What's Rashi Zevachim 22a reason to say דלא חשיבא שיעור זוטרא דרביעית לבטולינהו as explanation of
ודכוותיה בנטילת ידים לא משלמי שאם היתה בו רביעית מים ונתן ממינים הללו לתוכו רובע רביעית ונטל כנגדם פסולה
Why doesn't ביטול ברב work according to Rashi's reason, why should that bitul process be affected by how much volume is in the water being mevatel the minority substance inserted into it?
In משנה אחרונה משניות מקוואות פרק א משנה ז ופרק ז משנה ב
very interesting that Chachamin entirely stopped ביטול ברב של שאובין במקוה to the extent of kulah when they fall into זוחלין
Possible mehalech for netilas yadayim but need sources.
Further the concept of דבר חשוב not batel, one could argue that if something unimportant falls into something unimportant, the faller takes the status of דבר חשוב not batel and to stretch to argue that this is what Rashi means. I don't like that bc Rashi stresses that the water the fruit juice fell into is so small as to not have chashivos to be mevatel.
What is the source that a bitul target that isn't chashuv can't be mevatel? That the faller, if chasuv, isn't mevatel seems to be well sourced.
Daniel Gray, Canada
Shalom R' Daniel,
It's great to hear from you again, and thank you for a sharp question.
To start, the Sefas Emes asks essentially your question, adds several related points, and leaves it as Tzarich Iyun. In recent Sefarim on Mikva'os and Netilas Yadayim, this issue is discussed at length, especially how to define the Revi'is for Netilas Yadayim. Is there a notion of the water in the Kli having a Ko'ach Taharah or "Chashivus," or is the Shi'ur purely functional, meaning only that a Revi'is must reach the hands? Some try to read Rashi here as proof one way or the other.
In any case, your direction from the Mishnah Acharonah is appealing. He shows that there is no Bitul b'Rov by Mikva'os, as seen from the fact that a minority of She'uvin can invalidate a Mikveh and are not Batel. If so, the later "leniency" -- where one first adds invalid waters and then draws out from the valid until the Mikveh repairs itself -- is not standard Bitul b'Rov at all. Rather, it works with a different logic: as long as the Mikveh retains the status of a complete, kosher Mikveh, the invalid waters can be subsumed because they do not change that status, and after they have been subsumed one may even draw out from the valid, even though now the invalid waters are part of what keeps the Mikveh kosher. This kind of mechanism likely applies only to a large body that carries a halachic "Shem" (status) of Mikveh.
For a Revi'is of Netilas Yadayim, however, the Shi'ur is functional, not a "status-bearing" entity. You cannot treat that small quantity as a "Chashuv" target to which a small amount of Pesul can be "joined." That helps explain why Rashi's line about a small volume lacking significance blocks Bitul in our case of Yadayim, even though Mikva'os have a different pathway.
All of this is on the level of suggestion. The question is excellent, and this is only a possible approach.
Kol Tuv,
Aharon Steiner