The Principle of Rubo Umakpid
The Gemara quotes Rav as stating that the laws of chatzitza are halacha l’Moshe misinai. The Gemara concludes that Rav’s mention of the laws of chatzitza refers specifically to the principle of Rav Yitzchak. Rav Yitzchak states that in order for the chatzitza to invalidate an immersion by Torah law, two requirements are necessary. Firstly, the chatzitza must cover rubo – the majority of the body, and secondly, the person has to be makpid – particular to want it removed.
The Rishonim discuss which part of the body Rav Yitzchak refers to in his famous statement. Rashi gives an example of a chatzitza covering rubo as where “most of his hair is dirty with mud, or the hairs are tangled together.” From the fact that Rashi focuses on hair, Tosafot infer that Rashi holds that Rav Yitzchak’s limitation (that a chatzitza mide’oraita is only defined as one of rubo umakpid) only applies to hair. But any chatzitza on the skin as opposed to the hair would not be subject to these limitations. Hence, even the smallest chatzitza on a person’s skin, even if a person is not particular about it, would be considered a chatzitza, and disqualify the immersion on a Torah level.
Tosafot elsewhere also posit, as do other Rishonim, that this is indeed the opinion of Rashi, but challenge it from the following Gemara. The Gemara quotes Rava as saying that if a pregnant, gentile woman undergoing conversion immerses in the mikveh, the fetus need not immerse in the mikveh again to achieve the status of a convert, for the immersion of its mother suffices for the baby as well. The Gemara initially suggests that the reason for Rava’s ruling is Rav Yitzchak’s statement that a chatzitza only invalidates an immersion if it is rubo umakpid (it covers the majority of the body and the person is particular to remove it). Since the unborn child is obviously not particular to remove the mother from surrounding it, the immersion is therefore valid on a de’oraita level. The Gemara then rejects this as an explanation for Rava, since Rav Yitzchak’s principle does not apply where the entire body (as opposed to just the majority) is covered by a chatzitza (in this case, the mother). The Gemara then offers a different answer as to why the immersion of the mother also suffices for the fetus.
From this Gemara, it is clear that Rav Yitzchak’s rule was not limited to hair, but also to the body as well (since the chatzitza referred to is the mother herself). Hence, Tosafot and the other Rishonim reject Rashi’s opinion. The Rosh also deduces that Rashi understood Rav Yitzchak’s ruling to be limited to hair, but, like Tosafot, he feels that this contradicts the explicit Gemara cited above.
It is important to emphasize the great stringency inherent in Rashi’s ruling. According to this understanding of Rashi, if one finds the smallest chatzitza on one’s body, it invalidates the immersion mide’oraita, notwithstanding whether a person is makpid about it or its size.
The Kehillot Yaakov explains the reasoning behind Rashi’s opinion. Regarding the skin, the Torah writes, “v’rachatz et kol besaro,” he must wash his entire flesh. If there is even a minority that is covered by a chatzitza, the requirement of “kol besaro” will not have been fulfilled. However, regarding hair and vessels, the verse does not state “kol – the entirety,” hence, Rav Yitzchak’s leniency can only apply to hair but not to the body.
All of the other Rishonim rule like Tosafot that the limitation of “rubo umakpid” applies to the entire body and not just to the hair. This includes the Rambam and the Shulchan Aruch, leaving Rashi as a da’at yachid (minority opinion) in his unique approach.
Hair Measured Independently From the Body
The Ritva opines that Tosafot, the Rashba, and other Rishonim misunderstood Rashi. In his opinion, Rashi does not mean that the limitation of rubo umakpid only applies to hair. Rashi is explaining that when discerning whether a chatzitza is considered rubo, we do not view the body and hair as one unit. Rather, the surface area of the skin is viewed as one unit and hair is viewed as another. Hence, if there is a chatzitza on the majority of one’s hair and one is particular about it, it would be a chatzitza mideo’raita. Similarly, if the chatzitza was on the majority of the body, it would be a chatzitza mide’oraita.
This approach of viewing hair and the body as two independent units is also the opinion of the Geonim. The Rambam quotes the Geonim as holding that if the majority of one’s hair is tied in a knot, it is considered a chatzitza, and if one is makpid, it is a chatzitza mide’oraita. The Rambam rejects this assumption and writes, “it seems to me that a person’s hair is considered part of his body and not as a body on its own.”
What is the source for the opinion of the Geonim (and Rashi, according to the Ritva)? The Ran explains that since there are two separate derivations from the pesukim that teach us about chatzitza, one for chatzitza of the hair and one for chatzitza of the body, it seems that there are different laws for each.
The vast majority of Rishonim agree with the Geonim (at least l’chumra, to be strict) and this is how the Shulchan Aruch rules as the halacha.,
The Chiddush of the Geonim
One can explain the ruling of the Geonim in one of two ways, similar to the sides of an uncertainty raised by the Perisha. The Perisha is unsure whether the hair on the entire body is measured as one unit, or each area of hair (i.e., head, armpit, etc.) is measured separately. The Perisha may have been unsure whether the ruling of the Geonim that the hair on the head is assessed separately is because of its importance or because hair is somewhat external to the body. According to the second understanding, one must assume that all the hair of the body is considered one unit, while according to the first, the distinction of the Geonim relates only to the hair on the head.
The Tiferet Moshe rules that each grouping of hair (such as on the head, under the armpit, and in the genital area) is measured independently. Thus, as long as there is a chatzitza on the majority of that part of hair on the body, the immersion is disqualified. The Aruch Hashulchan also raises this issue and rules similarly that each group of hair is measured separately.
What Is the Source of This Dispute?
The Meiri explains that the dispute between the Geonim and the Rambam is based on differing versions of the text of the Gemara. To fully understand his explanation, let us refer back to the Gemara in Sukka, which is the source of the entire discussion.
The Gemara initially suggests that Rav’s statement that the halacha of chatzitza is a halacha l’Moshe misinai applies to hair. In other words, the pasuk quoted in the Gemara (of “v’rachatz besaro b’mayim” from Vayikra 14:9) teaches that the rules of chatzitza apply to the rest of the body, while the halacha l’Moshe misinai indicates that the same rules apply to hair as well. The Gemara then claims that an additional derivation from the same pasuk (the word “et” in the pasuk, which actually reads “v’rachatz et besaro b’mayim”) indicates that hair too is subject to chatzitza mide’oraita, and not only from the halacha l’Moshe misinai. The Gemara responds (in the Meiri’s version of the text): כי איצטריך הלכתא לרובו ומיעוטו , the halacha l’moshe misinai is relevant regarding the rule of rubo (i.e., R. Yitzchak’s rule).
This version of the Gemara, found in our printed texts, is the version of the Rambam. But the Geonim and “gedolei rabbanim” (in the words of the Meiri, referring to Rashi) had a different version of the text in the Gemara that states: “ אלא כי איצטריך הלכתא לרובו ומיעוטו”.
This one word “ela – rather,” creates a connection and relationship between the two stages in the Gemara; in the first stage the Gemara presents Rav’s opinion regarding the halachot of chatzitza as referring to hair, but in the next stage, the Gemara brings a more precise opinion as a renewed ruling of chatzitza in hair – the rule of “רובו ומקפיד ” does not exist for other parts of the body, but only for hair. This explanation was further elaborated upon by the Ohr HaChaim HaKadosh.
Another explanation of the dispute is offered by the Griz based on logic rather than textual variants of the Gemara. The Griz explains that in other areas of halacha, the hair and the body are considered two separate entities, while in regard to the halachot of chatzitza, the Torah gives an additional ruling about hairs, as seen from the Gemara’s offering a distinct pasuk to teach the rule of chatzitza concerning hair. The Rambam and the Geonim dispute what novelty the Torah added when teaching that hair is included.
The Geonim assume that the halachot of chatzitza a priori do not apply to hair. The novelty of the Torah is thus that the laws of chatzitza also apply to hair, even though they are independent of the body. The Rambam, on the other hand, understands that the Torah regards the hair and body as two separate entities, while regarding chatzitza, the novelty is that we assume them to be one unit.
To summarize, we discussed the rule presented by the Gemara of “רובו ומקפיד” as the criteria for a chatzitza de’oraita and we discussed the stages that the Gemara went through to reach this rule. We also explained how the Rishonim differed as to whether this principle applies just to hair or to the entire body. Rashi claims that it refers to the hair, while Tosafot and others claim that it applies to the entire body. We mentioned several explanations for the above dispute and expanded on one specific approach in which Rashi holds like the Geonim that hair is measured independent of the body. We explained that according to this approach, the chumra attributed to Rashi (that even a mi’ut hamakpid in the hair constitutes a chatzitza de’oraita) is not necessarily his opinion. Rather, instead of being a da’at yachid, Rashi’s approach is actually the position codified by the Shulchan Aruch.
 Sukka 6b
 Sukka 6b, s.v. rubo
 Sukka 6b, s.v. devar Torah
 This is how the Ritva explains Rashi, but the Kehilot Yaakov understands that even according to this opinion, the requirement of makpid still exists for any chatzitza mide’oraita.
 Eiruvin 4b, s.v. devar Torah
 Yevamot 78a
 Chullin 8:15
 This is how the Ritva quotes the Rishonim as explaining Rashi. The Kehilot Yaakov (quoted below), though, understands that it would be a chatzitza mide’oraita (even when it is a minority) only if the person is makpid.
 Sukka, siman 5, s.v. ul’che’ora
 Hilchot Mikva’ot 1:12
 y.d. 198:1
 Ritva, Eiruvin 4b, s.v. ki itztarich
 Hilchot Mikva’ot 2:15
 Ran on the Rif, Shavuot 7a
 See below, where the more complete version of the discussion in the Gemara Sukka is quoted.
 y.d. 198:5
 It should be noted that in his responsa, the Rambam mentions the opinion of the Geonim l’chumra, that chatzitza disqualifies the tevila even though it is not on the majority of the body, and the Shulchan Aruch rules in accordance with the chumra of the Geonim. On the other hand, there are several halachot in which the Geonim rule l’kula, about which the Acharonim are divided as to whether to accept.
 y.d. 198
 y.d. 198 s.v. ul’aniyut da’ati
 y.d. 198:25
 Beit HaBechira, Eiruvin 4b
 The version of the Meiri is based upon the text in Eiruvin, which is slightly different than the version in Sukka that states כי אתאי הלכתא לכדרבי יצחק וכו’, but nonetheless conveys the same idea. There is another difficulty with the Meiri, though, that the word ela usually signifies a complete retraction from the previous answer, not a revision of the same idea (that it still refers to hair). See footnote 108 to the Meiri here by Rav Moshe Hershler in the Machon HaTalmud Hayisraeli version of the Meiri who elaborates on this issue and suggests a different way to read the Meiri. It is interesting that the Ran in Shavuot (loc cit.) also suggests that the dispute hinges on Rashi having a different version of the text, but he suggests that Rashi did not include the word “ela” in his text (as opposed to the Meiri, who says he did), while the other Rishonim did include it, as follows: אלא כי אצטריך הלכתא לרובו ומיעוטו. According to the Ran, the other Rishonim understand the word ela here as signifying a rejection of the previous answer in the Gemara, while Rashi understands it as a continuation of the previous answer concerning hair, which he therefore explains as meaning that the principle of rubo umakpid refers only to hair, and not other parts of the body.
 Rishon L’tzion on the Talmud, Sukka 6a, s.v. v’ra’iti shekatav
 Chiddushei Maran Riz HaLevi on the Rambam, Mikva’ot 2:15