In a previous exchange I brought up the statement of the Tosafos Yomtov in Divrei Chamudos on the Rosh that erva depends on social factors, and therefore the upper arms are not considered erva. What I am trying to figure out (and I haven't seen everything inside)is how the Tosafos Yomtov therefore understood the statement in the gemara here that tefach isha is erva. The only possibility is that he would say this refers to the customs of dress in the times of the gemara, but this does not necessarily apply to all times since not all parts that were considered erva at that time are erva in later generations.

David Goldman, USA