The Torah in Parashat Tzav (7:23) introduces the prohibition against eating the cheilev – certain fats – of kosher animals: “Kol cheilev shor ve-khesev va-eiz lo tokheilu” (“You shall not eat any of the ‘cheilev’ of an ox, sheep or goat”). The Gemara in Masekhet Yoma (74a) infers from the word “kol” (“all,” or “any”) in this verse that the Torah includes in its prohibition even “chatzi shiur” – quantities less than the amount for which one is liable to punishment by Beit Din. A basic principle in Halakha establishes than unless indicated otherwise, the act of “eating” is halakhically defined by the consumption of the quantity of a ke-zayit (the volume of an olive). Therefore, when the Torah forbids eating certain foods, the a priori presumption is that it forbids only the consumption of this amount. However, the Gemara cites a berayta inferring from the word “kol” in this verse in Parashat Tzav that consuming any quantity of cheilev is forbidden, notwithstanding the fact that punishment is administered only for the consumption of a ke-zayit. The Gemara views this provision as a precedent which informs all prohibitions, such that any food forbidden for consumption is forbidden in any quantity.
Reish Lakish, as the Gemara cites, was of the opinion that the inference made from this verse in Parashat Tzav constitutes an “asmakhta” – an allusion to a law that was actually enacted later, by Chazal. In Reish Lakish’s view, the rule of chatzi shiur applies only on the level of rabbinic enactment, as according to Torah law, consuming less than a ke-zayit of forbidden food is allowed. However, Halakha follows the view of Rabbi Yochanan, who maintained that the principle of chatzi shiur applies on the level of Torah law. Although the Torah established certain quantities for certain violations, it also established that its violations are transgressed regardless of quantity, the difference being that Beit Din administers punishment only for violations involving the stipulated quantity for the given prohibition.
In explaining the law of chatzi shiur, the Gemara comments that the Torah forbids even a half-quantity because “chazi le-itzterufei” – it is capable of combining with another half-quantity to constitute a punishable, halakhic act of eating.
The Gemara does not, however, clarify why this factor is significant, and capable of extending Torah prohibitions to smaller quantities. If a halakhic act of eating is defined as the consumption of a ke-zayit, why does the consideration of “chazi le-itzterufei” yield a prohibition against partaking of even smaller quantities?
As Rav Asher Weiss discusses in his essay on the topic, two different perspectives may be taken – and have been taken – to explain the concept of “chazi le-itzterufei.” The first is that the Torah established a safeguard of sorts to its own prohibitions. Fundamentally, when the Torah forbade eating certain foods, it forbade only the consumption of a ke-zayit. However, since the consumption of half this amount could result in a violation if one again eats half this amount (within a certain time period), the Torah prohibited the consumption of any amount. One who eats an amount smaller than a ke-zayit is not liable to punishment by Beit Din because he did not violate the essential prohibition, but the Torah nevertheless forbids consuming smaller amounts in order to protect against violations of the actual prohibition.
Alternatively, it could be explained that the consideration of “chazi le-itzterufei” forces us to acknowledge the halakhic significance of even half-quantities of forbidden food. According to this perspective, consuming a chatzi shiur is forbidden not as a practical measure to prevent against the consumption of a full quantity, but rather because even a half-quantity of forbidden food has the technical halakhic status of forbidden food. The fact that a person who eats a chatzi shiur and a moment later eats another chatzi shiur has violated the Torah’s command demonstrates that each chatzi shiur has halakhic significance as forbidden foodstuff. Therefore, although the primary prohibition is not violated until the consumption of a full quantity, a half-quantity is nevertheless prohibited for consumption.
The practical difference between these two perspectives would perhaps arise in situations where there is no possibility of “chazi le-itzterufei” – meaning, where one eats a half-quantity without any possibility at all of later eating a second half-quantity to violate the prohibition. According to the second perspective presented above, eating the first chatzi shiur is certainly forbidden even in such a case. This perspective views a chatzi shiur as intrinsically significant, and thus it is prohibited even in situations when as a practical matter it cannot lead to a violation. According to the first perspective, however, it could be argued that the chatzi shiur prohibition would not apply in such a case. Since this prohibition was established as a sort of safeguard, it applies only when the danger exists that a second half-quantity will be consumed to complete the forbidden act of eating.
Tomorrow, we will iy”H examine several such situations, where a half-quantity is unable to combine with another half-quantity to complete a halakhic violation.