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The Talmud is laden with extrapolations of the Torah and controversies between Tannaim and Amoraim. In order to understand the mechanisms at play and the means of deciding a Machaloket, it's incumbent to study the rules. Some are explicit in the Gemara, but their applications can get tricky, especially when competing with other rules and considerations. Over the centuries, various works, such as Mevo HaTalmud, Halichot Olam, and their commentaries were compiled summarizing the rules and weighing them against one another. Often, their discussions consist of a deluge of citations proving or disproving a point by referencing sugyot spanning the entire corpus of Talmudic literature. Though adding all of those citations to this page would be heplful, thanks to the Sefaria plugin, due to the tediousness of the endeavor, as a minimum, we will suffice by quoting the Klalim Sefer at hand and leave it to the reader to do the rest of the groundwork. Most of these Sefarim are readily available and portions of many of them are printed in the back of the standard Masechet Berachot.
History of the Talmud
- According to some, Rabbi Yehuda HaNasi condensed Shas into six Sedarim, but others contend that was done already by Beit Shammai and Beit Hillel.
Talmudic Phraseology (Leshonot Hagemara)
- Sometimes, the Gemara will use the same phrase in different places but refer to totally different concepts, while, other times, it will use different phrases in different places to refer to the same concept.
- Sometimes, two parts of a Tannaitic statement, such as in a Mishnah or Baraita, will have contradictory implications, i.e. the Reisha will imply that changing a parameter will result in -X, while the Seifah says that the Halacha is -X only with a different parameter, implying that changing the second parameter already results in X, without the first parameter.. There are a number of possible means of resolving the difficulty, of varying levels of plausibility.
- "Na'aseh KeMi She..." (נעשה כמי ש...) - The first half if the main point, and the second is just detailing how the middle case is essentially the same as the case two parameter changes away. According to the some, this is only a viable resolution when both parameters and results are functions of the same driving Halacha/logic. Some say Na'aseh is not applicable when the Seifah begins with "Aval," but many disagree. Also, if there are two points made together in the Reishah and then the parallel points are separated in the Seifah, the implications are too vague to apply Na'aseh. Certainly Na'aseh cannot be applied to teach the opposite of what it says in a different source.
- "Tavra, Mi Sheshana Zo Lo Shanah Zo" (תברא, מי ששנה זו לא זנה זו) - Break the statement, the one who said this one didn't say the other one. Meaning, it's a Machaloket Tannaim and each half of the statement should be attributed to a different Tanna. Albeit a difficult resolution, this one is better than "Na'aseh..." as it doesn't force us to reinterpret the words of the Tannaim to say something they didn't actually say, so if it or a better answer is available, we will avoid resolving the issue with "Na'aseh..." The Yad Malachi notes how the Gemara is willing to apply this even to two contradictory statements of a Tanna between a Mishnah and a Baraita. Some say the Gemara is willing to do it even if it doesn't know for certain that there is another view, but the Gemara will sometime attempt to ascertain that afterwards. However, some point out that the Gemara will only do that if it can't apply Na'aseh. Meaning, Na'aseh is preferred rather than Tavra when the Gemara doesn't know for sure that there are actually two positions among the Tannaim, unless Na'aseh is not applicable, such as if there's more than one driving factor.
- "Kedi Nesavah" (כדי נסבה) Or "Aidi de..." (איידי ד...) - Really, the first half is the main point, but the second one mentions it for nothing, in haste. Since the first half mentioned the parameter, then we'll mention the inverse, as well. (Bava Kamma 48b).
Names and Titles of Tannaim and Amoraim
- Rabbi Eliezer when mentioned without further detail refers to Rabbi Eliezer ben Hyrcanus.
- Rabbi Yehoshua when mentioned without further detail refers to Rabbi Yehoshua ben Chananya.
- Rabbi Yehudah when mentioned without further detail refers to Rabbi Yehudah bar Ilai.
- "Chasid Echad" ("a certain pious one") refers to either Rabbi Yehuda bar Ilai or Rabbi Yehuda be Bava.  However, when the Rambam quotes this rule he only mentions it referring to Rabbi Yehudah bar Ilai. 
- Rabbi Elazar when mentioned without further detail refers to Rabbi Elazar Ben Shamua HaKohein.
- Rabbi Shimon when mentioned without further detail refers to Rabbi Shimon bar Yochai.
- Ben Azai, Ben Zoma and Ben Nanas refer to Shimon ben Azai, Shimon ben Zoma and Shimon ben Nanas.
- Ben Beteira refers to Rabbi Yehoshua Ben Beteira.
- Ben Bag Bag refers to Rabbi Yochanan Ben Bag Bag.
- "Acheirim" (others) refers to Rabbi Meir and "Some say" refers to Rabbi Natan. This was a punishment for their attempt to replace Rabbi Shimon Ben Gamliel as Nasi.
- Rabbi Meir is referred to in many ways. "A disciple of Rabbi Yishmael stated in the presence of Rabbi Akiva." He is also called Rabbi Nehorai (Aramaic equivalent of Meir). His original name was Rabbi Nechamia (though its possible not all agree to this). As mentioned above, he is also referred to as "Acheirim."
- Yochanan Kohein Gadol refers to Yochanan Ben Matityahu from the time of Chanukah.
- When Chazal say "It was discussed before the Sages," they are referring to Rabbi Shimon ben Azzai, Rabbi Shimon ben Zoma, Rabbi Shimon ben Nannas Chanan and Chananya of Ono.
- When the Mishna refers to "Chachamim" sometimes it refers to one of the Rabbis whose name was mentioned earlier; other times it refers to the multitude of Rabbis at a given time. Sometimes the Gemara will say that the view of Chachamim is Rabbi So and So but that means that his opinion was accepted by many Rabbis.
- Rabbi Yehudah HaNasi is also known as "Rebbi," "Rabbi Yudan HaNassi," and "Rabbeinu," but he is not known as "Rabban," even though he was a Nasi, possibly because he refrained from referring to himself as such in the Mishnayot out of humility.
The Gemara provides a few examples and general guidelines about how to decide debates between individuals mentioned in Shas. Many assume these guidelines apply to every instance in Shas, while a some argue that they only apply to cases that have practical application as a means to allow for confident Halachic observance, whereas the Halacha about debates in topics like Kodashim and Tahorot remain to be determined.
- "Ein Halacha KeShitah" (אין הלכה כשיטה) - In Torah literature, brevity is an oft used tool. As such, when the Gemara lists Tannaim or Amoraim who espose a similar view, it is indicating that they are the minority and their opinion is not accepted. Some say that this is only true when it's formulated as "פלוני ופלוני אמרו דבר אחד" and not "פלוני ופלוני כולהו סבירא להו כך וכך," while others argue the opposite.
Talmidei Rabbi Akiva (R' Meir, R' Yehudah, R' Shimon, and R' Yose)
- Rabbi Meir vs. Rabbi Yehuda, the Halacha follows Rabbi Yehuda.
- "רבי יוסי נמוקו עמו" - R' Yose's reasoning is with him, meaning the Halacha follows him when he disagrees with other Tannaim. Many assume this is only when R' Yose is disagreeing with an individual Tanna, not a majority, while others think that's not so obvious. For these purposes, a Stam Mishnah would be considered a majority.
Rabban Shimon ben Gamliel
- The Rif does not accept the rule of following Rabban Shimon ben Gamliel's positions mentioned in Mishnayot unless it's very logical, but the Rosh does regardless.
Rabbi Yehuda HaNasi
- The Halacha follows Rabbi Yehuda HaNassi, colloquially known as "Rebbi," against another Tanna, but not against a group of them.
- The Rif and Rosh point out that this is not true when Rebbi disagrees with his father, Rabban Shimon ben Gamliel.
Rabbi Shimon ben Elazar
- Yerushalmi that states that the Halacha follows Rabbi Shimon ben Elazar in "Shabbat," "Avodah Zarah," and "Avel," and there are different levels of specificity given when listing them - the general categories, specific sections of those categories, or a particular case in each of them. The Ramban questions why the Geonim would cite this klal when they generally don't follow the rulings of the Yerushalmi and concludes they must have had a tradition regarding the matter (they don't quote the source outright). Yad Malachi points out that the Rif, Rambam, Rosh, and Samag also seem to accept it, while Tosafot and the Baal HaMaor do not.
- Amoraim often elucidate the shitot of Tannaim in Mishnayot even if the Halacha doesn't follow them, so there's no proof to be brought from the fact that the view of a certain Tanna in a Mishnah is elucidated to prove which the Halacha should follow. However, proof may be brought from such an instance with respect to a Tanna in a Baraita or another Amora.
- It's usually assumed that Amoraim cannot argue on Tannaim, but some say it's merely an honorary non Halachic distinction. Some say that anybody, an Amora, or anybody else can argue about non-Halachic issues, such as history or the source for a Derasha, with Tannaim.
Rav and Shmuel
- When Rav and Shmuel debate, the Halacha follows Rav in ritual law (Issur veHetter) and Shmuel in monetary matters (Dinei Mammonot).
- According to the Rosh, this is true only if the majority of Amoraim don't side with either Rav or Shmuel, in which case, we would just follow the majority, while Tosafot believe it to be true in any case.
- If Shmuel himself elucidates the Mishnah according to Rav's position in a case of monetary matters, then the Halacha follows Rav even in that case.
- If a later Amora elucidates Shmuel's opinion in a matter of Issur veHetter, the Rif takes it to mean we pasken like Shmuel, while the Rosh argues that there's no proof. It's normal for later Amoraim to elucidate the words of earlier ones, so it's not a test for whose position is accepted.
Rav and Rabbi Yochanan
- Rav vs. Rabbi Yochanan, the Halacha follows Rabbi Yochanan.
- According to the Rif, this rule only applies with Rabbi Yochanan only disputes Rav's position, but if he's disputing both Rav and Shmuel, then the Halacha follows Rav and Shmuel, whereas the Rosh rules that the rule is true in any case.
Rav Yochanan and Other Amoraim
- Rav Yochanan vs. R' Yose bar Chanina is a Machaloket, the Rosh and many others claim one should follow Rav Yochanan, as he was the latter's rebbe, while the Rambam follows R' Yose bar Chanina, because he was "lan be'umka dedina" (very deeply engrossed in Din).
Rav Acha and Ravina
- In Kol HaTorah Kullah, whenever the Gemara presents a dispute between Rav Acha and Ravina, it won't match the names to the opinions but rather say "Chad Amar X veChad Amar Y" (one says X and the other says Y). We assume that Ravina is always the identifiable with the lenient view except for three cases discussed in Chullin Perek Gif HaNasheh, where Rav Acha takes the lenient position. In all instances, the Halacha follows the lenient view, unless stated otherwise explicitly.
- According to some, this rule only applies when only Rav Acha and Ravina are mentioned. If other Amoraim weigh in, this rule is inapplicable, whereas others disagree.
- In monetary matters, the borrower's benefit is considered the lenient view.
- Some consider is distasteful to rely on this for prohibitions related to food.
- When Rav Yochanan and Resh Lakish dispute Rami Bar Chammah and Rav Yirmiyah, the Halacha follows the former group.
- The Rif follows a Stam Mishnah over a Maaseh Rav, while the Rosh argues the Halacha follows a Maaseh Rav over Klalim like Stam Mishnah, R' Yochanan vs. Rav, and Halacha keRabban Shimon Ben Gamliel BeMishnatenu.
- Mevo HaTalmud attributed to Rav Shmuel HaNaggid with the Kitzur Klalei HaTalmud commentary
- Halichot Olam with commentaries Klalei HaGemara by Rav Yosef Karo and Yavin Shmua by Rav Shlomo Algazi
- Kenesset HaGedolah (Klalei HaTalmud)
- Yad Malachi (Klalei HaTalmud)
- Sefer HaKeritut
- Shem HaGedolim vol. 2 Seder Tannaim veAmoraim
- Mevo HaTalmud by Maharitz Chayus
- Ein Yitzchak vol. 1, by Rav Yitzchak Yosef
- As an aside, Rav Hershel Schachter (Sanhedrin 5775 #73) is of the opinion that Klalim are postscriptive, not prescriptive, meaning the later generations voted on each issue and the results indicated that in certain situations a specific Tanna's position was usually followed. Thus they established the Klal as a Siman, not a Sibah, for deciding a Machaloket, but, of course, there are exceptions. This is just the general rule. This position is based on the writings of Rav Elazar Meir Preil in HaMaor (vol. 1 Shu"t Siman 78:6)
- Shem HaGedolim (Gedolim, Kuntress Acharon, Resh 2)
- Numerous Rishonim cited in Halichot Olam 3:8, Yad Malachi Klalei HaTalmud 374
- see Kiddushin 5b and Bava Kamma 48b
- See Kiddushin 5b. Tosafot Chullin 16a s.v. Amar Ribbi Elazar, Halichot Olam 3:2:14 and Klalei HaGemara ad loc.
- Yad Malachi (Klalei HaTalmud 488). See Matnat Yado ad loc.
- Yad Malachi (Klalei HaTalmud 489)
- Yad Malachi (Klalei HaTalmud 490). See also Yad Malachi (Klalei HaTalmjud 491)
- Halichot Olam 3:2:16. The Yad Malachi (Klalei HaTalmud 630) translates Tavra as "By a Shevuah," meaning "I swear to you that..."
- Tosafot Bava Kamma 48b s.v. Eimah Seifah, Shitah Mekubetzet Bava Kamma 48b at the end quoting Shitah, Yad Malachi (Klalei HaTalmud 632). See also the Rosh's answer in the Shita ad loc. and Devash LeFi (Taf, 40)
- Yad Malachi (Klalei HaTalmud 630)
- Ramban Yevamot 108b, Yad Malachi (Klalei HaTalmud 631)
- Yavin Shemua ad loc.
- Halichot Olam 3:2:13
- Halichot Olam 3:2:13
- This may be the strongest argument, as it maintains the singularity of authorship of the Mishnah, which may be a value depending on a Machaloket Amoraim in Beitzah.
- Rambam Introduction to the Mishna Chapter 6
- Temura 15b, Baba Kama 103b
- Horayot 13b
- Rambam Introduction to the Mishna Chapter 6 writes that Rebbi Nechemia is Rabbi Meir's original name. However in his Introduction to the Mishna Torah, the Rambam writes that Rabbi Nechemia was Rabbi Meir's friend. Seemingly the Rambam changed his mind though it is also possible that the Rambam thought there are two people named Rabbi Nechemia in the Talmud.
- Shem HaGedolim (Gedolim, Kuntress Acharon, Resh 2)
- The Maharik (Shoresh 165) argues that the Klalim were never meant to decide every single case in Kol HaTorah Kullah but, rather, to enable us to actually figure out what to do when it mattered. In cases where the issue is of no practical relevance, the Klalim do not apply. Others argue that there is no indication of this from the Rambam, Rosh, or other poskim until his day, except for maybe on Tosafot in Shabbat 70. The Maharik's view has been accepted by some Acharonim, as listed in Yad Malachi (Klalei HaTalmud 234), but rejected by many, as well. See Chavot Yair 94:1, Yad Malachi ibid, Ezrat Nashim (Shemot Anashim, Avshalom), the Chida in a number of places (Sha'ar Yosef Horayot 2a, Achorei Tara ad loc, Heseg Yad ad loc 40, Chaim She'al 2:31:5 s.v. atah, Ein Zocher (Heh 13)), Divrei Malkiel 2:108, and Rav Kook's letter Rehita DeChalkaei printed in Sdei Chemed vol. 10 pg 1960b and Otzrot HaReiyah vol. 6 pg. 33.
- Halichot Olam 5:3:7 and Klalei HaGemara ad loc.
- Eruvin 45a
- Gittin 67b
- Halichot Olam (5:1:1). Yad Malachi (Klalei HaTalmud 430) thinks that all the Rishonim clearly state or assume that the rule is not true by a majority, but many Acharonim, such as the Chida disagreed with him.
- Yad Malachi (Klalei HaTalmud 431)
- Korban Netanel (Klalim 12)
- Eruvin 46b
- Korban Netanel (Klalim 11)
- Ba'al Halachot Gedolot (Siman 21 s.v. Amar Rav Menashya) specifies the Perakim "Klal Gadol" and "Lifnei Eideihem" in Shabbat and Avodah Zarah, respectively. With respect to Shabbat, the Yad Malachi (Klalei HaTalmud 88) finds many difficulties with accepting this Bahag's limitation, as a number of Stam Mishnayot are opposed to R' Shimon ben Elazar in that Perek. He suggests, therefore, that it really should read perek "HaMotzi Yayin," but it can't be correct, because the Ramban and Nimukei Yosef in Moed Kattan weren't bothered by this when they quoted the Bahag. He and Rav David Pardo (Chasdei David, Avodah Zarah 1:2) identify Avodah Zarah to refer to the specific Tosefta Avodah Zarah 1:2.
- Milchemet Hashem, Moed Kattan 16a s.v. u'mah
- Klalei HaTalmud 88
- Korban Netanel (Klalim 13). See Yad Malachi (Klalei HaTalmud 23, 355) who seems to disagree about elucidating against one's own position.
- Kessef Mishneh (Hilchot Mamrim 2:1), Klalei HaGemara on Halichot Olam (2:2:10), Chazon Ish (Kovetz Iggerot vol. 2 Iggeret 24, Orchot Ish page 186)
- Biur HaGra (Choshen Mishpat 25:6), See Tosafot (Ketubot 8a s.v. Rav Tanna Hu uPalig) and Kovetz Shiurim (Bava Batra 633) who says similarly in the name of Reb Chaim Soloveitchik. Rav Hershel Schachter (Nefesh HaRav page 36) takes this stance, as well. Rav Elchanan Wasserman also engaged the Chazon Ish in correspondence on this issue, after he wrote in Kuntress Divrei Sofrim (Siman 2, see Da'at Sofrim ad loc) that Chatimat HaMishnah and HaTalmud were enabled by the gathering of all the Chachmei HaDor (Kibutz Chachamim), which gave them the status of Beit Din HaGadol. The latter took an opposing view, as it discounted the inherent loftiness of the individual Chachamim and implied there was little different between them and later generations. (Kovetz Iggerot ibid). Rav Asher Weiss finds grounding for Reb Chaim in the Meiri, but he believes that given the Rambam says one cannot disagree without confidently understanding the difficult opinion at hand, there are just some generations that were so far from the previous one that a line must be drawn. See also Rav Asher Weiss's (I, II, III and Rav Aryeh Lebowitz's shiurim on the topic.
- Chochmat Shlomo (Maharshal) Sanhedrin 52b s.v. Gemara Ta'ah, Shoshanim LeDavid (Yoma 8:6 s.v. vekhol). See Rabbi Avraham Ben HaRambam (Introduction to Aggadot ch. 2 s.v. da ki) writes that for passages of midrash one shouldn't believe opinions purely based on the one who said it without understanding whether it is right or wrong. He adds that with respect to statement of chazal regarding medicine and science one is not obligated to believed them as we are indeed obligated to follow and believe them with respect to their interpretation of Torah and halacha.
- Menachot 41b
- Korban Netanel (Klalim 16)
- Korban Netanel (Klalim 14)
- Korban Netanel (Klalim 17)
- Yad Malachi (Klalei HaTalmud 556)
- Korban Netanel (Klalim 15), Yad Malachi (Klalei HaTalmud 556)
- Rosh Bava Kamma 4:4. The Yad Malachi (Klalei HaTalmud 570) discusses the contradiction in the Rosh: in Bava Kamma he considers R' Yose bar Chanina to be Rav Yochanan's student, while elsewhere he considers R' Yose bar Chanina to be older than Rav Yochanan. Some suggest there were two R' Yose bar Chanina's, but he's not convinced. See Maharitz Chayut Bava Kamma 39a.
- Rambam (Hilchot Nizkei Mammon 6:3)
- Bava Kamma 39a
- Pesachim 74b, Chullin 93b, Gilyon HaShas ad loc, Halichot Olam 5:2:6. Yad Malachi (Klalei HaTalmud 561) points out how almost all Rishonim agree, but the Mordechai says that Rav Acha is usually the lenient one and Ravina the stringent one. He surmises it's either a copyists error or the Mordechai had a different girsa of our gemara. Note Matnat Yado footnote 97 that this was also the Raavan and Raavayah's girsa.
- Halichot Olam 5:2:6 and Klalei HaGemara ad loc. See Yavin Shemua ad loc for additional interpretations of this caveat.
- Yad Malachi (Klalei HaTalmud 562)
- Klalei HaGemara 5:2:6. Note Yad Malachi (Klalei HaTalmud 563 might be disagreeing with this based on a Ran.
- Yad Malachi (Klalei HaTalmud 564).
- Yad Malachi (Klalei HaTalmud 301)
- Korban Netanel (Klalim 8)
- Yad Malachi (Klalei HaTalmud 169)