Bechoros 46a - Who is the halachic mother?

The issue of surrogacy and determining whether parenthood depends on genetics or on birth is very complicated in halacha and difficult to prove. See here for an article by Rav Zalman Nechemia Goldberg Shlit"a where he proves from various sources that the mother who gave birth to a child is considered the mother in halacha, not the mother who donated the genetic material. This is not the forum to weigh in on such a major topic but one of the cases in our mishna opens it up for discussion. 

Regarding fatherhood, it would seem that it is determined by the one who contributed the semen, since that is the only active role the father takes in producing the child. However, we find that if a man would have relations with a non-jew, the child born would not be halachically related to the father. Rashi writes that if a woman converts while pregnant, the child wouldn't inherit from the biological father since conception happened with a mother who was a goy, the Torah no longer connects the semen to the father - דזרע מצרי רחמנא אפרקריה דכתיב וזרמת סוסים זרמתם. Tosafos agrees, but comments that if the mother converts while pregnant, the child anyway isn't related to the father because the child is considered a convert and גר שנתגייר כקטן שנולד דמי breaks his relationship with his biological family. Therefore, it would seem that in a situation where the bio mother and the surrogate mother are both jewish, we would consider the father to be the father. But, if either one is not Jewish, whether the father is considered the father would seem to depend on who is the mother. If the bio mother is considered the mother, perhaps we would consider the bio father the father even though his semen eventually was placed in the uterus of a non-jewish woman. But, if we consider the surrogate mother to be the mother, the biological fathers connection would likely be broken as well.

It seems that the answer to who is the mother may also lie in this case. When a woman converts while pregnant, we consider the child born after conversion to be a bechor regarding pidyon ha'ben - he is the פטר רחם. It would seem that before we entertain the ability of the child to be considered the פטר רחם of this woman, we must first consider him the child of this woman. The gemara says in Yevamos 78a that when a woman converts while pregnant, the conversion works for the child also and he is considered a convert (the womb isn't a chatzitza for the tevilla). Since we would apply כקטן שנולד דמי at the time of conversion, we would not consider the woman pregnant with her own child (even if conception would normally determine motherhood), yet when the child is born we consider him to be a פטר רחם. It would seem that birth determines the relationship between the mother and child because otherwise we shouldn't consider this child to be the פטר רחם. One can disagree with this logic by underlying the assumption. Perhaps motherhood is not a prerequisite for this child to be a פטר רחם. Therefore, even though we wouldn't consider him to be the child of this mother, he would still have kedushas bechor for pidyon ha'ben.

R. Zalman Nechemia cites an excellent proof that it is dependent on birth from the gemara in Yevamos 97b that says when a woman converts while pregnant with twins, the two brothers are considered brothers for the prohibition of אשת אח (if one would have relations with the others wife after he dies). Even though conception would not consider them brothers because they went through a conversion in the process, the halacha still considers them to be brothers because they are born from the same womb. Just as the relationship between the two brothers is determined at birth, the relationship to the mother should also be determined at birth. According to this approach it is not gestation or incubation of the surrogate mother that would determine her to be the mother in halacha, because the gemara indicates that the same halacha would be true if the mother converted well into her ninth month, a day prior to the birth of the child. Rather, it is the actual birth that would determine the familial relationships.

Rav Zalman Nechemia points out that the gemara in Chulin 70a would seem to imply the exact opposite. The gemara discusses a case where an animal gives birth to a bechor directly into the uterus of another, the second animal then gives birth to this bechor and the gemara wants to know whether a child that doesn't belong to it can exempt it from bechor (in the future). The implication of the gemara is that the child doesn't belong to the second mother, even though it also gave birth to it. However, Rav Zalman Nechemia rejects this proof. He points out that since the first animal also gave birth to it, the child already has a mother, therefore the second mother isn't considered a mother. But if the surrogate mother is the first to give birth to the child (as a viable human being or animal), the surrogate mother would be considered the mother.
According to Rav Zalman Nechemia Goldberg the proof from Yevamos 97b is sufficient evidence that the family relationship is established at birth, therefore the surrogate mother is considered the mother. It would therefore follow that if he surrogate mother were a non-jew, even if the genetic mother was jewish, the child would not be jewish.
However, my uncle, Rav Shabtai Rappaport has a very unique (and complex) approach to this issue that I found in an article online - see here. He considers the gemara in Yevamos 97 evidence for determining the family relationships in regard to עריות but not for the purpose of determining status as a Jew. He suggests that the fact that the gemara in Yevamos 78 considers the child of a pregnant convert to be going through his own conversion, implies that the child's religious affiliation is determined at conception by the genetic mother. Since the genetic mother is a non-jew at the time of conception, the child would not be a Jew unless we consider him to have undergone his own conversion. Even if the mother converts while pregnant and the child is born to a Jewish mother, this would not transform him into a Jew since his genetic material wasn't Jewish at the moment of conception. In the case of surrogacy it would then follow that the surrogate mother is considered the mother, but the genetic mother determines whether the child is a Jew. When the surrogate mother is a non-jew and the genetic mother is a Jew, the child will be Jewish but his "mother" will be the non-jewish woman.
The approach of Rav Shabbtai Rappaport is novel, but it is odd to separate between the question of who is the mother and the one who passes on the Jewish "gene". To me it seems that the proof from the pregnant mother converting doesn't force us to say that Jewishness is passed on by the genetic mother. Perhaps if the mother were able to convert without also converting the fetus she is carrying, the child would still become Jewish upon birth from a Jewish mother. But, since the conversion of the mother automatically works on the child that she is carrying, the child is considered Jewish due to conversion rather than a result of being born to a Jewish mother.

Bechoros 45b - Kohein Marrying a Gerusha

The Mishna says that a kohein who marries a woman who is forbidden to him must make a neder to make her off limits in order to be kasher to do avoda. The gemara says that even if he hasn't actually divorced her, he can make the neder to continue doing the avoda and divorce her when he is done with the avoda. The gemara explains that we insist on a neder rather than just a formal acceptance that she should be off-limits to him (which is what we require for a kohein who is me'tamei l'meisim) because there more of a yetzer ho'rah for women who are forbidden to him.

The Shulchan Aruch (128:40) writes that a kohein who is married to a divorcee is not allowed to do birchas kohanim, nor is he entitled to any privileges of a kohein such as reading first in the torah. Even if he actually divorces her, he isn't entitled to these privileges until he makes a neder על דעת רבים which cannot be overturned that he will not marry women who are forbidden to him. Although the gemara seems to allow him to continue to do avoda after making the neder, even before divorcing her, we demand both that he divorce her and that he make the neder. The Be'er Hei'tev explains that the gemara only allows him to temporarily complete the avoda because he will divorce her immediately when he is done, but he is not allowed to simply make a neder and continue to stay married to her (he must divorce her at the first opportunity).

The M.B. explains that this penalty applies only to aveiros that are specific to kohanim, not to aveiros that apply to regular Jews as well (such as chilul shabbos). The M.B. quotes the Rambam who explains that when a kohein is lax in one mitzvah we don't add to his laxity in mitzvos by forcing him to forfeit the mitzvah of birchas kohanim. The concern of a rasha giving a bracha to klal yisroel he downplays because the bracha is really from Hashem, not from the Kohein.

The situation recently arose about a kohein who has been living with a non-jewish woman for many years and was recently told that he can no longer du'chan. What is the status of a Kohein who is living with a non-jewish woman? Does this qualify as a violation of something that we penalize him for by removing his privileges to du'chan and get the first aliya, or is this considered to a be a violation of other aveiros that doesn't ruin his rights as a kohein (which the mishna berura says includes even arayos)? Would we consider being married to a gerusha worse in this sense than being "married" to a non-jewish woman? To me it would seem very strange that a kohein who is "married" to a non-jewish woman would be kasher to duchan but if she would convert (making the issur slightly less severe), he would be passul. It is possible that although we don't remove privileges of a kohein who violates arayos or other aveiros, that is because each aveira is separate and in between he is not in a state of doing aveira. But, when he is "married" to a goy, since he is in a constant state of "being married" (meaning living b'kvius with her), it is not better than being married to a divorcee and we don't let him du'chan. A similar distinction is made by the Biur Halacha who discusses a kohein who is me'tamei l'meisim. The language of the Shulchan Aruch implies that even if he only does it once he becomes passul, but the language of the Mishna implies that only if he does it regularly does he become passul. The Biur Halacha asks, why when he marries women even one divorcee would he become passul, he only did it once? To this he answers - כיון דהוא מחזיקה לאשה ועומד במרדו הלא הוא מועד לאיסור זה. Meaning, a kohein who marries a gerusha is in constant violation of the prohibition, and the same may be said when he "marries" a goy. It seems to me that although there is to תפיסת קדושין to a goy, the penalty should still apply. Just as those opinions who hold that there is no tefisas kiddushin between a kohein and a gerusha would certainly agree to the Mishna that we penalize a kohein from "marrying" a gerusha, the same can be said for a goy. Even though there is no technical tefisas kiddushin, the k'vius of being legally married or living together permanently could be similar to marriage to a divorcee.
I just found that the Aruch La'ner addresses this question in his teshuvos Binyan Tziyon (6).  SEE HERE. He seems to assume that a goy is considered a p'sul kehuna because the Rambam writes that a kohein who has relations with a goy receives lashes for relations with a "zona". The Rambam clearly considers a goy to be from the p'sulei kehuna. Yet, he leans toward being ma'tir since the issur here seems to only be a penalty d'rabonon and we only find it in a situation where he is actually married. However, he isn't willing to be matir l'ma'aseh unless another posek would agree with him.

Bechoros 38b - Is a Mum that can be cured considered a mum ka'vuah?

It is clear that when a bechor has a mum that will heal by itself, it qualifies as a temporary mum. Although it cannot be sacrificed as a korban until the mum heals, it would not constitute a mum to permit the shechting of the bechor as the gemara said on 37b. Tosafos discusses a mum that will not heal on it's own, but is curable through medical intervention. According to the first approach of Tosafos any mum that is curable, even if it will take medicines or surgeries, would qualify as a temporary mum thereby retain full kedusha of bechor. According to the second approach of Tosafos, a mum that requires some form of medical intervention to heal it, would qualify as a permanent mum and the bechor my be shechted and eaten without the medical intervention. 

This second approach of Tosafos opens up a very peculiar status. One can have a bechor with a mum that is curable but will not heal on it's own and is permitted to shecht it since it doesn't retain the kedusha of bechor. But if he decides to offer the medical treatment to cure the mum, the kedushas bechor will return. The Maharit Algazi questions whether this it is possible for the kedusha of a bechor to be restored through the healing of it's mum. It is very different than a temporary mum where the bechor retains it's full kedusha status even while it has a mum, just that it can't be brought as a korban. Here the kedusha status actually disappears when it gets the mum that will not heal on it's own, therefore you can shecht the animal and eat it, but if you fix the mum the original kedusha status will return. 

The Maharit Algazi cites a very interesting source for this phenomenon. The gemara says in Yoma 64a learns from a pasuk that after a temporary mum heals the animal can be brought as a korban. Why would we need a source for this, can't we simply learn from bechor that after the temporary mum passes the animal becomes fit for a korban? It must be that the pasuk comes to teach us that even when the mum is a mum that won't heal on it's own so that it qualified as a permanent mum and the animal lost it's kedusha status, after the mum is healed through medications the kedusha will return.

Bechoros 37a - Doing Avoda with Temporary Mum

The gemara says clearly that a temporary mum doesn't qualify as a mum at all to permit the shechting of a bechor outside the mikdash, or for redeeming pesulei hamukdashin.  However, it qualifies as a mum to prevent the animal from being brought as a korban until the mum heals. It isn't clear if a temporary mum would invalidate a kohein from doing the avoda even temporarily.

The Chachamim in the braisa say that a kohein cannot become a nirtzah since it will require the making of a mum and invalidate him from doing avoda. From this the gemara proves that the piercing is done in the cartilage part of the ear, rather than the fatty part, since in the fatty part it wouldn't make a mum. Rashi explains that a hole in the fatty part would heal and therefore not be considered a mum. Rashi implies that since the mum will heal, it isn't considered a mum at all to invalidate the kohein from doing the avoda, even temporarily. The Maharit Algazi points out that the third answer of Tosafos (d.h. ka'an) that a temporary mum would invalidate the kohein temporarily seems to be against Rashi.

Bechoros 31a - Paskening For Yourself

The Braisa says that one is not allowed to pasken on their own Bechor that it has a mum to allow himself to eat it. The gemara explains that we are speaking about a kohein who was given a bechor and qualifies as a יחיד מומחה who can normally pasken by himself, but we don't allow him to pasken on his own animal because we are afraid that he will be mo'reh heter for personal benefit.

Tosafos asks that based on this we should never permit anyone to pasken for themselves on any question of issur v'heter. Furthermore, the gemara in eiruvin says in that a talmid chacham can pasken for himself - how does this fit with our gemara?

The Rash in Negaim (cited by Gilyon HaShas) asks Tosafos question and says that it is dependent on whether it is אתחזק איסורא. When the item has a status of being forbidden and relies on the p'sak of the chacham to permit it, one cannot permit their own. But, when there is no default status of issur, one may pasken on their own. The Binas Adam (sha'ar issur v'heter 2) elaborates about this Rash and explains that when a question of issur v'heter would arise on the kashrus of an animal in the shechita process, that would qualify as a chezkas issur where one cannot pasken on their own. But, when it comes to checking the shechita knife on which there is no chezkas issur, one can check their own. It should follow from this that if the shechita knife would get a p'gam in it causing it to be invalid for shechita, the shochet shouldn't be able to check his own knife. However, the Lechem Chamudos (cited by binas adam) explains that anything which is one's control to fix, he is believed on even if it is אתחזק איסורא. Since the schochet can fix his knife by sharpening and removing the nicks, he is believed to say that it has been fixed.

The Binas Adam adds that we learn from our gemara that in a case which is אתחזק איסורא and not in one's own control to fix, even a talmid chacham isn't believed. This is clear from the case of Bechor where a יחיד מומחה isn't believed to pasken on his own.

Following this approach, the Chochmas Adam (109:6) paskens that although a husband may pasken on the bedika cloth of his wife (and she may pasken on her own), if a question develops about chatzitza while immersing in a mikva, the husband cannot pasken. The rationale for the distinction is that he can only pasken when it is not אתחזק איסורא. Once she is established as a Nida and the question is about her becoming tahora, it is אתחזק איסורא.

Bechoros 30b - Accepting Mitzvos Except for One

The Braisa says that a Goy who accepts Mitzvos with the exception of one mitzvah, is not accepted as a convert. R. Yossi Bar Rav Yehuda adds that even for a detail that is d'rabonon we don't accept him. It is unclear from the gemara whether אין מקבלים אותו means that l'chatchila the Beis Din pushes him off, or that even bidieved would prevent the conversion from being binding. In the Teshuvos Beis Yitzchok (cited by Achiezer 3:26:5) he questions whether this is only lichatchila or even bidieved. The gemara in Shabbos 31 about the story with Hillel and the ger who didn't want to accept the oral torah implies that it is only lichatchila. If acceptance of everything would be essential to the geirus working, Hillel couldn't have converted him today just because he was confident that later on he would truly accept. But if it is only a lichatchila, it would be possible for Hillel to convert him today and wouldn't reject him because he was confident that with time he would fully accept (Even within the approach of Rashi who says that he didn't reject the oral Torah just didn't trust it's divinity, it would still seem impossible for Hillel to accept him today unless it would be binding bidieved regardless).
R. Chaim Ozer (Achiezer) rejects the notion that this requirement is merely lichatchila. The Rambam writes that the acceptance of the mtizvos is integral to the conversion (similarly Tosafos in Yevamos writes that it must be done by day in the presence of a Beis Din), the gemara in Bechoros seems to simply be defining "accepting the mitzvos". Therefore, if one doesn't accept a Torah mitzvah the geirus isn't binding. But R. Chaim Ozer questions that perhaps the rejection of a Rabbinic mitzvah wouldn't invalidate the geirus on a Torah level. R. Moshe Feinstein (E.H. 2:4) concurs with R. Chaim Ozer that the accepting of all the mitzvos is essential and not doing so would undermine the conversion entirely. Just as for the Kohen and Chaver mentioned in the braisa, if they lack commitment to their requirements, their acceptance would be void even bidieved, the conversion of the goy would also be void bidieved.

However, there is a very fundamental dispute between R. Chaim Ozer and Rav Moshe regarding the definition of חוץ מדבר אחד. They were faced with Jews coming to convert who were living with non-jewish women and would be Rabbinically prohibited to stay with them after the conversion. Therefore, the entire conversion was with the assumption that they would be violating the issur of staying together. Another example would be a Kohein who comes to convert his non-jewish wife, and clearly plans on staying with her after the marriage. This would be a conversion with the intent of violating a Torah prohibition.
Rav Chaim Ozer (3:26:4) writes that one who converts with the realization that their desires to violate a mitzvah is too strong and they will be in violation, would not qualify as a חוץ מדבר אחד and the conversion would be binding. The Braisa only intends to exclude one who stipulates that they are converting on the condition that such activity will not be prohibited to them. They are essentially picking and choosing which laws will be part of their Torah. But one who accepts all of them, just that he or she intends to violate some of them, would be a valid convert. R. Chaim Ozer realizes that following this approach one can potentially "accept" all 613, but not keep to any of them - would their conversion be valid!? He qualifies this by saying that if we are sure that he will definitely violate major prohibitions in the Torah such as Shabbos and Kashrus, it is and indication that he doesn't mean to truly accept mitzvos, and the lip service of declaring his acceptance is worthless. It is hard to understand where exactly R. Chaim Ozer would draw the line. Perhaps he would not consider violation of details an invalidation of the conversion, only the uprooting of an entire mitzvah. The underlying approach of R. Chaim Ozer seems to be that one need not commit to fulfill every detail, but they have to accept and recognize that this is a prohibition which they should be keeping. Based on this R. Chaim Ozer permits accepting a convert who is honest about where he stands and says that he will not be strong enough to keep one of the mitzvos in the Torah.

Rav Moshe takes a much clearer and harder line on this issue. Anyone who converts with the understanding that they will not be fulfilling one of the mitzvos in the Torah, even if they theoretically recognize it and accept it's divinity, cannot be a convert and the conversion isn't binding. Acceptance by definition is accepting to keep it. Although a ger may be ignorant and doesn't need much education to convert (the gemara in shabbos discusses a case of a ger who wasn't aware of the issur to worship idolatry), he must accept to follow the mitzvos of the Torah as he is taught them. Rav Moshe is troubled with the gemara in Shabbos where Hillel converted someone who wasn't willing to recognize the oral torah. This seemingly is no worse than חוץ מדבר אחד so how was the geirus binding? He explains Rashi to be saying that the convert wasn't rejecting the oral Torah, rather the convert didn't yet believe that the p'sakim of Hillel and Shamai were part of that divine torah. He hadn't yet come to terms with the sages of the generation being able to convey the divine message but wasn't rejecting any particular law. Even so, Hillel wouldn't have accepted him as a convert unless he was confident that in the future he would recognize that even that the discussions of the Rabbis were part of the oral torah. Rav Moshe understands from Rashi that had this qualified as a חוץ מדבר אחד, the geirus wouldn't be binding even bidieved, but since it was merely a lack of education which misled him to think that the torah discussed by hillel and shamai wasn't part of the oral torah, Hillel's confidence that education  would change his attitude was sufficient to convert him today.
The D'var Avrohom (3:28) wrote a letter to R. Chaim Ozer thanking him for sending him a copy of his sefer and offers some comments on this particular teshuva. He writes to R. Chaim Ozer that after reading his distinction of "accepting the mitzvos" and "keeping" the mitzvos, he laughed - ואני חוכך בזה. In this aspect he concurs with R. Moshe that if one "accepts" something with the intent of violating, it doesn't qualify as an acceptance. But regarding the first issue whether the חוץ מדבר אחד is enough to invalidate the geirus, he questions that it may only be a lichatchila requirement as suggested by the Beis Yitzchok. Strangely enough, Rav Moshe (Y.D. 3:106) in a later teshuva leans toward saying that the חוץ מדבר אחד is only a lichatchila for the beis din to reject him, but is not me'akev the geirus. He bases this on the point that was mentioned by R. Chaim Ozer that the rejection of a d'rabonon couldn't invalidate the geirus on a Torah level, therefore it would just be a lichatchila. Since the same language is used for the rejection of a Torah mitzvah - אין מקבלים אותו, this would also only be lichatchila.

There are some orthodox batei dinim that are lax in their insistence on kabalas ha'mitzvos. According to R. Chaim Ozer this would often not prevent the geirus from being binding, but according to Rav Moshe (in the earlier teshuva) any mitzvah that wasn't fully accepted at the time of the geirus would invalidate the entire process.
Unfortunately, I have seem many converts who reject certain halachos such as hair covering and other tznius related issues very soon after their conversion, and there is reason to believe that they had never intended to adhere to these rules. R. Moshe (y.d. 3:106:1 end of section) writes that when the religious people of that community are lax in certain halachos, it wouldn't be fair to consider these things a חוץ מדבר אחד to invalidate the geirus because the fact that all the "religious" women don't abide by it, causes the convert to think that it is just a chumrah being imposed by the beis din.Therefore, rather than regarding this as a חוץ מדבר אחד where she fails to accept something, it can be regarded as a lack of education which would not invalidate the geirus.

Bechoros 29a - Payment for Mitzvos

The Mishna says that one is not allowed to receive payment for judging, testifying, or doing the mitzvos associated with para aduma, and if one receives payment he is penalized that we invalidate what he did. The gemara explains that this is based on a general principal of מה אני בחנם אף אתם בחנם, which is learned from a pasuk that demands that we model ourselves after G-d and not take payment for the doing of mitzvos such as teaching Torah or paskening on questions. Although there is already a prohibition against a judge taking a bribe, Tosafos explains that this source is necessary to forbid him from taking payment that is not meant to influence the outcome of the judgement (but if it influences the outcome in either direction, it is regarded as a bribe).

When the gemara cites the source for not accepting payment as being the requirement to model G-d and do it for free, Rashi gives the examples of authorizing a p'sak i.e. din, and teaching Torah. Rashi fails to mention the issue of testifying and preparing the para aduma waters. The Cheishek Shlomo suggests that accepting payment to testify according to Rashi is only prohibited m'drabonon, not from the Torah. If it were forbidden m'doraysa it would be tantamount to a witness taking money to testify falsely categorizing him as a רשע דחמס and being passul for all testimonly. The Mishna implies that we only invalidate this testimony, implying that his violation isn't d'oraysa. It also isn't clear from Rashi whether payment for other mitzvos is forbidden m'doraysa or only m'drabonon.

The Rashash cites the Bartneura who elaborates about those who officiate gittin and take payment. He is assuming that sidur ha'get qualifies as din and would invalidate the gett. However, the Rama (E.H. 154) says that it doesn't qualify as din, just as limud ha'torah. The Rashash points out that this would justify the gett being kasher, but wouldn't justify the practice to accept payment for officiating a gett since it would still be a violation of מה אני בחנם אף אתם בחנם as we find by talmud torah. Tosafos justifies those who take payment for studying Torah based on the דייני גזירות in Yerushalayim who relied on this for their livelihood and therefore became the community responsibility to support them so that they can maintain their important work. This logic may also apply to mesadrei gittin or those who do other mitzvos i.e. milah for their livelihood. Someone asked me how I can charge to do a bris - i answered that the mitzvah of bris milah is to cut. I don't charge for the mitzvah of doing a bris, I only  charge for stopping the bleeding.

Bechoros 25a - More about Davar She'eino Miskavein

The gemara suggest that R. Yossi Ben Meshulam agrees with Rav (who paskens like R. Yehuda) that דבר שאינו מתכוין is forbidden. How then does he permit the cutting of the black parts of the hairs of the פרה אדומה leaving behind only the red parts, although he isn't intending to be גוזז but to fix the parah a'duma, it should still be a violation? The gemara implies, and Rashi explains explicitly that since his intent when he is cutting the black parts of the hair is to fix the cow rather than take the hairs, it would be considered a דבר שאינו מתכוין. Tosafos points out that this seems to be a very strange application of דבר שאינו מתכוין. Normally a דבר שאינו מתכוין is where one doesn't even intend to do the ma'aseh issur, but where one intends to do the act of issur just that he is doing it for a different purpose than it is normally done for, it would be considered a מלאכה שאינה צריכה לגופה (which is a special p'tur in hilchos shabbos due to מלאכת מחשבת- it doesn't apply to other areas of halacha and even on shabbos is exempt from punishment but forbidden). In this case where the person is cutting the hairs of the parah a'duma intending to do the act of cutting, it would be similar to a standard מלאכה שא"צ לגופה, but shouldn't qualify as a דבר שאינו מתכוין? Tosafos asks this question in very few words -

 דאין זה כשאר לשון "אין מתכוין" בעלמא דכיון דבכוונה גוזז במספרים. Why does the gemara consider this to be a davar sh'eino miskavein? 

It seems to me that by certain מלאכות the purpose of the act is so integral to the melacha, that when the act is done for a different purpose it is tantamount to not intending to do the act at all. The prohibition of גוזז on kodshim is that it is forbidden to do things that enable one to take the products of the animal (whether it is the wool, the work in the field or the milk), while it is still alive. Although Tosafos (d.h. sa'ar) explains that the issur is a ma'aseh issur of cutting the wool, unlike the issur of the milk which is an issur on the product, the nature of the issur to cut the wool is because normally one would do this act to obtain the product. When one is גוזז but has no interest in the wool, it undermines the act of גוזז to the point where we consider him to not be intending for גוזז at all. Therefore, when he cuts the blackened parts of the hairs for the purpose of fixing the parah aduma, not for the purpose of using the hairs, it is considered as if he isn't intending to do the act of issur.

Bechoros 24b - Davar Sh'eino Miskavein

There is a machlokes between the Teruma HaDeshen and the Magen Avrohom whether we can be matir one to do a פסיק רישא דלא ניחא ליה - an inevitable action where he isn't interested in the issur outcome, when the issur is only d'rabonon. The Terumas HaDeshen permits a פסיק רישא דלא ניחא ליה באיסור דרבנן and the Magen Avrohom forbids it (O.C. 314:5). R. Akiva Eiger proves that the Magen Avrohom is correct from a gemara in Succah.

Normally we pasken like R. Shimon that a דבר שאינו מתכוין is permitted, not like R. Yehuda who forbids it. However, when it is inevitable - פסיק רישא, even R. Shimon admits that it is forbidden as the gemara says 25a. When the gemara speaks about a p'sik reisha it is usually in a context where the person is interested in the issur outcome. But when the person isn't interested in the outcome - פסיק רישא דלא ניחא ליה, Tosafos in Kesubos 6a cites the Aruch who permits it even by an issur d'oraysa. Tosafos disagrees and holds that it is forbidden at least by an issur d'oraysa. The Terumas HaDeshen and Magen Avrohom argue if we can be matir by an issusr d'rabonon.

Tosafos explains in our sugya that even though Rav paskens like R. Yehuda who forbids a דבר שאינו מתכוין, that is when the issur is d'oraysa. But if the issur is d'rabonon (either because it is mekalkel, or because תולש לאו היינו גוזז), it would be permitted. It seems that a דבר שאינו מתכוין  according to R. Yehuda is worse than a  פסיק רישא דלא ניחא ליה according to R. Shimon. The Aruch holds that פסיק רישא דלא ניחא ליה is permitted, so even though we hold like Tosafos that it is forbidden, we see that there is grounds to be matir. It would be logical to assume that if Tosafos holds that even R. Yehuda would permit a דבר שאינו מתכוין when it is only d'rabonon, according to R. Shimon who is always matir דבר שאינו מתכוין, but is machmir for a פסיק רישא דלא ניחא ליה, he would at least be meikel when the entire issur is only d'rabonon. This would seem to support the opinion of the Terumas HaDeshen, against the Magen Avrohom. However, the M.B. writes that l'ma'aseh, most achronim agree with the Magen Avrohom to forbid a פסיק רישא דלא ניחא ליה even when the nature of the issur is only d'rabonon.

Bechoros 23a - Understanding Bitul B'rov

The gemara raises a concept of an item which is batul whether it is viewed as כמאן דאיתיה דמי. The gemara assumes that if we regard an item that is batul as if it doesn't exist then when a tamei item is batul it wouldn't even be me'tamei by carrying, but if we regard it as existing even while it is ba'tul it would be me'tamei through carrying but not through touching. The gemara leans toward the distinction between carrying and touching implying that we view the tu'mah to be in existence even while it is batul. The rationale for the distinction between carrying and touching is that when one touches something they cannot be touching every molecule at once. Therefore, we can only consider him to be touching an item of tu'mah if the majority is ta'mei, otherwise we would consider the entity to be not tamei. However, when it comes to ma'sah, since when something is carried, every molecule in it is carried, the existence of the tu'mah even as a minority would render the carrier tamei.

Tosafos (d.h. 23a) asks that eating an item should be more similar to tu'mas ma'sah than to tu'mas ma'ga. Why do we permit one to eat an issur that has been batul in rov? Since the minority is considered to still be in existence, it should be comparable to ma'sah where the entire item is being carried or eaten and therefore should be eating issur? Tosafos answers that when one eats something, every small amount that is swallowed is batul b'rov and is therefore similar to ma'ga where the touching of multiple times doesn't make it as if were touched at once. Therefore, just as by tu'mas ma'ga we would identify the entity based on the majority ingredient, the same would be for eating. Tosafos assumes that it would be impossible to eat the entire amount all at once. Perhaps it is because the בית הבליעה can only contain a beitza at one time which it 2 kezaysim. For there to be a full kezayis of issur in the בית הבליעה at once of something that has been batul b'rov, there would have to be more than 2 kezaysim in the beis ha'blia at one time, which is impossible. Furthermore, there should be an issur of eating even a chatzi shiur of issur, unlike tu'mah for which there is no contamination if it is less than the amount needed to be metamei.

The Rosh (Gid HaNashe end of 37) asks the very same question as Tosafos except that the Rosh preempts the answer of Tosafos in his question and says that one should have to be careful to eat in a way where every swallow could potentially contain only the heter food and not the issur food so that it would be more similar to ma'ga than ma'sah? The Rosh answers that we cannot compare tu'mah to issur. There are two types of tu'mah, therefore the chiddush of bitul b'rov may apply to one and not the other, such as to ma'gah and not ma'sah. However, regarding eating, if we would consider there to be any issur in what the person was consuming, the Torah wouldn't allow it's consumption. The fact that the Torah allows one to eat issur that has been ba'tul is a gezeiras hakasuv that in the world of issur, we view it כמאן דליתיה דמי, as if it weren't in existence. Therefore, a piece of issur that is batul in two pieces of heter can even be cooked together (on a torah level) and eaten all together as if the issur disappeared.

The approach of the Rosh seems to assume that the concept of tu'mah that has been batul being metamei by carrying to be d'oraysa, whereas Tosasfos concludes that it is likely only m'drabonon.

Bechoros 22a - Shiur for Opening of Uterus

The gemara quotes the Mishna in Ohalos (7,4) which says that the shiur for pesichas ha'kever is עד שיעגילו ראש כפיקה. The gemara explains that it is the size of a פיקה של צמר which is used for the שתי stitch. The context of the mishna is to know at which point the cervix is considered open enough so that the dead fetus inside can no longer be considered טומאה בלועה and will be me'tamei the vessels that are in the same room as her. It is unclear if this is also the shiur for פתיחת הקבר in the context of the statement in nidah - אין פתיחת הקבר בלא דם. The Nodeh B'Yehuda cited by the Pischei Teshuva (Y.D. 194,4) says that even forcing the cervix open from the outside would qualify as an opening of the cervix and we would have to be concerned that some blood was let out of the cervix. R. Moshe (Igros Moshe Y.D. 1, 83) says that although the binas adam and chasam sofer disagree with the nodeh b'yehuda, they only disagree when one would use a finger to open the cervix because they assume that a finger wouldn't reach through the cervix. However, even they would agree with the Nodeh B'yehuda that if a tool or instrument is used to enter the cervix, it could qualify as an opening of the cervix where we would say אין פתיחת הקבר בלא דם. R. Moshe (Igros Moshe Y.D. 1, 89) says that although the Nodeh B'yehuda says that only something with a very small diameter such as a pieces of straw wouldn't be considered an opening of the cervix, implying that if it were slightly larger it would be considered an opening of the cervix rendering her a nidah. R. Moshe disagrees because the only shiur that we find in chazal for the opening of the cervix is the shiur of כפיקה של צמר, which they also term as a פתיחת הקבר, therefore it is logical that this would be the shiur also in the context of אין פתיחת הקבר בלא דם. Although it is difficult to know exactly the size of the פיקה של צמר that is used for the שתי stitch, R. Moshe assumes that it must be smaller than the diameter of a small finger. Being that the Rambam paskens that it is possible to have an opening of the cervix without any bleeding, and it is possible that an externally forced opening wouldn't qualify as a פתיחת הקבר, R. Moshe is confident in being lenient with any instrument where the diameter is less than the size of an average persons pinky finger.

Bechoros 21b - What Can You Assume When Buying an Animal from a Jew?

The gemara has three opinions when one purchases an animal from a Jew and wasn't told whether or not it had already given birth to a Bechor. Rav says that the assumption is that the first born will be a bechor because if the it had already given birth the Jew would have mentioned it to praise his the item he is selling. Shmuel says that it is a safeik since the seller may have assumed that the buyer wanted it to shecht so it wasn't relevant whether or not it had already given birth. R. Yochanan says that the buyer can assume that it is not a bechor because there is an obligation on the seller to notify the buyer if the first born would be a bechor otherwise he would be in violation of lifeni iever (tosafos).

There is a machlokes Rashi, Tosafos and Rabbeinu Gershom within the opinion of Rav as to what the advantage would be in telling the buyer that it had already given birth. Rashi says that it would have more value since the animal born from here on wouldn't have to be given to the kohein. Rabbeinu Gershom says the advantage would be that it is an animal capable of providing offspring. Tosafos (quoting rashi) says that the advantage would be that the animal has proven it is capable of surviving child birth and therefore more valuable. The Maharit Algazi asks although when the seller doesn't say anything we don't have to be concerned that it actually gave birth to a viable child, but why are we not concerned that it miscarried (ti'nuf) which would also exempt the next born from being a bechor? He explains that according to the rationale of Rashi and Rabbeinu Gershom, the logic would apply to ti'nuf as well. According to rashi since ti'nuf exempts from having to give the next born to the kohein, the seller would notify about tinuf as well. According to Rabbeinu Gershom, perhaps even ti'nuf would be an advantage in showing that it is capable of conceiving (although wasn't able to produce a viable offspring). But, according to Tosafos where the advantage is that the animal is capable of surviving childbirth, this wouldn't apply to ti'nuf. According to Tosafos the seller would have no reason to tell the buyer about the ti'nuf so we should be concerned that it was me'taneif and the next born may not be a bechor? Perhaps this is why Tosafos offers an alternate approach.

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Tosafos writes that only a Jew would be believed about the advantage of having already survived a childbirth and therefore being more valuable but a goy wouldn't be believed about this. Tosafos proves from here that even if a goy is מסיח לפי תומו, talking without trying to make a halachic statement, he isn't believed since we assume he is lying to make the item seem more valuable. The Maharit Algazi asks that this implies that if the goy was truly מסיח לפי תומו and not trying to make his item seem more valuable he would be believed even for bechor. But, the gemara says in yevamos that a goy is never believed מסיח לפי תומו on an issur d'oraysa, he is only believed when he is מסיח לפי תומו on an issur d'rabonon, but this is an issur d'oraysa? From this the Maharit Algazi concludes that the Rov of most animals having already given birth after reaching the ages listed earlier in the perek, is a valid rov on a d'oraysa level, just m'drabonon not a good rov since it is dependent on an action (gemara 20a). Since m'doraysa we have a rov that the next born is not a bechor, and it is only d'rabonon that we can't rely on the rov, we can believe a goy if he is truly מסיח לפי תומו without any motive to glorify his item.

Bechoros 19b - Following the Majority

The gemara suggests that perhaps the halacha of following rov only applies to רובא דאיתא קמן, a rov that is in front of us such as the majority of the sanhedrin voting on an issue, or 9 kosher stores and one non-kosher. But a רובא דליתיה קמן may not command the same status and we wouldn't follow it. The gemara rejects this from the fact that we follow the majority in assuming that most children will not turn out to be a s'ris or ay'lonis, even though that is dependent on a statistic of רוב קטנים לאו סריסים ורוב קטנות לאו איילונית נינהו, which is a רובא דליתיה קמן. However, why do we consider the rov by ketanim to be a רובא דליתיה קמן - just as we consider the 9 stores to be a רובא דאיתיה קמן, we should consider the rov of ketanim to be רובא דאיתיה קמן since most ketanim that are alive in the world today aren't s'risim or ay'lonis? Rabbeinu Gershom seems to address this question and writes- דלא חזינא רובא דעלמא אי הוי סריסים אי איילונית אי לא ואפ"ה אזלי בתר רובא. Even though we have a statistic telling us something that exists right now, since the numbers aren't obvious and can't be counted in front of us, it would qualify as a רובא דליתיה קמן. Similarly, the fact that most cows aren't treifos is a רובא דליתיה קמן because the statistic will not create a רובא דאיתיה קמן since they cannot be counted in front of us.

On another note, the gemara says that we don't follow a rov that is dependent on an action such as the fact that most animals would be pregnant by a certain age, which is dependent on the action of mating with a male. The rationale for not following this rov, the Ramban (Halachos of Bechoros) writes that a mi'ut which happens by itself is stronger than a rov that is dependent on an action. Rashba in Chulin 9a says that this limitation is only d'rabonon. Meaning, m'doraysa we follow rov even if dependent on an action but the Rabbonon tell us not to. Therefore, the Chazon Ish writes that we can only be machmir to not follow a rov dependent on an action, but we cannot be lenient to do so. The Binas Adam (sha'ar rov v'chazaka) proves that the Rashba is correct that it is only d'rabonon based on Tosafos ד"ה אי בעית אימא who says that R. Meir who is concerned for the mi'ut is only d'rabonon. Since the first answer of Rava that the concern of the mishna that the animal born now is a bechor is only m'drabonon, the answer of Ravina about not relying on rov which is dependent on an action is also only d'rabonon. However, this proof isn't very solid because when there is a chazaka that supports the mi'ut even R. Meir would agree that we are concerned for the mi'ut even m'doraysa and here there is a chazaka that supports the mi'ut (as tosafos explains in d.h. me'chvarta). The issue of whether R. Meir is concerned for a mi'ut only m'drabonon or even m'doraysa (when there is no chazaka), is a dispute between tosafos and mordechai (mentioned in this blog on the first perek of chulin).