Consider various statements in the Gemara such as:

והלכתא כוותיה דאביי ביע"ל קג"ם

The Halacha follows Abaye in Ya'al Kegam

הלכתא כרב נחמן בדיני

The Halacha follows Rav Nachman by monetary issues

Or ones in the Rishonim such as:

הלכה כבתראי

The halacha follows later authorities

כל היכא דפליגי רב אחא ורבינא הלכה כדברי המיקל

Wherever Rav Acha and Ravina argue, the halacha follows the more lenient opinion

Where do these principles (and others like them) come from? Seemingly they're completely arbitrary, which is very unlike Gemara to do. How were these conclusions reached?


There is really only one rule of pesaq that depends on who said what -- acharei rabbim lehatos (lean toward the majority).

Within a court (such as the Sanhedrin), this was a law of bitul berov -- nullification by majority. Meaning, after the votes are counted in the court, the opinion is that of the court, and it is the number of judges in the court that gives the opinion its weight. Not the number of judges who voted for the winning opinion.

Tosafos (Eiruvin 13b) say that the heavenly voice that came down to tell us "אלו ואלו דברי אלהים חיים הן, והלכה כבית הלל-- these and those are the words of the 'Living' G-d, but the halakhah is like Beis Hillel" actually endorsed the majority. It is not that we are ruling according to Divine Revelation rather than halachic process (which Eiruvin 6b tells us we should not do). So, why did we need a heavenly voice? Tosafos explain, "דבית שמאי הוו חריפי טפי -- for Beis Shammai were sharper."

Another example where sharpness doesn't win is Rabbi Meir (also Eiruvin 13b).

אמר רבי אחא בר חנינא גלוי וידוע לפני מי שאמר והיה העולם שאין בדורו של רבי מאיר כמותו ומפני מה לא קבעו הלכה כמותו שלא יכלו חביריו לעמוד על סוף דעתו שהוא אומר על טמא טהור ומראה לו פנים על טהור טמא ומראה לו פנים

Rabbh Acha bar Chanina said: It is revealed and known before the "One Who Spoke and the World Was" that in Rabbi Meir's general, there was no one like him/ And why didn't they establish the halakhah to be like him? Because his peers couldn't get at his conclusions. [Rabbi Meir] would say that the impure is pure, and prove the point. And he would say that the pure is impure and prove the point.

Rabbi Meir would explain both sides of a dispute so thoroughly and his peers so couldn't keep up that they couldn't figure out what he ruled!

Although when his student Rebbe did know Rabbi Meir's ruling, "סתם משנה כר' מאיר -- an unattributed mishnah is like Rabbi Meir" and "הלכה כסתם נשנה -- the halakhah follows the unattributed mishnah" over a mishnah where the ruling has a citation.

And that is more typical. Usually the person with a the sharper line of reasoning gains followers, and so his position ends up winning. Like the way Abayei so impressed his peers in the discussion of those 6 topics, or Rav Nachman when discussing monetary laws. Not because sharpness wins -- as we saw with Batei Hillel veShammai, but because sharpness usually causes popularity.

Notice the portrayal of Beis Shammai in the gemara I quoted was that it was more of an "eilitist" school. Smaller, and only accepting the sharpest students.

This relates to what Maurice Mizrahi wrote in his answer, drawing from another part of the same discussion in the gemara. Beis Hillel merited gaining following not only because they were more numerous themselves, but also because they showed respect for all opinions. People had a choice between listening to a Shammaite promote his own view, or a Hillelite present both sides of the argument fairly. And that humility won them followers.

This is what the gemara means in part of his quote:

ללמדך שכל המשפיל עצמו הקדוש ברוך הוא מגביהו וכל המגביה עצמו הקדוש ברוך הוא משפילו כל המחזר על הגדולה גדולה בורחת ממנו וכל הבורח מן הגדולה גדולה מחזרת אחריו

This teaches you that God raises up those who humbles themselves, and humbles those who exalt themselves; that greatness flees those who seek it and follows those who flee it...

(Which I guess means you should believe Maurice Mizrahi's answer. Because unlike Beis Hillel, I gave my own answer first!)


Not really arbitrarily. Hillel prevailed against Shammai because his disciples were kind and humble, and always quoted the other side’s opinions before their own, as the Gemara says:

R. Abba stated in the name of Samuel: For three years there was a dispute between Bet Shammai and Bet Hillel, the first saying, ‘the halachah agrees with us’ and the second [also] saying,’the halachah agrees with us’. Then a heavenly voice [bat kol] was heard saying, ‘Ellu v’ellu divrei Elokim Chayyim – These and these are the words of the living God, but the halachah agrees with Beth Hillel.’

However, since both are the words of the living God, what was it that entitled Beth Hillel to have the halachah agree with them? Because they were kind and modest, and studied both their own rulings and those of Beth Shammai and were even so [humble] as to mention the opinions of Beth Shammai before their own.

This teaches you that God raises up those who humbles themselves, and humbles those who exalt themselves; that greatness flees those who seek it and follows those who flee it; that time forces back those who force it and stands by the side of those who yield to it. [I.e., those so anxious to succeed that they take great risks are courting disaster, but those who do not tax their abilities will succeed in due course.]

[Eruvin 13b]

Perhaps the reasons were similar for the others.

  • I think we don't understand the logical reasoning the same, many people confuse a reason and an excuse. Most statements in the Gemmora are excuses (תירוצים) and not logically following reasons (סיבות). Those rules were established hundreds of years after, so that could not possibly be the reason. – Al Berko Mar 21 at 15:26
  • I'm kinda with Al on this. A distinction needs to be drawn between halacha decided at the time with halacha decided decades later, and between halacha decided by a Bas Kol which we then came up with reasons to justify and halacha which had no Bas Kol intervention. I'm not downvoting because this is a relevant Gemara, but I'm not accepting either, because it doesn't fully answer the question. – DonielF Mar 21 at 15:28

Most of the time, it is decided by the majority, even if the minority is widely considered more learned

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    Welcome to Mi Yodeya! Please take a look at our tour for information about this site. Can you elaborate on this a bit, maybe explain how this is different from this more detailed answer? – DonielF Mar 26 at 23:03

My conclusion is that all the rules of Psika of the Gemmorah itself and the later Poskim were set post factum, after we have the final Gemmorah. However, in the times of the Tannoyim ar Amoroyim nothing was certain and ruled out. Everyone was practicing his own Halacha.

  • This is similar to what we have in Israel now. Some follow R' Elyashiv Z"l and some R' Oyerbach and its fine with everyone. But in some 50 or 100 years, there'll be a need to streamline the Halacha and either will be chosen to follow, and our kids will say "of course we have a rule that R"E overrides R"O in Mamonos but it's the opposite in Issurim" or whatever.

  • Another example is B"H and B"S - did B"S know that the Halacha as B"H? No, they fought them harshly to set the Halacha. The rule was decided by the following generations.

  • If you notice there are usually hundreds of years between the original statements and the "obligating" Halachah or that "rule of Gmmorah you're talking about.

  • And of course, you can always wonder how come Rove argued with Abaye if the rule says the Halachah follows Abaye?

Another point, the purpose of those rules is to remember, to give a Siman, to ease the learning process.

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    This doesn't answer the question at all. All you've said is that these statements were decided later; this doesn't answer the question of how the Gemara came up with these statements. – DonielF Mar 21 at 15:30
  • That happens, sometimes I find myself answering a different question. But you asked "Where do these principles (and others like them) come from? " and I answered "all the rules of Gemmorah were set post factum, hundreds of years after". – Al Berko Mar 21 at 15:35
  • You asked "How were these conclusions reached?" and I answer - they were not reached by the Gemmorah itself but by other later Rabbis – Al Berko Mar 21 at 15:37
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    That's answering when they were reached not how or from where – Double AA Mar 21 at 16:24
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    To give one example that jumps out at me - Rabbi Eliezer always wants things to be perfect, and if they're not he wants you to bring them back to where they're supposed to be. Some individual instances of this are Peah 4:9 and 5:4, Sheviis 5:3 and 9:9 (the chachamim in 9:9 are talking sarcastically, see Bartenura), Shabbos 19:1, and more. Can you unify every single statement of R' Eliezer across shas, and then do the same thing for every other tana and amora? Probably not. But there are still unifying threads that run through a good number of his statements. cc @DonielF – Heshy Mar 25 at 17:53

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