Tuesday, December 01, 2009

trei k'me'ah: quantity of proof vs. quality of proof

Two witnesses can charge that one or both of a pair of other witnesses are thieves (or some other psul) and disqualify them from testifying. However, two witnesses would not be believed if they charge that the testimony of other witnesses is a lie. We would be left with a case of trei u’trei, a standoff. Tosfos (B"K 72b d"h ain) asks: why in this second case would we not believe the accusing witnesses that their counterpart’s testimony is a lie migu that they could just accuse their counterparts of being thieves and disqualify them?

The first answer of Tosfos focuses on metziyus. Migu assumes that were someone to lie, he would tell the best lie possible; a defect in a claim is evidence of its truthfulness. This sevara does not apply when speaking of two witnesses because two people practically would be unable to coordinate a story to fabricate a better lie.

The second answer of Tosfos is based on a din. We know that the testimony of 100 witnesses is no better proof than the testimony of 2 witnesses: trei k’me’ah. We also know that the testimony of witnesses is stronger proof than migu. So if 100 witnesses are no better proof than 2 witnesses, QED that 2 witnesses + a migu are no better proof than 2 witnesses alone.

According to the second answer of Tosfos, migu adds no credibility. However, according to the first answer of Tosfos, were it theoretically possible to apply the sevara of migu, it would make a difference. What is the point of debate?

R’ Elchanan (Koveitz Shiurim) writes that there are two ways to understand trei k’me’ah.
1) Relative: One type of proof can be weighed against a qualitatively different type, e.g. ruba v’chazakah ruba adif, rov is better proof than chazakah, but there is no difference between a greater or lesser quantity of the same type of proof. All proof through testimony, be it from 2 or 100 witnesses, amounts qualitatively to the same thing.
2) Objective: testimony of two witnesses is by definition the highest degree of proof possible and therefore cannot be trumped by anything, even a greater quantity of witnesses.

If trei k’me’ah just tells us that different quantities of the same proof equal out, then adding a qualitatively different type of proof to the mix, e.g. adding migu to one side of the scale, tips the balance. However, if trei k’me’ah means that by definition there is no proof of any type superior to that of two witnesses, adding migu to the scale has no effect.

Question/observation: according to R' Elchanan's first approach, the scales only move when we compare and weigh qualitatively different forms of proof against each other, not different quantities. Sounds to me like this means that sugyos that invoke two chazakos beating one (e.g. the discussion in Nidah 2-3) work only if the chazakos being weighed are qualitatively different. It would be interesting to test if we could really come up with qualitative differences between all the various forms of chazakah, but that type of project is beyond me at this point.


  1. Here's how I explained it...

    Whatever was witnessed was thereby qavu'ah. Therefore terei kemei'ah is an instance of kol qavu'ah kemechtzah al mechtzah dami. More like REW's #2.

    I use this notion that qavu'ah, eidus and chazaqah demei'iqara operate on a different plane than rov and chazaqah disvara to answer some further questions. See Aspaqlaria: Halachah and Phenomenology part 2,
    part 3, and part 4.

  2. Kavua by eidus??? Never heard of such a thing. You don't have a ta'aroves so how can you apply kavu'a?

  3. I don't understand your objection.

    Who requires a taaroves? Ruba deleisa leqaman also lacks a taaroves. But more to the point, isn't the whole point of qavu'ah (translate the word) that there is no taaroves, which is why we can't apply kol deparish?

    As I wrote in the first of the posts I linked to, shu"t R' Aqiva Eiger #136 says the chiluq between parish and qavu'ah is as follows:

    There are forms of birur of the halakhah when the situation remains uncertain, and

    There are forms of birur that allow us to presume things about the situation.

    In other words, the doubt could be about the reality, and now we need a halakhah, or the halakhah could have once been set, but now we don’t know what it is.

    When something is qavu'ah, it is in the latter category. The halakhah in principle exists, but we don't know what it is -- the doubt is in the din, not the metzi'us.

    Rov only works when the doubt is in the metzi'us. In that series of posts, I give a theory as to why rov is sufficient WRT metzi'us that has to do with a more general theory about the role of mitzvos. (It starts with why we make birkhas hachamah on a celestial event that only exists in how our minds approximate things and why we care about taam in keilim. That's why I didn't link to part I.)

    I'm arguing that RAE's explanation about why rov can't be used WRT qavu'ah also applies in a case of terei uterei or terei kemei'ah. The eidim who are being honest established the din, now the safeiq is in that din, not in the metzi'us. Thus, rov is irrelevent.


  4. What does rov have to do with kavua? You can rov about human behavior, so it's obviously not a din in ta'aroves, but where do you ever have a case of kavua outside a ta'aroves? 9 frogs and 1 sheretz, 9 yiraelim and 1 kna'ani, etc.-- all ta'aroves issues. Bring me an example to the contrary.

  5. I'm still at a loss as to your question...

    I raised ruba deleisa leqaman to show that birur doesn't require a taaroves, e.g. we can apply rov without one.

    But in any case, I fail to understand your point. Is it against R' Aqiva Eiger's chiluq, my applying the same sevara to terei kemei'ah, or my stretching the word qavu'ah to cover all cases where that sevara applies?


  6. Anonymous9:31 PM

    No comparison between witnesses and chazaka. Chazaka is not a proof - the fact that something was so yesterday does not prove it is so today. Chazaka is guidance regarding what to do when you have a doubt. But it does not alleviate the doubt. (Yes I know there's a lot of disagreement on this but even those who disagree only hold chazaka is a "din-birur" not a real proof.) Tosfos was talking about proofs, not "dinei hanhaga."

    Also, it is possible that the idea of quantity vs. quality only applies to witnesses not to other types of proof. Because we learn trei k'meah from a posuk talking exclusively about witnesses - shnayim o sheoshah - so I dont see any compelling reason to extrapolate to other forms of proof.

    Or, it is possible that trei k'meiah really means not that 2 witnesess have the power of 100 but rather than 100 have the weakness of 2 - trei k'meah really means meah k'trei, in which case Migo would work in Trei UTrei (this may be used as an explanation of my previous idea, above).

    Reb Elchonon also says Migu may work by trie utrei if migu is a zechus hattaneh.

    Anyway, there are dozens of ways to look at this - so I dont think you can make your conclusion.

  7. R' Elchanan introduces the example of ruba v'chazakah here, not me, so he opened the door to stretching things beyond the paramters of eidus.
    I'm not sure I follow what you are driving at by saying chazakah is a hanhagah and not birur -- so what? If 2 proofs cancel each other out, kol she'kein opposing hanhagos?
    The question I am raising is how far you can take R' Elchanan's point, but I'm wondering what other dozens of explanations you have in mind for the Tos.

  8. >>>Reb Elchonon also says Migu may work by trie utrei if migu is a zechus hattaneh.

    Migu may work for the ba'al din (Koveitz Shiurim #4), but the discussion here is whether it works to bolster the ne'emanus of the eidim.

  9. Anonymous10:41 PM

    yes, r. elchonon is shver because he extended it beyond eidus.

    I dont agree with your kal vachomer - two proofs may cancel each other out because since proof tells us about a metzius, and the metzius can only be one way, two contradictory proofs nullify each other because you have to net them out to see the sum total of evidence; but a din hanhaga, because it is not contingent on representing the reality, can exist even if contradicted by another one. All you have in such a case is contradictory instructions, not a +1 and -1 that = 0.

    reasons why migu may work in trie utrie:

    1) trei kemeah may mean meah ketrei,

    2) trei kemeah may be limited to eidus not other forms of birur

    3) eidus may not be birur altogether but rather geziras hakasuv, like rambam in hilchos deos (I think thats where it is), in which case trei kemeiah has nothing to do with birurim altogether

    4) migu may be zechus hatanah, therefore not a birur and would work in trie utrei like a chazakah does

    5) migu may be halachah lmoshe misinai - bais yaakov kesuvos 9 - and so may not be a birur and therefore work in trei utrei

    6) migu may be from the gezeiras hakasuv of peh sheasar (kesef nivchar) and therefore may not be birur and therefore work in trei utrei

    7) The migu of tosfos is that the second pair can make the first pair posul, which works even though trei kemeiah - so if migu is zechus hataaneh then they would obtain that special ability to work even though trei kemeiah in their testimony (this is different than #4 which simply means that zechus hatanah is not a birur so it would work like chazakah in trei utrei. Now I am saying the migu works due to the particular nature of the better taaneh - a different migu would not work)

    ...that's all I can conjure up right now...

  10. Anonymous11:22 PM

    and if memory serves, reb elchonon also says zechus hataaneh can work for eidim too

  11. The only problem with all your theories is that Tosfos says black on white that migu does not work in a case of trei u'trei -- the only question is why. Before getting into whether your suggestions are right or wrong, you first need a Rishon who says argues on Tos. and says migu works. I don't think R' Elchanan says this, but if you know where he does, by all means pls. let me know and we can continue the discussion.

    A few months ago I wrote about how the issue of hanhagah/birur plays into trei u'trei -- see here:

  12. After a quick glance at the reasons you provide, they all revolve around the same central point: migu is a different type of proof than eidus and therefore it helps. But the whole point of R' Elchanan is that if eidus is the strongest form of proof possible, then whatever other cards you hold -- whether another form of birur or a hanhaga or something else -- will not help. Nothing trumps eidus.

    You can only start the discussion of why migu may help if you forst accept R' Elchanan's chiddush that eidus is not an absolute trump card -- it is just a trump card relative to other eidus. Without that, you don't have a leg to stand on.

  13. FWIW, my extention of RAE's shitah works for migu. (As discussed at length on Aspaqlaria.) Terei uterei produces a situation where more vs less evidence goes out the window.

    One thing that could break the tie is a chazaqah demei'karah (Sheiv Shemaatesa 6:22). I suggested that this is because it too is a birur of the metzi'us (unlike rov, a birur of the din), and prior in time to the current unresolvable safeiq. And therefore that chazaqah's metzi'us is the only one we can still go on.

    I also discuss the odd implied prioritization of birur:

    The mishnah on Qiddushin 64 discusses the case of a dying man r”l who says he has children. Abayei adds to the case (because of a contrast to a halakhah in a related beraisa) that we didn’t know anything about his having children. Therefore after his death, she stands in a chazaqah of not being a yevamah — she obviously wasn’t one before he died!

    The man stood to gain nothing from his claim. This is a case of “mah li leshaqeir” (”what do I gain by lying?”) which is similar enough to migo to be considered a subtype by numerous rishonim ad loc. Credibility is given to the claimant again because assuming he is lying would make his action irrational. Here it’s a different reason then the existence of a better lie (migo) but the point is the same.
    So, permitting her to remarry is supported by a chazaqah, but prohibiting her is a migo (or a migo-like structure).
    The man is believed. The conclusion of the gemara is that a migo “trumps” a chazaqah.

    This fits nicely within the model we have been developing. The presumption of the chazaqah dimei’ikara is only a chazaqah, a presumption, and can only apply in the absence of a new, credible po’al experience. It tells us to continue with what was last perceived about the reality. Migo established a new observation; the claimant establishes a new perception, and thus a new halakhah.

    Notice, this means something very unexpected.

    1- We just said that given a chazaqah supporting one side’s position, and a migo supporting the other, the migo has the stronger claim.

    2- In the previous section we saw that migo in the context of conflicting testimonies has no weight (as we said earlier, this is because we don’t compare quantities of testimony);

    and yet:

    3- chazaqah in the case of conflicting testimonies does factor in.

    To highlight the oddity, note that cases (2) and (3) imply that:

    3b- If the chazaqah and the migo conflicted in the situation where contradictory testimonies were also presented (trei utrei), the migo would be ignored, the chazaqah would not. Unlike case (1), the same situation in the absence of trei utrei, where migo would have priority over chazaqah!

    This non-intuitive conclusion can also be explained using our model for qavu’ah logic. The two rules differ on the time of the reality that is established....


  14. BTW, migo shouldn't help for simple balebatisher reasons... The whole point of migo is that had he wanted to lie, he would have told the more legally powerful lie. Therefore, the weaker lie can't be any less compelling.

    However, the presence of testifying witnesses might curb someone from making the stronger lie for other reasons, leaving him only the one he made.


  15. Anonymous1:29 PM


    My leg to stand on is the idea that while eidus is the greatest birur possible, Migu is not a birur and therefore can tell us what to do without contradicting the eidu. In other words, in a case of trie utrei you can never prove what happened no matter what evidence you bring. Migu comes and says it doesnt matter what happened in reality - if you have a safek, the person with the migu gets the money not because his verison of the story is true but because when in doubt, the person with the migu wins, gezeiras hakasuv.

    The same as chazaka works in trei utreei and even R. Elchonon admits that - trei utrei sefeika drabonon - so too migu works for the same reason.

  16. I hear what you are saying, but think you can still be mechaleik. Chazakah works by trei u'trei because it deals with the facts of the case, not with the eidim themselves. The parallel would be migu of a ba'al din, which we know works. Here the migu has nothing to do with the facts of the case -- it's being used solely to bolster the credibility of eidim.

  17. Anonymous6:19 AM

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