A "miut hamatzui" is a phrased used to express a case where because of a small concern that something exists, or might happened, or does happen that the halacha is affected by this. An example is if there is a certain type of "treifah" by a kosher animal that is found in a small amount therefore this must be checked after that animal is shechted.

However what is the amount of a "miut hamatzui"? What are the different opinions in this?

(I don't feel my explanation of a "miut hamaztui" is adequate enough however it's difficult for me to express in English. Perhaps someone can edit it.)

  • 2
    related judaism.stackexchange.com/a/11570/759
    – Double AA
    Apr 11 '13 at 20:59
  • 1
    @DoubleAA thanks. But, makor? (aside from R' Shechter)
    – Yehoshua
    Apr 11 '13 at 21:21
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    @Yehoshua The generally cited mekor is the Mishk'nos Ya'akov (Vol. 1, YD § 17).
    – Fred
    Apr 11 '13 at 22:34
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    @Fred Sounds like an answer. However any other opinions, b'frat from earlier sources?
    – Yehoshua
    Apr 11 '13 at 22:48
  • It would be interesting to compare this to the pyschological studies on the same topic.
    – avi
    Dec 23 '13 at 13:27

Miut Hamatui has four opinions as brought down in the new Yalkut Yosef.

1) Rav Shelomo Zalman Aurbach who holds it is around 10%.

2) Shevet HaLevi who holds it is even less but doesn't specify.

3) Rav Bension Aba Shaul who says around 17%.

4) The opinion of the Rivash and Hacham Yishak Yosef Shelit"a who hold that it is much closer to 50% but doesn't specify.


Rav Eitam Henkin provides sources for all the various opinions on pages 39-62 of this kuntres.

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    please summarize the points incase the link goes bad.
    – avi
    Dec 23 '13 at 15:06
    – Avi M
    Oct 21 '18 at 12:18

Many poskim put it at 10% -- thank you Fred, Mishkenos Yaakov 1:YD17 first puts it that way. (See Rabbi JD Bleich's "Is the Milk We Drink Kosher?" in Tradition). This is the general OU opinion.

We find the figure of 10% by combining a law in Terumot -- about whether you must check that a bottle of wine in the case has spoiled before taking terumah from the batch -- with a law in Bava Basra -- about 10% being the normal spoilage rate when selling a case of wine.

The next question becomes -- 10% of what? Do I say "so long as the odds of eating a bug is <10% in this serving of lettuce, I can eat this serving"? Or perhaps we need "so long as the odds of finding a bug in this bag is <10%, I can buy this bag"? Or perhaps we even need "I can buy this case of lettuce without checking only if the odds of finding a bug anywhere in it are <10%"?

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