What level of concern must we have that people will see a person performing an activity that is permitted and mistakenly suspect that it is forbidden?
The Sages established a category of Jewish law that pertains to such suspicious looking acts, which is called mar’it ha-ayin. Sometimes, permissible actions, which might be mistaken by an observer for prohibited conduct, were prohibited by Rabbinic decree, both to prevent people from unjustifiably suspecting others of misconduct, and to prevent people from incorrectly inferring that prohibited actions are permissible.
Rav Yehuda said that Rav said: Wherever the Sages prohibited an action due to the appearance of prohibition, even in the innermost chambers, where no one will see it, it is prohibited. When prohibiting an action, the Sages did not distinguish between different circumstances. They prohibited performing the action in all cases.
This statement of Rav is similar to a previous statement recorded in his name, that anything that the Sages prohibited doing in the public domain is also prohibited in the privacy of one’s courtyard. His reasoning is based on the principle: “The Sages do not distinguish.” Once the Sages issued a decree prohibiting a particular action, they did not want to differentiate between different circumstances and prohibit performing that action in certain cases and permit it in others. To do so would undermine the very authority of the rabbinic decrees.
Ultimately the Gemara suggests that the tanna’im differ regarding this question. In contrast, the Talmud Yerushalmi quotes a series of Mishnayot that clearly distinguish between activities done in public – which are forbidden – and in private – which are permitted, based upon which, the Yerushalmi rejects Rav’s teaching entirely. The Rashba and others suggest that there is room to differentiate between cases where there is suspicion of an act that is truly forbidden and cases where people mistakenly think that a given action is forbidden. In the latter cases the Sages forbade performing such an action publicly, but permitted it to be done in private.