A (technically) proper, but ineffective, shehitah, in the sense that the shehitah does not render the flesh of the slaughtered animal fit to be eaten, e.g., the shehitah of a tereiphah, is the subject of a dispute between R. Meir and R. Shimon concerning whether such a shehitah is termed a “shehitah,” i.e. whether it has any halakhic standing. A practical distinction could arise if shehitah was performed on an animal and its offspring in one day: if either the parent or the offspring is a tereiphah, would performing shehitah on both in one day violate the biblical prohibition? Or would the blood shed when performing shehitah on a tereiphah be subject to the Biblical obligation to cover the blood spilt in slaughtering the animal? Discussing this disagreement, the Gemara (Hullin 85a-b) concludes that, according to both R. Meir and R. Shimon, there are exceptional cases. R. Meir, who normally holds that an ineffective shehitah is termed a shehitah, nevertheless agrees that the flesh of a living 9-month fetus in the womb of a tereiphah upon which shehitah was performed may not be eaten although, if the mother were not a tereiphah, the flesh of the live 9-month fetus would have been permissible, and R. Shimon, who normally holds that an ineffective shehitah is not termed a shehitah, concedes that an ineffective shehitah performed on a tereiphah does prevent the slaughtered animal from becoming a neveilah upon death.
The Gemara explains that R. Meir infers that an ineffective shehitah is termed a shehitah from the prohibition of performing shehitah on a sacrifice outside Tabernacle (a forbidden, and therefore ineffective, shehitah being called a shehitah) while R. Shimon infers that an ineffective shehitah is not termed a shehitah from the verse in Genesis 43:16 (“וטבוח טבח והכן”), the shehitah performed for Joseph and his brothers having rendered the flesh of the slaughtered animal fit for consumption. But R. Shimon’s inference is not logically compelling, so presumably his opinion must have been based either on a long-standing tradition or on reasoning (סברה), not a mere semantic connection. But if so, R. Meir’s position seems more persuasive than R. Shimon’s, there being no intrinsic defect with an ineffective shehitah; the ineffectiveness resulting only from an external factor preventing the shehitah from rendering the flesh of the slaughtered animal fit for consumption. There seems to be no good reason why a proper, but ineffective, shehitah should have no halakhic standing. If performing a shehitah on a tereiphah after having performed, that same day, shehitah on the animal’s parent or offspring would violate the prohibition against performing shehitah on an animal and its offspring in one day, and performing shehitah on a tereiphah would trigger the obligation of kisui dam after that shehitah. Why would the verse cited by R. Shimon lead one to conclude otherwise?
The basis for R. Shimon’s opinion must be that, following R. Akiva, he believes that every effective shehitah fulfills the positive commandment embodied in the verse (Deuteronomy 12:21) “וזבחת ואכלת . . . כאשר צויתיך”, as the Rambam writes at the start of Hilkhot Shehitah: “There is a positive commandment for anyone who wishes to eat the flesh of an animal or fowl to perform shehitah before eating its flesh.” It is therefore only when performing shehitah fulfills that positive commandment, thereby removing the prohibition of eiver min ha-hai from the animal and rendering the flesh of the slaughtered animal immediately fit for consumption, that shehitah is halakhically effective. But when shehitah is performed on a terephah, and therefore fulfills no positive commandment, the flesh of the animal not being rendered fit for consumption, such a shehitah, like nehirah in the desert, does not remove the prohibition of eiver min ha-hai until the animal dies. The shehitah of a tereiphah, however, does prevent the ritual impurity of neveilah from devolving upon the slaughtered animal, the redundant word “מן“ in the verse “כי ימות מן הבהמה” implying that ritual impurity does not devolve upon every dead animal, the exception being a tereiphah upon which shehitah is performed, as explained at Hullin 74a. But in such a case the shehitah only prevents ritual impurity from devolving upon the animal, but does not, unlike an effective shehitah, immediately remove the prohibition of eiver min ha-hai.
The dispute between R. Meir and R. Shimon concerning an ineffective shehitah therefore derives from their positions concerning the dispute between R. Yishmael and R. Akiva. R Meir, as previously explained, follows the opinion of R. Yishmael that even a proper shehitah does not remove the prohibition of eiver min ha-hai before the death of the slaughtered animal inasmuch as there is, according to R. Yishmael, no positive commandment to perform shehitah. If so, there is no intrinsic difference between an effective and an ineffective shehitah, the cause of an ineffective shehitah being some external characteristic of the slaughtered animal, not a defect in the act of the shehitah. But following the opinion of R. Akiva that performing shehitah fulfills the positive commandment to perform shehitah introduced upon entry into the Land, R. Shimon believes there is an intrinsic halakhic difference between an effective and an ineffective shehitah, so that any effective shehitah would immediately render the flesh of the slaughtered animal fit to be eaten even before its death. But an ineffective shehitah, fulfilling no positive commandment, does not remove the prohibition of eiver min ha-hai from the flesh of the slaughtered animal before its death, so that, according to R. Shimon, such a shehitah has no halakhic consequence except to prevent the status of neveilah from devolving upon the slaughtered animal.