Resources for Yevamos daf 101
1. The גמרא says that a son who is מסופּק which one of two men is his real father and hits them both at once, according to one version of רבי יהודה he is פּטור. The גמרא explains that we have a דרשה that says that you are only חייב on הכאה when there is no "שותפות". The קרן אורה has an interesting הארה: what if a son hit his father and a stranger at one time? Would we say he is פּטור as well since there is a שותפות of his father and the stranger or would we say this דרשה only means that since you wouldn’t be חייב on either person without the other then it’s considered שותפות but if each one doesn’t need the other than it isn’t a שותפות? The קרן אורה says that from our גמרא it’s משמע like the second צד but says the first צד seems to be brought by the תוספתא. Nonetheless, the ירושלמי is almost explicit that you would be פּטור in that case and since our גמרא sounds like that too he seems like he is נוטה that way.
2. The משנה discusses the מצוה of חליצה. There are a few basic discussions that are important to be aware of. First: is חליצה really a מצוה like shaking a לולב or is it just a מתיר like גט such that if the יבם and יבמה have no interest in marrying anyone (e.g. they are both very old) then there is no need to do חליצה at all? Second, is חליצה part of the מצוה of יבום where one simply chooses to do the מצוה one way or another or is חליצה a completely independent מצוה Where if you don’t want to do the מצוה of יבום you can do the מצוה of חליצה? As to the first question, the חכם צבי in סימן א as well the בית שמואל in סימן קס"ה ס"ק ט says that it is just a מתיר like גט, although the בית שמואל admits that according to the זוהר that one must do חליצה since the נשמה of the deceased has no rest until it is done. The עמק יהושע in סימן כ"ג says it is a regular מצוה. As to the second questions, theרמב"ם in ספר המצוות counts יבום וחליצה as separate מצוות whereas the ספר המצות לרס"ג counts it as one מצוה.
3. The משנה says that for חליצה you need a בית דין of three הדיוטות. The גמרא brings a ברייתא that explains that the פּסוק says זקני which means two judges and we understand from סברא that you need a third or else the ב"ד will have an even number and you won’t be able to break a tie. תוספות in ד"ה ואין ב"ד points out that at first glance that doesn’t seem to make sense in this case since this ב"ד isn’t going to have a two opinions since they are just there to watch the חליצה take place! He answers that there are still שאלות that can come up and you may need a הכרעה. However, in his second תירוץ he explains that for ב"ד to be considered a valid ב"ד they must have an odd number. The משנת יעב"ץ in חושן משפּט סימן ד points out that according to the first answer of תוספות, the only time you need a ב"ד of three is if there may be some הכרעה needed, but if you know that won’t be relevant then you don’t need three to be a valid ב"ד. Furthermore, if the only reason to have three people is in case when there is a מחלוקת, בדיעבד if one had only had two דיינים and there was no מחלוקת one would think it is not מעכב. However, according to the second תירוץ of תוספות, the ב"ד isn’t even called a ב"ד if there is an even number in which case it would be מעכב even בדיעבד. Theרמב"ם in in פּרק א׳ הל׳ ד explains the requirement to have three people in a ב"ד is because you can’t have an even number but never says you can’t have a ב"ד of 4 or 6. The משנת יעב"ץ suggests that the רמב"ם holds that the need to have an odd number of judges is simply part of the לימוד as to what the שיעור for a ב"ד is, but the concept of having an odd numbered ב"ד in and of itself is not מעכב so if you had four or six it would be a valid ב"ד.
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