 referred only to the adult male population in the camp, and once women and children were included, it would have been far higher.

Although Rabbeinu Tam explains that the area under the wagons was indeed used by all the people when they travelled, and we use the number 600,000 because it is the only number actually mentioned in the text, other Rishonim such as the Rambam do not make mention of the 600,000 requirement at all, possibly for these reasons.

One could possibly explain alternatively  that Rashi did not mean that all areas of the public domain needed to be frequented by 600,000, but if the area as a whole was indeed frequented by that number of people, all areas in it are also considered part of the same public domain. Perhaps this is part of what Rabbeinu Tam meant.

If this true, how we define which areas are considered part of this public domain requires more information, but it seems clear that the area underneath the wagons was indeed part of the biblical camp.

All these issues guide the debate regarding where an eruv can and cannot be built, and it is not surprising that there different, sometimes extreme views on either side regarding whether one may or may not rely on eruvim in bigger cities that are subject to these doubts.