57a: 2/3 down the page, beginning of the gemara: question: why is a reshut harabim defined by the amount of people there( if there is 3 or more people there)? should it not be defined by physical/geographical terms( 16 amot wide or something like that)? or if the concept is related only to the amount of people around, why is it not termed something else like (be'rabim/ be'far'hes'ia)?
thanks
ike sultan, west orange, NJ
Hello there and thanks for your question. Your assumption is correct. The term "Reshus ha'Rabim" with regard to Safek Tumah, is not identical to the same term when used with regard to Hilchos Shabbos. In the case of Safek Tumah we derive the rule that in Reshus ha'Yachid one is ruled Tamei from the laws of Sotah. The case of Sotah is where one man was secluded with the married woman. Thus in a case where there are more people involved it is treated as Reshus ha'Rabim. This is defined clearly in the Rambam Avos ha'Tumah 20:1-3 and the rest of the Perek.
As you point out it is a bit confusing. The Rosh in his Perush to Tamid (5:5) rejects the opinion that the Azarah was a Reshus ha'Rabim with regard to carrying on Shabbos. He says this mistake is a result of misunderstanding the Gemara in Pesachim 19b which says that the Azarah is a Reshus ha'Rabim. The Rosh explains that the statement in Pesachim was only with regard to Safek Tumah, but not with regard to carrying on Shabbos. So as you see, the issue you raise led to misunderstandings even in the days of the Rishonim.
All the best.
Y. Landy