There are instances in the Talmud (usually fleshed out by the Rishonim) where we learn a concept that is **so logical** that we don't need a pasuk or drasha to teach it to us, THAT'S how logical it is.

A few examples:

  • "המוציא מחברו עליו הראיה"- If my ox gored and killed your pregnant cow and the cow’s fetus was found dead at its side- and it is not known whether the cow gave birth before (ie unrelated to the goring) or whether it gave birth after the ox gored it, if you want me to pay you have to prove the latter because: "the burden of proof rests upon the claimant" Bava Kamma 46a

  • "כל דאלים גבר"- In a financial dispute between two people where there is neither evidence nor presumptive ownership for either litigant, "whoever is stronger prevails" Bava Basra 34b

  • "כְּדֵי שֶׁלֹּא יְהֵא חוֹטֵא נִשְׂכָּר" - If dough became impure accidentally, one need take 1/48 for challah. However if the dough became purposely impure, the amount for challah one must take is 1/24. Why? "so that the sinner does not profit [from his sin]" Challah 2:7 (expounded further here)

My question is why is svara used sparingly as a halachik source/ reason only in certain areas? "Don't kill" and "don't steal" are both pretty obvious- yet we have explicit p'sukim telling us not to.

Why isn't svara applied for these two or for any other seemingly logical mitzvos?

Edit: the examples listed above don't explicitly state the word "svara" even though that's the concept at work: Thus here are links for each that explains how each is a "svara"

המוציא מחברו עליו הראיה - see "הכלל ומקורו" number 3

כל דאלים גבר- under “מקור וטעם”

כְּדֵי שֶׁלֹּא יְהֵא חוֹטֵא נִשְׂכָּר- under “מקור”

  • I write it as comment. But it's an answer. In logic and mathematics, and linked sciences, there are DEMONSTRATIONS. Often in Talmudic learning to, there are logical demonstrations. The value of common sense is also equivalent to demonstrations. Because logical mathematical demonstrations are also based on "natural deduction" which is in reality common sense
    – kouty
    Commented Feb 27, 2019 at 4:42
  • @kouty Interesting, but I'm assuming there are other halachot that can also be learned out from "demonstrations"... yet nonetheless are learned from drasha, gezeiras ha'kasuv, or any of the 13 middos. Why would this be necessary if they could all be learned out via being a svara or demonstration?
    – alicht
    Commented Feb 27, 2019 at 5:28
  • @alicht because they cannot. It's very rare to proof by reasoning only. But sometimes it's possible and they say למה לי קרא סברא היא
    – kouty
    Commented Feb 27, 2019 at 12:06
  • I've heard that some details of "don't kill" or "don't steal" aren't logical, which is why we need a verse.
    – robev
    Commented Feb 27, 2019 at 19:06
  • @robev interesting- like which details?
    – alicht
    Commented Feb 27, 2019 at 20:01

2 Answers 2


Your question and its formulation are excellent. You deserve a real answer, or at least an honest attempt to provide one. The three examples that you gave are used in different contexts. Each will be explained separately.

With regard to the example of hamotze mchavero alav haraya [Bava Kamma 46a], the Gemara states, the burden of proof rests upon the plaintiff, because he is the party claiming redress. This is similar to one claiming to be ill, having the burden of finding a medical clinic [Rav Ashi, id.]. Every rational legal system recognizes the plaintiff has the burden of proof (as a general rule). Accordingly, Chazal state, “Lamma lee kra? Svora hu.”

Although Torah laws themselves must be stated in order to provide sufficient warning [Sanhedrin 56b] and ample reward [see, eg., Chulin 142a], the underlying logical concepts need not be stated. Sefer HaChinuch views most of the ten commandments and many mishpatim as necessary to prevent destruction of civilization [see, Mitzvos 33-37, 49-54]. These mitzvos, commonly understood as essential, or mitzvos sichlios (rational mitzvos) are nonetheless written in the Torah. The logical concepts on which they are based are not stated and they are not independent mitzvos. Tzlach [Berachos 21a] states that logic is insufficient to create a mitzvah d’Oraisa.

The phrase “lamma lee kra” is common throughout the Gemara when seeking to discover why the Torah states a particular point that otherwise would not have been understood. However, the specific phrase, “Lamma lee kra? Svora hu” seems to be reserved for only three concepts. The first, was your example of hamotze mchavero. The second is mai chazis d’dammach didach sumach t’fei (what makes it appear that your blood is redder) [Sanhedrin 74a; Pesachim 25b; Yoma 82b]. This means, no person has the right to claim that his life is more precious than another’s life. There is an equal right to live. The third is peh sh'asur peh sh'hitir (the mouth appearing to restrict, is the same mouth that permits). This means, one may qualify his own statement, so that it is understood in its entire context [Kesuvos 22a]. Thus, the Gemara stated, “Lamma lee kra? Svora hu” only with regard to the most basic rights: life, freedom of expression and ownership (life, liberty, property).

Regarding mai chazis, logic alone is not the basis of the mitzvah in the Torah not to take another’s life. The logic of mai chazis is dependent upon the commandment of lo seertzach (you shall not murder). Only after the Torah commands us not to murder, is logic able to dictate that murder is prohibited even to preserve one’s own life. Since this prohibition is fundamental to coexistence, logic is merely used to extend lo seertzach to a situation where one’s personal desire to live might cause him to contemplate taking another’s life. However, the exceptions to lo seertzach must be explicitly stated in the Torah. These include, killing a rodef (to stop murder or certain cases of rape)[Sanhedrin 74a, based on Devarim 22:26]; habba b’machteres (for self defense)[Sanhedrin 72a, based on Shemos 22:1]; and Rabbi Akiva’s ruling that one should drink from his own canteen in order to survive, rather than sharing the water and thereby perishing [Bava Metzia 62a, based on Vayikra 25:36].

It might be argued that there is a fourth case mentioning, “Lamma lee kra? Svora...hu.” However, the wording states, “Sevora b’alma hu” [Niddah 25a]. Here, the Gemara uses the usual format of seeking to discover circumstances where a pasuk discloses an aspect of halacha that would not be understood on the basis of logic. (Similar examples include Yevamos 47a; Kiddushin 41b; inter alia).

With regard to your second example, of shlo tehay choteh niskar, this is a basic principle in every society. A criminal should not benefit from the fruit of his crime. This concept is found in Tanach several times. For example, in Malachim I [21:19], “will you murder and also inherit?” Again, this is a principle upon which rulings are made. It is not an independent mitzvah.

A related concept is not permitting one to transgress, in order to prevent another from sinning. This is expressed as, vchee omrim chateh keday sh’yiske chavercha? [Shabbos 4a]. As such, one may not harm himself spiritually in order to benefit another. In this regard, Rambam stated, “I have never heard a more remarkable saying than that of the Rabbis in Talmud Yerushalmi, in the ninth chapter of Nedarim, where they strongly criticize those who obligate themselves by oaths and vows, resulting in being bound like prisoners. The exact words they use are, ‘Rabbi Edy said in the name of Rabbi Yitzchak, “Don’t you think, what the Torah prohibits is sufficient, that you need to take on more prohibitions?” [Shemona Perakim, Chap. 4]. This is a remarkable example of the basic logic of not impairing oneself. Similarly, the Mishnah [Bava Kamma 90b] states that one does not have the right to physically harm himself. Yet, the Torah does not expressly prohibit it as an independent mitzvah.

With regard to your third example, kull d'allim gvar (stronger position prevails) [Bava Basra 34b], this is limited to a financial dispute where, as you stated, there is neither evidence nor presumptive ownership. It applies to circumstances where neither party had prior possession. Therefore, there can be no presumptive ownership. Since evidence is not available, it is wrong for a court to become involved with a matter it cannot resolve. This is the reason the parties are left to resolve their dispute outside of beis din. The logic of kull d'allim gvar is, the resoluteness of a party investing more effort to obtain the item in dispute, indicates he may be right. He may eventually come up with proof, since he is making more of an effort [Rosh, Bava Metzia 2a]. The opposing party would reason, why should I bother, when it is possible my opponent will be able to produce evidence the next day? [Id.] In the interim, kull d'allim gvar has no evidentiary value. It simply recognizes the possibility of someone having legitimate possession of an item that had previously been in dispute. Obviously, the Torah does not need to state various possibilities of what may happen when there is no judicial resolution.

There are other logical concepts that are commonly shared by civilized peoples. For example, the act of snatching is inherently dishonest [Bava Basra 33b-34a; Shevuos 32b] and during a legal proceeding, failure to deny a claim is generally construed as an admission [Yevamos 87b; Bava Metzia 37b]. These are principles that provide a framework for rulings that are based on human experience. Since the Torah deploys the speech of people [Berachos 31b], so we can relate to it, certainly the Torah does not need to tell us basics of human interaction. No system of law attempts to do so, but similarly relies on logic.

  • Did you see Rav Asher Weiss today?
    – Dr. Shmuel
    Commented May 4, 2020 at 1:09

A very unpopular but seemingly true answer:

Judaism lacks consistent and systematical methodology. Totally. Practically, when you go through the Rabbinical argumentation in the Gemmorah, everything goes. Why?

  1. The Rabbinical Judaism (as opposed to the Kabbalah or science for example) focuses mainly on setting the code of behavior - the Halacha, not researching the underlying mechanisms or inner structure.

  2. The Halacha is "created" by Rabbis presenting their own opinions/attitudes and defending them.

  3. The essence of the Halachic dispute is to convince either the competitors (other Rabbis) themselves or the next generations of the Poskim. Once you do it, by any means, your opinion is the Halachah, no matter how it is derived.

    A wonderful example of such Halachic "war" is brought in my question "what-happened-in-r-chananyas-penthouse" in Yerushalmi Shabbos 9a:

תנא ר' יהושע אונייא תלמידי ב"ש עמדו להן מלמטה והיו הורגין בתלמידי ב"ה. תני ששה מהן עלו והשאר עמדו עליהן בחרבות וברמחים. תני שמונה עשרה דבר גזרו ובשמונה עשרה רבו."

It was taught: R. Yehoshua taught, "The students of Beis Shamai stood bellow and were killing the students of Beis Hillel." It was taught: Six of them went up and the rest stood over them with swords and spears. It was taught: Eighteen decrees were enacted on that day...

As you see, everything goes, and if you need a majority of votes, you just ... I think it speaks for itself.

  1. So Rabbis' focus is put on argumentation for the sake of a specific Sugya in the discussion. Therefore every Sugya takes a different path - some take things for granted, some rely on common logic, some on common knowledge, some on tradition, some on Asmachtot from the Torah etc. Pretty much randomly.

Sorry to break the myths. I would love to be proven wrong, but -1s just don't cut. So if you want to help please argument.

  • 5
    I don't know what with the downvotes but I observe that answers without sources don't do well. I saw by coincidence (on this SEDE query, run it then click on average score in results) that your average answer score is negative. You are the only one in top 100 users to be like this. Maybe it is time to play more by the rules of the game, and invest more in less questions. I'm not saying this as criticism, just making an observation, since I find it a pity that someone who knows a lot gets such reception
    – mbloch
    Commented Feb 27, 2019 at 17:56
  • 6
    FYI, if you keep arguing with people giving well-reasoned arguments why they gave a downvote to sourceless and easily disproven answers, eventually people will get tired of trying to repeatedly explain why something is wrong and just downvote it and move on. Commented Feb 27, 2019 at 18:33
  • 2
    Since you've failed to convince or "overcome" anybody with your arguments, according to your own system you must be wrong.
    – Heshy
    Commented Feb 27, 2019 at 20:02
  • 6
    Al, it is not the responsibility of anyone else to prove you wrong. You aren't "right until proven wrong". If nobody wants to bother talking to you they don't need to. They should still downvote wrong material in order to not let it mislead anyone.
    – Double AA
    Commented Feb 27, 2019 at 20:44
  • 3
    Generally on this site nobody downvotes for sourceless answers. True, they don't seem to upvote too much for sourceless answers, but that doesn't seem to invite mass downvotes. When an answer is downvoted this much, it usually means there is a general consensus that the answer is wrong or offensive. This answer is in fact both. It is certainly deserving of many downvotes.
    – user6591
    Commented Feb 28, 2019 at 2:53

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