Gemara

(Beraisa): If one cooked milk in a pot used for meat; and the milk absorbed the taste of meat, it is forbidden. If one cooked Chulin in a pot used for Terumah, and the Terumah gave taste to the Chulin, it must be eaten like Terumah.

Question: Granted, in the Seifa, a Kohen may taste the food. However, in the Reisha, one may not taste the milk. Perhaps it is forbidden!

Answer (Rava): We rely on a Nochri Kefeila (chef), like R. Yochanan said.

(Rava): Sometimes, Chachamim say that we taste food. Sometimes, we rely on a Kefeila.

Bava Kama 114b (Rav Ashi): We rely on l'Fi Tumo (one who speaks unaware of the consequences) only for Edus Ishah (testimony that a man died, to permit his wife to remarry).

Question (Ravina): We rely on it regarding a swarm of bees!

Answer (Rav Ashi): Ownership of bees is only mid'Rabanan. (I discuss Torah laws.)

Question: A case occurred in which a child recounted l'Fi Tumo that he was captured with his mother, and he was constantly with her. Rebbi permitted her to a Kohen.

Answer: Chachamim were lenient about a Shevuyah (a hostage).

Rishonim

Rambam (Hilchos Ma'achalos Asuros 15:30): If meat and milk, Yayin Nesech, Orlah or Kil'ai ha'Kerem fell into honey, a Nochri tastes it and we rely on him.

Rosh (7:25): The Gemara said that a Nochri chef tastes the food. We learn that one may rely on what he says l'Fi Tumo. We do not inform him that this pertains to Isur v'Heter.

Tosfos (97a DH Samchinan): Even though the chef is a Nochri, he would not lie, lest he lose his profession.

Ran (34a DH u'Min): Since we say 'Kefeila', this implies that we do not rely on a Stam Nochri who is not a chef, for Nochrim lie. A chef would not (lie and) ruin his reputation. Since this is the reason, he need not speak l'Fi Tumo. Rashi says that all the more so, he will not ruin his reputation if he knows that we are concerned (whether the Isur can be tasted). We rely on a Yisrael whether or not he is a chef. The Gemara said that a Kohen may taste. It did not stipulate that the Kohen is a chef!

Rashba (cited in Beis Yosef YD 98 DH Kasav): The Nochri need not be a professional (chef). When we are unsure whether Chulin absorbed a taste of Terumah, a Kohen may taste the food. The Gemara did not stipulate that the Kohen is a chef! Also, Rava taught that sometimes, Chachamim say that we taste food, and sometimes, we rely on a Kefeila. He lists these separately. this shows that 'taste' refers to something that anyone can taste. He mentioned a Nochri chef only because a Stam Nochri might lie. A chef fears to lie, lest he ruin his reputation. Therefore, we may rely on a Nochri chef even if he knows that we rely on him for Isur v'Heter. We may rely on any Nochri who speaks l'Fi Tumo. Some are stringent, and rely only on a chef speaking l'Fi Tumo. One should be concerned for their opinion.

Terumas ha'Deshen (79): If one bought eggs from a Nochri on Yom Tov after Shabbos, and the Nochri said l'Fi Tumo that they were born two or three days ago, we do not rely on this to permit eating them today. Perhaps they were born yesterday, on Shabbos, and there is a Torah Isur of Hachanah (food for a Kodesh day must be prepared on a Yom Chol. We hold like Rabah (Beitzah 2b, who says so.) Edus Ishah and a Shevuyah are the only Torah Isurim for which we rely on l'Fi Tumo. The Mordechai says that one may rely on a Nochri regarding eggs. This is when Yom Tov is not after Shabbos, for then there is no concern for a Torah Isur. Rashi and the Or Zaru'a say that we rely on a Nochri l'Fi Tumo to taste whether Isur can be tasted in a mixture. Why may we? R. Tam forbids Ta'am k'Ikar (if an Isur can be tasted in a mixture, the mixture is forbidden like the Isur) mid'Oraisa regarding Min b'Eino Mino (a mixture of diverse species)! We can say that a chef is different. He would not lie or speak imprecisely, lest he ruin his reputation. The Tur says that the Rosh requires that he be a chef and he speaks l'Fi Tumo. The Rashba holds that either suffices by itself. How can the Rashba answer? He must hold like Rashi, that Ta'am k'Ikar is mid'Rabanan. We may not rely on l'Fi Tumo for a Torah Isur.

Poskim

Shulchan Aruch (YD 98:1): If an Isur became mixed with Heter,Min b'Eino Mino, e.g. Chelev with meat, a Nochri tastes it. If he says that he cannot taste the Chelev, or its taste is Pagum (detrimental), it is permitted.

Beis Yosef (DH veha'Rosh): The Tur says that the Rosh holds, like the Rashba, that the Nochri must speak l'Fi Tumo. It is not clear whether the Rosh is stringent also to require a chef.

Rebuttal (Taz 2): The Rosh is clear! He defines Kefeila to be a Nochri chef, i.e. we require a chef! The Rosh would not write this if it were not relevant. However, the Rosh connotes that if the Nochri knows that we rely on him for something other than Isur v'Heter, this is called l'Fi Tumo. This is not true for other cases of l'Fi Tumo, such as Edus Ishah. The Tur teaches that here, it helps.

Mishbetzos Zahav (Sof 2): E.g. if we tell the Nochri that people wagered about whether the Isur can be tasted, but he does not know that it affects Isur v'Heter, we rely on him here, but not in a similar case of Edus Ishah.

Beis Yosef (DH umi'Divrei): The Rambam connotes that we rely on any Nochri. He did not mention a chef. He holds that the Gemara mentioned a chef because this is a common case. Or, perhaps anyone who tastes something is called Kefeila, for this is something that chefs do. The Rambam does not require that he speak l'Fi Tumo. If he did, he should have specified. 'We rely on him' connotes that he knows that we rely on him for Isur v'Heter. Since the Rambam is lenient, we may rely on Tosfos, the Rashba and Ran, who do not require a chef to speak l'Fi Tumo. We may rely on the Rambam and Rashba to rely on a Stam Nochri. We do not see that the Rosh argues. However, he must speak l'Fi Tumo.

Taz (2): The Beis Yosef derived that the Rambam does not require the Nochri to be a chef. If so, we rely on him because he speaks l'Fi Tumo. The Ro'oh and Terumas ha'Deshen asked that we rely on l'Fi Tumo only for Edus Ishah. The Ro'oh said that this is because it is only a Giluy Milsa (something prone to become known). The Beis Yosef said that the Rashba rules that Ta'am k'Ikar is mid'Oraisa. Perhaps this is letter of the law, but for l'Fi Tumo, he relies on Rashi and the Rambam who say that it is mid'Rabanan. The Terumas ha'Deshen (2:130) also challenged the Rosh, who holds that l'Fi Tumo helps whenever the Nochri does not praise his merchandise. I answer that the Rashba and Rosh hold that the Gemara said that l'Fi Tumo helps only for Edus Ishah, i.e. when testimony is needed. Isur v'Heter does not need proper testimony. Any proof suffices. We find that one witness is believed to permit Isurim! The same applies to l'Fi Tumo, since there is reason to say that there is no Isur. We rely on a Kefeila, for he would not ruin his reputation. This would not suffice if we needed testimony. However, the Tur and Shulchan Aruch (YD 316:1) rule that we do not rely on l'Fi Tumo for a Bechor, therefore we never rely on l'Fi Tumo for any Torah Isur.

Question (Shach 2): The Beis Yosef says that we rely on any Nochri l'Fi Tumo, and on a chef even if he is not l'Fi Tumo. However, in Sa'if 2, he rules that Min b'Eino Mino that gives taste is an Isur Torah. If so, why may we rely on l'Fi Tumo? L'Fi Tumo helps for Edus Ishah, but not for any other Isur Torah! Bahag, the Rif, Rosh and Semag rule like this. The Rambam and other Poskim connote that here we rely on a Stam Nochri l'Fi Tumo, but perhaps they hold like Rashi, that Ta'am k'Ikar is not mid'Oraisa. Terumas ha'Deshen asked this against the Rashba, who forbids Ta'am k'Ikar mid'Oraisa! It is difficult to say that he said so for a mere stringency, and we rely on the lenient opinions regarding a Nochri l'Fi Tumo. My father-in-law asked that the Rosh requires a chef, but this is not because he would not ruin his reputation, for he speaks l'Fi Tumo. Rather, only a chef can perceive the taste. However, the Rosh rules like R. Tam (that Ta'am k'Ikar is mid'Oraisa). How can he rely on l'Fi Tumo? Also, if we relied on his concern for his reputation, we would not require l'Fi Tumo! The Mechaber rules that we rely on a Stam Nochri l'Fi Tumo even nowadays. The Yam Shel Shlomo (7:33) agrees, but in 7:46, he is stringent like the Rashba for Torah laws!

Shach (2): Some answer that in Bava Kama, we said that l'Fi Tumo helps only for Edus Ishah, i.e. when we know that there was an Isur. Here, perhaps there is no taste. This is difficult. There we asked why we permit a Shevuyah through a minor, l'Fi Tumo. We answered that we were lenient about a Shevuyah. What was the question? Perhaps she was never forbidden! The Rivash (433) says that a Nochri l'Fi Tumo is not believed about bottles used for wine 12 months ago, for even if we rely on l'Fi Tumo for Min b'Eino Mino, even if the Nochri is not a chef, here is different, for we know that there was an Isur. Surely, they used the bottles for Asur wine, and we seek to permit them through his testimony. We must say that the Rivash can distinguish because he holds like Rashi, that Ta'am k'Ikar is an Isur mid'Rabanan, just like we must distinguish according to the Rema (YD 137:6). Surely, for an Isur Torah we do not distinguish. I say that when we can never find out, we do not rely on a Nochri l'Fi Tumo for an Isur Torah. We can find out about Min b'Eino Mino, through giving it to a Nochri chef, therefore we rely on a Nochri l'Fi Tumo. It is clear that the Rivash distinguishes like this.

Gra (5): Why did the Shulchan Aruch omit that a Kefeila is believed in every case? This is like the Rambam, who omitted this. However, the Rambam holds that the Gemara mentioned Kefeila only because he recognizes the taste! There are four opinions. Tosfos requires a Kefeila. The Rosh requires a Kefeila who speaks l'Fi Tumo. The Rashba requires a Kefeila or any Nochri l'Fi Tumo. The Rambam does not require either.