I don't know if this has been asked before, perhaps with different terminology.

There is a well-known fallacy, that in the realm of religious debates, comes up often especially with regards to "The One True Way of [insert religion]"™, and that is the No True Scotsman Fallacy, which was explained simply thus:

Person A: "No Scotsman puts sugar on his porridge."
Person B: "But my uncle Angus is a Scotsman and he puts sugar on his porridge."
Person A: "But no true Scotsman puts sugar on his porridge." (from Wikipedia)

In other words, appealing to a higher or greater truth is not a way to dispute other views that rise from within the same group being discussed or debated, because what right do you have to claim the truth for yourself? (I hope I defined it properly).

With regards to Judaism, there are several different sects and denominations, and within these there are sub-groups as well, all with differing views on halacha, kabbalah, interpreting the Torah, hashkafah, and so forth. It's not uncommon that when speaking to a non-Jewish party about your Jewish beliefs that they'll ask: "Well, so and so, who's from a different Jewish group, believes X, while you believe Y. How do you know that you're right and he's wrong?" In such a case, answering: "So and so doesn't believe in True Judaism™" doesn't work, because who are you to say what "True Judaism" is?

Therefore, I was wondering whether within Orthodoxy there is a way around this fallacy, or should we simply say: Have emunah, wait for the Mashiach (or work to bring him) and in the end the world will know the truth? True, in some cases it's possible to simply point out internal contradictions within other groups, but the same case can be made against Orthodoxy, as well as considering that this doesn't work 100% of the time.

  • Judaism has no official stance on basically anything, so there is no "true Judaism". Judaism is what the Jew makes it
    – ezra
    Commented Mar 8, 2022 at 11:38
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    Would the Rambam's 13 Ikkarim act as a guide for "True Judaism" at least in the mind of those who follow him?
    – rosends
    Commented Mar 8, 2022 at 11:44
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    Wait and see if their great-grandchildren identify as Jews and attend synagogue. That one works pretty well. Rabbi Emanuel Feldman shlit'a suggests that homiletically as an explanation for the Gemara's "Elders of the Academy of Athens" riddle about "the placenta of a mule." You can hybridize all kinds of things with Judaism, but the ones that don't belong don't last for more than one generation.
    – Shalom
    Commented Mar 8, 2022 at 12:51
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    I think you're missing the problem with using this kind of argument. The fallacy is only relevant if you care about the term "Scotsman" for some other purpose (meaning for some reason it's relevant to know who is and isn't officially a Scotsman). I don't care if you define "Judaism" to include Christianity, just if you do so know that that's #NotMyReligion. I know what my religion is no matter what you call it. The whole thing is a word game; everyone agrees it's not fallacious to define whatever groups you want.
    – Double AA
    Commented Mar 8, 2022 at 13:48
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    I’m not sureI quite get what you are asking. Is your question simply how to justify something that you can’t prove to be true?
    – Alex
    Commented Mar 8, 2022 at 13:49

2 Answers 2


This is a totally different question from the "no true Scotsman" fallacy. That fallacy is a way for members of a group to disassociate themselves from other members of a group who claim to be acting on the group's behalf. For example, when religious extremists (of any religion) perform violence in the name of their religion, it's a fallacy for other members of the religion to say, "Those people aren't real members of my religion." Traditional Judaism in particular is very unlikely to fall into this fallacy because we tend to believe that there are objective, measurable, and well-known criteria for being considered Jewish.

The scenario you're describing is totally different. Here, there are two people making conflicting assertions about what "Judaism" believes. The real answer to "How do you know that you're right and he's wrong?" is simply, "This is what I believe". Who is correct and who is wrong is unverifiable.

  • You seem to be differentiating between disassociating from certain people and disassociating from certain ideas or beliefs. I don't understand why the latter is different from the NTSman fallacy. In the end, the disassociation from people is due to them having beliefs that are different from yours and you find those to be illegitimate. I don't see how the traditional Jewish criteria for Jewishness is relevant here.
    – Harel13
    Commented Mar 9, 2022 at 21:57
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    @Harel13 because the "No True Scotsman" fallacy is entirely about identity. That's just what it is. It's not a logical fallacy to say "Reform Judaism is wrong;" it's an opinion.
    – Daniel
    Commented Mar 10, 2022 at 23:44
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    The first two sentences of the Wikipedia page concisely define NTS: "No true Scotsman, or appeal to purity, is an informal fallacy in which one attempts to protect their universal generalization from a falsifying counterexample by excluding the counterexample improperly.[1][2][3] Rather than abandoning the falsified universal generalization or providing evidence that would disqualify the falsifying counterexample, a slightly modified generalization is constructed ad-hoc to definitionally exclude the undesirable specific case and counterexamples like it by appeal to rhetoric."
    – Daniel
    Commented Mar 10, 2022 at 23:47
  • The "No true Scotsman" fallacy has less to do with porridge these days than belonging to the SNP (which I call the Scottish Nationalistic Party). For what it's worth, I put cinnamon and honey into my porridge - and I am a true Scotswoman who belongs to a clan that goes back a long, long, long, long way. I've even got the tartan to prove it!
    – Lesley
    Commented Mar 11, 2022 at 21:12

Orthodox Judaism and being a true Scotsman aren’t analogous. The latter is a cultural situation that no one can really determine. There are no “Scotsman principles” that all Scotsman claim to follow.

Conversely Orthodox Judaism does have boundaries that can not be crossed to be considered a member of the group. Someone who says they do not believe that the Torah was given on Har Sinai or that there was a binding oral Torah given with it can not claim to be an Orthodox Jew according to any definition of Orthodox Judaism accepted by any group that calls itself Orthodox. Anyone claiming to say something that denies those beliefs can be told "this is something an Orthodox Jew would say" Even if the person/rabbi/group saying it claims to be Orthodox. Those are more broad examples you can narrow it down further.

In the secular world this is a common concept as well. I’m reading these days that Trumps lawyers (a law professor himself) trying to advance a legal argument to Trump even after being told by fellow lawyers “You can argue that in a law school classroom but no judge would accept it” borders on the crime of the century . Along with plenty of other sanctions and possible disbarment for other lawyers of his who didn't break any laws but are accused of advancing lawsuits when they "had no reasonable basis to believe the lawsuits filed were not frivolous". Is that the Scotsmans fallacy or l'havdil like saying "there is no basis in Halacha to say such a thing" , "you can't rely on Rabbi X because he says things that have no basis in halacha" etc.?

  • I’m not sure I see the difference. Surely there are some people that everyone would agree are not Scottsmen, and surely there are some people that everyone would agree are Scottsmen. The uncertainty is only where the line is drawn. This is much the same as with Orthodoxy. There will be some people that everyone agrees are Orthodox, some people that everyone agrees are not Orthodox, and some people in between.
    – Alex
    Commented Mar 10, 2022 at 23:28
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    The difference is there is no actual rules for being a Scotsmen. There are rules in Orthodox Judaism . Where the line is drawn would depend on the question but there is an ability to draw that line based on principles of Orthodox Judaism and disqualify those who pass it. By a Scotsman due to absence of a Scotsman authority those lines can not be determined by anyone. If someone is on the border being questioned if he is a Scotsman or not the opinions both way would boil down to "because I said so"
    – Schmerel
    Commented Mar 10, 2022 at 23:50
  • What would it boil down to if someone on the border is questioned if he is Orthodox?
    – Alex
    Commented Mar 11, 2022 at 0:00
  • If he can make a valid argument to vouch for his Orthodoxy based on Orthodox Jewish law. The ones to decide it's validity would need the expertise in Orthodox Jewish law to do so. If someone is sincerely trying to meet that criteria they would be able to determine it.
    – Schmerel
    Commented Mar 11, 2022 at 0:46

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