Yesterday, we noted a question that arises concerning the metzora’s purification ritual, which includes two birds, one of which is slaughtered, and the other is dipped in the first bird’s blood and then set free. As we saw, Rashi (14:4) writes that a tereifa – a bird with a terminal medical condition – may not be used for this ritual, giving rise to the question of how the second bird’s suitability could be ascertained. As this bird is set free without ever being slaughtered, there is no possibility of an internal examination to ensure that it did not suffer any terminal condition. Presumably, this halakha reflects the famous concept of rov, which allows relying on a statistical majority for halakhic purposes, and thus allows us to presume that the live bird, like most birds, is healthy. The question, then, arises as to why the Gemara makes no mention of the birds of the metzora’s purification ritual in its famous discussion in Masekhet Chulin regarding the Biblical sources of the principle of rov. The Gemara notes several different Torah laws that seem to establish this rule, but does not point to the precedent of the metzora’s birds. Apparently, the Gemara felt that the disqualification of a tereifa for this ritual does not necessarily prove the rule of rov, as even if the Torah did not allow relying on a statistical majority, it would still be possible for the metzora to complete his requirements for purification, despite being unable to examine the live bird. The question, of course, arises as to how this is possible without the principle of rov.
As we noted yesterday, this question was posed to Maharil Diskin, who offered several different answers. One answer he offered is a clever observation that if there was no rule of rov, then the metzora’s status of impurity to begin with would be uncertain. The Mishna in Masekhet Nega’im (3:1) states that a person afflicted with a tzara’at infection does not attain the status of metzora until the kohen who inspects his skin makes a formal declaration to this effect. Thus, a metzora’s status is entirely dependent upon the declaration of specifically a kohen; if a non-kohen declares that a person stricken with tzara’at is a metzora, the declaration is halakhically meaningless. Now a kohen’s status as a kohen is itself dependent upon the principle of rov. As the identity of a person’s father cannot be definitively determined, and the status of priesthood passes from father to son, a kohen is presumed to be a kohen only by virtue of the statistical majority that most children are fathered by their mothers’ husbands. Therefore, if there was no rule allowing us to rely on a statistical majority, the status of any given metzora would, by definition, be uncertain, because we cannot definitively conclude that the kohen who declared him a metzora is indeed a kohen. Therefore, the uncertain status of the live bird used in the purification process does not necessarily prove the rule of rov. Without this rule, we could, conceivably, understand the Torah as saying that since the metzora’s status to begin with is inconclusive, the procedure for his purification can likewise involve a degree of uncertainty. For this reason, perhaps, the Gemara did not draw proof from this halakha that the Torah allows us to rely on a statistical majority.