Based on a Shiur by HaRav Aharon Lichtenstein*
The concept of "chatzi shiur" ("half the quantity") appears in many different halakhic contexts, and it is reflected in a wide variety of halakhic realms. This stems from the fact that, generally speaking, precise measurements and quantities constitute an exceedingly important dimension in Halakha. It is only natural then that there should be intensive discussion of the nature of chatzi shiur. My discussion of this concept will be divided into two: we will first consider chatzi shiur with respect to prohibitions, and then we will focus on chatzi shiur with respect to positive commands.
CHATZI SHIUR WITH RESPECT TO PROHIBITIONS
Chatzi shiur – Rabbi Yochanan said: "This is forbidden by Torah law;" Resh Lakish said: "This is permitted by Torah law."
Rabbi Yochanan said: "This is forbidden by Torah law – since it can add up [to the full measure], he eats something that is forbidden."
Resh Lakish said: "It is permitted by Torah law [but forbidden by rabbinic decree] – the Torah speaks of eating, and that is absent."
Rabbi Yochanan brought a beraita against Resh Lakish: "'I only know that anything which is punishable is prohibited. As for… chatzi shiur, since it is not subject to punishment, should I say that it is not subject to prohibition? Therefore the verse (Vayikra 7:23) states: "Any fat."'" (Yoma 74a)
According to Rabbi Yochanan, chatzi shiur is not forbidden by Torah law. According to him, just as one is forbidden to eat a ka-zayit (olive's volume) of meat from an improperly slaughtered animal (neveila), so too one is forbidden by Torah law to eat less than a ka-zayit of such meat. In contrast, Resh Lakish maintains that a chatzi shiur is forbidden only by rabbinic decree.
As is evident, the Gemara proposes two possible explanations for the position of Rabbi Yochanan: 1) a derivation from the verse "any fat," which teaches that eating "any" amount of a food that may not be consumed is forbidden by Torah law, and not just eating the full ka-zayit; 2) the logical argument that since a chatzi shiur is fit to be combined with more of the prohibited food to make up the legal quantity, it itself is forbidden. Tosafot (ad loc.) ask: why are two different explanations necessary? I shall address the difference between them below.
WHAT IS MEANT BY "IT CAN ADD UP"?
As for the rationale "it can add up," two understandings are suggested by the Acharonim:
1) Since a person who eats two half-measures of a forbidden food violates a prohibition, the Torah forbids one to enter "the danger zone" and eat the first chatzi shiur.
2) "It can add up" is not the reason for the prohibition, but rather a symptom, indicating that it is forbidden. That is to say, were it permissible to eat a chatzi shiur, then it should also be permissible to eat a full shiur, for zero plus zero is equal to zero! Since we know that eating the ka-zayit of a prohibited food is forbidden, even the eating of half a ka-zayit must be subject to some kind of prohibition. Hence, the eating of a chatzi shiur must be forbidden by Torah law.
There is a practical difference between the two understandings in a case where a person eats a chatzi shiur in such a manner that he cannot complete the required quantity: for example, a person who eats a chatzi shiur at the very last moment of Yom Kippur. If the reason that eating a chatzi shiur is forbidden is the ability to combine it with a second chatzi shiur (the first explanation), then in such a case eating the chatzi shiur should be permitted, for there is no possibility of combining it with another chatzi shiur in order to complete the required quantity. However, if chatzi shiur is independently forbidden (the second understanding), then even in such a case, eating the chatzi shiur should be forbidden, even though there is no way of combining it with another chatzi shiur to complete the required quantity.
"THE TORAH SPEAKS OF EATING, AND THAT IS ABSENT"
As we saw above, the discussion regarding chatzi shiur is brought in the context of forbidden foods. In response to Rabbi Yochanan's argument that chatzi shiur is forbidden by Torah law because it is fit to be added to another chatzi shiur, Resh Lakish offers the counter-argument: "The Torah speaks of eating, and that is absent." According to him, eating less than a ka-zayit is not considered eating, and therefore eating a chatzi shiur of a prohibited food is permitted by Torah law. In order to understand this disagreement, we must consider the following fundamental distinction regarding the law of chatzi shiur.
The Me'iri raises a question with respect to the prohibition of chatzi shiur: if on Shabbat a person carries an object two cubits in the public domain – when the Torah prohibition is to carry an object four cubits – does he violate a prohibition of chatzi shiur with respect to his carrying? The Me'iri answers that such an action is permitted even if a chatzi shiur is forbidden by Torah law. According to him, a distinction must be made between performing a complete action with respect to an incomplete measure, and performing an incomplete action with respect to a complete measure. When a person eats a chatzi shiur, he performs a complete action of eating on an incomplete measure of food, but carrying an object two cubits in the public domain is not considered an act of "transporting." Therefore, whereas performing a complete action on an incomplete measure is forbidden, performing an incomplete action is never prohibited by biblical law.
The Me'iri brings another example from the prohibited labor of baking on Shabbat: whereas baking half the volume of a dried fig on Shabbat is forbidden based on the law of chatzi shiur, baking the full volume of a dried fig at half the requisite temperature is not forbidden. Baking at a low temperature is not defined as an act of baking, in contrast to baking a small amount (less than the size of a dried fig) at the proper temperature, which is defined as baking and therefore forbidden by Torah law.
According to this distinction, whenever we encounter the idea of chatzi shiur, we must determine whether we are dealing with a half-action or a half-measure. It is possible that Resh Lakish and Rabbi Yochanan disagree on this very point. According to Resh Lakish, eating a chatzi shiur is not defined as an act of eating ("the Torah speaks of eating, and that is absent"), and a half-action is never prohibited. Rabbi Yochanan might agree that we are dealing with a half-action but maintain that even a half-action is forbidden based on the law of chatzi shiur.
Alternatively, the disagreement between Rabbi Yochanan and Resh Lakish may be understood as follows: both agree that only a half-measure is forbidden, not a half-action. According to Rabbi Yochanan, eating a half-measure is regarded as a complete action performed with an incomplete measure; whereas according to Resh Lakish, we are dealing with a half-action.
A SEPARATE PROHIBITION OR AN ANCILLARY PROHIBITION?
Together with the previously mentioned distinction, another fundamental question regarding the nature of the law of chatzi shiur must be raised. The Acharonim ask: what is the foundation of the prohibition of chatzi shiur? Surely every prohibition has its own quantity, and when the action is performed on less than that quantity, it does not meet the criterion set for that transgression. Why then is the action forbidden, whether by Torah law or by rabbinic decree? The Acharonim propose two possibilities:
1) Indeed, a chatzi shiur should be permitted, but there is another general prohibition, unconnected to the specific prohibition, that forbids the violation of prohibitions even when performed with a chatzi shiur. According to this understanding, someone who eats half a ka-zayit from a neveila does not violate the prohibition of eating prohibited food, but rather a separate prohibition – the prohibition of chatzi shiur. This prohibition gives expression to the fact that the Torah forbids us to disobey the word of God even partially.
2) Chatzi shiur is an ancillary prohibition, subordinate to the particular prohibition under which it is subsumed. According to this understanding, a person who eats the size of half a ka-zayit of meat from a neveila violates a prohibition of eating prohibited food, though we are dealing with the prohibition to eat a chatzi shiur of that food, not the prohibition to eat a full measure.
These two possibilities seem to correspond to two opinions brought by the Ramban.
The Gemara in Yoma states that one is permitted to cure a person who has a life-threatening disease by feeding him prohibited foods, though this should be done in the manner of "the more lenient prohibition first." That is to say, the patient should first be fed foods that are subject to less-stringent punishments; for example, since eating a ka-zayit of forbidden fat carries the punishment of excision and eating a ka-zayit of pork carries the punishment of flogging, it is better to feed pork than fat to the sick person. The Ramban asks: surely it is possible to feed the patient less than the legal quantity, in which case it should not matter which prohibition is the least stringent – for all half-measures are of equal stringency! The Ramban proposes two answers:
Nevertheless, since when there is a full measure, the one is more stringent than the other with respect to punishment, even when there is less than the full measure, the one is more stringent than the other. Alternatively, in this case it is assessed that [the patient requires] the full measure, eaten within a time period that would combine [all of the half-measures into a single act of eating]. (Torat Ha-adam, Sha'ar Ha-michush, 4)
According to the first answer, just as there are different degrees of stringency regarding prohibitions, there are different degrees of stringency regarding chatzi shiur. According to this understanding, eating a chatzi shiur of fat is more stringent than eating a chatzi shiur of pork. According to the second answer, however, there is no difference in the level of prohibition between the two; it happens to be that the Gemara is dealing with a case in which the patient requires a full measure of prohibited food.
The two answers seem to correspond to the two understandings raised above. According to the first answer, chatzi shiur is a prohibition that is connected to the prohibition of the full measure; therefore, just as there are gradations regarding the prohibitions themselves, so too there are gradations regarding chatzi shiur. According to the second answer, there is no differences between the different cases of chatzi shiur. All cases of chatzi shiur are equal in their stringency, regardless of the original prohibition to which they are related. Thus, according to this answer, the Gemara's case must be limited to a particular case where the patient requires a full measure of prohibited food.
IS THERE CHATZI SHIUR WITH RESPECT TO THE RESULTS OF SIN?
We should mention another point in the Ramban's words regarding chatzi shiur.
According to the Rambam, when it comes to a woman who falls into the category of an erva, such as a married woman or one's sister, hugging or kissing her is forbidden by Torah law, based on the verse, "You shall not approach… to uncover her nakedness" (Vayikra 18:6). The Ramban agrees that we are dealing with a Torah prohibition, but he maintains that the source of the prohibition is different:
Since they did not do this, we may understand that according to them the prohibition is by rabbinic decree, or else it is by Torah law – because any derivation of pleasure from something that is prohibited is forbidden, like chatzi shiur. (Ramban, Sefer Ha-mitzvot, Negative 353)
From the words of the Ramban, it might be understood that hugging and kissing are forbidden by Torah law as a chatzi shiur of the prohibition of sexual relations. According to him, since hugging and kissing provide limited sensual pleasure, they are forbidden based on the law of chatzi shiur. Some Acharonim understand that the Ramban's position on the matter is part of a more general approach. According to them, the Ramban maintains that even when a person performs an action that is altogether different from the original prohibition, it is forbidden based on the law of chatzi shiur, provided that the results of the action (in this case the pleasure from hugging or kissing an erva) are similar to the results of the particular prohibition (the pleasure of sexual relations with an erva).
In my opinion, however, what the Ramban says here should not be taken too far. What may be inferred from this is that regarding transgressions that are defined as deriving pleasure from something that is forbidden, partial pleasure is forbidden based on the law of chatzi shiur, even if the action which yields that partial pleasure is entirely different from the action explicitly forbidden. However, even if we accept this qualification, we are still dealing with an exceedingly novel position, for the prohibition of forbidden foods also stems from the fact that pleasure is derived ("she-ken neheneh"); that is to say, the prohibition is to derive pleasure from the forbidden food. Thus, it is possible that with respect to forbidden foods as well, any action that causes pleasure should be forbidden, based on the law of chatzi shiur, even if it does not involve a legal act of eating.
It is possible that Rabbi Yochanan and Resh Lakish disagree on this point. Both agree that eating less than the legal quantity is not defined as an act of eating, and they also both agree that the law of chatzi shiur does not apply to a half-action. However, Rabbi Yochanan maintains that since the prohibition of forbidden foods is defined according to the pleasure derived from them, then even an action that is not defined as eating but nevertheless provides pleasure is forbidden based on the law of chatzi shiur. Resh Lakish, on the other hand, disagrees with the Ramban's novel position. According to him, an action that is entirely different from the recognized prohibition is not forbidden, based on the prohibition of chatzi shiur, merely because the results of the half-action are similar to those of the recognized action.
CHATZI SHIUR WITH RESPECT TO POSITIVE COMMANDMENTS
Thus far we have dealt with chatzi shiur with respect to prohibitions. We shall now consider this law with respect to positive commandments.
The main question that must be raised is whether there exists any law of chatzi shiur with respect to positive commands. It seems that the answer to this question depends on the source of the law regarding prohibitions: if the law is derived from the verse "any fat," it should be restricted to prohibitions and not extended to positive commandments; on the other hand, if it is derived from logic, this argument might apply to the world of positive commandments as well.
In any event, if we assume that the law applies to positive commandments as well, it seems that there are several contexts in which, a priori, it may be applied. I shall briefly mention these contexts:
1) Chatzi shiur regarding the object (cheftza) of the mitzva: for example, if a person eats half a ka-zayit of matza or korban pesach (the paschal offering), has he fulfilled his obligation? It should be noted that several explicit passages in Tractate Menachot conclude that a half-measure regarding meal-offerings, libations and sacrifices is not effective. From here, it would appear that a chatzi shiur of the mitzva object has no significance.
2) Chatzi shiur regarding the number of units required: for example, does taking two aravot or one hadas on Sukkot count? Here too, the Gemara concludes that one who takes less than the required number has not fulfilled his obligation.
3) Chatzi shiur regarding similar parts of the same unit: for example, does putting tzitzit on three corners of a garment, rather than four, count? In this context as well, chatzi shiur is ineffective.
4) Chatzi shiur regarding an action: for example, does blowing a shofar for less than the required duration count? Another example is connected to a well-known disagreement regarding the mitzva of dwelling in a sukka. The Gemara in Sukka (27a-b) brings a disagreement regarding the mitzva of sitting in a sukka. According to Rabbi Eliezer, in order to fulfill the mitzva, one must sit in a sukka all seven days of Sukkot, whereas according to the Sages, one fulfills the mitzva each time he sits there. It might be argued that a single meal in the sukka is a chatzi shiur of the mitzva to sit in the sukka all seven days, and Rabbi Eliezer and the Sages essentially disagree whether the law of chatzi shiur applies to positive commandments.
Despite what has been said thus far, it seems to me that we must make a distinction between chatzi shiur with respect to prohibitions and chatzi shiur with respect to positive commands. In the case of the positive commands, the mission falls upon the person. When he executes only part of that mission, he has not fulfilled the mission that falls upon him. On the other hand, in the case of prohibitions, there are no missions, but rather restrictions. It stands to reason that a person should distance himself as far as possible from forbidden actions – even from half-measures thereof.
(Translated by David Strauss)
* HaRav Lichtenstein delivered this shiur on 25 Adar I 5768 at the "Mifgashmar." The shiur was summarized by Shaul Bart. It has not been reviewed by HaRav Lichtenstein.