On these daf, the Gemara deals with some of the most important principles in all of Halacha.

The Mishna on 35a records a dispute between Rabbi Meir and Rabbi Yossi regarding a case where it is uncertain whether the eruv techumin was valid during the critical period of twilight on Erev Shabbos.

Various examples are given:

1.       If the Eruv rolled outside his shabbos domain, and it is not clear if this happened before or after dark.

2.       If the Eruv was covered by landslide or burnt, and it unclear whether this happened before or after dark.

3.       If the Eruv consisted of Teruma, became impure, and it is unclear whether this happened before or after dark.

In such cases, Rabbi Meir and Rabbi Yehuda hold that he is treated like a “חמר גמל” (literally someone who is in charge of both a donkey and camel.)

As Rashi explains, the camel pulls from behind its leader, while the donkey pulls from  in front, making him remain stuck in place!

So also, it is unclear whether the Eruv is valid, allowing him  up to an extra 2000 amos in one direction, while limiting his movement  in the opposite direction, or whether it is invalid, keeping the status quo valid and allowing him 2000 amos in either direction.

As such, he is treated stringently and needs to avoid both areas of doubt, essentially making him “stuck” in the area of certainty between his house and where he placed the Eruv (roughly speaking, though probably really in the area where the two techumim overlap.)

In contrast, Rabbi Yossi and Rabbi Shimon rule that in case of doubt as to the validity of an eruv techumim, we are lenient and the eruv is kosher, allowing him to travel in a radius of 2000 amos from where he placed it.

It is unclear from their wording whether they mean that we treat the eruv as kosher out of doubt, thus also allowing him to walk anywhere within a 2000 amos radius of his house, or whether such an eruv is treated as if it is definitely kosher, thus preventing him from the later.

It is also unclear whether this debate is unique to a doubt regarding an eruv techumim, or applies to any case of doubt regarding a rabbinical law, as per the famous rule of ספק דרבנן לקולא (in case of doubt in a rabbinical matter, one may be lenient.)

The Gemara on 35b seems to take it for granted that this ruling is not unique to Eruvin, but applies to other areas of rabbinic law also, and questions Rabbi Meir’s ruling based on his lenient ruling in another case.

The case referred to is one where a person is impure  and goes down  to the mikva to immerse. himself.

Like in our case, there is some doubt as to whether his action was effective, for one of the following reasons:

1.       He is not sure if he actually immersed himself

2.       He is not sure if he immersed in a sufficient amount of water

3.       There were two mikvaos, one containing enough water and one which does not, and he is unsure which one he immersed in.

Rabbi Meir rules that if the person was impure on a biblical level, he is treated as impure, but if he was only impure on a rabbinical level, he is treated as if he is pure.

This seems to fit perfectly with the general halachik principle of ספק דאורייתא לחומרא  (in case of doubt in a biblical matter, we are stringent) and ספק דרבנן לקולא .

Rabbi Yossi, in contrast, holds that even if he was only rabbinically impure, he is still treated as impure out of doubt.

Here, it is Rabbi Meir who is lenient in the case of doubt, and Rabbi Yossi who is stringent.

Putting the issue of Rabbi Yossi’s apparent self-contradiction aside for a little, the Gemara focused first on Rabbi Meir, and answers that Rabbi Meir is of the view that the law forbidding one to leave one’s shabbos domain is actually biblical in nature.

As such, there is no inconsistency, and Rabbi Meir goes along with the general rule that ספק דרבנן לקולא.

On 36a, the Gemara turns to Rabbi Yosi and tries to explain the discrepancy in his ruling.

After various suggestions are given, the explanation of Rava is given.

Rava explains that although Rabbi Yossi indeed usually agrees that ספק דרבנן לקולא, in the case of the impure person, it is different because he started out with a חזקת אסור  (a forbidden status quo.)

The famous rule of following a person’s original status quo when there is doubt about his status (see Chullin 10a)  apparently overrides the rule of ספק דרבנן לקולא, or alternatively, redefines it as no longer subject to doubt, but as definitely impure.

There is tons more to discuss about the scope of these basic principles and how they relate to Eruvin and other situations- I wish to add that the continuation of the sugya seems to imply that Rabbi Yossi does not only limit the rule of ספק דרבנן לקולא to a case where there is no חזקת אסור working against it, but might even require a חזקת היתר  together with the doubt in order to be lenient.

This would be a huge novelty, with major ramifications, and would contradict much of what we know or assume about this rule- It would then come out that Rabbi Yossi is actually much stricter than Rabbi Meir (and perhaps the other opinions) regarding the scope of this leniency, contrary to what it seemed when we first learnt our Mishna!

Such is the beauty and complexity  of Gemara!

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.