What’s the confusion with eating in the sukkah and Shemini Atzeret? If you took a poll of who does what in the sukkah on Shemini Atzeret, it would go something like this: “Yes, we eat all meals in the sukkah on Shemini Atzeret.” “We do too, but without reciting ‘Leishev Basukkah.’ ” “We only eat lunch in the sukkah but not dinner.” “We make Kiddush in the sukkah and then eat in the house.” “We don’t eat any meals in the sukkah on Shemini Atzeret.” “We sleep in the sukkah on Shemini Atzeret.” “We don’t.”
There’s nothing wrong with being uncertain, but what exactly are we uncertain about?
Here’s the problem. The Torah tells us that Sukkot is on the 15th of Tishrei and that Shemini Atzeret is 7 days later, on the 22nd of Tishrei. Now, the Jewish calendar, instituted in 358 CE by Hillel, tells us that Elul is a chodesh chaser, which means it has 29 days and that the 30th day following the first of Elul is the first of Tishrei. So we know that Shemini Atzeret is celebrated 22 days following the 29th day of Elul.
Before the institution of the Jewish calendar, during the time of the Second Temple, a chodesh chaser was determined by the empirical evidence of two witnesses, who testified in the Jerusalem court of law that they had seen the new moon on the 30th day of Elul. Once their testimony was accepted, the 30th day, counted from the first of Elul, was declared Rosh Chodesh Tishrei. If no witnesses came on the 30th day of Elul, Rosh Chodesh Tishrei was declared by default on the 31st day, rendering Elul a chodesh maleh of 30 days.
Those Jews in the Diaspora who lived too far away from Jerusalem for the emissaries to arrive and advise them, before Sukkot, whether the month of Elul was a chodesh maleh or a chodesh chaser, had a problem. Should they celebrate Shemini Atzeret 22 days following the 29th of Elul on the assumption that Elul was a chodesh chaser of 29 days, or should they celebrate Shemini Atzeret 23 days following the 29th of Elul on the assumption that Elul was a chodesh maleh of 30 days?
If, based on the assumption that Elul was a chodesh chaser, they chose to celebrate Shemini Atzeret on the 22nd day following the 29th of Elul, when in fact, it turned out to be a chodesh maleh, they would have been celebrating the Yom Tov of Shemini Atzeret on the day that in fact was Hoshanah Rabbah. Today, even though we have Hillel’s calendar and therefore know the month of Elul is chaser and Shemini Atzeret is the 22nd day following the 29th of Elul, we, the Diaspora Jews, are required by the rabbis to perpetuate the doubt as if we do not know for sure. So on one and the same day we have to conduct ourselves as if it were both the Yom Tov day of Shemini Atzeret and the Chol Hamoed day of Hoshanah Rabbah. This may lead to inconsistencies. Therein lies the problem.
The main potential inconsistency is the question of sitting in the sukkah. The Torah commands us to sit in the sukkah for seven days. Should we sit in the sukkah on a day that may be the eighth day when we are not commanded to sit in the sukkah at all? If we should, would we not be violating the prohibition of ba’al tosif, which forbids human additions to mitzvot? If we do sit in the sukkah, should we recite the usual blessing of Leshev Basukkah? Should we sleep in the sukkah, too, on the day we celebrate as Shemini Atzeret?