Brachos 2a - Reading Shema After Chatzos

Last night we were zocheh to make the a siyum ha'shas in Palo Alto, CA. This was probably the first time a group ever learned through the entire shas together in this area of the world. 

Mazal Tov to ALL!

We have a machlokes in the Mishna between Rabban Gamliel and the Chachamim whether Shema must be read by chatzos. It is clear from the Mishna that on a Torah level, the actual end time to read shema is alos ha'shachar (or maybe sunrise), and the end time of chatzos is only m'drabonon to prevent people from being negligent and coming too close to the actual end time and violating an aveira.

It would seem that the entire argument would be lichatchila. Meaning, all would agree that if you haven't read by chatzos that you should still read afterward to fulfill the mitzvah d'oraysa. This is clearly the approach of the Rambam (Hil. Krias Shema, 1:9). However, this approach doesn't fit well into the Mishna because the Mishna seems to illustrate the opinion of Rabban Gamliel by citing a story where he told his sons to read shema even after chatzos. How does this illustrate the opinion of Rabban Gamliel? Even the Chachamim agree that you can read after chatzos if you haven't read beforehand?

Rabbeinu Yona has an alternate approach. He understands that the machlokes between Rabban Gamliel and the Chachamim must be bidieved because lichatchila one must read it immediately when the time arrives. Rabbeinu Yona learns this from the gemara later 4b that explains that we try to avoid a situation where a person sits down to eat prior to the reading of Shema, even if there is plenty of time until chatzos. Since all agree that one must read shema immediately, they must be arguing about the bidieved. According to this approach, Rabbeinu Yona struggles with why the chachamim would say that even if chatzos passed and one hasn't read shema, it is too late and there would be no point in reading it. Why wouldn't you read it to fulfill the Torah obligation? Some suggest that they no longer allowed you to say the brachos, but shema should still be said. However, Rabbeinu Yona himself says that after chatzos there is nothing at all to do. He draws a parallel to when chazal uprooted the mitzvah of shofar and lulav when yom tov falls on shabbos. Similarly, chazal exempt linen garments from tzitzis, even though they are obligated m'doraysa, in order to prevent a shatnez violation. Here too, they uproot the Torah mitzvah after chatzos to prevent the violation of this mitzvah.

The Sha'agas Aryeh disagrees with this Rabbeinu Yona. We only find that chazal would uproot a positive mitzvah to prevent one from avoiding a more serious violation such as shabbos or shatnez. But here there is no potential violation of any external prohibition. The entire concern would be that one would violate the mitzvah of krias shema. What sense would there be to uproot the mitzvah of shema to prevent the violation of the mitzvah itself? Apparently, Rabbeinu Yona understands that it is worthwhile for chazal to uproot the mitzvah of shema for this individual this one time, to preserve the general mitzvah of shema by others and even for this individual for the future. They felt that had they left the z'man to be alos ha'shachar, many would be negligent and violate this mitzvah, but by making the end time chatzos they would ultimately be gaining the preserving the fulfillment of this mitzvah.