Shemini, Shemos 11:3. The Signs of Kashrus in Animals.

The Lubavitcher Rebbe, in his Likutei Sichos, Volume One Year One, brings from the Rogotchover, (Tzofnas Pa’anei’ach on the Rambam, at the beginning of Ma’acholos Asuros,) a ch'kira; are the simanim a siman or a sibah? In other words, are the signs of kashrus the sibah, the reason they are kosher, i.e., the cause, or are they only a siman, evidence of kashrus, but these animals' kashrus is because of some other reason. (I probably shouldn’t phrase that as “are the simanim a siman,” but instead use the Lubavitcher’s terms, ‘Goreim or Mavdil.’)

This is a classic example of an analytical truism: when you find that two factors, A and B, are always found together, does that mean that A causes B, or perhaps there is some unknown C that causes both A and B.

He brings a proof from the din that a kolut, an animal with single hooves, that is born from a she’suah, e.g. a normal cow, is kosher, because “hayotzei min hatohor tohor.” If it’s a siman, the din is poshut, because the mother’s siman shows that the species is kosher, and an anomalous case is insignificant. But if the simanim are a sibah, we have to say that the kolut should be treif, and that it is only kosher because of a gzeiras hakosuv that anything born from a kosher animal is kosher, even if, for example, a cow bore a pig.

He asks, why should we care whether the kolut is be’etzem kosher, or tomei but hutar by the gzeiras hakosuv?

He answers on the basis of perhaps the strangest Chazal I ever saw. See the Yerushalmi end of 9th perek of Shabbos. The Yerushalmi says, Reb Yehuda said that it is assur to play with things that are kosher to eat. (This sounds like everyones' mother saying "don't play with your food!") Asks the Yerushalmi, why, then, is it muttar to play with the Levioson (Livyoson zeh yatzarta l'sacheik bo)? It must be kosher, because it will be served at the seudas Moshiach. The Yerushalmi answers, it really is a min tomei, but it will be huttar michlolo, there will be a special dispensation granted for the feast of the Mashiach. (So we see that a dovor tomei that is huttar by a special din is treif enough to play with.) Asks the Yerushalmi, then why does it say one may play with a bird? The Yerushalmi answers that birds are assur until they are shechted, so you can play with them while they are alive. So this would be true by a Kolut as well: is it kosher, and therefore muttar to play with, or treif but muttar to eat, in which case it would be assur. In any case, he says that the Yerushalmi indicates that kashrus is intrinsic in the simanim, and the singular dispensation which makes them kosher to eat does not change the fact that the Livyoson does not have simanei kashrus and are therefore essentially, irreparably, treif.

The reason he brings this here is to say that if the simanim are just a siman, there is nothing to say, because we cannot possibly know why Hashem made some animals kosher and not others. But if they are a sibbah, we should try to understand what it is about having split hooves and being malei geirah that causes an animal to be kosher. The remainder of his dvar Torah will be primarily of interest to those that have a taste for Lubavitcher-style Torah.

(Later in that piece, the Rebbe quotes the “Rashab,” the earlier Rebbe, in a story. He was once talking to a chossid who went into the business of galoshes, and he was completely involved in the strategies and plans of the galoshes business. The Rebbe said, “Fees in galoshin hob ich gezehn; a kop in galoshin hob ich kein mohl nisht gezehn”)

On the same topic: See Rambam Moreh Nevuchim 3:48, where he states explicitly that the Simanim are "not a reason, but only a sign with which we can recognize" what is kosher and what is not. See also Reb Elchonon in Kovetz Shmu'os to Chulin 67b:27, where he says this is the machlokes R' Shimon and the Rabanan, and he uses it to explain the two answers in Tosfos regarding Tranegol/Tarnegolta; See also See also Avnei Nezer O’C 487:6, Ritvah Niddah 51b d’h Yagdil, Maharit I:51, and Chasam Sofer in Chullin 66b d’h Avol. Also: Zerah Avrohom, the correspondence between R’ Meir Simcha’s SIL R’ Avrohom Luftbir and Menachem Ziemba, 11:17 and 13:1, who not only bring the Maharit, but also mention that he talks about the simanei gadlus in people. The same methodology has been used for Tzeis Hakochavim and the definition of night.