לזכות הרב אליעזר זאב בן דבורה וכל בני ביתו
ר' אריה בן דבורה וכל בני ביתו
ר' דניאל יעקב בן שרה ליבא וכל בני ביתו
R' Eliezer maintains that if one transgresses a תולדה במקום אב he is חייב two חטאות [Bava Kamma 2a].
The גמרא therefore asks why there is a distinction between אבות and תולדות. There seems to be no practical difference whether a מלאכה is an אב or a תולדה. If one transgresses an איסור שבת intentionally and was warned beforehand, he receives סקילה regardless of whether it was a אב or תולדה. And if he did both an אב and תולדה in one forgetting [בהעלם אחד] he is חייב שתים. So what is the difference according to him between an אב and תולדה?
Tosfos will (initially) argue that it is important to categorize the מלאכות into אבות in order to warn the transgressor properly.
Asks Tosfos: But let us say that there is a consequence in referring to certain מלאכות with the term אב regarding the warning which the transgressor must receive in order to be punished; it is necessary to warn for the transgression of a תולדה by its specific אב otherwise the transgressor cannot be punished As the גמרא states in פרק תולין and asks; on account of which אב do we warn one who is משמר (strains wine) on שבת? The גמרא continues that it is a dispute - רבה אמר משום בורר רבי זירא אמר משום מרקד. Rabba [not a woman Rabbi:-)] maintains that he is warned on account of the מלאכה of בורר (selecting); while ר' זירא maintains that he is warned on account of מרקד (sifting). It seems evident from that גמרא that it is necessary to warn a תולדה, by mentioning the אב. It is therefore understood why the חכמים divided the מלאכות into various אבות; in order to properly warn a transgressor. The question therefore is, why does the גמרא ask that according to ר"א what is the purpose of calling certain melachos "אבות" when there is an obvious purpose?!
תוספות answers that this is indeed what the גמרא here answers; ‘these מלאכות which were in the משכן are called אבות’ and it is necessary to warn the תולדה in the name of the אב . The question which תוספות initially asked (which would answer the s'גמרא question), is indeed what the גמרא actually answers. The חכמים instituted אבות in order to be able to warn the תולדות. The אבות were chosen to be those מלאכות which were in the mishkan.
תוספות answers that this is indeed what the גמרא here answers; ‘these מלאכות which were in the משכן are called אבות’ and it is necessary to warn the תולדה in the name of the אב . The question which תוספות initially asked (which would answer the s'גמרא question), is indeed what the גמרא actually answers. The חכמים instituted אבות in order to be able to warn the תולדות. The אבות were chosen to be those מלאכות which were in the mishkan.
Ad kan divrei Ha-Tosfos [with help from Tosfosinenglish.com].
FREGT the Minchas Chinuch: According to Tosfos one must give התראה by mentioning the name of the אב and if התראה were given with no specific Av Melacha then he would not be punished, even if he mentioned the תולדה. But this doesn't work with the Rambam [Sanhedrin 12-2] who writes that התראה just requires telling the person that what he is doing is a punishable aveira. And even according to Rashi [Shvuos 20b] who holds that one must give התראה by mentioning the pasuk of the לאו, why is it not enough to say that he is going to transgress the pasuk of לא תעשה כל מלאכה when he does this תןלדה. Why should he have to mention the לאו? So Tosfos seem to be alone in their understanding which also seems to defy logic.
HaGaon Rebbi Abba Berman explained Tosfos as follows: There are two ways of looking at the איסור of מלאכות שבת. One is that there is an umbrella [which happens to be muktzeh on Shabbos] name called "Shabbos" under which we categorize all 39 melachos. Another perspective is that each of the 39 Avos melachos is a שם איסור בפני עצמו and all of these independent איסורים are include under the לאו of Shabbos. Tosfos understood the second way. Thus we understand why specifically the Av must be mentioned.
That reminded me of this post where we quoted a Tosfos Rid [who Rebbi Abba cites] who says just that and we added mareh mekomos.
