Last Friday I started but never finished discussing the machlokes Rambam and Rashba re: hadlakas menorah and hadlakas neiros Shabbos. The Rashba holds that Chanukah candles may always (not only on Friday) be lit before shkiya, and proves the point from our lighting of Shabbos candles. The purpose of Shabbos candles is to burn into the night and enhance our enjoyment of Shabbos and our meal; however, the candles must be lit before dark. The purpose of Chanukah candles is to publicize the miracle by burning after dark, but that should not prevent their being lit beforehand. Why does the Rambam disagree?
Bluke's referred me to his post which sums up the issue well, so I will just add a few other points. The Brisker Rav (see Kuntres Chanukah u’Purim #1) notes that the Rambam in two places cites the need to light Shabbos candles: in ch 5 of hil shabbos, and again in ch 30 of hil shabbos. The Rambam is not repetitive - there are in fact two dimensions to the mitzvah: to have candles burning on Shabbos itself for the purpose of enhancing oneg Shabbos, and secondly, the act of lighting candles on Friday, which is an aspect of kavod Shabbos done to welcome in the Shabbos. The Rashba's proof is incolclusive. Unlike Chanukah candles whose function of publicizing the miracle of Chanukah can be fulfilled only after dark, the Shabbos candles fulfill a function of welcoming the Shabbos and kavod Shabbos on Friday afternoon when they are lit.
Last week I pointed to the machlokes BH”G and Tosfos/Rashba regarding whether one should light shabbos candles or chanukah candles first. BH”G holds that lighting Shabbos candles is itself an act of accepting Shabbos which would prevent lighting chanukah candles afterwards, but Rashba writes that Shabbos candles are done first because of the rule of tadir. Perhaps this machlokes is l’shitasam - the BH”G (and Rambam) associate Shabbos candles with kabbalas Shabbos and preprations of kavod Shabbos. Rashba, however, sees Shabbos candles only as connected with their function of providing light on Shabbos night itself, but not as an act of kabbalas Shabbos.
The gemara tells us that Shabbos candles should not be lit too early; Rashi (23b d”h l’hakdim) explains that the lighting must be recognizable as done for the sake of Shabbos. Tosfos (25b d”h chovah) cites Rabeinu Tam that if a candle is already burning on Friday it should be extinguished and relit for the sake of Shabbos. These halachos seem to point to the fact that the lighting of the candles itself is part of the procedure for welcoming Shabbos and it far more than just a means to insure proper oneg Shabbos by eating at a lighted table.
There is yet another aspect of this machlokes, so stay tuned…. I need to get this all in before Chanukah is over : )