1. The Sukkah on Shemini Atzeret: Background and Rationale
Many people wonder why, on the 8th day of Shemini Atzeret, some do not sit in the sukkah at all, while others, such as Chabad, do sit in the sukkah but refrain from reciting the leishev basukkah—the blessing for dwelling in the sukkah. The reasoning behind this practice is rooted in uncertainty, or safek—doubt regarding which day is truly Yom Tov. In ancient times, especially outside of Eretz Yisroel, our ancestors were unsure of the exact date due to delays in calendar communication. Although today we have a fixed calendar and know precisely when the 15th of Tishrei falls, historically there was ambiguity.2. The Calendar Doubt and Its Implications
The Torah commands us to sit in the sukkah for seven days starting from the 15th of Tishrei. If one began on what was believed to be the 15th but it was actually the 14th, then the seven days would extend into Shemini Atzeret. This uncertainty led to the practice of observing two days of Yom Tov both at the beginning and end of Sukkot outside Eretz Yisroel. Thus, Shemini Atzeret is observed for two days in chutz la’aretz—the diaspora.3. The Conflict Between Sukkah and Kiddush on Shemini Atzeret
On Shemini Atzeret, a unique conflict arises: if we sit in the sukkah because perhaps it’s still Sukkot (the seventh day), we might feel compelled to recite leishev basukkah. However, at the same time, we are making Kiddush and celebrating Yom Tov as if it is Shemini Atzeret (the eighth day). This creates a contradiction: if it’s still Sukkot (requiring a sukkah and its blessing), then Kiddush for Shemini Atzeret would be inappropriate; if it’s truly Shemini Atzeret, then sitting in the sukkah with its blessing would be out of place.4. The Halachic Resolution: No Blessing on Sukkah
To avoid this contradiction, our custom is to sit in the sukkah without reciting leishev basukkah. This approach satisfies all opinions: we honor both possibilities without making a definitive statement through a blessing that could contradict our observance of Yom Tov. For example, in Eretz Yisroel where only one day is observed, Friday after Shemini Atzeret is simply a weekday—they put on tefillin, as usual. In contrast, outside Eretz Yisroel we continue with Yom Tov practices due to lingering doubt.5. The Role of Tradition and Rabbinic Authority
The sages established that safek de-yoma—doubt about which day is truly Yom Tov—overrides weekday practices such as donning tefillin. Even though by weekday standards we would wear tefillin or perform other weekday activities, rabbinic tradition instructs us not to do so during these additional days of Yom Tov out of respect for ancestral custom (minhag avoteinu beyadeinu). Thus, even at the expense of certain mitzvot like tefillin, we maintain two days of Yom Tov outside Eretz Yisroel.6. Avoiding Contradictory Declarations Through Practice
If one were to recite leishev basukkah on Shemini Atzeret while also making Kiddush for Yom Tov, it would amount to making conflicting declarations about what day it truly is—a situation akin to making a mockery (chuchah ve'itlula) out of halachic observance. Therefore, by refraining from saying the blessing but still sitting in the sukkah (as a stringency or personal preference), no contradiction arises.7. Liturgical Practices Reflecting Calendar Doubt
This principle appears elsewhere as well: during Chol HaMoed, when there’s doubt about which day it is, two verses are recited in Musaf corresponding to both possible days (e.g., b’yom ha-chamishi, b’yom ha-shishi). However, on actual Yom Tov days such as Shemini Atzeret or Simchat Torah outside Eretz Yisroel—when tradition alone dictates observance—only one verse is said so as not to undermine or question the sanctity of that day.8. Halachic Debate and Contemporary Practice
There remains debate among authorities regarding these customs. While Chabad follows this approach strictly according to Shulchan Aruch and most poskim—sitting in the sukkah without a blessing—other communities may have different practices based on their traditions or interpretations. Ultimately, eating a meal in the sukkah without reciting any blessings or prayers poses no halachic issue; it remains simply an act of personal stringency rather than an official mitzvah fulfillment for that day.