Resources for Kesubos 90

1.     The גמרא says in the name of רב that in a case where a  נכרית married a נכרי and they both convert, the wife gets the עיקר כתובה of מנה מאתים from the כתובה they wrote each other as גוים. תוספות in ד"ה לא שנו asks that even if they never wrote each other a כתובה the wife would get the עיקר כתובה since they are now Jewish and halachically married and it’s a תנאי ב"דso whats the relevance of the original כתובה? He answers that the חידוש is that she still gets the 200 even though now when he is remarrying her after conversion she is really a בעולה who gets 100. Theרמב"ם  in הלכות אישות פּרק י"א הל׳ ז says that a קטן’s wife gets 200 after he gets bigger but the גר’s wife only gets 100. The מגיד משנה there explains that this is because a נכרית is always בחזקת בעולה after three years of age. This leaves us with a question on תוספות: why did he say the גיורת would get 200? The תוספות יו"ט asks this question and answers that the נפקא מינה is that you have to pay the currency of the place it was originally written, בין לקולא בין לחומרא. This would not be an answer for תוספות.

2.     The גמרא discusses cases where it is unclear whether כתובת בנין דיכרין should apply. There is an interesting שילטי גיבורים here on מ"ט ע"ב בדפּי רי"ף אות א that discusses whether כתובת בנין דיכרין ever applies today. He quotes רבים מהגאונים who say that it shouldn’t apply today for the following reason: the purpose of חז"ל being מתקן  a כתובת בנין דיכרין was to make it that a father would be willing to give his daughter the same amount of money as his son. Nowadays, say these גאונים, people give their daughters more than their sons so the reason for the תקנה doesn’t exist anymore. Therefore, the תקנה is בטל. However, רבינו האי גאון says that it still applies since we can’t just throw out a תקנת חכמים just because the reason doesn’t apply anymore. What is the basis of this מחלוקת הגאונים? This would appear to hinge on a very broad מחלוקת as to when we say that once a תקנה is made it cant be undone and when we don’t. For example, we typically say it can’t be undone unless you have a ב"ד which is greater בחכמה ובמנין. However, sometimes we say that once the reason is gone then the תקנה is gone such as by the הלכה of גילוי where we say you can drink uncovered water since there are no snakes in American cities. In the ספר עקבי הצאן in סימן י"ט, Rav Schachter שליט"א suggests the following יסוד: we know that כל דתקון רבנן כעין דאורייתא תקנו. We also know that by a דיני תורה we have a rule of לא דרשינן טעמא דקרא which means we can’t pasken הלכות based on what we assume to be the reason of a מצוה. This is against the opinion of ר"ש who holds we can be דורש טעמא דקרא. However, the גמרא says that everyone agrees that if the reason for a מצוה is מפורש בקרא then you can pasken based on that reason. Similarly, one can suggest that if the reason for a מצוה דרבנן is included in the נוסח התקנה itself then one can pasken based on that reason. Rav Schachter suggests that by any case where חז"ל were עוקר דבר מן התורה they had to build in the reason for the תקנה into the תקנה since if it appears like a something they forbade for no reason it would be going against the תורה and חז"ל can only make גזירות to be a סייג לתורה. Therefore, by כתובת בנין דיכרין where it is going against the תורה’s prescription for how נחלה should work it is a כעין עקירת דבר מן התורה so the reason for the תקנה must be part of the תקנה.