(a) Rabanan and Rebi Yehuda argue about whether Yovel is included in the count of the 7-year Shmitta cycle, or not. We presume that this has implications as to whether the cycle is 49 or 50 years. If so, surely the answer can be readily settled by Mesora - i.e. what it is that the Tannaim who lived in Israel did? Surely they still maintained the year count?

(b) (While discussing, we had the same answer on the machloket between Rashi and Rabbeinu Tam re: Tefillin - surely a machloket which could easily be checked in reality by opening a set of Tefillin?

Marc Abrahams, Yad Binyamin, Israel