As I mentioned in the previous shiur, because the general topic of our study is Shabbat Eve in the home, we can now skip over the intervening sections of the Shulĥan Arukh which deal mainly with the communal aspects of the synagogue ritual on Friday night, and move on to the next item on our more limited agenda: what happens in the home when we return from synagogue.
We left the issue of lighting the Shabbat candles at section 263 and the issue of Kiddush (Sanctification) in the home is taken up from Section 271 onwards. However, I have chosen to preface to that discussion Section 269, which is concerned with Kiddush in the synagogue, because it has relevance for our wider considerations.
When we rend down the concept of Kiddush to its essential details we should say that Kiddush is a solemn declaration announcing the sanctity of the day. When we recite Kiddush we are in fact declaring that "this day is holy". When we reach Section 271 we shall investigate the origins of the requirement to recite Kiddush; but that is not necessary for our present purposes. Suffice to say that each individual person is in duty bound to recite Kiddush or at least to hear Kiddush recited before sitting down to the celebratory meal on Friday night.
In earlier times (apparently, long before the middle ages) it was customary to house wayfarers in the synagogue over Shabbat. (Nowadays individuals would invite such people to their home, but in earlier times this honour was given to the community as a whole: the wayfarers were the guests of the whole congregation.) We must remember that in much earlier times the synagogue was not just a sanctuary, a place of worship: it was the communal hub of the community in which many other activities also took place. One of its functions was to be a kind of hotel where travelers could spend the night at no cost. Of course, these travelers would have to be fed as well. It seems that as an economic measure it was decided that the cantor would recite Kiddush during the synagogue service: since in this way all the guests would have heard Kiddush - and thus fulfilled their religious duty - the congregation would be spared the cost of providing each of them with wine.
However, this economically motivated measure creates an halakhic problem. There is a rule which governs Kiddush: "Kiddush may only be recited where the meal is taken". For the travelers this is no problem: they are hearing Kiddush in the place where they will be taking their meal, in the synagogue. But the cantor, reciting the Kiddush for them has not fulfilled his religious duty, because he is not reciting Kiddush in the place where he will be taking his meal. So he may not drink the wine over which he has recited Kiddush. In order that he not have recited a berakhah (benediction) to no valid purpose a child should drink some of the wine.
Already by the time we reach the middle ages the function of the synagogue to serve as a hotel had long fallen into desuetude. But the custom of reciting Kiddush in the synagogue on Friday night had taken on a life of its own, as it were, and was continued even though the reason for the recitation was no longer present. Rabbi Karo clearly feels ill at ease with this situation: he would much prefer that the custom of reciting Kiddush in the synagogue be discontinued since there are now no travelers who will be eating there. In most congregations in the diaspora today the custom still persists. However, the synagogues of Eretz-Israel historically never served the function of a hotel and therefore the custom of reciting Kiddush in the synagogue was never needed in Eretz-Israel. As Rabbi Karo points out, synagogues in Eretz-Israel to this day should not have Kiddush recited on Friday night as this would truly be a berakhah levatalah - a benediction recited needlessly, thus taking God's name "in vain".
We should note one last point: in his note on this section Rabbi Isserles does not deny Rabbi Karo's essential thesis; he just glosses over it in silence. But he does make a point of teaching that when Kiddush is recited in the synagogue everyone should stand. In all probability he recommends this so as to distinguish this Kiddush from the real Kiddush recited at the dinner table, which should be recited while seated - as we shall see.