The Torah in Parashat Shemini presents the basic guidelines regarding the permissibility of different species of creatures for consumption, famously establishing the properties required of a species of animal for it to be permissible. Specifically, a species may be eaten if it chews its cud and has split hooves (11:3). When it comes to fowl, however, the Torah does not specify any particular properties that render a species permissible or forbidden, and instead simply lists twenty-four forbidden species of birds (11:13-19), clearly indicating that all other species are permissible. However, due to the uncertainty surrounding the identity of these species, the Gemara (citing Rabbi Yitzchak) states that we may only eat a bird regarding which there is an oral tradition affirming its permissible status. The various details relevant to this law are discussed by the Shulchan Arukh (Y.D. 82:1-3), though the Rama (82:3) notes the accepted practice not to partake of any bird unless there is a tradition to permit it.
Amidst its discussion of the permissibility of birds, the Shulchan Arukh (Y.D. 82:4) addresses the case of a bird regarding which one community has a tradition affirming its permissibility, but other communities do not. If one community has a tradition permitting a certain bird, does this tradition suffice for other communities to partake of that species? Or, must each community follow its time-honored practice, irrespective of the traditions of other communities? The Shulchan Arukh writes that different views exist on this issue, and it is proper to be stringent in deference to the stringent position, and not to eat a species of fowl based on a different community’s custom.
The Shakh (82:10-11) presents the background to this issue, and boldly contends that the Shulchan Arukh erred in discerning a halakhic debate surrounding this question. The source of what the Shulchan Arukh understood as a stringent ruling is the Rashba’s discussion in Torat Ha-bayit, where the Rashba writes that each community should follow its practice. Communities that are accustomed to eating a certain species of fowl may continue doing so, the Rashba rules, as they may assume that this custom arose out of an authentic tradition received from previous generations that this species is permissible. The Rashba then adds that other communities, which are accustomed not to eat this species, should continue this practice, as it is possible that a conscious decision was made in an earlier generation to forbid this species, perhaps due to its resemblance to a different, non-kosher species. On this basis, it appears, the Shulchan Arukh noted that according to one view, a tradition to allow a species in one locale does not suffice for other locales. However, the Shakh noted that the Rashba ruled stringently only in the case of a community with a tradition specifically forbidding the species in question. The Rashba did not address the case of a community that had no tradition one way or another regarding a certain species of fowl. In such a case, the Shakh contends, communities may rely on the tradition received by a different community. The Rashba writes explicitly that a tradition to permit a certain species may be presumed authentic, and adds simply that a tradition to forbid a certain species must also be presumed authentic, as reflecting a conscious decision to abstain from that species for what is likely a valid reason. This has no bearing on the case of a community that did not have any specific custom regarding a species of fowl – such as in geographic regions where that species was not found. Such a community, the Shakh contends, can certainly partake of the species in question, on the presumption that the tradition received by the other community is indeed authentic.