In this week’s parsha we derive the rule that we may rely on a rov (majority). The Torah states: “acharei rabbim lehatos.” The Gemara (Chullin 11a) says that these words refer to the Sanhedrin who should follow the majority opinion of its judges. Similarly, when someone finds a piece of meat that could have only come from one of 10 stores – nine of which are kosher –the meat is kosher mi’de’oraisa since we assume it came from one of the kosher stores.
The Gemara (ibid.) says that there are two types of rovs. The first is illustrated by the two aforementioned examples and is known as ruba d’eissa kaman – all the possibilities are in front of us. In such a case, we may act in accordance with the majority.
The other type of rov is called ruba d’lessa kaman, whereby the options are not in front of us. This rov relies instead on facts of nature or life, e.g., the majority of animals are not treifos. We do not have all the world’s animals in front of us with a breakdown of which ones are kosher and which ones aren’t. We simply know, in general, based on experience, that most animals are not treifos. We know that we can follow a ruba d’lessa kaman from the first type of rov and other sources as well.
As we just mentioned, due to ruba d’lessa kaman, we are not required to check animals for treifos. The only treifa we do check for is in the lungs, and this checking is only a rabbinic requirement (because of the greater number instances of problems in lungs). Biblically we may rely on the fact that animals’ lungs are clear most of the time.
How does all of this relate to the requirement to check clothing for shatnez? Many poskim maintain that if a person buys an inexpensive suit he need not check it for shatnez since the vast majority of inexpensive suits are shatnez-free.
However, the following question arises: There is a halachic principle called kavuah, under which we cannot apply the halacha of rov if the doubt originates from a place that is set. For example, if one went into a store and bought meat, and subsequently forgot which store he went into, the meat cannot be eaten even if there were only 10 stores in the area and nine of them only sell kosher. Why? Because the stores are kavuah – fixed in place. If that is the case, though, how then can we rely on a rov when it comes to buying a suit? How can we assume that the suit came from the majority of suits that do not contain shatnez? Why don’t we apply the halacha of kavuah?
Some answer that it is not clear that the stores in question ever sold any suit with shatnez, and kavuah is only a problem if one of the stores sold shatnez and we are unsure from which store the suit was bought.
I’d like to suggest another reason why kavuah does not apply: Kavuah only affects a ruba d’eissa kaman. If all the possibilities are present and they are fixed, we cannot assume the item belongs to the majority. Kavuah, however, does not play a role regarding a ruba d’lessa kaman since the possible options are not present.
I believe the issue of whether a suit is shatnez is subject to the halachos of ruba d’lessa kaman, not ruba d’eissa kaman. We do not have a count on all the suits in the world; rather, we know, in general, based on how suits are made, that most of them do not contain shatnez, i.e., they don’t have linen. In other words, the rov of shatnez is a ruba d’lessa kaman and therefore is not restricted by the halachos of kavuah.
A person should consult his local Orthodox rabbi to determine if he is obligated to check his suit for shatnez.