QUESTION: The Mishnah (73b) lists the five prohibitions of Inuy on Yom Kippur: Achilah and Shetiyah, Rechitzah, Sichah, Ne'ilas ha'Sandal, and Tashmish ha'Mitah (eating and drinking, washing, anointing with oil, wearing shoes, and marital relations). The Beraisa says that while all of these acts are forbidden on Yom Kippur, only Achilah and Shetiyah are punishable with Kares.

The Beraisa implies that all of the Inuyim are forbidden mid'Oraisa. However, if they are forbidden mid'Oraisa, why does the Mishnah state that a king and a bride may wash their faces and a woman who gave birth ("Chayah") may wear shoes on Yom Kippur? The Rabanan cannot permit these acts if the Torah forbids them.

(a) TOSFOS (77a, DH d'Tenan) quotes RABEINU TAM who says that the other four Inuyim, besides Achilah and Shetiyah, are forbidden only mid'Rabanan and not mid'Oraisa. When the Rabanan prohibited those acts, they prohibited them only when they give a person pleasure. When they do not provide pleasure but they serve a basic necessity (such as in the case of a king, Kalah, and Chayah), the Rabanan did not prohibit them.

(b) RASHI (DH Shabason, and in Shabbos 114b, DH Talmud Lomar Shabason) implies that all of the Inuyim are forbidden mid'Oraisa. This is also the opinion of the RAMBAM (Hilchos Shevisas Asor 1:4-5). Why, then, are some of the Inuyim permitted for a king, Kalah, and Chayah?

The SEFER YERE'IM explains that a king and Kalah may wash their faces because the Torah does not forbid the act of washing the face alone. The Isur d'Oraisa of Rechitzah involves washing one's entire body. Washing part of the body is forbidden only mid'Rabanan, and in the case of a king and Kalah the Rabanan permitted it.

Why, though, is a Chayah permitted to wear shoes?

The TOSFOS YESHANIM suggests that, according to those who maintain that the Inuyim are mid'Oraisa, perhaps the prohibition against wearing shoes applies only to a "Min'al" (a shoe that covers the entire foot). A "Sandal," though, is permitted mid'Oraisa.

(c) The RAN explains that even if all of the Inuyim are forbidden mid'Oraisa, the Torah empowered the Chachamim to determine what act is considered an Inuy. The Chachamim determined (based on their understanding of the concept of Inuy) that the Torah forbids as an Inuy only an act which is considered pleasurable. Consequently, a king and a Kalah are permitted to wash their faces, and a Chayah is permitted to wear shoes, because those acts are not acts of pleasure but acts of necessity.

The Ran asks that the Mishnah later (82a) states that children are not required to observe the prohibitions of Inuy. The Mishnah implies that an adult is permitted to wash a child on Yom Kippur. However, the Halachah states that an adult may not feed an Isur d'Oraisa to a child or help a child perform an act which the Torah forbids an adult to perform (Yevamos 114a, and as cited by Rashi on 78b, DH Inshi Avdu Lei). Why, then, may an adult wash a child on Yom Kippur, when the washing certainly is pleasurable for the child?

The Ran does not answer this question. We may suggest that the prohibitions of Rechitzah, Sichah, and Ne'ilas ha'Sandal (which are not punishable with Kares) are actually secondary prohibitions derived from the Torah's commandment to observe the primary Inuyim of Achilah and Shetiyah (which are punishable with Kares). Since an adult is permitted to feed a child on Yom Kippur because of Piku'ach Nefesh (it is dangerous for a child to fast), an adult is also permitted to give the child the secondary Isurim which are derived from Achilah and Shetiyah. (See also KESEF MISHNEH, Hilchos Shevisas Asor 1:5. This approach necessitates a re-evaluation of the Gemara on 78b; see Insights there.)

OPINIONS: Rebbi Yochanan and Reish Lakish argue about the prohibition of "Chatzi Shi'ur." Rebbi Yochanan maintains that the Torah forbids Chatzi Shi'ur. Reish Lakish maintains that the Torah permits it, but the Rabanan prohibit it. The Gemara explains that Rebbi Yochanan derives that Chatzi Shi'ur is Asur mid'Oraisa from the verse, "Kol Chelev" (Vayikra 7:23). He gives a logical explanation as well: Since a partial Shi'ur of Isur is able to join with another partial Shi'ur to make a complete Shi'ur ("Chazi l'Itzterufi") which is certainly Asur mid'Oraisa, a partial Shi'ur is also Asur. This logic also explains why Chatzi Shi'ur is forbidden for all Isurim in the Torah and not only for those that involve eating (see Rashi to Shabbos 74a).

The Acharonim suggest a number of ways to understand the logic of "Chazi l'Itzterufi."

(a) The most simple way to understand the logic of "Chazi l'Itzterufi" is as follows. When a person eats one Chatzi Shi'ur of a prohibited food and then eats another Chatzi Shi'ur of the same food, he transgresses the Isur d'Oraisa of eating a complete Shi'ur of the prohibited food item. The Torah therefore prohibits one from eating the first Chatzi Shi'ur as a preventative measure, lest one eat a second Chatzi Shi'ur and thereby transgress the Isur by eating a full Shi'ur.

According to this explanation, there are grounds to suggest that when a person eats a Chatzi Shi'ur at the last moment of the day on Yom Kippur, that Chatzi Shi'ur is not Asur mid'Oraisa. Since there is not enough time to eat a second Chatzi Shi'ur on Yom Kippur, the logic of "Chazi l'Itzterufi" does not apply. (See ACHIEZER 2:21 and others.)

(b) The CHACHAM TZVI asserts that even according to Rebbi Yochanan, the Torah forbids Chatzi Shi'ur only for transgressions which involve eating. When one eats something, he gives it value and importance through his act of eating it ("Achshevei"), and therefore it becomes forbidden by the Torah. (In other words, the amount of Isur that the Torah forbids is based on the amount that is considered "significant.") The Isur d'Oraisa of Chatzi Shi'ur does not apply to other types of prohibitions, such as the prohibitions of Bal Yera'eh and Bal Yimatzei on Pesach, where one does no act to give the object of Isur significance.

The Rishonim, however, apply the Isur of Chatzi Shi'ur to all types of prohibitions. (See Rashi to Shabbos 74a, and Rambam in Perush ha'Mishnayos to Shabbos, end of chapter 12.)

(c) The SHA'AGAS ARYEH explains that the prohibition of Chatzi Shi'ur is more than a safeguard against eating a full Shi'ur (as described in (a) above). He asserts that the logic of "Chazi l'Itzterufi" teaches that a Chatzi Shi'ur is forbidden because the partial Shi'ur of Isur itself may end up forbidden mid'Oraisa. If a person eats one Chatzi Shi'ur and then he eats more of the prohibited food, the first Chatzi Shi'ur he ate retroactively becomes a part of a full Shi'ur which is prohibited mid'Oraisa. At the time that he eats the first Chatzi Shi'ur, it is considered as though he eats a Safek Isur d'Oraisa (because he might eat more later), and therefore it is forbidden (like every Safek Isur d'Oraisa).

According to this explanation, the Isur of Chatzi Shi'ur does not apply to an Isur such as Bal Yera'eh and Bal Yimatzei. In order to transgress Bal Yera'eh and Bal Yimatzei, the full Shi'ur of a k'Zayis of Chametz must be in one's house all at one time. One transgresses Bal Yera'eh without doing any action with the prohibited item; he transgresses only when the full Shi'ur is in his possession. In contrast, one transgresses an Isur Achilah, a prohibition against eating a forbidden food, even when he performs two acts at two different times (within Kedei Achilas Peras) with two partial Shi'urim which join together to make one full Shi'ur. When no action is involved in the transgression, no temporal element can join two partial Shi'urim; one must have the entire Shi'ur at once in order to transgress. Accordingly, a Jew is permitted to own a "Chatzi Shi'ur" on Pesach, because the "Chatzi Shi'ur" of Chametz cannot become forbidden retroactively. If another "Chatzi Shi'ur" of Chametz is brought into the house later, only from that point on does the first "Chatzi Shi'ur" become forbidden. (See also Insights to Pesachim 29:3 and Yoma 45:1:e.)

The MINCHAS CHINUCH uses the Sha'agas Aryeh's explanation to answer a question on the RAMBAM. The RAMBAM (Hilchos Chametz u'Matzah 1:7) rules that eating a Chatzi Shi'ur of Chametz on Pesach is forbidden mid'Oraisa because of the verse, "Lo Ye'achel."

Why does the Rambam need a special verse to teach that a Chatzi Shi'ur of Chametz is forbidden? Chatzi Shi'ur is forbidden for all prohibitions! (See KESEF MISHNEH there.)

The Minchas Chinuch explains that perhaps the Rambam maintains that the normal Isur of Chatzi Shi'ur does not apply to the prohibition against owning Chametz because, as the Sha'agas Aryeh explains, that partial Shi'ur will never be forbidden as a partial Shi'ur. For this reason, the Rambam needs to cite a verse to show that a Chatzi Shi'ur of Chametz is forbidden to be eaten in and of itself, and not just because of "Chazi l'Itzterufi." The purpose of the prohibitions of Bal Yera'eh and Bal Yimatzei is to prevent a person from transgressing the prohibition against eating Chametz (Avos d'Rebbi Nasan chapter 1); if there is no prohibition against eating a partial Shi'ur of Chametz, then the prohibitions of Bal Yera'eh and Bal Yimatzei should also apply to half a Shi'ur of Chametz -- even without relying on the logic of "Chazi l'Itzterufi." (If the prohibition against eating a partial Shi'ur of Chametz would have been because of "Chazi l'Itzterufi," a preventative measure but not an Isur in its own right, then the prohibitions of Bal Yera'eh and Bal Yimatzei would not have applied since they would have been a preventative measure to prevent the transgression of what is itself only a preventative measure.)

(d) The MESHECH CHOCHMAH (Vayikra 7:23) and others suggest that "Chazi l'Itzterufi" means something entirely different. It does not mean that perhaps one will eat a little more later and thereby transgress the full Shi'ur of an Isur d'Oraisa. Rather, the logic of "Chazi l'Itzterufi" means as follows.

When the Torah forbids a certain food (such as the meat of a non-kosher animal) and teaches that one transgresses only when he eats a minimum Shi'ur of that food, it is not logical to say that one who eats less than that Shi'ur eats a permissible item. If the Torah forbids, with a punishment of Malkus, the act of eating a k'Zayis of meat of a non-kosher animal, it would not give outright permission to eat a little bit less than a k'Zayis. If the Torah permits each bite until one has reached the Shi'ur of k'Zayis, what changes at the last bite, at the moment that he eats a k'Zayis? Why should the last bite of meat be more forbidden than the others?

Rebbi Yochanan explains that Chatzi Shi'ur is forbidden mid'Oraisa, but one is not liable for Malkus until he repeats the Isur many times by eating a k'Zayis. "Chazi l'Itzterufi" means that if the Torah punishes a person for eating a k'Zayis, it must be that it also forbids any amount of the item. A k'Zayis is merely the amount for which a person is punished. (Perhaps the Meshech Chochmah understands that the logic of "Chazi l'Itzterufi" serves as a sign that Chatzi Shi'ur is forbidden, but not as a reason to forbid it.)

However, according to the Meshech Chochmah's explanation for "Chazi l'Itzterufi," how does Reish Lakish refute Rebbi Yochanan's logical argument by saying that Chatzi Shi'ur is not called "Achilah"? Although it is true that eating a partial Shi'ur is not considered an act of Achilah, an Achilah is necessary only in order to administer the punishment of Malkus but not to prohibit the food. The food is prohibited even if the act is not an Achilah.

According to the other explanations for "Chazi l'Itzterufi," the way Reish Lakish refutes Rebbi Yochanan's logic of "Chazi l'Itzterufi" is straightforward. He says simply that if eating less than a k'Zayis is not considered an act of Achilah, then there are no grounds to say that the Torah establishes a preventative measure to prohibit a Chatzi Shi'ur lest one eat a full Shi'ur. In addition, since there is no reason to suspect that a person will eat more of the prohibited food and thereby transgress an Isur d'Oraisa, there is no reason to say that the first half-Shi'ur retroactively becomes forbidden when one eats a second half-Shi'ur.

Reish Lakish apparently maintains that a food item itself is not inherently forbidden. Rather, the Torah prohibits a person from performing an act of Achilah with the food. An act of Achilah is defined as the consumption of a k'Zayis through the normal manner of consumption. Until one eats a k'Zayis of the forbidden food, he has not performed an act of "Achilah" and thus everything he ate until now was permitted. Only at the point at which he eats a full k'Zayis has he performed an act of Achilah and transgressed the prohibition.

(Rebbi Yochanan, in contrast, maintains that the act of eating less than a k'Zayis is not fundamentally different than the act of eating a k'Zayis. The difference between the two acts is merely in the quantity of the Isur consumed.) (M. Kornfeld)