When it comes to Eruv Techumim, we have seen that the golden rule regarding whether the eruv is valid is that if it is valid during the period of בין השמשות at the beginning of shabbos, it is valid the whole shabbos, even if the eruv food is later lost,eaten, or destroyed .
When it comes to ערוב חצירות and the מחיצות required for them, the situation is less simple.
At the bottom of Eruvin 93a, רב הושיעא asks what happens if new inhabitants enter a courtyard on shabbos?
Do we say that seeing as they were not there for the beginning of shabbos and their lack of participation in the eruv thus never invalidated everyone else’s eruv, the eruv remains valid for the whole shabbos despite their lack of participation therein, or do we say that seeing as they cannot join the eruv on shabbos, their presence now invalidates the eruv for the rest of the shabbos ?
Rashi gives the example of two courtyards separated by a common wall, who both make their own eruvin.
The wall then falls down, and each courtyard suddenly has a whole lot of new “inhabitants” that could render their eruv invalid.
Rav Chisda suggests a proof from the Mishna which says that if a large courtyard’s boundary wall with a smaller one is breached, the inhabitants of the large courtyard invalidate the eruv of the smaller courtyard.
He assumes that this is referring to if it was breached on shabbos, and we see from this that even if an eruv was valid for part of shabbos, it can be invalidated on shabbos through “new inhabitants.”
Rabbah, however, says that this Mishna might be referring to when the breach occurred before shabbos, and Abaya notes that according to Rabbah, it MUST be referring to such a case, as Rabbah himself had told Abaya that he has asked Rav Huna who in turn asked Rav Yehuda about a related case:
This was about two courtyards that made a joint eruv by means of an opening in their shared boundary wall which became sealed during the course of the Shabbos, possibly invalidating the eruv.
Rav Yehuda answered with the principle that שבת הואיל והותרה הותרה – Once Shabbos has been permitted (at its onset), it remins permitted (even if the entrance the eruv is based on becomes closed up.)
Similary in our case, once the smaller courtyard made its own eruv and the wall separating it from the neighboring larger courtyard was standing at the onset of shabbos, the eruv remains valid even if the wall falls down, introducing “new inhabitants.”
It follows that according to Abaya, Rabbah, and Rav Yehuda, we follow the rule of שבת הואיל והותרה הותרה , and at least according to Abaya and probably Rabbah, this is a broad principle that applies both in cases where a wall falls down (destroying a partition) and where a gap in the wall is filled (recreating the partition.)
The Gemara then records a debate between Rav and Shmuel regarding a similar case where the boundary wall between two courtyards that both made their own עירוב חצירות falls down on Shabbos.
Rav holds that the inhabitants of each courtyard invalid the eruv of those of the other and carrying more than 4 amos within in the area is forbidden.
Shmuel, on contrast, holds that each courtyard’s inhabitants may carry up to where the boundary wall was, based on the rule of שבת הואיל והותרה הותרה .
Although we usually follow Rav against Shmuel, seeing as the later Amoraim like Abaya and Rabbah seem to hold like Shmuel, there is a strong argument at this point that we would do so too.
However, the discussion is far from over- In the Mishna at the bottom of Eruvin 94a, there is a debate between Rabbi Yehuda and Rabbi Yossi regarding what seems like related cases.
There, a house or courtyard collapses on two sides bordering the public domain on shabbos , or the pole or beam of a מבוי collapse on shabbos.
Rabbi Yehuda holds that even though the מחיצות that separate them from the public domain have collapsed, we apply the rule of שבת הואיל והותרה הותרה and carrying within them remains permitted for the duration of that Shabbos.
In contrast, Rabbi Yossi holds that the duration of Shabbos is no different to the next shabbos, and the Gemara on Eruvin 95a understands this to mean that just like carrying within them will be forbidden the next shabbos, it is also forbidden for the duration of this shabbos and we do not apply the rule of שבת הואיל והותרה הותרה .
Rabbi Chiya bar Yosef rules like Rabbi Yosi, whereas Rav Yehuda quotes Shmuel as ruling leniently like Rabbi Yehuda.
The Gemara questions whether Shmuel could really have ruled leniently in this case.
In a different context, Rav Yehuda quoted Shmuel as saying that we always follow Rabbi Yehuda’s (lenient) rulings when in comes to eruvin, which at first glance appears to be consistent with the ruling quoted here.
However, Rav Chanan of Baghdad had asked Rav Yehuda to clarify whether Shmuel would even be lenient when it comes to the post or beam of a מבוי being removed on shabbos, and Shmuel said that the lenient rule he had mentioned applied only to Rabbi Yehuda’s lenient views regarding the eruv itself, but not regarding the מחיצות that are required for it.
As such, when it comes to disputes regarding whether מחיצות are valid or not, the rule of כדברי המיקל בערוב הלכה does not apply- in our case, Shmuel would accordingly be stringent like Rabbi Yosi and not say שבת הואיל והותרה הותרה !
Rav Anan reconciles that apparent contradiction in Shmuel’s words by distinguishing between a private domain that opens to a רשות הרבים and one that opens to a כרמלית .
In the former case, any dispute regarding the validity of the מחיצות is effectively a dispute regarding a biblical prohibition, and being stringent is consistent with the general rule of ספק דאורייתא לחומרא.
In contrast, if only a רשות היחיד and a כרמלית are involved, the dispute only involves rabbinical matters, and the rule of ספק דרבנן לקולא and its stronger “extension” of הלכה כדברי המקיל בערוב should logically apply.
It could follow that according the conclusion of the sugya, if certain components of the מחיצות that validate the eruv, such as a boundary wall, or the pole or beam of a מבוי, fall down on shabbos, the eruv remains valid for the duration of that shabbos, so long as the previously enclosed area is not open to a biblically defined public domain.
This could be an extremely useful tool for many of our city eruvin which are based on the assumption that the public areas are not busy or large enough to be considered a biblically defined public domain ((רשות הרבים דאורייתא
Another huge נפקא מינה (practical ramification) could be when it comes to debates regarding the precise length of halachik measurements such as a טפח and an אמה which are used to measure the validity of מחיצות.
Assuming that the rule of הלכה כדברי המקיל בעירוב applies to disputes amongst later authorities as well (which of course needs its own discussion,) then according to Rav Anan’s distinction, so long as no biblically defined public domain is involved, one might be permitted to rely on the more lenient opinions (for example measure a לבוד taking a טפח as closer to 10cm rather than closer to 8cm when measuring the maximum gap between the wires of a fence.)
However, while Rav Anan has succeeded in reconciling the contradiction in Shmuel’s words, and he does seem to have the final word in this sugya, it is not a foregone conclusion that we follow Shmuel either in this particular case of שבת הואיל והותרה הותרה or in his general rule (as understood by Rav Anan) that הלכה כדברי המיקל בערוב applies even regarding מחיצות when no רשות הרבים is involved.
There are other sugyas that discuss this issue (see for example Eruvin 17a, Eruvin 70b,Eruvin 81b) which need to be put together with the various pieces on our three daf before a clearer idea of the halacha can be seen, but we shall suffice for now to point out that Tosfos rules against Shmuel even when the previously enclosed area opens to a כרמלית seeing as Rav rules like Rabbi Yosi. This seems to be the general consensus of other Rishonim as well, though a thorough study of their views is obviously required still, and as such, it seems that when a problem occurs on shabbos with the מחיצות , the rule of הואיל דהותרה הותרה cannot be applied.
When the problem is created by the closure of a gap in the מחיצה and not the lack of a מחיצה , however, Tosfos points out that even Rabbi Yosi agrees with the rule of שבת הואיל והותרה הותרה.
Whether Rav Anan’s extension of כלכה כדברי המיקל בערוב to rabbinically required מחיצות in other disputes where Rav does not rule against Shmuel requires further analysis, and could impact our second question regarding disputes over the sizes of the טפח and אמה!
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