The gemarra often employs the different types of derashos/hermeneutics such as kal vachomer/a fortiori arguments and hekesh/juxtaposition of phrases or terms. Also often, is these derashos are rejected due to some flaw, known as a pircha. For example, a law can't be derived from one verse to another through a hekesh because there's some special reason the first verse should have the law, which doesn't apply to the second verse.

Rabbi Yosef Tzvi Salant in Be'er Yosef suggests that when a pircha is introduced, the derasha isn't totally rejected. It remains a doubt, and in fact it could still prove true, if some later evidence appears that it's true.

I was wondering if this is his own insight, or is there an earlier source for such an idea, or is this not even a novelty, but the basic understanding of derashos/pirchos.

  • How is this practically different from saying that when a derasha is refuted we don’t know the law?
    – Alex
    Oct 20 '19 at 18:02
  • @Alex I don't know about practical difference, but it will affect if you can answer his question with the answer he gives in the link :-)
    – robev
    Oct 20 '19 at 18:10
  • @Alex I put emphasis on the fact that it's doubtfully true, as opposed to definitely not true
    – robev
    Oct 20 '19 at 18:15
  • 1
    Slightly similar Yerushalmi sheviis 1.1
    – Dr. Shmuel
    Oct 20 '19 at 19:23
  • It sounds just like a logical point. If you reject a drasha, it doesn't tell you anything about the din. It doesn't logically prove that the din derived by the drasha is not true.
    – Daniel
    Oct 20 '19 at 21:46

The Ramchal wrote a couple of sefarim on logic esp. as applied to Gemara (derech tevunos and sefer hahigayon). From what I remember, once a kal vachomer has a pircha asked on it, it is no longer a valid proof at all, and even if the halacha were true, it would need a different source. The exception is if the pircha itself is disproved, leaving the original kal vachomer.

The reason is that kal vachomer's and other middos have rules, and if the rules aren't satisfied, it is not a derasha.

  • Can you find where he says this? Although this doesn't necessarily answer the question, but is more of an opposing opinion to this Be'er Yosef. Either way, I'm curious.
    – robev
    Apr 8 at 13:49
  • Derech Tevunos perek 8. It isn't so black and white there, but what I understood from context is that once your kal vachomer has a pircha, it no longer teaches anything, the reason being if there is one exception to the relative kal vs. chomur of the subjects, there might be another, so you are back to square one.
    – N.T.
    Apr 9 at 0:50

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .